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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
0123456789
10
Low temp, 50 HRC High temp, 51 HRC
Mirrax ESR420 ESR
Mirrax ESR vs. 420 ESR, 10 x 24”
CV
N Im
pac
t To
ug
hn
ess
(Jo
ule
, ST
@ c
ore
)
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