FM ALLOY®

Mold Steel for Plastic with Corrosion Resistance and Mirror ﬁnish-ability

PROVA Series

Mold Steel for Plastic with Corrosion Resistance and Mirror ﬁnish-ability

PROVA Series

The PROVA series are high quality stainless steelsthat are the best for molds on plactic molding.
Features• Excellent mirror ﬁnish-ability.
• Good machinability.
• Superior corrosion resistance.
• Good wear resistance.
• Small deformation by heat treatment.
• Materials can be provided as already hardened (32HRC).

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Relationship
Schematic diagram

PROVA-500

8Cr grade
60

PROVA-450
Hardness (HRC)

50PROVA-400
P21 grade40
P20 grade
30PROVA-400
PROVA-450

20(Already hardened)

S55C
10Better
05,000010,000

15,000Mirror polishability (Grain mesh)

Steel GradeGradeMirror ﬁnish-ability Corrosion resistance Wear resistance

Cost

PROVA-400

◎

○○

○

PROVA-450

○○

○

◎

PROVA-500○○◎△Applications• Mold for plastic with ﬁre-retarding material orPVC which are strongly corrosive .............................. Corrosion Resistance• Mold for thermo-setting resin or plastic with glass ﬁber ... Wear Resistance• Mold for transparent plastics which are usedfor optical or medical devices ..................................... Mirror Finish-ability• Mold for high-pressure plastic injection (PROVA-500) ............................. Rigidity
Plastic Material

Examples of ﬁnish product

PVC, PS, PE, PF, PC, PMMA,PP, EP, ﬂame resistant materials

Light guide plates, cellular phone enclosure,lense, high-quality plastic containers, and more

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PROVA Series characteristics
Mirror finish-ability（PROVA-400）◆ PROVA series have minimum non-metallic inclusions to show superior mirror like ﬁnish.

Example: Polishing the mold for a cellular phone enclosure to a mirror ﬁnishSurface after polishing PROVA-400：pinholes

Surface after polishing Equivalent material in market

0.1㎜

0.1㎜

Sample hardness: 53 HRC, Polishing condition: #1,500 Emery paper → Diamond compound (#2,000 → #3,000 → #5,000)◆ Mirror surface polishing procedure (example)❶ Oil stone (using kerosene)↓❷ Sandpaper (using kerosene)↓❸ Diamond compound＃180 → ＃240 → ＃320 → ＃400 → ＃600 → ＃800
＃600 → ＃800 → ＃1,000 → ＃1,200 → ＃1,500＃1,200 → ＃1,800 → ＃3,000 → ＃8,000 → #14,000• Polish with as light a load as possible to reduce unevenness and pinholes on surface being polished.
• When changing grade of abrasive, also change polishing direction 90˚ and check that no polish marks remain.
• Completely remove all the previous abrasive powder when changing abrasive grades.
• Do not skip any grades of abrasive.
• Only diamond compound can be used.
• Use rust prevention measures when polishing work is interrupted.

◆ Mirror ﬁnish quality

GradePROVA-400

PROVA-450
PROVA-500

3Hardness (HRC)

Mirror ﬁnish quality

Application

Already hardened 29 to 35

Maximum #8,000

Transparent productHardened/tempered 50 to 53

Maximum #15,000

Ultra-mirror ﬁnish productAlready hardened 29 to 35

Maximum #8,000

Transparent product

Hardened/tempered 50 to 53

Maximum #13,000

Mirror ﬁnish product

Hardened/tempered 58 to 62

Maximum #13,000

Mirror ﬁnish productMachinability（PROVA-400）◆ Optimized design of components in PROVA series gives it superior machinability, which reduces tool costs and improves automation.

Results of test for machinability with ball endmill
Condition
Equivalent material B in market

Cutting tool (Ball endmill): NACHI GS Mill Ball R3 x 9 x 80 x φ6 2GSR3
Cutting speed at cutting point: 42 m/min (RPM: 7900 min-1)

Wear on cutting edge (mm)0.10

Feed: 920 mm/min (feed rate 0.058 mm/t)
Cutting Depth: cutting depth aa = 0.12 mm x 2 passes, pick feed Pf = 0.3 mm
Cutting Fluid: Water soluble emulsion

PROVA-400

Equivalent material A in market

Test machine: Matsuura FX-5
0.05

Work dimension (test specimen): 40 x 40 x 200 hardened and tempered (53 HRC)
Image of work

Ball endmill
GoodPROVA-400 shows less wear of ball endmillcompared to equivalent material A and B.

0.00

020

4060

80

100

Work material

aa=0.12mm

Cutting length (m)Wear on cutting edge when milling pocket with ball endmill

Comparison of wear on cutting edge ofball endmill after rough cutting of mold

Pf=0.3mm

Cutting edge after milling PROVA-400 (48 HRC)

Cutting edge after milling Equivalent material in market (48 HRC)

Condition
Cutting tool: Carbide Ball endmill R3. 0 × 12.0, tooth length 12, shank φ6
Cutting speed at cutting point: 81 m/min (RPM 4300 min-1)
Feed: 520 mm/min (feed rate 0.06 mm/t)
Cutting Depth: aa = 0.2 mm, pick feed Pf = 1.5 mm, cut length 19 m

Possible to continue using tool

Excessive damage to cutting edge ends life of tool

◆ Surface roughness of PROVA series after grinding is good, which helps shorten lead times.

Comparison of ﬁnish quality using ball endmill
Condition
Cutting tool: Carbide Ball endmill R2, tooth length 8, underhead 8, shank φ4, rpm: 20,00 min-1
Feed: 1,600 mm/min, Cutting Depth aa = 0.001 mm, Cutting Fluid: oil mist, machine: YASUDA YBM640V
Rt: Maximum cross-section height of roughness curve

GradeResults of measuring surface roughness

RtPROVA-400(52HRC)

1.7

Equivalent material
in market(52HRC)

3.54

PROVA Series characteristics
Corrosion resistance (PROVA-400, 500)
◆ PROVA Series are superior for corrosion resistance.

1.0Corrosion weight loss ratio

Corrosion weight loss ratio

1.0
0.8

0.6
0.4

0.6
0.4

0.2

0.0

PROVA-400

Equivalent material Ain market

GoodGood

0.2

0.8

Equivalent material B
in market

0.0PROVA-500

Test reagent: 5% sulfuric acid Temperature: 40°C Immersion time: 5hrs

SUS440C

8Cr grade

Test reagent: 10% sulfuric acid Temperature: 40°C Immersion time: 4hrs

Cleanliness (PROVA-400, 450)
◆ PROVA series has dramatically reduced non-metallic inclusions.
A sulﬁdeGradeNon-metal inclusions ranking (ASTM-E45 D reg)

B aluminum

C silicate

D granular oxides

THTH

TH

T

H

PROVA-400

0000000.5

0

PROVA-450

0000000.50.5

Equivalent material in market

001.00001.00

Physical properties
Coefﬁcient of thermal expansion (x 10-6/K)

Grade

30〜100˚C

30〜200˚C

30〜300˚C

30〜400˚C

30〜500˚C

10.9

11.4

11.8

12.2

12.5

PROVA-400, 450

Coefﬁcient of thermal conductivity (W/m･K)

Grade

Room temperature

100˚C

200˚C

300˚C

PROVA-400, 450

20.6(27˚C)

21.6

23.2

24.5

PROVA-500

16.6(22˚C)

18.1

19.8

21.4

PROVA-400, 450：Quenched and tempered (53 HRC)

Speciﬁc heat (J/kg･K)
400˚C

500˚C

R.T.

25.4

26.0

455
(27˚C)

22.5

23.3443(22˚C)

PROVA-500：Quenched and tempered (61 HRC)

Mechanical properties (PROVA-400, 450)
Tensile strength (N/mm2)

Elongation (%)

Drawability (%)

Impact resistance (J/cm2)*

1950

11.8

35.5

49.5

Test material is quenched and tempered (53 HRC) material, φ20 rolled round steel used in rolled direction*Room temperature #4 impact test material (JIS Z2202 mold material impact test)

Welding (PROVA-400, 450)

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Heating temperatures

Status of heat treatment

Weldability

Already hardened 29 to 35 HRC

AWS：ER420（JIS：SUS420J2）

200〜250˚C650˚C

Quenching-tempering 50 to 53 HRC

AWS：ER420（JIS：SUS420J2）

200〜250˚C250˚C×2 (When anti-corrosion is important)
510˚C×2 (When breakage during EDM is important)Pre-heat

Post-heating

PROVA Series heat treatment
Heat treatment conditions
HardeningTempering

GradeDemand properties
Pre-heat (˚C)

PROVA-400

PROVA-450

PROVA-500

600〜850600〜850820〜860

Austenitizing (˚C) Temperature (˚C) Hardness (HRC)
200〜400

51〜53

Corrosion resistance /Low age-deformation

490〜510

51〜53

Avoid breaking at electric discharging

200〜400

51〜53

Corrosion resistance /Low age-deformation

490〜510

51〜53

Avoid breaking at electric discharging

150〜200

60UP

Corrosion resistance /Low age-deformation

500〜550

58UP

Avoid breaking at electric discharging

1,000〜1,050

1,000〜1,050

1,070〜1,120

Dimensional distortion (PROVA-400, 450)
◆ Homogenizing process greatly reduces dimension variations during heat treatment.

+ 0.10Dimensional distortion (%)

RadialLength+ 0.05

+ 0.00- 0.05- 0.10
0100

200

300

400500Tempering temp. (°C)
Conditions austeniﬁzing: 1,030˚Cx60min Vacuum furnace N2 gas pressure quenching (130 kPa)
Sample size: φ50×150L

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S4304E-2
2010.10.Y-ABE-ABE