Tooling Materials for Plastic Molding Applications Factors That Determine Mold Steel Requirements

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

Working Grade Description 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 Precipitation hardening stainless with outstanding corrosion Corrax 46 - 50 resistance PM stainless steel with an excellent combination of Elmax 56 – 60 corrosion and wear resistance 31 – 36 Royalloy Pre-hardened, free-machining stainless holder material (290-330 BHN) Pre-hardened, beryllium copper alloy for high thermal 30 HRC or BeCu Alloy 172 conductivity 40 HRC The size of the sphere corresponds to the relative corrosion resistance Stavax ESR – 420 modified

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 Mold Polishing & Finishing Polishing Sequence

240 SiC

6µ Diamond Paste

1µ Diamond Paste Sulfide “Stringers”

• Polishability • Corrosion • Toughness Non-Metallic Inclusions

Relatively Hard Inclusion 1 Steel Matrix

Void 3 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 mold hardware • 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 Uddeholm Mirrax ESR

C Si Mn Cr Ni Mo V Nitrogen Mirrax ESR 0.25 0.35 0.55 13.3 1.35 0.35 0.35 +

• 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) 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

Mirrax ESR

surface centre

Type 420 Stainless Impact Testing Impact Toughness Mirrax ESR vs. 420 ESR, 10 x 24”

10 9 8 7 6 5 Mirrax ESR 4 420 ESR 3 2 1

CVN Impact Toughness (Joule, ST @ core) CVN Impact Toughness 0 Low temp, 50 HRC High temp, 51 HRC Uddeholm Mirrax 40

C Si Mn Cr Ni Mo V Nitrogen Mirrax40 0.21 0.9 0.45 13.5 0.6 0.2 0.25 +

• 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 Corrax

C Si Mn Cr Ni Mo Al Corrax 0.03 0.3 0.3 12.0 9.2 1.4 1.6 • 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. Corrax

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

1) Not suitable for Optical or SPI #1 Finish applications (expect similar polishabilty to our P20) 2) Material will shrink during the aging (hardening) process 3) Reduced cutting speeds (Vc) relative to a Type 420 stainless PM Facility – Kapfenberg, Austria

Established 1999 Production capacity: > 6000 metric tons MICROCLEAN PM Process

Gas Atomization / Powder Collection Special Melting / Refining Practice

"3 rd Generation" Capsule Powder Technology Filling

Capsule Welding Hot Isostatic Pressing (HIP) to 100% Density MICROCLEAN PM Powder Production

Rapidly Solidified Powder

100 µµµ

Gas Atomization (N 2) Spherical Shape / Uniform Composition Consolidation to 100% Density by Hot Isostatic Pressing (HIP)

Standard Capsule Dimension 17.7- 21.7”Ø (450-550 mm) x 67” (1700 mm); 2 to 3 mtons

fabricated steel canister loaded with powder Consolidation to 100% Density by 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

C Si Mn Cr Mo V ElmaxSuperClean 1.7 0.4 0.3 18.0 1.0 3.0

• 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) Non-Stainless Grades for Mold Applications

Working Grade Description Hardness (HRC) Orvar Superior PremiumH13, 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 Outstandingtoughness & high polishability 54 –61 PM – 4% Vanadium, excellent combination of wear resistance 58 - 62 Vanadis 4 Extra and toughness K294 Microclean PM – 10% Vanadium, extreme abrasive wear applications 58-64 Orvar Superior Premium 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

C Si Mn Cr Mo V W360 Isobloc 0.50 0.20 0.25 4.5 3.0 .55

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

C Si Mn Cr Mo V Caldie 0.7 0.2 0.5 5.0 2.3 0.5

• Matrix Tool Steel – Essentially free of Primary Carbides • Produced using PESR • Typical working hardness 56-61 HRC Tempering Curves S7 and Caldie Caldie Microstructure

Matrix Tool Steel HSS Microstructures

Conventionally Cast P/M Production Route Uddeholm Vanadis 4 Extra

C Si Mn Cr Mo V Vanadis4 Extra 1.4 0.4 0.4 4.7 3.5 3.7

• Typical working hardness 58-62 HRC • Excellent choice for resins containing abrasive fillers • Smaller, core/cavity inserts with complex geometries Böhler K294 Microclean C Si Mn Cr Mo V K294 Microclean 2.5 0.9 0.5 5.2 1.3 9.7

• Typical working hardness 58-64 HRC • Extreme, abrasive wear applications • Injection molding components such as screws, nozzles and barrel liners Thruhard Supreme High Hard

C Si Mn S Cr Ni Mo V

Thruhard 0.26 0.10 1.45 0.002 1.25 1.05 0.50 0.10 Supreme

• 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

Co + Ni Be Cu BeCuAlloy 172 0.25 1.9 97+

• 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 BeCu Alloy 172 APPLICATIONS

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

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