p.1 

OAR Box 1413 

Prepped by Ollie Stewart 

Document Number: 

65) 11-1-65 

Docket Number: 

A-94-52 

Printed 7/9/2008 3:11:23 PM Sheet 65 of 114 
P.2 

NSIDE 

jl'^U Mrimm By Donn*.^*

 Qawson, Senior Editor 

NJ ECTION DIE PULTRUSION! 

ILOSED SYSTEM, WIDE 

3PEN TECHNOLOGY 

A 945'— 

11-1-65 

!ab floor is first composite 

rimary structure on Class 8 truck 

nd the biggest part made so far 

y injection pultrusion. 

-technological advances in injection die pultrusion are improving the T2000 semi-truck 

designed and built by Kenworth Truck Co. 

irkland. Wash.), with the production of a sand-

.ch panel with integrally pultruded core which will 

rve as the truck's cab and sleeper floor. 

In production since October 1996, the 2-inchick panel produced by Hexcel Industrial 

ructures (Kent. Wash.) is the largest structure 

oduced by this process to date. The panel weighs 

at 240 Ib and measures 88 inches wide by 117 

ches long. 

According to Rick Warner, director of new busies development for Hexcel Industrial Structures, 

e panel is also the first composite primary strucre on a Class 8 truck, a designation given to 

jcks with a gross vehicle weight of 33.000 lb or 

eater. The monocoque structure replaces a stanird metal assembly consisting of sheet metal, aluinum profiles, nuts, bolts and rivets that can add 

) to more than 100 pieces. Kenworth describes its 

1000 as the next-generation Class 8 truck, which 

"totally new from the ground up," using compos-

: materials in the exterior aeropackage and cab as 

fli as in the sleeper interior, both for aerodynam5 and to lighten the overall weight (CT Sept./Oct. 

)96). 

Hexcel's one-piece iloor design, made of E-glassinibrced vinyl ester laminate skins with a core of 

id-grain balsa wood, won oui over a dozen other 

jor concepts that Kenworth evaluated lor weight, 

in count and assembly cost reductions. Warner 

edicts this pan is a first step forward broader 

•ceptance of large composite structures for major 

joking applications. 

The pultruded panel provides a 

rigid assembly platform for the cab 

and sleeper sidewails. which bond 

to the floor perimeter. The finished 

floor is exceptionally flat, "typically 

holding better than 2 mm tolerance." according to Michael Zavell. Hexcel's plant 

manager. In addition, natural insulation provided 

by the fiberglass sandwich structure significantiy 

cuts road noise and heat loss when compared to a 

metal floor, earning it the name ThermaCore Floor. 

Hexcel warrants die floor for three years or 

300,000 miles and anticipates a service life of 

1.000.000 miles under normal operating conditions, according to Jeremy Hale, engineering sales 

manager for Hexcel Industrial Structures. 

INJECTION DIE VS. OPEN BATH 

PULTRUSION 

Injection die differs from standard pultrusion processing in the way the resin is applied to wet-oui 

the fibers. From that point on. the processes are 

Figure 1. An 88-inch-wide 

pultruded monocoque panel 

is the first composite primary structure on a Class 

8 truck, replacing the traditional multi-piece metal 

floor assembly in Kenwonh's 

new T2000 semi-truck. 

(Source: Hexcel). 

COMPOSITES TECHNOLOGY JULY/AUGUST 1997 19 
P.3 

WLKmiUli t n/.-«•.. 

&* 

ssentially identical. ii 

In both processes, pultrusion makes i 

instant cross-section parts by continuusly pulling resin-wet fiber reinforce-i! 

ients through a heated die, where the1 

;sin crosslinks and cures. The heart of 

ny pultrusion machine is its pulling 

lechanism. which usually consists of 

vo hydraulically driven clamping/I 

ulling devices that shuttle back and 

>rth, alternately clamping and releasing 

ie cured stock to pull it down the line1 

ito a cutting system. 

Standard open bath pultrusion wets 

ut the fibers ahead of the die. pulling 

lem through an open resin bath. The 

'et fiber/resin package then passes 

arough forming tooling and into the 

eated die. In contrast, for injection die 

ultrusion. preformed dry fibers are 

ulled into the heated die and resin is 

ljected under pressure through special 

oris directly into the closed die. 

:LEAN OPERATION, 

ILEAN AIR 

ijection die pultrusion has a number of 

dvantages over open-bath pultrusion. 

erhaps the most important is the elimiation of open resin sources and nearly 

11 styrene emissions. A close second is 

limination of the extensive clean-up 

perations necessary during and after 

art manufacture when running with 

pen systems. Clean-up of Hexcel's 

losed injection system consists mainlyiof 

leaning the injection ports and cleaning 

he die by pulling dry fiber through it. 

Hale points out that resin injection 

also allows manufacture of parts with 

lower void content and higher fiber volume and gives better control of fiber 

alignment. The dry preform retains its 

fiber orientation better than wet material 

as it enters the die. and the die prevents 

the enclosed fibers from shifting during 

resin injection. Hale emphasizes the 

importance of this feature: "We tailor the 

fiber reinforcement to achieve the 

required stiffness in both longitudinal 

and transverse directions, and injection 

gives us better control over that critical 

fiber orientation." The injection die pultrusion technique also represents a highvolume, automated manufacturing 

process that reduces labor cost while providing reproducible quality in finished 

parts. 

Hexcel manufactures the T2000 floor 

panel using pultrusion machinery 

designed and built by CPE Inc. (Haslet. 

Texas). The machine uses 100,000-

pound hydraulic pull force to power its 

two shuttles at a pre-set speed as they 

pull the large panel out of the die. Pull 

speed and other machine motions, as well 

as all process parameters, are controlled 

through an Allen Bradley programmable 

logic controller. 

The 34.000-lb. 100-inch-wide die fits 

within the pultrusion machine's 103-

inch-wide and 15-inch-deep maximum 

part size. The die's inside dimension is 88 

inches. 

Designed and built by CPE in two 

pieces (top and bottom) from hard 

chrome plated 4140 steel, the big die 

posed major handling, clamping and 

Creel system for 

dry fabric/tow 

Preforming 

guides 

Computer Aided Manufacturing 

CRTMTM Die 

Pinch shuttle #1 

engaged) I—\

mi 

T 

Pinch shuttle #2 

(disengaged) \* t 

. . / 

Controlling resin injection 

Flying 

cut-off saw Finished beam 

"tjfure 2. CRTM combines continuous injection die pultrusion and resin transfer molding io produce 

conomtcai. hiijh quality laminates. (Source:.Hexcel) 

!0 COMPOSITES TECHNOLOGY JULY/AUGUST 1997 

thermal expansion challenges. If the die, 

which expands when heated, is not sufficiently filled, excess resin can build up 

resulting in inconsistency in part size. 

CPE approached the problem through the 

die table design and a unique clamping 

system which holds the top and bottom 

die pieces together. The final design 

boasts a die thermal deflection of ±0.004 

inch and a flatness tolerance of ±0.002 

inch. 

A COST-DRIVEN PROCESS 

Using the CPE pultruder. Hexcel has 

developed its own proprietary version of 

injection die pultrusion. trademarked 

CRTM for continuous resin transfer 

molding, and has added highly automated off-line systems to help keep production costs down. Hale names cost as the 

important driver in this development. 

"CRTM does away with hand lay-up of 

preforms, combining the high throughput rates of pultrusion with traditional 

resin transfer moldmg to produce high 

quality laminates using tailored fabrics 

and high performance resins." he says. 

This makes it far more economical than 

current hand lay-up approaches used in 

RTM and other molding processes." 

Hexcel further cut costs in the T2000 

floor by using the lowest-cost basic materials — for instance, woven fabrics 

instead of higher-priced stitched preforms for strengthening the panels in offaxis directions. Fiberglass woven fabric 

with warp and weft (0° and 90°) fiber orientation, supplied by Fiber Glass 

Industries (Amsterdam. NY}, is arranged 

with four plies on the top and four on the 

bottom skin for a balanced laminate construction. Zavell says Hexcel saved 

Kenworth additional cost by precisely tailoring the proprietary fiber architecture 

to meet transverse and longitudinal stiffness requirements. 

CRTM MANUFACTURING 

STEPS 

The first step in any pultrusion process 

is to set up and load the material delivery systems. Hexcel has automated 

material handling starting at the resin 

mixing station. 

A base vinyl ester resin, produced by 

Dow Chemical Co. (Midland. Mich.), is 

automatically drawn from an outside bulk 

storage tank directly into a day tank and 

then into a mixing chamber located in a 

-y 
P.4 

^ • ;ciM explosion-proof room. The resin is 

i y* 

v

, j xed with filler, mold release, curing agent 

h,"' d other resin system components, which 

: also automatically drawn directly from 

>rage tanks in pre-programmed 

lounts. 

The operator simply enters the desired 

sin weight, into the programmable logic 

ntroller and the computer controls the 

act proportions for mixing that batch of 

sin. 

The mixed resin is dispensed into a 

)sed pressure pot. When filled, the pot is 

nnected to die injection ports. As one 

essure pot runs out of resin, another is 

nnected. The completely closed delivery 

stem ensures control of the resin's ambitt temperature and consistent viscosity. 

Fiberglass roving and fabric reinforceents are loaded onto racks and creels 

id led through preforming guides that 

ign the material into a near net shape 

:fore it enters the die. Designing tooling 

id oversized rollers to keep the materials 

raight and running true presented 

lother challenge for Hexcel. The preform 

compacted close to final profile dimenons in the initial section of the die. before 

reaches the resin injection area, 

nidirectional roving is pulled through the 

des of the panel, along with woven fabric, 

i prevent resin from flowing out through 

ie die entiy or exit. As fabric runs low, 

ad material from new rolls is attached to 

ie end of the previous roll by bonding 

:rim cloth across the two joining edges, a 

andard technique in pultrusion. Zavell 

ays Hexcel engineered and built all infeed 

>oling and is working on "splice-and-run* 

:chniques that would allow totally autolated material delivery. 

Hexcel receives preshaped 88-inch 

ide. 4-ft long, 2-inch thick balsa sheets 

•om Diab's ProBalsa Division (DeSoto. 

exas) stacked 20 sheets to a pallet. The 

allets are loaded onto a 10- to 15-ft-long 

hain-driven track which pulls them into 

•osition for delivery to the die. Four full 

•allets at a time feed onto a scissor jack in 

. loading mechanism adjacent to the pulrusion machine. Tlie loading mechanism 

>ulls the top sheet from the top pallet and. 

.s each sheet is removed, the scissor jack 

aises die next sheet into position for 

emoval. A bonding adhesive is applied to 

he leading edge of die core, which is 

mshed up against the preceding piece of 

>alsa to maintain continuity. A sensor siglals che controller to remove each pallet as 

t is emptied and. when tlie stack of balsa 

in the loading mechanism runs low. 

another sensor signals the controller to 

bring up four new pallets. 

The balsa is conveyed down the line 

through stationaiy gib saws that trim the 

edges to ensure consistent width of the 

material. The dimension of the core is 

critical to the process as well as to the economics.'* Zavell explains. "A core that's too 

wide or too thick may jam the die. and one 

that's too narrow or too thin may not adequately bond to the skin laminate, allowing resin flows to fill up the gap. driving 

material costs up and affecting weight and 

physical properties as well." After trimming, the loading mechanism delivers the 

core directly into the die. 

After the initial loading, the machine is 

prepared for start-up by pulling the reinforcements through the open die. They are 

tied off on a rigid bar. which is placed in 

the first shuttle. Then puller speed, die 

heat, resin injection pressure and other 

(proprietary) process parameters are 

entered into the programmable logic controller. All parameters are computer-controlled and monitored by multiple sensors. 

Finally, the die is closed and the machine 

is ready for start-up. 

The actual processing starts with resin 

wet-out. Resin is pumped from the pressure pot and flows into the dry preform 

through multiple injection ports located on 

the top and bottom of the injection die. 

After preliminary wet-out near the die 

entiy. the partially impregnated preform is 

pulled through a tapered region in the die 

that gradually compacts the material into 

the final part configuration. A multidimensional resin flow surrounds the 

fibers and thoroughly saturates them as 

they are compacted. 

Following wet-out is the curing/molding process, which occurs in conjunction 

with the pulling operation. The impregnated preform is pulled into the die's cure 

region, where the temperature profile is 

controlled in several heat zones. Die heat 

is ramped up to 175°F and then to 2453F 

through multiple zones from the die entry, 

and down again at the exit to tighten control over gel. crosslinking and final cure. 

Die temperature is closely linked with pull 

speed and injection pressure, so if the 

temperature profile is changed, as a general rule the others must be adjusted as 

well. "If you're pulling faster, you need to 

cure more quickly, so you need elevated 

temperatures or a longer cure zone." Zavell 

explains. "You also need to increase the 

delivery of the resin (injection pressure) in 

order to increase running speed." The 

cured product cools at ambient temperature between the die exit and the shuttle. 

The final step of the pultrusion process 

is part cut-off, which is accomplished by a 

single 34-inch-diameter diamond blade 

mounted on a flying cut-off saw section at 

the downstream end of the machine. The 

computer is signaled to initiate the cut 

when the panel reaches a pre-set length. 

The saw section is synchronized with 

pulling speed to travel downstream while 

the blade cuts across the width of the 

panel. 

Because of the size and weight of the 

part. Hexcel has reduced manual handling 

to a minimum. In an automated take-off 

system that is similar to the core delivery 

system, the cut panel is removed from the 

saw and conveyed directly to a pallet and 

scissor jack on a chain-driven conveyor. 

The panels are then conveyed to a separate scissor-jack loading system. This system employs an ovenhead vacuum shuttle 

and vacuum cups to pick up the top panel 

and locate it in the computer numerically 

controlled (CNC) equipment for secondary 

fabrication trimming and drilling. The fabricated floor panels are similarly vacuumremoved from the cutting table and 

stacked on another scissor jack/pallet. 

The edges of the core are then sealed and 

the panels are packed for shipment to 

Kenworth's assembly line. 

Hexcel is producing about 45 floor panels per day with maximum capacity estimated to be 90 floors per day. or approximately 875 linear ft of pultruded panels. 

Zavell claims that heat, pressure, and pull 

speed are not pacing factors at this time. 

"The bottleneck has not been the pultrusion process: it's been downstream trimming, sealing and packing operations. 

We've been able to increase the speed of 

the CNC by using creative cutting tools." 

he says, adding that this technique was 

something the company spent a lot of time 

developing and the approach is highly proprietary. "As we continue to improve CNC. 

speed and other downstream operations, 

we will work on increasing pultrusion 

speed, with die ultimate goal of doubling 

our production rate." he explains. 

$100 MILLION MARKET 

The Kenworth floor-production contract 

marks a milestone in Hexcel's global 

strategic plan to diversity from its role as 

COMPOSITES TECHNOLOGY JULY/AUGUST 1997 25 
STEP l a STEP l b 

R3_ 

vlaterial deliveiy: Resin is never exposed to the environment throughout com- Reinforcements are loaded onto racks and creels and led through preforming 

puter-controlled mixing, delivery to the machine and injection into the die. guides and rollers to preform near net shapes before die entry. 

STEP1C STEP 2 

Balsa core is edge-trimmed and delivered to the die without any manual handling. 

Resin injection: Resin is injected into the preform through multiple ports 01 

the top and bottom of the die. 

STEP 3 A STEP3B 

Molding and pulling: The material cures in the heated die and die 88-inchwide. 2-in-thick molded sandwich panel exits the die. Reciprocating shuttles with 100.000-lb pull force continuously pull Uie p; 

els oui of the die. 

H 
P.6 

STEP 4 STEP5 

it-off: Saw secUon travels downstream with the part while a circular blade 

ts the panel to length. 

Off-line finishing: Automatic handling systems move the panel offline for CNC 

trimming and drilling, sealing and packaging. 

producer of high-performance composite materials and strucxes for the aerospace industry by applying its expertise to non-

:rospace transportation and recreation businesses. Warner 

unes the company's target markets for the CRTM process as 

lass 7 and 8 trucks, infrastructure, marine/offshore and shipng containers. He estimates that those segments represent an 

'erall annual market of $50 to $100 million. "Since the growth 

potential is highly related to the success of Kenworth's innovative T2000 truck, we are optimistic about the long-run potential 

for CRTM in this market segment." Wamer says. 

For more information, circle the number on the Reader 

Service Card: core, 274; reinforcements, 275: vinyl ester 

resin. 276; pultrusion equip.. 277. 

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COMPOSITE S TECHNOLOGY miy/.AMIDST IOQ7 27