Mike Koebel Western Moldmakers Trade Fair November 11, 2015

Tooling Materials for Plastic Molding Applications

Factors that Determine Mold Steel Requirements

Aggressive Resins:

• corrosive by-products

• abrasive fillers

Design Requirements:

• complexity of parts

• process

Lens Quality/Cosmetic Appearance:

• polishability

Stainless Mold Steels

Grade DescriptionWorking

Hardness (HRC)

Stavax ESR 420 modified stainless steel 46 – 52

Mirrax ESR 400 series stainless for medium to large molds 46 - 51

Mirrax 40 400 series stainless delivered in the pre-hardened condition 40

CorraxPrecipitation hardening stainless with outstanding corrosion resistance

46 - 50

ElmaxPM stainless steel with an excellent combination of corrosion and wear resistance

56 – 60

Royalloy Pre-hardened, free-machining stainless holder material 31 – 36

(290-330 BHN)

BeCu Alloy 172Pre-hardened, beryllium copper alloy for high thermal conductivity

30 HRC or 40 HRC

The size of the sphere corresponds

to the relative corrosion resistance

C Si Mn Cr V S

AISI 420 0.15 min 1.00 max 1.00 max 12.0 – 14.0 0.030 max

Stavax ESR 0.38 0.90 0.50 13.6 0.30 0.003

• Small-to-medium size cavites and cores where high polishability is required and/or when corrosive plastics are molded

• Compression molds

• Dies and calipers for plastic extrusion

• Structural components

• Long running molds

Stavax ESR – 420 modified

Mold Polishing & Finishing

Polishing Sequence

240 SiC

6µ Diamond Paste

1µ Diamond Paste

Sulfide “Stringers”

• Polishability

• Corrosion

• Toughness

1

2

3

Relatively Hard Inclusion

Steel Matrix

Void

Non-Metallic Inclusions

Polishability

ESR vs. Standard

Perfect polished finish

Poor polished finish caused by impurities in steel

Ingot Casting

The long solidification time results in the formation of large, blocky carbides that will later align themselves with the rolling/forging direction.

Electroslag Remelting (ESR)

ADVANTAGES OVER CONVENTIONAL STEELS• An improved solidification microstructure

• More homogeneous material

• Cleaner material

Stavax Heat Treatment

Continuous Cooling Transformation (CCT) Curve

Grain Boundary Carbides

Stress Corrosion Cracking (SCC)

Ensure that the cooling water chemistry does not encourage SCC

• Maintain chlorides below 10 ppm and pH-level between 5-8

Eliminate dead zone in the cooling circuits

• Design to create and maintain turbulent flow conditions throughout the entire cooling circuit

• Ream out cooling lines when possible• Minimize sharp cooling line junctions especially in combination with thin walls

Choose plugs, baffles and other mold hardware to minimize galvanic corrosion effects

• Choose 300/400 series stainless, plastic/Teflon, etc. versus brass for moldhardware

• Avoid pipe taps, use straight taps with O-ring plugs or use expansion plugs as an alternative

Pressure/Protective Gas Electoslag Remelting (PESR)

EQUIPMENT DATA:� Remelting under pressure

and/or protective atmosphere � Ability to alloy steel with nitrogen� Low level of alloy segregation� Extremely low sulfur content� Minimum levels of other

nonmetallic inclusions

C Si Mn Cr Ni Mo V Nitrogen

Mirrax ESR 0.25 0.35 0.55 13.3 1.35 0.35 0.35 +

Uddeholm Mirrax ESR

• Better corrosion resistance and better ductility than a 420 ESR mold steel.

• Pressurized Electro-Slag Remelted (PESR) yields a clean, homogeneous material, ideal for lens quality tooling.

• Typically quenched & tempered to a hardness level of 49 – 51 HRC.

Mirrax ESR• Produced via Pressurized-ESR

• Sound microstructure at the mold center (area where cavity is machined and/or cooling lines are located)

• Higher toughness levels• Improved corrosion resistance

• Improved resistance to pitting and SCC

• Increased hardenability – important for thicker cross sections

• High temperature temper • Lower residual stresses

Mirrax – Note Heat Treatment Considerations

Corrosion Resistance

• Mirrax ESR has better corrosion resistance compared to current Type 420 stainless steel

• Salt spray test (5% NaCl solution, pH 3 at 68°F)

Mirrax ESR

Type 420 Stainless

centresurface

Specimens taken from heat treated blocks with dimension:10 x 19.7 x 24” (254 x 500 x 610 mm)1870°F + 930°F (1020°C + 500°C) / 2x2h

Impact Testing

Impact Toughness

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10

Low temp, 50 HRC High temp, 51 HRC

Mirrax ESR420 ESR

Mirrax ESR vs. 420 ESR, 10 x 24”

CV

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pac

t To

ug

hn

ess

(Jo

ule

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ore

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C Si Mn Cr Ni Mo V Nitrogen

Mirrax 40 0.21 0.9 0.45 13.5 0.6 0.2 0.25 +

Uddeholm Mirrax 40

• Prehardened stainless steel ~40 HRC (360 – 400 BHN)• No heat treament is required (simplifies tool building process

& reduces cost)• Pressurized Electro-Slag Remelted (PESR) yields a clean,

homogeneous material, ideal for polishing• Excellent machinability and high-level of ductility & toughness

C Si Mn Cr Ni Mo AlCorrax 0.03 0.3 0.3 12.0 9.2 1.4 1.6

Corrax

• Precipitation hardnening stainless • As-supplied ~34 HRC (solutionized condition)• Working hardness range 34 – 49 HRC (age-hardened) • Polishability is comparable to P20; not recommended

for optical finishes.

1) Not suitable for Optical or SPI #1 Finish applications (expect similar polishabilty to our P20)

2) Material will shrink during the aging (hardening) process3) Reduced cutting speeds (Vc) relative to a Type 420 stainless

Three important points to bring to the attention of the customer:

Corrax

PM Facility – Kapfenberg, Austria

Established 1999Production capacity:

> 6000 metric tons

MICROCLEAN PM Process

"3rd Generation"

Powder Technology

Gas Atomization / Powder Collection

Capsule Filling

Special Melting / Refining Practice

Capsule Welding

Hot Isostatic Pressing (HIP)to 100% Density

MICROCLEAN PM Powder Production

Rapidly Solidified Powder

Gas Atomization (N2) Spherical Shape / Uniform Composition

100µµµµ

fabricated steel canister loaded with powder

Consolidation to 100% Densityby Hot Isostatic Pressing (HIP)

Standard Capsule Dimension

17.7- 21.7ӯ (450-550 mm)

x 67” (1700 mm); 2 to 3 mtons

Consolidation to 100% Densityby Hot Isostatic Pressing (HIP)

Capsule is heated to 2100°F (1150°C)

Compaction @1000 bars(~14,500 psi)

Comparison of Microstructures

Conventionally Cast P/M Production Route

Uddeholm Elmax

• Typical working hardness 56-60 HRC • Abrasive wear applications where corrosion resistance is required • Injection molding components such as screws and barrel liners• Molds for the electronics industry (IC, connectors, switches)• High wear inserts (nozzles, gate areas)

C Si Mn Cr Mo VElmax SuperClean 1.7 0.4 0.3 18.0 1.0 3.0

Non-Stainless Grades for Mold Applications

Grade DescriptionWorking

Hardness (HRC)

Orvar Superior Premium H13, excellent toughness and polishability 44 – 52

Dievar Outstanding toughness (greater than H13) 44 - 52

W400 VMR Optimal toughness level 44 – 52

W360 Isobloc Additional wear resistance and compressive strength 52 - 58

S7 MQ High toughness, shock resistant 52 - 56

Caldie Outstanding toughness & high polishability 54 – 61

Vanadis 4 ExtraPM – 4% Vanadium, excellent combination of wear resistance and toughness

58 - 62

K294 Microclean PM – 10% Vanadium, extreme abrasive wear applications 58 - 64

Orvar SuperiorPremium H13

• Good wear properties and resistance to indentation• Outstanding polishability and texturing characteristics• Excellent toughness• Electro-slag remelted (ESR)

C Si Mn Cr Mo V

Orvar Superior 0.39 1.0 0.4 5.2 1.4 0.9

As-delivered: 180 Brinell

Typical Application Hardness 44 – 52 HRC

Mold Quality S7

• Good toughness and wear resistance• Injection, compression and transfer molds• Mold components (slides, ejector pins, core pins and

stripper rings)

C Si Mn Cr Mo S

Mold Quality S7 0.53 0.30 0.7 3.2 1.5 0.005

As-delivered: 200 Brinell

Typical Application Hardness 52 – 56 HRC

Böhler W360 Isobloc

• Typical working hardness 52 – 57 HRC • ESR quality; excellent cleanliness and toughness

C Si Mn Cr Mo VW360 Isobloc 0.50 0.20 0.25 4.5 3.0 .55

Uddeholm Caldie Composition

• Matrix Tool Steel – Essentially free of Primary Carbides

• Produced using PESR

• Typical working hardness 56-61 HRC

C Si Mn Cr Mo VCaldie 0.7 0.2 0.5 5.0 2.3 0.5

Tempering Curves S7 and Caldie

Caldie Microstructure

Matrix Tool Steel

HSS Microstructures

Conventionally Cast P/M Production Route

Uddeholm Vanadis 4 Extra

• Typical working hardness 58-62 HRC • Excellent choice for resins containing abrasive fillers• Smaller, core/cavity inserts with complex geometries

C Si Mn Cr Mo VVanadis 4 Extra 1.4 0.4 0.4 4.7 3.5 3.7

Böhler K294 Microclean

• Typical working hardness 58-64 HRC • Extreme, abrasive wear applications• Injection molding components such as screws, nozzles and

barrel liners

C Si Mn Cr Mo VK294 Microclean 2.5 0.9 0.5 5.2 1.3 9.7

C Si Mn S Cr Ni Mo V

ThruhardSupreme

0.26 0.10 1.45 0.002 1.25 1.05 0.50 0.10

Thruhard Supreme High Hard

• Prehardened to 310 to 355 BHN (~33 to 38 HRC)• Polishability up to a 600 grit (high gloss finish)• Good weldability• High thermal conductivity

BeCu Alloy 172

• High Hard: 36-42 HRC and Low Hard: 26-32 HRC• High thermal conductivity; 3-4 times that of steel• Good corrosion resistance• Anti-galling properties• Weldable

Co + Ni Be CuBeCu Alloy 172 0.25 1.9 97+

APPLICATIONS

•Blow molds: pinch offs, neck rings, handle inserts•Injection molds: molds, cores, inserts•Injection nozzles and manifolds for hot runner systems

BeCu Alloy 172

Filler Metal for Welding Plastic Mold Materials

Grade Diameter (mm) - Type Diameter (mm) - Type

Impax 2.5, 3.2, 4.0 - Electrode 1.0, 1.6 – GTAW/TIG

Caldie 2.5, 3.2 - Electrode 1.0, 1.6 – GTAW/TIG

*Stavax -- 1.0, 1.6 – GTAW/TIG

Mirrax -- 1.0, 1.6 – GTAW/TIG

Corrax -- 1.0, 1.6 – GTAW/TIG

Moldmax -- 1.6, 2.4, 3.2 – GTAW/TIG

*Available as 0.2, 0.3, 0.4, 0.5 and 0.6 mm diameter for laser & micro welding

Plastics Mold Steel www.bucorp.com

1-800-638-2520