A Characterization of the
Repeatability and Performanceof Stratasys Fused Deposition
Modeling (FDM) Systems
Rachael Wratkowski, Eric O’Hara, Bruce Solheim,
Chris Cates, Chris Rollag, Sanja Wallace, Adam R. Pawloski

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Stratasys Inc., Manufacturing Business Unit,
7665 Commerce Way, Eden Prairie, MN 55344

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ABSTRACTWhite Paper

Additive Manufacturing, using FDM® technology,
has provided an innovative method for creating
manufacturing aids, tools, and production partsfor a wide variety of industries. Substantial
investments, both from a supplier and end
user perspective, have been directed towards
producing and utilizing these solutions for widescale use and diverse applications. In order
for any additive manufacturing technology to
be thoroughly integrated into a manufacturing
workflow, it is essential that the solution combining
hardware, software, and material deliver a robust
and predictable performance. In particular, therepeatability of the solution to deliver consistentintra- and inter-machine results over time is ofparamount interest. This paper characterizes theperformance of printed parts, through mechanicalproperty analysis, dimensional repeatability, andvarious other metrics of print quality, on theStratasys F370™, Fortus 450mc™, and F900™
systems using multiple materials. The data
presented indicates excellent intra-system controlof mechanical properties (XZ in-plane) with lessthan 5% coefficient of variation across each system
type, using the entire system build volume and over
several months of testing. Similarly, inter-systemcomparisons show excellent system-to-system
consistency, generally within the 5% coefficient ofvariation for all materials and conditions tested.
Properties in the z-axis (ZX) (upright) indicate theexpected limitations of layer by layer processing by
FDM, increasing variability in mechanical properties
to generally less than 10% variance for all materials
and conditions tested. Dimensional precision of
printed geometry was shown to lie within 2%
variation for all systems, materials, and geometries
evaluated. Additionally, across the 1200 builds
over the 16 systems, three materials, and various
geometries used, the FDM systems performed
with better than a 92% success rate for first time
job completion. The data presented provides auser of these solutions confidence in printed part
performance within a system, across multiple
systems, and over time.

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INTRODUCTIONWhite Paper

Additive Manufacturing (AM) is a proven approachfor simplifying, reducing costs, and acceleratingtime to market for products from design to delivery.
The essence of AM is simplification. By building
parts additively, many of the processes needed to
set up and create specific parts from computer
designs are eliminated, for example tooling andmolds, thereby reducing time and costs to produce
the needed parts. With these advantages, AM
technologies are now widely being integrated
into manufacturing operations in many industries.
Adoption is, however, limited by the performancecapabilities of any given technology and the extent
by which it can be trusted to deliver consistent,
dependable, and repeatable performance. To thisend, manufacturers seek to fully characterize theperformance of their equipment, software, andmaterial so that uncertainty and risk is removed.
Fused Deposition Modeling (FDM) is one such
AM technology that is finding swift adoption by
manufacturers. As a material extrusion technology,
FDM is advantageous for its simple workflow
and outstanding range of permissible materials,
enabling the highest levels of mechanicalperformance. The process is inherently simple.
Thermoplastic materials are melted and extruded
into ‘beads’ along a toolpath defined by the partgeometry, in a layer-by-layer fashion. The motionof the extrusion head and the gantry is coupled
to the extrusion of plastic so as to keep as close
as possible to the ideal part geometry. At themacroscale, the geometry is replicated superbly,
yet at the microscale, one begins to understandthe questions that arise by the new technology
when comparing it to conventional methods likemachining or injection molding. An FDM parthas a unique structure, more akin to lamellar
composites than to bulk plastic. It becomes clear

when observing the construction of the part, that
how the part is constructed matters. For example,
the strength of the material in the direction of thebead will be stronger than perpendicular to thebead. In the direction of the bead, the material ismelted, extruded, and cooled together, making
a largely homogeneous extrudate. Whereas
in the direction perpendicular to the bead, thestrength is defined by interlayer bonding of two
different beads, heated and cooled at different
times. It is important to recognize that whilethese technology details make the FDM process
different than conventional processes, it is in no
way an obstruction. Machining and molding haveunique challenges themselves with issues likestress cracking, burring, and knit lines, all of which
are overcome by careful characterization andunderstanding. AM processes are different, but not
an obscurity that cannot be learned.
Rigorous characterization of FDM printed partsis therefore a prerequisite for building confidence
in the technology. In this paper, three highperformance FDM systems from Stratasys areevaluated across many configurations of printing,multiple materials, multiple machines, and overtime. The goal of the study was to generate alarge, statistically significant dataset that would
represent a user’s expected outcome for any ofthese systems operating in good working order.
By such thorough characterization, a user will
understand the normally expected variation forthese systems, and therefore significantly reduce
uncertainty and risk to incorporating the process
into manufacturing operations. For this study theStratasys F370, Fortus 450mc, and F900 systems
were chosen. Table 1 outlines the basic systemcapabilities and functions for these hardware
solutions, demonstrating that these products cover4
a significant range of capabilities from part size,
material compatibility and performance.
As will be described in depth herein, therepeatability and performance of these systems
were tested through a serious of rigorous
evaluations. The systems were run for weeks undercontinuous use to simulate a production operation.
Mechanical properties were determined from theprinting and testing of thousands of coupons invarious orientations and locations on the platen,
enabling statistically relevant determination ofvariation. Each system was studied for its intrasystem variation, and then multiple systems of
the same model were compared to evaluate intersystem variation. The precision and consistency ofthe systems was compared by repeatability checkparts, as was the ability for the systems to print
parts without warping, curling, or the presence ofprint quality errors. The amassed data illustrates
what a user can confidently expect to achieve
when using these systems in their environment.

Table 1 - System Capabilities and Functions
F370

Fortus 450mc

F900

Build Size

14 x 10 x 14 in.
(35 x 25 x 35 cm)

16 x 14 x 16 in.
(41 x 35 x 41 cm)

36 x 24 x 36 in.
(91 x 61 x 91 cm)

System Accuracy (X-Y) 1± 0.200 mm (± 0.008 in.) or ±0.002 mm/mm (± 0.002 in./in.),whichever is greater± 0.127 mm (± 0.005 in.) or ±0.0015 mm/mm (± 0.0015 in./in.), whichever is greater± 0.089 mm (± 0.0035 in.) or ±0.0015 mm/mm (± 0.0015 in./in.), whichever is greater

ThermalExtruder ≤300° C

Extruder ≤435° C

Extruder ≤435° C

Chamber ≤110° C, active
convection

Chamber ≤220° C, active
convection

Chamber ≤225° C, active
convection

Materials

PLA, FDM® TPU 92A, ABSM30™, ASA, PC-ABS, ABSESD7™, Diran™ 410MF07,
ABS- CF10

ASA, ABS-M30, ABS-M30i,
ABS-ESD7, Antero™ 800NA,
Antero™ 840CN03, PC-ABS,
PC-ISO™, PC, ULTEM™ 9085
resin, ULTEM™ 1010, FDM®
Nylon 12, FDM® Nylon 12CF

ASA, ABS-M30, ABS-M30i,
ABS-ESD7, Antero 800NA,
Antero 840CN03, PC-ABS,
PC-ISO, PC, ULTEM™ 9085
resin, ULTEM™ 1010, PPSF,
FDM Nylon 12, FDM® Nylon 6,
FDM Nylon 12CF

Support Material

Dual extrusion, breakaway andsolubleDual extrusion, breakaway andsolubleDual extrusion, breakaway andsolubleSlice Height Options

0.005, 0.007, 0.01, 0.013 in.

0.005, 0.007, 0.01, 0.013 in.

(0.13, 0.18, 0.25, 0.33 mm)(0.13, 0.18, 0.25, 0.33 mm)

0.005, 0.007, 0.01, 0.013,
0.02 in.
(0.13, 0.18, 0.25, 0.33, 0.50 mm)

Material Environment

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1

Pre-dried, vacuum sealed, anddesiccant packed spools. Sealed
material bay.

Pre-dried, vacuum sealed, anddesiccant packed sealed metal
canisters, plus onboard dry-air(-70 °C dewpoint)

Pre-dried, vacuum sealed, anddesiccant packed sealed metal
canisters, plus onboard dry-air(-70 °C dewpoint)

Accuracy is geometry and material dependent. Achievable accuracy specification derived from statistical data at 95% dimensional yield.

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EXPERIMENTAL

This study consisted of over 1200 builds across 16 systems printing three different materials and numerous
part geometries. Table 2 presents an overview of systems and materials used. A minimum of four systems
were used for each system type (F370, Fortus 450mc, F900). ASA was printed on all three machine types,
whereas FDM Nylon 12 Carbon Fiber (Nylon 12CF), and ULTEM™ 9085 resin are only available for thehigher temperature-capable Fortus 450mc and F900 systems. The builds on each machine were completed
over a consecutive three week duration of continual system use. For one material, ASA, an additional weekof builds was collected on all systems after turning these systems over to other users and projects for athree week period. The systems were not restricted or controlled during this three week period, allowing
users to change material types. When collecting the final week of builds, no extra work was performed prior
to completing the builds, other than a routine material change back to ASA for this study. All parts were built
in 0.010 inch layer thickness due to its common use and availability for all materials. Table 2 includes the tip
size that was used for each material.
Table 2 - Systems and Materials
Material (Tip Size)
ASA(T14/T16)1

Nylon 12CF
(T20C)ULTEM™ 9085 resin(T16)
1

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2

Machine Type

Number of Machines Tested

F370

4

Fortus 450mc

4

F900

5

F370

N/A2

Fortus 450mc

4

F900

4

F370

N/A2

Fortus 450mc

4

F900

4

T14 is the tip size for the F370, whereas the other systems utilize the T16 tip for 0.010 in. layers for ASA.
Nylon 12CF and ULTEM™ 9085 resin are not available on the F370 due to system temperature constraints.

Print Duration
3 consecutive weeks plus 1
additional week after 3 weeks
of use for other projects
N/A
3 consecutive weeks

3 consecutive weeks

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FDM Systems
For this study, the systems that were used were
all located within an applications development
laboratory at Stratasys headquarters in Eden
Prairie, MN. The systems in this lab are utilized
for a wide variety of projects, and systems areroutinely operated with a variety of materials
and slice heights. All printers were up to date on
preventative maintenance and in good operational
condition. The systems vary in age from being
produced in the past year to ones that are over 10
years old. This allows for a realistic representationof systems with different ages that are found in
the field. The printers used in this study were in
an indoor space that houses over 20 systems
in multiple rooms. The ambient air temperatures
typically ranging from 65-70° F. The environmentis temperature controlled by air conditioning, but
humidity is not precisely controlled and can varyduring different seasons. This experiment was
running primarily in the summer, which tends tosee higher humidity in the lab than other seasons.

Relative humidity and room temperature were notrecorded during the experiment.
Table 3 lists the systems that were used for thisstudy, the details on those systems, and whichmaterials were printed on each. Each system namebegins with the first two numbers of the system
type (i.e., 37 for a F370) and then the third digit isunique to be able to differentiate the systems fromeach other. The manufacture date identifies the ageof each system. The systems range in age froma Fortus 900mc that was produced in 2010, andsubsequently upgraded to an F900, to an F370
that was produced in 2019. Based on differencesin age and utilization of the machine, the machines
have a variety of operational hours on them. The
build odometer reading listed in Table 3 contains
the number of days that each system has built
parts after conclusion of the build sequences
for this project. As expected, the older systems
typically have spent more time building parts thanthose that are newer.

Table 3 - History of FDM Machines
System Machine Manufacture Build Odometer3
Type
Name
Date1
(Days)
Machine Notes

F370

Fortus
450mc

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F900

371

Dec-2018

78

ASA

372

Dec-2019

73

ASA

374

Mar-2017

291

ASA

375

Mar-2017

262

ASA

451

Sep-2014

2270

Gen1 with High Performance Upgrade

ASA, ULTEM™ 9085 resin
ASA, Nylon 12CF,ULTEM™ 9085 resin452

Oct-2014

2195

Gen1 with High Performance Upgrade,
Composite material hardware upgrade453

Sep-2014

2220

Gen1 with High Performance Upgrade,
Composite material hardware upgrade

ASA, Nylon 12CF,ULTEM™ 9085 resin454

Sep-2014

2259

Gen1 with High Performance Upgrade,
Composite material hardware upgrade

ASA, Nylon 12CF

455

Dec-2015

895

Gen2

ULTEM™ 9085 resin

456

Mar-2018

39

Gen2, Composite material hardware
upgradeNylon 12CF

901

Mar-2010

1806

900mc Gen I, Fortus 900mc PLUS upgrade

ASA, ULTEM™ 9085 resin902

Aug-2015

134 (since
Feb -2020)2

900mc Gen II, F900 system upgrade

ASA, Nylon 12CF,ULTEM™ 9085 resin903

Aug-2011

1195 (sinceApr-2013) 2

900mc Gen I, Fortus 900mc PLUS upgrade

ASA, ULTEM™ 9085 resin905

Apr-2012

1296

900mc Gen I, F900 system upgrade

Nylon 12CF

906

Jul-2018

255

F900 Gen III

ASA, Nylon 12CF,ULTEM™ 9085 resin909

Apr-2018

324

F900 Gen III

Nylon 12CF

The first manufacture date is documented by the first entry in the machine log.
The system computer or hard drive was replaced, thus a full history of the machine was not available.
3
Days on the build odometer are the number of days (24-hour periods) of accumulative system use.
1
2

Materials Printed
on System

7Part Geometries
Due to the nature of FDM as a material extrusion process, the part orientation matters as it impacts themechanical properties of the part, as well as the surface finish, build time, and material usage. Whendescribing the orientation of a part per the ASTM F2921 standard, one generally describes the first axis by
the axis of the longest dimension of the part, followed by the axis of the second longest dimension of thepart. The axes are typically labeled such that ‘Z’ represents the vertical axis and ‘X’ and ‘Y’ represent theaxes of the build plane. For this experiment, the axes for listing part orientation are as shown in Figure 1.

Ma
ch
ine
fro
nt
Figure 1 - Coupon build orientations according to ASTM F2921.

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Many part geometries were used for this study and are described in Table 1. All part CMB files wereprepared in Insight 14.4 Build 952. Each part geometry was imported into the software in STL file format
and the toolpaths were generated for each the seven machine-material combinations. All files were prepared
for a slice height of 0.010 inch using the tips listed in Table 2. Default (‘green flag’) system settings wereused for all parts, except for mechanical coupons in the ZX (upright) orientation. For these parts, stabilizer
walls were added. Some differences in default parameters occur across system type, even for the samematerial, as settings are derived from optimizing part quality of a material independently on different
systems. The best overall settings for a material are not necessarily the same across systems. For example,
for ASA the default part interior style is ‘solid’ for the Fortus 450mc and F900, whereas it is ‘sparse-highdensity’ for the F370. The difference in interior style results in a smaller raster width of 0.018 inch on F370,
compared to 0.020 inch on Fortus 450mc and F900 systems. By using default parameters the experimental
plan removed any risk of unintended and unexpected print quality issues. After each part was sliced,
supports generated, and the toolpaths generated, CMB files were saved and submitted to each machineusing Control Center™ software.

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Table 4 - Part Geometries
Part Name

Image

9 Inch Check Part

A 9x9 inch square part oriented in the XY plane withpredominantly flat geometry and minimal support material
that can be printed on all three systems in any material. Partdimensions can be measured by automated programing on acoordinate measuring machine (CMM) and compared to CAD
dimensions.

Mechanical Coupons

Coupons for mechanical tensile testing in the format of ASTM
D638 Type 1 specimens. Coupons are built in two orientations,
XZ (on edge) and ZX (upright). Stabilizer walls were added to ZX(upright) coupons during printing. The printed coupons are tested
for tensile strength, stiffness, and elongation at break.

Density Cube

Solid printed 1x1x1 inch cubes. Density cubes provide simple
and fast measurement of the consistency of material deposition
by measuring the mass of the printed cubes.

QA PartThe Quality Assurance (QA) part can be visually inspected
as a rapid diagnostic for any part flaws that might indicate
a suboptimal performance of the system. It is built in the XY
orientation with minimal support material.

Shovel Grip

Image not available (A handle like thaton a shovel used for yard work. The
shovel handle is roughly 6 inches inheight and 4 inches across.)

Prototype part example used for visual inspection of print quality
in a sloping and supported geometry. The part is approximately
6 inches tall and 4 inches wide as printed. Parts were printed
upright in the ZX (upright) or ZY (upright alternate) orientations.

Connector

Image not available (A small
connector, less than 1.5 inches in any
dimension, like what would be used
for connecting wires to an array.)Prototype part example used for visual inspection of print quality
in a fine feature geometry. The part is less than 1.5 inches in thelongest dimension. Parts were printed upright in the ZX (upright)
or ZY (upright alternate) orientations.
The pin array is used to visually inspect the minimum feature
resolution afforded by the current print conditions. The part isvisually inspected to determine what size pin that the machinematerial configuration can print. The part is printed in either theXZ (on edge) or YZ (on edge alternate) orientation, with the flat
portion of the part on the build platen.

Pin Array

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Description

Image not available (A flat plate,roughly 8 inches square, with several
hundred small pins, roughly 0.75 inchtall and 0.10 inch in diameter, in a gridarray with pins roughly 0.25 inch fromeach other.)

The pin plate allows for an aggressive test of continuous short
tool path print sequences. The approximate 8x8 inches square
geometry includes several hundred small pins, roughly 0.75 inchtall and 0.10 inch diameter, in a grid array with pins positioned
roughly 0.25 inch from each other. After printing the pin plate, theplate is removed and the number of strings between the pins canbe counted. The pin plate is built in the XY orientation.

12 Inch Z Tower

The 12-inch Z Tower can be used to test dimensional precisionin the vertical direction. The part contains touch points every
2 inches in vertical rise. The part was built in the ZX (upright)
orientation.

Curl Bar

A 10 inches long, solid bar used to provide an indication ofresidual stresses in a material during printing. After printing, thepart can be measured for curl by the maximum deviation froma reference flat surface. The curl bars were printed in the XZ (onedge) and YZ (on edge alternate) orientations.

Angled Wall

The angled wall geometry enables qualitative evaluation ofpotential part warpage from thermal effects. The part was printed
in the YZ (on edge alternate) orientation.

Hollow cylinder

The hollow cylinder (3 inches high and 1.58 inches in diameter)part is used to evaluate extrusion control in seams. The part isa hollow cylinder printed with only 2-contours as the structureof the cylinder. The position of the seams on each layer are
vertically aligned for the entire part height. Measuring the partthickness at the seam, and comparing to another location,
indicates the consistency of the seam. The part is printed suchthat the base is flat on the XY plane.

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Build Sequence

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To allow for consistency of builds between printers,a build sequence was established that defined theorder for all of the parts to be built. Table 5 shows
the build sequence for the systems that built
ASA parts. Table 6 contains the build sequence
used for parts built in both Nylon 12CF andULTEM™ 9085 resin. The build sequences were
designed to keep the systems running in a nearcontinuous fashion over many days, with one or
two jobs run on each machine per day. The startof the sequence was initiated on each system
independently, with various systems running inparallel. Jobs were set up so that each system
could run a complete build during the day that was
between four to eight hours long, and a longer
build overnight to maximize the utilization of thesystem. Machines remained idle over weekends
after the last overnight job completed until the next
job was initiated on Monday morning. As a benefitof its large build platen, the XZ (on edge) and ZX(upright) mechanical coupon builds were combined
into one job for the F900 system to reduce thenumber of operator actions.

The build sequence for ASA parts included
deliberate break periods in the sequence. After
3 weeks of the sequence, the machines werereleased for unrestricted use on other projects.
Each system was used in varying ways, including
material changes. Figure 2 summarizes how eachof the eight systems printing ASA parts were usedduring this 3 week break period. These additionalsources of variation were purposefully introduced
to simulate environments where these systems
experience multiple use conditions. On day 43
in the sequence, jobs were restarted in the ASA
sequence for an additional week of builds. At day
48 an additional one- or two-week break was
taken, again with machines released for use on
other projects. The build sequence was restarted
after day 57 (or day 64) to complete a final seriesof sample parts in ASA. Not all parts collectedduring the print sequence were used for analysis,
but the entire collection of parts were used toevaluate metrics for the success rate of jobs andparts.

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Table 5 - Build Sequence for Printing Parts in ASA
Day

Build

Parts Produced

1

1

9-Inch Check Part

2

2

15 Mechanical Coupons – XZ (on edge) orientation2

2

3

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

3

49-Inch Check Part3

5

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

46

15 Mechanical Coupons – XZ (on edge) orientation2

4

7

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

589-Inch Check Part

5

9Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

81015 Mechanical Coupons – XZ (on edge) orientation2

8

11

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes29129-Inch Check Part

9

13

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

1014

15 Mechanical Coupons – XZ (on edge) orientation2

10

15

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

1116

9-Inch Check Part

11

17

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

1218

15 Mechanical Coupons – XZ (on edge) orientation2

12

19

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

15

20

9-Inch Check Part

15

21

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

16

22

15 Mechanical Coupons – XZ (on edge) orientation2

16

23

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

1724

9-Inch Check Part

17

25

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

18

26

15 Mechanical Coupons – XZ (on edge) orientation2

18

27

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

1928

9-Inch Check Part

19

29

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

22-42

3 week break in sequence - machine released for use on other projects

4330

15 Mechanical Coupons – XZ (on edge) orientation2

43

31

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

44

32

9-Inch Check Part

44

33

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

45

34

15 Mechanical Coupons – XZ (on edge) orientation2

45

35

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes246

36

9-Inch Check Part

47

37

15 Mechanical Coupons – XZ (on edge) orientation2

47

38

20 Mechanical Coupons – ZX (upright) and 4 Density Cubes2

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48- 56+

1 to 2 week break in sequence3 - machine released for use on other projects

57+

39

Pin Plate58+40

12-Inch Z Tower

59+

41

12-Inch Z Tower

60+

42

12-Inch Z Tower

61+

43

Curl Bars, Angled Wall, & Hollow CylinderThis build sequence was used for all printers that built parts in ASA, except for 906. Parts in ASA printed on 906 followed the Nylon 12CF andULTEM™ 9085 resin build sequence, listed in Table 6.
2
Mechanical coupon builds for XZ (on edge) and ZX (upright) orientation were combined into one job for F900s.
3
The final break period varied between different systems over a one to two week range.
111Figure 2 - Volume of model material built (bar chart - left axis)) on each system during the 3 week break in the build sequence of printing ASA parts.

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The build sequence for parts made from Nylon 12CF and ULTEM™ 9085 resin on Fortus 450mc and F900
systems is listed in Table 6. The sequence followed a three-week period of builds similar to ASA, but did notextend past the third week. Some substitutions were made in the parts that replaced visual inspection parts
with alternate geometries such as Z towers and curl bars. Similar to the sequence in ASA on the F900, XZ(on edge) and ZX (upright) coupons were combined into one job file, taking advantage of the large F900 size
to reduce the number of operator actions.

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Table 6 - Build Sequence for Printing with Nylon 12CF and ULTEM™ 9085 Resin Materials
Day

Build

Parts Produced

1

1

9-Inch Check Part

2

2

15 Mechanical Coupons – XZ (on edge) orientation1

2

3

15 Mechanical Coupons – ZX (upright) and 4 Density Cubes1

3

49-Inch Check Part

3

5

12-Inch Z Tower

4

6

15 Mechanical Coupons – XZ (on edge) orientation1

4

7

15 Mechanical Coupons – ZX (upright) and 4 Density Cubes1

589-Inch Check Part

5

9

Pin Plate

810

15 Mechanical Coupons – XZ (on edge) orientation1

8

11

15 Mechanical Coupons – ZX (upright) and 4 Density Cubes19129-Inch Check Part

913

12-Inch Z Tower

1014

15 Mechanical Coupons – XZ (on edge) orientation1

10

15

15 Mechanical Coupons – ZX (upright) and 4 Density Cubes1

1116

9-Inch Check Part

11

17

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin Array

1218

15 Mechanical Coupons – XZ (on edge) orientation1

12

19

15 Mechanical Coupons – ZX (upright) and 4 Density Cubes1

15

20

9-Inch Check Part

15

21

Curl Bars, Angled Wall, & Hollow Cylinder

16

22

15 Mechanical Coupons – XZ (on edge) orientation1

16

23

15 Mechanical Coupons – ZX (upright) and 4 Density Cubes1

1724

9-Inch Check Part

17

25

12-Inch Z Tower

18

26

15 Mechanical Coupons – XZ (on edge) orientation1

18

27

15 Mechanical Coupons – ZX (upright) and 4 Density Cubes1

1928

9-Inch Check Part

19

29

Visual Inspection Parts – QA Part, Shovel Grip, Connector & Pin ArrayWhite Paper

1

Mechanical coupon builds for XZ (on edge) and ZX (upright) orientation were combined into one job for F900s.

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Build trays were arranged in Control Center 14.4 build 952. Working through one machine-material
combination at a time, the part CMBs were imported into Control Center and arranged to minimize themotion of the heads between parts. For mechanical coupons, an equal number of coupons was placed ineach corner and the center of the platen. The coupon order was arranged to prevent the head from passing
over a coupon additional times per layer. Control Center defaults were used to define use of a sacrificial
tower. CMB files were saved for each machine and material combination, with the one file submitted toeach respective machine type. Figure 3 displays examples of build tray arrangements used for printing
mechanical coupons on an F370 and F900.

A

B

Figure 3 - Examples of build tray arrangement for printing mechanical coupons. A) Arrangement of 15 XZ (on edge) coupons on an F370 system,
including a standard purge tower. B) Arrangement of a build on an F900 system including 15 XZ (on edge) coupons, 20 ZX (upright) coupons, four
density cubes, and a single purge tower. Numbering superimposed on the diagram indicate the order that the parts were built. Note figures A and
B are not to the same scale.

Build Process

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To build the parts, each machine underwent amaterial change as needed to get the machine tothe correct material and tip combination. Machineoven temperatures were stabilized prior to the tipto-tip calibration on the system. Once the machine
was calibrated, the build sequence printing began
using standard operator procedures such as
inserting the build sheet or build tray and starting
the build.
A large quantity of material was consumed
during the course of this study. Table 7 lists thereported volume of material that was consumed(from machine logs) and the calculated minimum
number of material canisters and spools required.
The F370 utilized spools each containing 60 cubic
inches of ASA, whereas 92-cubic-inch canisters
were used on Fortus 450mc and F900 systems
for all materials. During the execution of the work,

systems were running simultaneously, so the actual
number of canisters and spools used was larger
than the calculated minimum indicated in Table 7.
Tracking of individual ASA spools and canisters
was not performed. For Nylon 12CF, material
usage included 48 individual canisters from sevenunique production lots. For ULTEM™ 9085 resin,
54 canisters were used from 11 unique production
lots. All material was new or recently opened
canisters that had been stored with the canister
sealed per standard product recommendations.
Within the materials of each type, canisters wereselected randomly for loading onto machines, andoperators followed standard best practices for
preparing material for printing. For jobs producing
coupons for mechanical testing and dimensional
accuracy check parts, it was verified prior tostarting the job that sufficient material was available
to complete the build without changeover ofmaterial.

14

Table 7 - Volume of Material Consumed
Volume of material consumed (in3)

Minimum number of material
canisters/spools1 consumed

Model Material(Support material)

F370

450mc

F900

F370

450mc

F900

ASA
(QSR / SR-30)2

2572
464

2781
305

3485
373

43
8

30
3

38
4

Nylon 12CF
(SR-110 Support)

N/A3

1924
101

1911
90

N/A3

21
1

21
1

ULTEM™ 9085 resin(ULTEM™ Support)

N/A3

1829
107

2115
107

N/A3

20
1

23
1

F370 utilized spools with 60 in3 of material, whereas the Fortus 450mc and F900 utilized canisters that contain 92 in3 of material.
QSR is the support material for ASA on the F370, whereas the Fortus 450mc and F900 utilize SR-30 for ASA support material.
3
Nylon 12CF and ULTEM™ 9085 resin are not able to be printed on the F370.
1
2

Canisters of ULTEM™ 9085 resin were tested formoisture per ASTM D7191 prior to mechanicalcoupon builds to ensure that the moisture content
was below the 0.04% by mass. Best practices
have shown that ULTEM™ 9085 resin mechanicals
are sensitive to moisture content above 0.04%
by mass. If the moisture content exceeded thislimit, the canister was dried in a vacuum oven at
70 ºC until moisture content was less than 0.04%.
Canisters and spools of ASA and Nylon 12CF wereused as received.

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All build errors were recorded and classified.
Unsuccessful builds included builds that failed tofinish, fallen parts, or machine issues. Unsuccessfulbuilds were repeated after any machine issues
were resolved. Any build pauses during mechanicalor dimensional parts were deemed unacceptable
and required that the job be rebuilt. If a pause
occurred during a visual part due to a minor issue
such as a failed auto changeover, it could beresumed if the machine had only been paused fora short duration and no impact to part quality wasvisually observed.
After a build was completed, parts were removed
from the build sheets while they were still warm.
ULTEM™ 9085 resin is paired with a breakaway
support, so all supports were removed manuallywhile warm. ASA and Nylon 12CF are paired withsoluble support materials. Supports were removed
by dissolution in a recirculation tank filled witha solution of WaterWorks™ at recommended
processing temperatures. Nylon 12CF parts arerecommended to be placed in the WaterWorkstank for at least four hours to rehydrate the material
and increase the part strength. All Nylon 12CF
parts that were measured, tested, or visuallyinspected were placed in the WaterWorks tank until
the support was dissolved and it had been in thesolution for at least 4 hours. All parts placed in thetank were rinsed and soaked in water to remove
the WaterWorks solution and then air dried beneathcirculating fans.
Dimensional Measurements
To check machine repeatability for dimensional
precision, the 9-inch check part was used on all
systems. For the 9-inch check part in ASA, fourof the parts from each system were selected formeasurement to capture effects over time and theuse of multiple systems. Parts were selected frombuilds 4, 16, 28, and 36 (see Table 5 for the build
sequence) as these builds were spread out within
the three-week build and the one-week of followup. For ULTEM™ 9085 resin and Nylon 12CF, twocopies of the 9-inch check part were selected formeasurement. The selected parts were from builds
4 and 28 on each system (see Table 6 for the build
sequences). The Nylon 12CF parts were processedin WaterWorks overnight to dissolve support, thensoaked in water and dried in ambient air prior tobeing measured.

15
Specific dimensions on the test parts were
measured by automated programming of a
Mitutoyo Quick Vision Apex coordinate measuringmachine (CMM) by a combination of touch probe
and optical inspection. The automated programmeasured 43 dimensions on each part, ranging
from 0.14 inch (3.52 mm) to 9.0 inches (228.60mm). For the largest dimensions measured ataround 9 inches, the accuracy of the CMM in x
and y coordinates was specified as better than
0.000086 inch by machine specification.
Measurement of Mechanical Coupons
With thousands of mechanical coupons built
throughout the build sequences for all systems andmaterials, it was not practical to test every coupon
due to cost and timeline. In total, 1,400 mechanicalcoupons were tested for this study. Table 8 lists
the builds that were selected for analysis ofmechanical coupons. Builds were selected acrossthe duration of the build sequence to capture
variation over time. Coupons were selected toevaluate variation in mechanical performance intraplaten, inter-system, and over-time in both the XZ(on edge) and ZX (upright) orientations. For eachmachine and material combination, five coupon
locations were tested for each of the listed builds.
For example, a total of 30 XZ (on edge) couponsand 30 ZX (upright) coupons were tested on eachmachine printing ASA. To characterize intra-platen
variation, coupons were selected from each of thefive build locations shown in Figure 3 from different
jobs in the build sequences on each system. The
data from the four corners and the center of theplaten represent the spread that occurs across theplaten by including data from the points that are
furthest apart. Note that the separation distances
are different for F370, Fortus 450, and F900 due tothe differences in platen size.

Table 8 - Mechanical Coupons Selected for Testing
Material
ASA

Machine Type

CouponOrientation

Build IDs Tested

F370, Fortus 450mc, F900

XZ (on edge)

2, 10, 18, 26, 30, 37

F370, Fortus 450mc
F900

Nylon 12CFULTEM™
9085 resin

3, 11, 19, 27, 31, 38
2, 10, 18, 26, 30, 37

Fortus 450mc, F900

XZ (on edge)

2, 10, 18, 26

Fortus 450mc, F900

ZX (upright)

3, 11, 19, 27

Fortus 450mc, F900

XZ (on edge)

2, 10, 18, 26

Fortus 450mc
F900

Coupons were tested over the span ofapproximately three months. All coupons wereconditioned prior to testing, and conditioning
varied by the material type. Coupons printed in
ASA were tested at room temperature and ambient
humidity. Coupons printed in Nylon 12CF were
tested within 72 hours from removing support
material. Re-hydrating Nylon 12 and Nylon 12CF
parts for a minimum of four hours (usually during
support removal) is recommended to maximize themechanical properties and dimensional accuracy ofWhite Paper

ZX (upright)

ZX (upright)

3, 11, 19, 27
2, 10, 18, 26

the parts. Printed coupons in ULTEM™ 9085 resin
were conditioned for 24 hours minimum (72 hours
maximum) at 250 °F in an oven. The coupons wereplaced in a fixture that allowed them to be evenly
spaced and positioned on edge. After the parts
were conditioned, the fixture and coupons wereplaced in a desiccator container, the container
sealed, and allowed the coupons to cool. The
coupons were then removed three at a time fortesting.

16
The mechanical coupons were tested on a Zwick
30kN Allround Tisch static material testing machinewith a 10kN load cell. Apart from conditioning,
testing followed the ASTM D638 test procedures.
Test speed was 0.2 in./min. A jig was used to markin ink the gage section of the coupon and where
the bottom of the coupon should align within thegrips to ensure consistent testing of the coupon.
For each specimen tested, strain (%), standard
force (N), and both crosshead and extensometer
travel (mm) were recorded.
For each specimen that was tested, a photo
was taken of the broken pieces after testing wascomplete. The location of the break was identified
for each coupon according to Figure 4. The gagesection is the constant diameter portion of thespecimen where ideally all specimens break. Thisregion is appropriately covered by the span of theextensometer. To evaluate elongation correctly,
the break must occur between the extensometer
arms, therefore only specimens that break inside
the gage region should be included in the dataset

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Figure 4 - Break locations of D638 coupons.

for elongation at break. The ‘narrowed section’ of
the specimen has the same cross-sectional area
as the gage length, but falls outside of the armsof the extensometer. The section identified as ‘inradius’ denotes a break in the area where thecross-sectional area is changing and the section
identified as ‘grips’ denotes a break at the outeredge of the coupon where the testing machine’s
grips are engaged with the coupon. Any visual
defect on the coupon, such as a blob of additional
material, was circled in ink prior to testing. The
location of the break was identified as ‘at defect’
if the coupon broke at that location. Data from
coupons that broke at the grips, in the radius, ata defect location, or that had testing error (e.g.,
extensometer slip) were not included within theanalysis of the data. For evaluation of strength,
all data from break locations in gage or in the
narrowed section were included. Only data from
coupons that broke in the gage was reported forelongation at break, as only those coupons had thebreak within the span of the extensometer.

17

RESULTS ANDDISCUSSION
Dimensional Precision
Dimensional precision in a manufacturing process
is critical to hitting part tolerances. Making
dimensionally consistent parts time-after-timeenables high part yield. To demonstrate thedimensional precision of the FDM process on
the F370, Fortus 450mc, and F900 models, the9-inch check part from Table 4 was printed in ASA.
The check part was printed four times on eachmachine, once per week for three consecutive
weeks and then one final time several weeks later.
Four separate machines were used for each model
totaling 16 check parts per model.

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On each check part, specific feature dimensions
were measured by an automated program of a

Figure 5 - Measured width for 0.140-inch wide rectangular bar feature (AA1).

Mitutoyo Quick Vision Apex coordinate measuringmachine (CMM) utilizing a combination of touchprobe and optical inspection. For 9-inch andsmaller features, dimensional measurement
accuracy of the CMM was listed as better than
0.000086 inch. As such, measurement error will
be assumed insignificant for the remainder of theanalysis.
By looking at individual features on the check part,
it is possible to quantify the dimensional precision
over time and between machines. One feature(AA1), a thin rectangular bar section with a nominal
width of 0.140 inch, is examined for illustration.
Results in Figure 5 are plotted as a deviation fromthe nominal CAD dimension (measured width –nominal width [0.140 inch]).

18
The flatness of each of the connected lines represents the consistency of each machine over time. The
clustering of lines represents the machine-to-machine variability, which is tightest on the F900. The overall
spread between measurements can be assessed by looking at the standard deviation of the measurements
for this feature. To quantify the impact of machine-to-machine variation, ANOVA was used. ANOVA showsthat machine-to-machine variation was significant for the F370 (F = 93.29, p = 0.000, α = 0.05) and
Fortus 450mc (F = 78.25, p = 0.000, α = 0.05), but was not significant for the F900 (F = 3.31, p = 0.057,
α = 0.05). This agrees with the graphical analysis in Figure 5.
Table 9 - Standard Deviation for Feature AA1 Measured Width
ModelStandard Deviation Feature AA1 (inches)

F370

0.0021

Fortus 450mc

0.0011F900

0.0005

Continuing this analysis to the broader set of feature measurements from the 9-inch check part, the average
standard deviations are presented in Table 10. The calculations are split between features equal to or
smaller than 2 inches (31 features) and those larger than 8 inches (12 features). Note, there are no features
between 2-8 inches on the 9-inch check part. This reflects the standard accuracy regimes for FDM.

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Table 10 - Summary of Dimensional Variability within Measured Features by FDM Product Model
Model

Average Standard Deviation for
Features 2 Inches and Under (inches)

Average Standard Deviation for
Features Over 8 Inches

F370

0.00120.0119Fortus 450mc

0.00090.0141F900

0.00090.0032

19
Summaries of the collected measurements are plotted here for each machine by feature. Note, AA1 is in theupper left panel of each of the small feature summary charts. Consistent with the example illustrated earlier,
FDM produces consistent results over time with little variation between machines.

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Figure 6 - Small (<2 inch) features for ASA 9-inch check part on F370.

Figure 7 - Small (<2 inch) features for ASA 9-inch check part on Fortus 450mc.

20Figure 8 - Small (<2 inch) Features for ASA 9-inch check part on F900.

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Figure 9 - Large (>8 inch) features for ASA 9-inch check part on F370.

21

Figure 10 - Large (>8 inch) Features for ASA 9-inch check part on Fortus 450mc.

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Figure 11 - Large (>8 inch) Features for ASA 9-inch check part on F900.

22Capability analysis assesses the ability of a manufacturing process to produce parts within tolerance. As
an example, the same feature as above will be analyzed from the F900. Tolerances are specific to part
requirements. In absence of defined part requirements, a common industry tolerance of +/-0.005 inch isused here as a proxy for engineering requirements for this feature.

Figure 12 - Capability analysis for 0.140-inch wide rectangular bar feature on ASA 9-inch check part with tolerance +/-0.005 inches.

The capability analysis yields a Cp value of 3.66 and a CpK value of 2.9. The Cp is the ratio of the spreadof the data at 6σ to the tolerance range. It shows that the data easily can fit within the specifications. CpK
accounts for the centeredness of the data and is lower because the mean of the data is not equal to thenominal target of 0.140. The Cp value exceeds 1.67 and thus the process is controllable. The CpK value
exceeds 1.67, so the process is also controlled.

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For some features in the analysis, the geometry is not as centered as the example shown above. For
example a rectangular boss feature with nominal measurement of 0.520 inch in width, has a mean deviationfrom the nominal target outside the tolerance band, but is still precise enough to be controllable.

23White Paper

Figure 13 - Comparison of a feature within tolerance (AA1) and a feature outside of tolerance (RectR1).

Figure 14 - Capability analysis for RectR1, a 0.520-inch wide rectangular boss feature on ASA 9-inch check part with tolerance +/-0.005 inches.

24
Capability analysis on feature RectR1 yields a Cpof 2.21 and a CpK of -1.69. Thus, this feature
production is controllable, but the process needs
improvement to be controlled. The procedure forapproaching this is described next.

property evaluation largely focuses on ultimate
tensile strength in XZ (on edge) and ZX (upright)
orientations, however an overall summary ofstrength, stiffness, and elongation is included uponconclusion of this section in Table 14.

Centeredness within specification is what
differentiates Cpk from Cp. Centeredness
is a measure of accuracy. FDM accuracy isdependent on part geometry. In both Insight™
and GrabCAD Print™ software, the translationfrom CAD geometry to toolpathing is done using
cartesian shrink factors. These factors accountfor the thermal contraction that occurs as thepolymer cools from extrusion temperature to room
temperature. These factors are experimentally
tuned for each machine-material-slice height/tip
combination. In the vast majority of cases, thesefactors work well to generate accurate parts
relative to the CAD model. Some features will not
be as accurate due to the neighboring geometry
resulting in nonuniform cooling causing differential
shrinkage. In the cases where the toolpaths
generated do not result in acceptable dimensions,geometric adjustments to the base CAD model canbe made to compensate. Due to tight dimensional
precision of FDM, once these adjustments are
made, the part can be reproducibly printed within
specification. As such, a high Cp value can be
adjusted to reach the desired Cpk value needed for
production.

The F370, Fortus 450mc, and F900 systems are
all capable of printing ASA, thereby providing
a common basis of material to compare themechanical performance achieved by threedifferent systems that vary in build size andhardware. Nylon 12CF and ULTEM™ 9085 resin
were evaluated only on Fortus 450mc and F900
systems due to availability only on that equipment.

Ultimate Tensile Strength of Printed Coupons

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In the course of this study, several thousand
coupons were built during the build sequencesused. Not all coupons were tested due to thesignificant size of this study. Out of the total, 1400
individual coupons were chosen for testing of
mechanical properties. The tested coupons werechosen as a representative sampling of eachmachine’s performance on each type of system at
different platen locations and over time. Mechanical

In total, 1400 mechanical coupons were tested
for this study. As described in the experimental
section, each specimen was visually inspectedduring the test to verify that the specimen failed
inside of the gage region of the coupon without
the presence of a notable printing defect. A
summary of the break location of all the coupons
is shown in Figure 15. This chart includes allmaterials and system types. Of all coupons, 1334
coupons (95%) broke within the acceptable regionsof the gage length and narrowed section. The
data from 66 coupons (5%) was excluded fromfurther analysis as the break locations were in theradius or grip regions of the coupon, or breakage
occurred at a defect location that was noted prior
to testing. Interestingly, all 66 of the coupons thatwere excluded were printed in the ZX (upright)
orientation. Fifty-three of these coupons broke inthe radius of the coupon, five in the grip region,
six coupons were identified with visual defects
that coincided with the break location, and two
were excluded from slippage of the extensometer
during testing. Although the number of specimens
rejected was small, less than 5% of the tests
performed, it remains best practice to remove thedata so as not to affect interpretation of mechanicalperformance and variation.

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Figure 15 - Summary of coupon break locations including all materials and machines.

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The break location varied by the material, machine type, and coupon orientation. Ideally, the specimens
would break exclusively inside the gage length. Unfortunately, many breaks of FDM coupons fall within
the narrowed section. For this data set of 1334 measurements, 55.8% of the coupons broke within the
narrowed section. Although not ideal for measuring elongation since breakage occurs outside the span ofthe extensometer, it was concluded that since the cross section of the printed part in the narrowed section
and the gage section are equivalent, that the measurement of strength was correctly calculated. Note thatsince the narrowed region is outside the span of the extensometer, tensile elongation was only calculated
from specimens that broke in the gage region.

26
Mechanical Performance of ASA
ASA is a common material option for the Stratasys
F370, Fortus 450mc, and F900 systems, enablingcomparison of these systems on a similar material
basis. In addition to hardware differences, there
are differences in the default parameters used forprinting ASA on each system due to independent
optimization of material performance, although thematerial chemistry is the same. Over the durationof the build sequence, six time points were taken
for analysis of mechanical coupons (see Figure16). Note that four of the time points were taken
within the first three weeks of continuous printing,and the last two time points were taken after theintentional three-week break in the build sequence.
Figure 17 displays the results for average ultimate
tensile strength in this material for coupons printed
in the XZ (on edge) and ZX (upright) orientationfor each of the three systems. Each data point
represents the average of 5 coupons taken atA

different locations on the build plane (four corners
and center). The work was repeated on four F370,
four Fortus 450mc, and five F900 systems.
Overall, individual systems exhibit excellent
consistency over two months of printing. No
obvious differences in performance are seen
before or after the intentional break period in thebuild sequence for which material changes anduncontrolled use of the systems were permitted.
As expected by the anisotropic nature of FDM andinterlayer bonding, the strength in the ZX (upright)
orientation is generally less than that of the XZ(on edge) orientation. Figure 17 also provides anindication of the relative magnitude of the effectsof build plate location, inter-system, and over-time
variations. As seen in the plots, each source ofvariation is generally overlapping, and no single
source emerges as a dominant contributor tomechanical strength variation.

B

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Figure 16 - Ultimate tensile strength of coupons printed in ASA on multiple F370, Fortus 450mc, and F900 systems, for A) XZ (on edge) and B)
ZX (upright) orientations. Each data point represents the average of the measured ultimate tensile strength from a build including five specimens
positioned across the platen at that point in time during the build sequence.

27

Figure 17 - Average ultimate tensile strength in ASA for coupons printed at specific locations on the build tray - back left (BL), back right (BR),center (C), front left (FL) and front right (FR). Data is presented in XZ (on edge) and ZX (upright) orientations and is averaged across multiple
systems for six points in time during the build sequence.

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To further explore if there were systematic
variations in the results across position on the build
plate due to the design of the system, for example
from thermal conduction or convection inside theheated build chamber, the data was averaged
over time and multiple systems per location on
the tray as show in Figure 17. The position ofeach coupon was recorded as back left (BL), backright (BR), center (C), front left (FL) and front right(FR). The resulting data is summarized for both XZ(on edge) and ZX (upright) orientations for eachsystem type. For the XZ (on edge) orientation,
the average strength across the build plate foreach system type varies within about a 100 psi
range, and for ZX (upright) orientation the variation

is within 500 psi, highlighting the consistency of
mechanical performance across position. For F900,
the trend in average strength values from back tofront positions could suggest that a slight thermal
profile in the large build chamber of the F900 may
exist. However, the distributions in the data for
all positions overlap, and no evidence is seen in
the XZ (on edge) orientation, making a definitive
conclusion doubtful. Since the standard deviations
at each position are overlapping on all systems inboth orientations, it is concluded that there are no
systematic variations in mechanical performancedue to part placement on the build plates for thesesystems.

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The collection of data collected for each machine
was averaged to evaluate the variation found persystem, including across build plate position andtime in the build sequence, and is presented inTable 11. Additionally, an overall average of thestrength data was calculated for all of the datameasurements with respect to multiple machines.
Inherently, these averages also include theuncontrolled variations due to differences in systemage, material lot, testing, and other factors thatwere not expressly controlled. The significant sizeof this study provides confidence that these results
are typical of those to be observed from any of thesystems under typical operating conditions. The
data reinforces the generally accepted conclusionthat variation from FDM processes is moresignificant in ZX (upright) orientation than in the XZ(on edge) due to interlayer bonding, as is evident
by the greater COV. In addition to reduced strength
in the Z axis, the variation in strength measurement
increases. For the F370 systems, the individualmachine variation is very low, with COVs less that
2-3%. For this specific machine type, the machineto-machine variation is larger than the variation
within a single machine. For the Fortus 450mc
and F900 systems, with their significantly larger
build volumes, the machine to machine variation
is approximately the same magnitude as themeasured intra-machine variation.

Table 11 - Average Ultimate Tensile Strength for ASA
XZ (on edge) Orientation
System Type

F370

Fortus 450mc

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ZX (upright) Orientation

Machine ID

Average
Ultimate Tensile
Strength (psi)

Coefficientof Variation(COV)

Average
Ultimate Tensile
Strength (psi)

Coefficientof Variation
(COV)

371

4365

1.8%

2826

2.9%

372

4346

1.6%

2621

2.8%

374

4496

1.1%

3061

2.6%

375

4812

1.1%

3105

1.8%

Overall Average:

4505

4.4%

2903

7.2%

451

4384

4.4%

3653

6.0%

452

4530

3.3%

3677

4.5%

453

4511

5.3%

3542

7.6%

454

4807

4.0%

3702

4.7%

Overall Average:

4558

5.5%

3643

6.0%

901

4601

6.3%

3831

13.7%

902

4462

4.6%

4045

6.2%

903

4511

3.8%

3882

10.2%

905

4495

3.9%

4010

7.7%

906

4425

3.6%

3687

9.9%

Overall Average:

4504

4.8%

3915

9.8%

29

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Figure 18 - Overall average ultimate tensile strength in ASA for coupons printed on F370, Fortus 450mc, and F900 systems
in XZ (on edge) and ZX (upright) orientation.

Figure 18 plots the overall average strength resultsfor each orientation and system type. All threemachine types perform similarly for strength of
ASA coupons in the XZ (on edge) orientation,with overlapping standard deviations. In thisorientation, each machine type achieves the same
result over its full build area and over the durationof the continuous build sequence on multiple
machines. Results in the ZX (upright) orientation
indicate performance differences between systemarchitecture. All three systems demonstrate an
anticipated anisotropy due to interlayer bonding,however the ASA specimens printed on the Fortus
450mc and F900 have superior strength in the ZX(upright) orientation over those printed on the F370.
For the coupons printed on the F370, the strength
in the ZX (upright) orientation is 64% of the strengthof the XZ (on edge) orientation, whereas on the
Fortus 450mc and F900 systems it increases to
80% and 87%, respectively. These differences
originate from different optimizations of material
printing parameters and the performance of the
hardware in managing the interface temperature
between layers during printing, which is known toaffect the strength of interlayer bonding. As noted
previously, the F370 default parameters use avalue of 0.018 inch for raster width, but the Fortus
450mc and F900 systems use 0.020 inch as thedefault. These small differences in bead width willaffect the contact area and fill density of materialand can affect interlayer bond strength. The ovenand extruder both affect the local temperature of
the plastic during printing. When material printing
parameters are determined for a specific system,
the temperature of the oven and the extruder
are varied to optimize general part performance.
One aspect of the optimization is mechanicalstrength, but other aspects also are important,such as adhesion with support material or thebuild plate, the ability to bridge over unsupported
geometries, print speed, bead diameter control,and numerous other considerations that contributeto part aesthetics, quality, or success rate inprinting. Ultimately, the parameters even for thesame material can differ across systems, and in
this case, the optimization of ASA material resulted
in a lesser value of ultimate tensile strength in theZX (upright) orientation. It is important to note that
although affected by anisotropy, the overall COV
values for strength are low, indicating very good
reproducibility and consistency of mechanicalstrength across many sources of variation.

30
Mechanical Performance of Nylon 12CF and ULTEM™ 9085 resin
Nylon 12CF and ULTEM™ 9085 resin materials require high temperature extrusion and build environmentsfor optimal printing and therefore are only available on the Fortus 450mc and F900 systems. Furthermore,as a carbon fiber reinforced material, Nylon 12CF requires additional hardware upgrades to prevent
premature wear on components due to the abrasive nature of carbon fiber. Figure 14 presents the results
for ultimate tensile strength of Nylon 12CF in the XZ (on edge) and ZX (upright) orientations for four
Fortus 450mc and four F900 systems over four time points of the build sequence, approximately one monthin duration. For each point in time, the data averages the results across five locations on the build plate.
Figure 15 illustrates the complementary data for ULTEM™ 9085 resin.

A

B

Figure 19 - Ultimate tensile strength of coupons printed in Nylon 12CF on four Fortus 450mc and F900 systems, for A) XZ (on edge) and B) ZX(upright) orientations. Each data point represents the average of the measured ultimate tensile strength from a build including five specimens
positioned across the platen at that point in time during the build sequence.

A

B

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Figure 20 - Ultimate tensile strength of coupons printed in ULTEM™ 9085 resin on four Fortus 450mc and F900 systems, for A) XZ (on edge)
and B) ZX (upright) orientations. Each data point represents the average of the measured ultimate tensile strength from a build including fivespecimens positioned across the platen at that point in time during the build sequence.

Note: Data depicted illustrates ULTEM™ 9085 resin performance with a T16 tip. Using a T16A tip will result in higher mechanical performance witha lower COV. T16A was only available on the F900 at the time of publication and it is not examined in this report.

31
The figures illustrate the relative effects of machineto-machine variation and repeatability over time.
Generally, strength varies within a range of lessthan 1000 psi for any individual machine, but
between machines the difference can be as muchas 2000 psi in some cases of the extremes. Bothmaterials exhibit nearly equivalent strength in theXZ (on edge) orientation despite very different
chemical compositions. The polyetherimide
polymer base of ULTEM™ 9085 resin is intrinsicallystronger than that of the nylon polymer base of
Nylon 12CF, however the alignment of carbon
fiber in the XZ (on edge) orientation leads togreater strength than the base material, and in thiscase equivalent to ULTEM™ 9085 resin. In theZX (upright) orientation, the differences between
polymer chemistry are seen, with ULTEM™ 9085
resin being stronger than Nylon 12CF.

A

B

The data collected for each point in time wassubsequently assessed by position on the build
plate, as shown in Figure 21 for both Nylon 12CF
and ULTEM™ 9085 resin. ULTEM™ 9085 resin
demonstrated a larger standard deviation instrength than Nylon 12CF across position of thebuild plate. For both materials, the average results
per position on the build plate did not indicate asignificant trend, as each position had overlapping
distributions in the results.

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Figure 21 - Average ultimate tensile strength in Nylon 12CF and ULTEM™ 9085 resin for coupons printed at specific locations on the build tray back left (BL), back right (BR), center (C), front left (FL) and front right (FR). Data is presented in XZ (on edge) and ZX (upright) orientations and isaveraged across multiple systems for six points in time during the build sequence. A) Nylon 12CF and B) ULTEM™ 9085 resin.

Table 12 and Table 13 tabulate the average
ultimate tensile strength and the COV in eachorientation for Nylon 12CF and ULTEM™ 9085
resin, respectively. The effects of anisotropy canbe seen by comparing XZ (on edge) and ZX(upright) orientations. For Nylon 12CF, which lacks
fiber reinforcement across layers, the strength
in the ZX (upright) orientation is about 45% of
the XZ (on edge) strength. For ULTEM™ 9085
resin, it is about 60% due to the stronger polymer
composition. As expected for material extrusion
processes, the COV for the strength of XZ (onedge) coupons is lower than for the ZX (upright)
orientations. Individual machines frequently
demonstrate lower COV than the overall COV forthe data, suggesting machine-to-machine variation
is a more dominating influence on variability,
however in some cases, the COV on a single
machine can be larger than the COV for the fullset of data. It is therefore anticipated that the data
represents the full expected range of variation thata user would experience on these systems withthese materials under normal operating conditions.
Consistency in strength is very good for the XZ (onedge) orientation in both materials, demonstrated
by COV values less than 7%, and in most cases
less than 5%. For the ZX (upright) orientation, theCOV is larger, remaining less than 12%, over all of
the factors included in this expansive study.

32

Table 12 - Average Ultimate Tensile Strength for Nylon 12CF
XZ (on edge) Orientation
System Type

Fortus 450mc

F900

ZX (upright) Orientation

Machine ID

Average
Ultimate Tensile
Strength (psi)

Coefficientof Variation(COV)

Average
Ultimate Tensile
Strength (psi)

Coefficientof Variation
(COV)

452

10851

2.5%

4357

6.7%

453

11060

4.4%

4296

9.5%

454

10955

2.2%

4434

5.9%

456

10609

3.1%

4392

5.7%

Overall Average:

10879

3.5%

4373

6.9%

902

10972

4.5%

4959

10.8%

905

10589

4.4%

5142

5.5%

906

10640

4.1%

5052

7.3%

909

10744

4.3%

5271

5.6%

Overall Average:

10736

4.5%

5106

7.7%

Table 13 - Average Ultimate Tensile Strength for ULTEM™ 9085 ResinXZ (on edge) Orientation
System Type

Fortus 450mc

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ZX (upright) Orientation

Machine ID

Average
Ultimate Tensile
Strength (psi)

Coefficientof Variation(COV)

Average
Ultimate Tensile
Strength (psi)

Coefficientof Variation
(COV)

451

11364

2.9%

7071

6.3%

452

11601

2.8%

6327

9.6%

453

11342

3.7%

6132

11.1%

455

10555

3.5%

6371

12.3%

Overall Average:

11215

4.7%

6467

11.1%

901

10432

5.8%

6458

10.3%

902

11644

3.7%

6933

10.2%

903

9894

3.2%

6726

12.3%

906

10491

3.5%

6479

11.5%

Overall Average:

10915

6.7%

6548

11.2%

33
Summary of Mechanical Performance
A summary of the ultimate tensile strength, tensile modulus, and elongation at break for each machine andmaterial is shown in Table 14 along with data from product datasheets. In most cases, values from data
sheets agree with those collected in this study within the experimental error demonstrated by COV values.
The anisotropic nature of FDM is evident in all materials and systems in which the XZ (on edge) orientationis stronger than the ZX (upright) orientation. Generally, modulus (stiffness) is less affected by orientation withthe exception of Nylon 12CF due to fiber alignment. All materials exhibit low elongation, as is typical formaterial extrusion processes.
Table 14 - Summary of Mechanical Performance for All Systems and Materials
XZ (on edge)
Material

ASA

Nylon
12CF

ULTEM™
9085
resin
1
2

Ult. Tensile
Strength (psi)TensileModulus (psi)Average

COV

Average

COV

Average

F370

4505

4.4%

247000

5.3%

450mc

4558

5.5%

235000

F900

4504

4.8%

246000Datasheet(F900)

4750

311000

9.0%

450mc

10879

3.5% 1225000 16.6%

3.3%

5.3%

4373

F900

10736

4.5% 1227000 13.6%

3.2%

3.4%

5106

Datasheet(F900)

9190

1370000

1.9%

450mc

11215

4.7%

340000

6.9%

5.8%

F900

10615

7.3%

3330004.9%

5.4%

Datasheet(F900)

9950

MachineUlt. Tensile
Strength (psi)TensileModulus (psi)COV

Average

COV

Average

COV Average

COV

6.5%

11.2%

2903

7.2%

197000

6.9%

1.8%

9.4%

11.6%

6.3%

21.5%

3643

6.0%

243000

7.6%

1.9%

11.5%

7.4%

6.0%

15.3%

3915

9.8%

262000

8.2%

1.7%

24.5%

348000Elongation at
Break (%)1

5.8%

4300

Elongation at
Break (%)12980003.0%

6.9%406000 22.4%

1.8%

14.2%

7.7%

488000 17.6%

1.8%

19.4%

4170

434000

1.2%

8.4%

6467

11.1% 299000

5.1%

2.5%

13.0%

8.8%

6639

11.2% 330000

6.2%

2.3%

16.9%

6100

3090002.2%

For elongation at break, only data from coupons that broke within the gage length are included.
Typical product testing for data sheets includes one set of ten specimens evaluated once per three different F900 systems, for a total of 30
measurements.

Material Throughput and Printing Speed

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ZX (upright)

Productivity of equipment is an importantconsideration for manufacturing operations
because the average cost of a part generally
decreases as throughput increases. In order tocompare the relative productivity of the Stratasys
F370, Fortus 450mc, and F900 systems, the log
files were reviewed for printing identical parts
during the build sequences. Two different parts
were evaluated; the 9-inch check part and the12-inch Z tower. For each part, only one copy ofthe part was built in the printer at a time. Table
15 and Table 16 compare the average build
duration, amount of model and support material
consumption, and the resulting average material

throughput for each machine-material combination
when printing these parts. The average material
consumption is calculated from the total volume ofmodel and support material printed.
As seen in the tables for both parts, the F370
takes more time to build the same part thanthe Fortus 450mc and the F900 in ASA. Due tohardware differences that include the extruder andthe gantry, the Fortus 450mc and F900 systems
are faster printing ASA than the F370. In ASA
and ULTEM™ 9085 resin materials, both theFortus 450mc and the F900 produce these twoparts with a similar build duration. For Nylon 12CF,
the F900 demonstrates an advantage in speed
over the Fortus 450mc.

34
Although the geometry is the same across thedifferent machine-material combinations, thematerial consumption is different for each of thetest cases. The Fortus 450mc and the F900
demonstrate nearly identical material consumption
when printing either of these parts in any of thethree materials. The F370 consistently uses lessmodel material and a larger amount of support
material compared to the other systems. Overall
these differences are due to multiple factors inprocess to optimize material print parameters ofthe material on each system. For example, theF370 uses 10 layers of support material by default
before initiating the first layer of the model material
in order to fully planarize the build surface over theremovable plastic build tray. The Fortus 450mc andF900 systems generally use fewer layers of material
prior to building a model. Similarly, the use of purge
towers on the F370 is a default practice, whereas
on the Fortus 450mc and F900 systems a printed
purge tower is generally not used but nozzle purge
steps over a purge station are used on each headswap. The volume of material spent on purging isdetermined empirically for different materials. The
differences in purge volume is likely the dominantfactor that results in a different volume of material
expended per system in these cases. However,other factors of defining the material extrusion suchas fill style, support style, and bead width can also
affect material consumed.

Table 15 - Build Duration, Material Consumption, and Average Material Throughput for Printing
the 9-Inch Check Part
Material

ASA

Nylon 12CFULTEM™ 9085
resin

Ave. Build
Duration(min.)

Model
Material
Volume (in3)

SupportMaterial
Volume (in3)

Average
Material
Throughput(in3/hr)

F370

298

8.0

3.4

2.3

Fortus 450mc

220

9.4

1.2

2.9

F900

222

9.5

1.2

2.9

Fortus 450mc

282

10.1

0.9

2.3

F900

241

10.1

0.9

2.7

Fortus 450mc

263

11.1

0.8

2.7

F900

262

10.7

0.8

2.6

MachineTable 16 - Build Duration, Material Consumption, and Average Material Throughput for Printing
the 12-Inch Z Tower
Material

ASA

Nylon 12CFWhite PaperULTEM™ 9085
resin

Ave. Build
Duration(min.)

Model
Material
Volume (in3)

SupportMaterial
Volume (in3)

Average
Material
Throughput(in3/hr)

F370

443

10.6

4.0

2.0

Fortus 450mc

376

12.6

2.3

2.4

F900

382

12.6

2.1

2.3

Fortus 450mc

411

13.6

0.7

2.1

F900

355

13.8

0.7

2.4

Fortus 450mc

361

14.0

0.6

2.4

F900

352

13.4

0.6

2.4

Machine

35
Reliability of Job Starts and Part Yield
The sum off all machine time spent during the build
sequences used in this work totaled 1,385 days
for all systems and materials. For each system,
the totals were 318 days on the F370, 541 dayson the Fortus 450mc, and 525 days on the F900.
More materials were utilized on the Fortus 450mc
and F900 systems, increasing overall printing time,
but these machines also have higher throughput
compared to the F370 and therefore the increased
time was less than a multiple of the F370 build
time.
During the build sequences, some issues occurredthat affected the completion of the programmed
jobs. The most severe issues included replacementof an electronics board responsible for oventemperature control on an F900 and replacementof a vacuum generator used for securing build
sheets on a Fortus 450mc. Neither of these issues
resulted in critical failure of the system, but theissues did affect the start of jobs on a system due
to temperature stability for running ULTEM™ 9085
resin and securing build sheets. Each of the threesystems recorded one instance of a job pause thatwas recovered in each case. There were a few
instances of fallen parts during builds, all from ZX(upright) coupons, in which the printer continued
to print ‘in air.’ Other minor issues included
a single occurrence of a canister with crosswound filament, two instances of clogged tips,
and a single failed auto changeover. The variety
of machine issues, and their relative frequencyof occurrence, was representative of the kindsof errors that users experience, as learned from
customer feedback by the authors.
Table 17 tallies the number of jobs starts andrebuilt jobs, and calculates a job yield for eachsystem type. The number of jobs starts includes
all jobs that were started on the system during thebuild sequence. The number of rebuilt jobs is thenumber of jobs that were rebuilt due to machine
errors, part quality issues, or due to human error,
such as the job being out of order with the definedbuild sequence. The job yield was calculated as thepercentage of jobs that passed on the first attemptof the build out of the total number of builds. There
were no instances in which a rebuilt job could not
be completed successfully. The three systems
demonstrated very good job yield values over theseveral hundred days of print time experienced
during this work.

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Table 17 - Number of Job Starts, Rebuilt Jobs, and Job Yield
System Type

F370

Fortus 450mc

F900

Number of Systems

4

6

6

Materials

ASA

ASA, Nylon 12CF,ULTEM™ 9085 resin

ASA, Nylon 12CF,ULTEM™ 9085 resin

Total Number of Job Starts

181

452

380

Rebuilt Jobs

9

52

21

Job Yield

95%

88%

94%

36
The reliability of these systems to produce parts
can additionally be viewed on the basis of partyield. Part yield is the percentage of ‘good’ partsout of the total number of parts attempted on thesystem. The total number of parts included thecount of parts from rebuilt jobs if required. Good
parts were defined as parts that successfully built
during a job per the intention of the job, without
any obvious failure or quality issue. If a job had
an unrecoverable error, any part that was notcompletely built through all layers of its design wascounted as a failure. It was therefore possible thatparts with fewer layers in the Z axis than otherparts of the build could remain counted as good,should an error have occurred late in a job. Parts
from a job that were rebuilt due to operator error,
such as jobs being built in the wrong order, did
not count towards the number of failed parts since
the equipment did not produce the error. Using
this logic, the part yield for each of the systems
is shown in Table 18. The reported part yields are
99%, 93%, and 92% for the F370, Fortus 450mc,
and F900, respectively, demonstrating very highcompletion of printed parts on these systems.

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Table 18 - Calculated Part Yield
System Type

F370

Fortus 450mc

F900

Total Parts

1586

3984

4844

Failed Parts

10

279

381

Good Parts

1576

3705

4463

Part Yield

99%

93%

92%

37

CONCLUSIONWhite Paper

In this work, printed parts from the F370,
Fortus 450mc, and F900 FDM systems have beencharacterized under variables of key concern
to manufacturers implementing an additive
manufacturing process into their operations. In
particular, the repeatability of a process is often far
more valuable to a manufacturer than the absolutemagnitude of a result. Equipment and processes
must be trusted to deliver the same results, every
time with confidence. It was the intention of thiswork to test these three systems under conditions
that represented those that a typical user would
experience for operations in a factory environment.
The study blended multiple variables together toarrive at results that should confidently represent
the variations seen by any customer under
expected use conditions. The build sequencesused in this work incorporated long durations ofcontinuous use, multiple systems of varying age
and history, occupying the full build area of theprinter, and working with different types of materials
across multiple material lots. The sum of all ofthese variables allows a user the confidence to set
expectations on printed part performance.
For the investigation of dimensional repeatability,
the use of ASA on all three systems allowed for
a comparison that was, in part, independent ofa material contribution. The data demonstrated
the F900 performed with the least variations,which lends significant benefit to users working
with the full build volume of the machine. The
Fortus 450mc and F370 systems also perform
extremely well. Target dimensions are achieved
with high precision over time and other variables,
without requiring repeated calibrations. The
effect of the material contribution on accuracy
to the CAD design is a well-known challenge inmaterial extrusion technology. Comparison of

the three materials demonstrated the benefitsof low thermal expansion materials, such as thereinforced Nylon 12CF, to hold tolerances withless variation. Overall, it becomes the precisionof the system and material combination that willdefine the repeatability of printed part dimensions.
All three systems demonstrated consistency andrepeatability that would enable a designer to makesmall adjustments to the CAD design to correct
for any material influences that might affect partaccuracy to the design for a specific geometry. In
the future, a more ideal situation will be material
model-based corrections that could predictively
adjust geometry during the print preparation stepof the workflow. Until then, the precision of thesemachines offers users consistency and wellunderstood expectations.
The evaluation of mechanical strength in printed
coupons similarly included a very large sample
size with emphasis on different types of variations
that a user might encounter in a factory floor
environment. One of the most important findings
is the low COV calculated from the overall averagedata. In the XZ (on edge) orientation, all materialand system combinations demonstrated a COV
in the range of 3.5 to 7.3%, with most of theresults being less than 5% COV. As expected formaterial extrusion processes, there was greater
variation in ZX (upright) orientation, with COV of
all material and system combinations in the range
of 6.0% to 11.2%. The evaluation from printed
ASA draws the conclusion that all three systems
produce equivalent strength parts in the XZ (onedge) orientation, but there are differences in thevertical ZX (upright) orientation. In that orientation,
the Fortus 450mc and F900 systems are able toprint stronger parts in ASA. The performance of
the Fortus 450mc and F900 was very similar on

38
the basis of strength in all three materials. And
furthermore, part position on the build plate was
not found to be dominant factor on strength for
any of the systems.
Overall, the F370, Fortus 450mc, and F900 wereproven by dimensional precision and mechanicalstrength to generate very consistent results.
Success rates for producing parts were greaterthan 92% for all of these systems over very longbuild sequences and a large number of variations
explored. Compared to each other, it is clearthat while all three systems perform well, theFortus 450mc and F900 systems offer advantages
in build size, strength in the ZX (upright) orientation,and high-performance material selections like
Nylon 12CF and ULTEM™ 9085 resin. With
respect to the performance against the broader
number of options for material extrusion printers,
there are no standards of comparison today.
Although direct comparisons were not readily
available or equivalent to include in this work,
previous studies have shown a significantly better
performance out of Stratasys FDM systems. We
believe the results and methods used in this reportgo well beyond the rigor of previous studies andshould be viewed by users as the most robust
benchmark for comparison.

Stratasys Headquarters

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+972 74 745 5000 (Fax)stratasys.com
ISO 9001:2015 Certified© 2021 Stratasys. All rights reserved. Stratasys, the Stratasys Signet logo, FDM, and Fortus are registered trademarks of Stratasys Inc. F370,
Fortus 450mc, F900, FDM TPU 92A, ABS-M30, ABS-ESD7, Antero 800NA, Antero 840CN03, PC-ISO, FDM Nylon 12, FDM Nylon 12CF,
Diran 410MF07, GrabCAD Print, Insight and Control Center are trademarks of Stratasys, Inc. ULTEM™ is a registered trademark of SABIC or
affiliates. All other trademarks are the property of their respective owners, and Stratasys assumes no responsibility with regard to the selection,
performance, or use of these non-Stratasys products. Product specifications subject to change without notice. WP_FDM_R & R report_1021a