Injection Mold Steel Selection Chart: P20 vs 718 vs H13 vs 420 for Resin Risk, Tool Life, and Spec Review

Industrial workbench with P20, H13, and 420 stainless steel sample blocks alongside an engineering selection chart.

Fig 1: Aligning steel grades with resin risk and polish targets before PO release.

Mold steel selection determines wear life, corrosion resistance, polish stability, and repairability. This engineering reference serves to verify if your steel spec is safe for the intended resin and production volume. It compares P20, 718, NAK80, H13, S7, and 420/1.2316 based on practical heat-treatment paths and failure risk mitigation.

Technical Note: Mismatched steel selection leads to predictable failures such as premature gate wear, corrosion pitting in PVC/FR programs, or unstable polish on cosmetic cavities.

Engineering Review Assets on this page:

  • ✔ Compare steel grades side-by-side by hardness route and wear resistance.
  • ✔ Map resin risk (GF, PVC, High-Gloss) to specific material callouts.
  • ✔ Review component-level recommendations for cavities, slides, and ejectors.
  • ✔ Identify heat-treatment, EDM recast layer, and weld-repair risks.

Need the technical foundation? See our mold steel selection framework

What Buyers and Engineers Should Verify Before Steel Purchase

Who this page is for

Use this reference to review mold steel decisions before RFQ approval, steel PO release, or mold design freeze. It is built for teams that need to verify steel callouts, hardness logic, and wear-critical component choices:

  • Tooling Engineers Reviewing if cavity and wear-surface steel grades match tool life and resin abrasion.
  • Sourcing Engineers Checking if supplier steel callouts and hardness routes are defined clearly in the RFQ.
  • Export Mold Buyers Reviewing quote transparency regarding steel grade and corrosion-risk assumptions.
  • Program Managers Identifying and flagging unresolved material risks before mold base release.

What engineering decisions this chart supports

Use the tables below to review whether the current mold steel specification is technically aligned with resin chemistry, finish, and tool-life targets:

  • Primary cavity and core steel
  • Hardness route for slides
  • PVC / FR corrosion mitigation
  • Steel for glass-filled wear
  • SPI A-1/A-2 polish cleanliness
  • Heat-treatment & EDM risk
  • Nitriding or coating limits
  • Steel for moving pairs friction

Included engineering reference assets

This page provides structural evidence to support your RFQ review and steel specification alignment:

■
60-Second Selection Logic: A technical review layer for verifying if the current steel direction is correct before detailed approval.
■
Side-by-Side Comparison Matrix: A working reference table for reviewing wear resistance, corrosion risk, and polish ceiling trade-offs.
■
Downloadable Engineering Cheat Sheet: A 1-page PDF reference for project files. Note that regulated programs may also require supporting quality documents, PPAP, and FAI deliverables.

Note: This chart is not a substitute for the mold specification sheet template for injection molding; it is a review reference used to verify whether the steel callout is technically consistent and appropriate for the intended program.

Quick Review: Injection Mold Steel Selection Rules

Tooling review table showing H13, 420 stainless, and polish-grade steel inserts for resin risk assessment.

Fig 2: Reviewing steel selection rules against resin abrasion and corrosion risk.

Injection mold steel selection should balance resin abrasion, corrosion risk, finish targets, and toughness before final specification approval. P20 or 718 is the baseline for non-abrasive programs; H13 is often justified for wear-critical gate and insert zones; 420/1.2316 is usually preferred for corrosion-prone cavity surfaces; and S7 provides the impact toughness needed to prevent shut-off chipping.

The 4 Decision Variables: Wear, Corrosion, Polish, Toughness

Before final steel approval, review your project against the four conditions that most often drive gate land wear, corrosion pitting, polish loss, or shut-off chipping. Every steel choice is a technical trade-off between upfront cost and long-term production stability.

1. P20 or 718 (Standard Baseline)

Appropriate for non-abrasive PP, PE, or ABS programs in low-to-mid volume tools. Engineering Risk: Rapid wear or corrosion pitting if used outside non-abrasive, controlled environments.

2. H13 Hardened (The Abrasion Rule)

Often justified for gates, cavity inserts, and other wear-critical zones running glass-filled resins. Engineering Risk: Soft steel in these locations leads to rapid gate erosion, flash, and loss of dimensional drift.

3. 420 / 1.2316 (The Corrosion Rule)

The correct baseline for exposed cavity, core, and other corrosion-exposed surfaces in PVC or FR programs. Engineering Risk: Acidic outgassing pits non-stainless steel, destroying finishes and causing part sticking.

4. S7 Impact Steel (The Toughness Rule)

Specified for fragile shut-offs or edge-loaded features where impact toughness matters more than hardness. Engineering Risk: Brittle steels chip under repeated impact, while S7 maintains edge seal integrity.

5. ESR Grades (The Polish Ceiling)

Usually required where polish retention and cosmetic consistency (SPI A-1 or A-2) are critical. Engineering Risk: Standard grades may reveal inclusions as pinholes or orange peel during final polishing stages.

If your program involves both glass-filled wear and PVC/FR corrosion risk, review this comparison: H13 vs S136 mold steel for wear resistance and corrosion risk .

Steel Comparison Table: P20 vs 718 vs NAK80 vs H13 vs S7 vs 420/1.2316 by Hardness, Wear, and Risk

Use this comparison matrix to review whether the current steel callout matches the expected resin behavior, finish target, and tool life before final mold specification approval.

The choice between pre-hardened (P20/718/NAK80) and through-hardened (H13/S7/420) steel determines the tool's dimensional stability and maintenance intervals. Hardness is only one factor; wear resistance and corrosion stability must align with your resin chemistry.

Mold steel comparison setup showing P20, H13, and 420 stainless inserts with hardness data.

Fig 4: Reviewing steel inserts by hardness route and polish ceiling.

Steel Grade Condition Typical Hardness Wear Polish Corrosion Best Use Case Main Failure Risk
P20 (1.2311) Pre-hard 28-32 HRC Fair Good Low Unfilled ABS/PP/PE Early gate wear with GF resins.
718 (1.2738) Pre-hard 32-38 HRC Moderate Better Low Large cavity plates Unstable finish for SPI A1.
NAK80 Pre-hard 37-43 HRC Moderate Excellent Moderate High-gloss PMMA/PC Brittle for high-impact slides.
H13 (1.2344) Hardened 48-52 HRC Excellent Good Moderate Abrasive GF Resins Heat checking if poorly tempered.
S7 Hardened 48-54 HRC Good Fair Low Impact shut-offs Not for mirror polish apps.
420 / 1.2316 Hardened 48-52 HRC Good Excellent V. High PVC / FR / Optical Overspec for low-volume ABS.

Hardness Route

Choosing between pre-hardened and through-hardened steel affects distortion risk and fitting time. Review the heat treatment inspection report template to ensure section uniformity before PO release.

Polish Stability

ESR (Electroslag Remelting) cleanliness is the dominant factor for SPI A1/A2 mirror finishes. Align your target with our mold finish standards guide to avoid inclusions and orange peel.

* This comparison table is a technical review reference, not a final component-level steel release document.

Component-Level Mold Steel Selection Logic: Reviewing Wear, Polish, and Corrosion Zones

A mold should not use one steel grade across every component. Core and cavity inserts, slides, and ejectors operate under vastly different wear modes, surface demands, and friction requirements.

Steel callouts should be assigned by local failure mode rather than by a single mold-wide default. For full geometry alignment, review our injection mold design decision guide.

Mold Component Recommended Steel Decision Logic: When to Upgrade Engineering Risk Mitigated
Core and Cavity Inserts P20 / 718H / H13 / 420 Upgrade to H13 or 420 when resin abrasion or corrosion risk increases; avoid overspec for low-volume programs. Gate wear, flash, and pitting.
High-Polish Inserts NAK80 / 420 ESR / S136 ESR grades are usually preferred for SPI A-1/A-2 to ensure cosmetic stability and polish consistency. Polish loss and surface instability.
Slides, Lifters, Gibs H13 / S7 / DF2 Nitriding is standard. A controlled hardness differential is often used between the moving pair to prevent cold-welding. Galling and mechanical seizure.
Ejector Pins & Sleeves SKD61 (H13-class) / HSS Through-hardened + Nitriding or DLC coating for high-speed cycles or abrasive resins. Scuffing, pin flash, and burrs.

Failure-Mode Evidence: When Component Steel Is Mismatched

Detailed view of gate land wear on a mold insert

Fig 5: Gate land wear under abrasive resin flow.

Gate Land Erosion Management

In glass-filled (GF) programs, gate areas see the highest flow velocity. Soft cavity steel leads to rapid fiber wash. Buyers should verify whether the gate area is treated as a local wear zone with a hardened insert strategy to maintain edge integrity over time.

Slide galling on mold components

Fig 6: Slide galling caused by insufficient pairing strategy.

Slide & Lifter Seizure Control

Moving components are prone to galling if the hardness route and surface treatment are mismatched. Moving mold pairs should be reviewed by hardness pairing and surface strategy, not steel grade alone, to ensure mechanical reliability.

Ejector scuffing and wear evidence

Fig 7: Ejector scuffing leading to molded-part flash.

Ejector System Clearance Integrity

Repeated motion causes scuffing if steel grade and coating are mismatched. Ejector wear should be reviewed as a clearance issue before it results in part flash. We utilize DLC or TiN coatings in high-cycle tools to prevent witness marks and sticking.

For the full selection framework behind these component callouts, review: how to select injection mold steel based on tool life, resin wear, and corrosion .

Resin-to-Steel Mapping: What Buyers Should Review Before Freezing the Steel Spec

Resin chemistry and gas behavior directly affect mold steel callout and local failure risk. Resin and steel selection should never be frozen independently. Use this matrix to verify if your material callout matches your resin's behavior.

Resin / Additive Primary Risk Primary Steel Treatment / Condition What Happens If Ignored Buyer Checkpoint
Unfilled ABS/PP/PE Minimal Risk P20 / 718 Pre-hardened Overspec increases cost without solving cooling issues. Is this a non-abrasive, mid-volume tool?
PC / PMMA (High-Gloss) Inclusions NAK80 / 420 ESR Mirror Polish Pinholes and unstable cosmetic gloss levels. Is the target SPI finish A-1 or A-2?
PA66+GF / PBT+GF Fiber Wash Hardened H13 Through-Hardened Rapid gate wear and dimensional drift. Has the exact filler percentage been confirmed?
PVC (Corrosive) Acidic Pitting 420 / 1.2316 Hardened Stainless Cavity pitting and cooling channel rust. Are you using stainless water manifolds?

Unfilled Commodity Selection

P20 is often sufficient for non-abrasive programs where the real limit is cycle efficiency. Upgrading steel too early does not solve geometry-related stability issues.

PA66+GF Abrasive Management

Glass-filled resins shift the decision toward wear-critical zones. If these areas remain under-hardened, fiber wash and flash growth become more likely much earlier than planned.

PVC / FR Corrosive Control

PVC programs should review exposed cavity surfaces and water-circuits together. Treating corrosion as a secondary issue leads to pitting and maintenance instability.

For the full selection framework, see our technical article on how to select injection mold steel based on tool life, resin wear, and corrosion .

What the Mold Steel Callout Affects — and What It Does Not

A higher-grade steel expands the performance window, but it does not guarantee wear life, polish stability, or dimensional consistency by itself. To avoid overspecification or premature failure, the steel callout must be reviewed together with the heat treatment path, gate geometry, venting layout, and maintenance planning.

Critical Verdict: Upgrading steel does not correct design mistakes such as an undersized gate, unstable shut-off geometry, or poor venting.

1. Steel Sets Capability; Heat Treatment Controls Outcome

Nominal HRC alone does not guarantee wear resistance if the heat treatment path, tempering sequence, or hardness uniformity are poorly controlled. For the full decision framework, review our guide on how to select injection mold steel based on tool life and resin wear.

Sourcing Review Checkpoints:

  • Is the hardness route defined by component (Cavity vs. Slide vs. Wear Plate)?
  • Does the spec define the tempering sequence (e.g., Vacuum HT + 3x Tempers)?
  • Does the supplier provide a certified heat-treatment chart and HRC uniformity report?

2. Why Gate Velocity Still Wears Out Hardened Steel

Standard through-hardened steel can still wear prematurely when gate velocity and localized shear rates create concentrated abrasive flow. In glass-filled applications, the gate region must be treated as a local wear zone with a specific insert strategy rather than a generic cavity surface.

Engineering Review Checkpoints:

  • Is the gate land designed as a replaceable wear-critical insert?
  • Has the shear rate at the gate been reviewed via Moldflow or flow simulation?
  • Is there dedicated cooling provided near high-velocity flow impact zones?

3. Why Stainless Does Not Replace Venting and Storage Protocol

Corrosion-resistant steel is only one part of the strategy. Total protection involves exposed surfaces, vented corners, and shutdown storage. Damage often appears at vented shut-offs where gas-traps occur or during humid storage without proper inhibitors.

Maintenance Review Checkpoints:

  • Are vent depths optimized for resin gas behavior to prevent trap-pitting?
  • Is a passivation treatment specified for stainless inserts after machining?
  • Does the maintenance SOP include condensate removal and rust-preventive protocols?

4. Tool Life = Steel + Heat Treat + Design + Maintenance

Long-life production stability is not defined by steel grade alone. Steel chemistry, hardness route, gate geometry, shut-off design, and spare-part planning must all be aligned to meet program volume targets.

Program Alignment Checkpoints:

  • Is the preventive maintenance interval defined by the specific resin wear level?
  • Are wear-critical spares (gate inserts, ejector pins) listed in the tooling package?
  • Does the DFM align steel selection with shut-off and parting-line flash risks?

Steel callouts should be reviewed after the gate, shut-off, and ejection strategies are defined. Finalize your upstream design decisions first:

Review the Injection Mold Design Decision Guide Before Steel Cut →

Component-Level Mold Steel Selection Logic: Reviewing Wear, Polish, and Corrosion Zones

A mold should not use one steel grade across every component. Core and cavity inserts, slides, wear strips, ejectors, and structural plates operate under vastly different wear modes, surface demands, and friction requirements.

Steel callouts must be assigned by local failure mode—such as gate wear, slide galling, or ejector scuffing—rather than by a single mold-wide default. For full design alignment, review our injection mold design decision guide.

Mold Component Recommended Steel Decision Logic: When to Upgrade Engineering Risk Mitigated
Core and Cavity Inserts P20 / 718H / H13 / 420 Upgrade to H13 or 420 when resin abrasion or corrosion risk increases; avoid overspec for low-volume ABS. Gate land wear, flash, and pitting.
High-Polish Inserts NAK80 / 420 ESR / S136 Cleaner ESR grades are required for SPI A-1/A-2 to prevent pinholes and orange peel during diamond polishing. Polish loss and cosmetic instability.
Slides, Lifters, Gibs H13 / S7 / DF2 (O1-equiv) Nitriding is standard. Ensure 2-4 HRC hardness differential between the moving slide and its wear interface. Galling, seizure, and cold-welding.
Ejector Pins & Sleeves SKD61 (H13-class) / HSS Through-hardened + Nitriding or TiN/DLC coating for high-speed automated programs and abrasive resins. Scuffing, pin flash, and burrs.
Mold Base & Structural S50C / 4140 Focus on stability and stress relief. Do not overspec with cavity-grade steel where rigidity is the real demand. Bowing and flatness drift.

Failure-Mode Evidence: What Happens When Component Steel Is Mismatched

Detailed view of gate land wear on a mold insert caused by abrasive glass-filled resin flow

Fig 5: Gate land wear and fiber wash, necessitating local hardened inserts for GF resins.

Gate Land Erosion Management

In glass-filled (GF) resin programs, the gate land area sees the highest flow velocity and shear rate. As shown in the evidence, soft cavity steel leads to rapid fiber wash. Our strategy involves treating the gate as a local wear zone, utilizing through-hardened H13 or S7 inserts that can be easily replaced or maintained without rebuilding the entire cavity.

Engineering Lesson: Wear-critical inserts near the gate must be reviewed against local resin abrasion levels before freezing the mold specification.

Internal view of slide galling on mold components due to insufficient hardness differential between mating pairs

Fig 6: Slide galling caused by identical hardness in moving pairs or poor surface strategy.

Slide & Lifter Seizure Control

Moving components are prone to galling and cold-welding if the hardness route and surface treatment are mismatched. We maintain a mandatory 2-4 HRC differential and specify nitriding for sliding interfaces to ensure mechanical stability. Moving pairs should be reviewed by hardness pairing and surface strategy, not steel grade alone.

Engineering Lesson: Sliding interfaces require specific friction-pair planning during the initial tooling review.

Ejector pin scuffing and sleeve wear evidence showing the root cause of molded-part flash and sticking issues

Fig 7: Ejector pin scuffing leading to molded-part flash and sticking risk.

Ejector System Clearance Integrity

Repeated sliding of ejector pins against sleeves causes scuffing and witness marks on the part surface. Ejector wear should be reviewed as a sliding and clearance issue before it becomes flash or sticking. We specify SKD61 (H13-class) or HSS pins with DLC coatings for high-cycle programs to maintain edge seal integrity.

Engineering Lesson: Not every component should follow the cavity steel callout; ejection stability is a separate wear mode.

For the full selection framework behind these component callouts, review our technical guide on how to select injection mold steel based on tool life, resin wear, and corrosion .

Heat Treatment, EDM, and Surface Treatment Review Points Before You Freeze the Spec

Steel grade alone does not define wear life, dimensional stability, or repair limits once the tool enters machining, heat treatment, and EDM. Before the steel spec is frozen, the hardness route, treatment window, and recovery logic must be verified at the component level.

1. Component-Level Hardness Route Logic

Pre-hardened steels (P20, 718H) are preferred for large plates where distortion control matters most. Through-hardened routes (H13, 420) should be reviewed for wear-critical or corrosion-exposed components where local duty justifies tighter hardness control and associated fitting risks.

2. EDM White Layer and Recast Recovery

Aggressive EDM creates a brittle "White Layer" (Recast Layer). After heavy EDM on hardened inserts, secondary stress relief and recast removal should be reviewed based on edge geometry and thermal load. Risk is highest on thin edges where EDM damage can trigger premature fatigue cracking.

Engineering Verification: Review the heat treatment inspection report template for mold components to ensure uniformity.

3. Treatment Boundaries: Nitriding, PVD/DLC, and Passivation

  • Nitriding: Applied to sliding interfaces to reach HRC 65+ surface hardness; review brittle-edge risk on shut-offs before specifying.
  • PVD / DLC: Performance multipliers for ejector pins and wear-prone interfaces where scuffing must be reduced without changing base steel.
  • Passivation / Electropolish: Specified for stainless components (420/1.2316) to recover surface integrity after machining, ensuring maximum corrosion resistance.

4. Weld Repair Permission and "No-Weld" Zones

For high-gloss cavities and precision shut-offs, weld permission must be explicitly defined. Where weld repair is allowed, the component, location, and post-weld hardness recovery should be defined in a rework SOP to prevent witness marks.

Required Engineering Fields for Your Mold Steel Specification

Component Group Steel Grade Target HRC Treatment Route Review Note / Risk Zone Weld Allowed?
Main Cavity 420 / S136 ESR 50-52 HRC Vacuum HT + 3x Temper ESR cleanliness for mirror polish. NO WELD
Gate Insert H13 / S7 52-54 HRC Through-Hardened Replaceable wear-critical zone. NO WELD
Slider Body 718H / H13 38-50 HRC Pre-hard / Nitriding Sliding faces only for nitriding. YES (With SOP)
Ejector Pin / Sleeve SKD61 / HSS Surface 65+ Nitriding / DLC Reduce scuffing in high-cycle tools. N/A
Wear Plate / Gib DF2 / O1 / Bronze 54-58 HRC Surface Hardened Maintain hardness differential. YES

A usable technical spec should define exceptions, not just defaults. Review the mold specification sheet template to ensure your component callouts are complete before release.

Supplier Review Inputs Before Mold Steel Recommendation

Mold steel recommendation must be based on a structured engineering review rather than material defaults. Before the steel callout is frozen, we analyze the following 10 inputs to ensure the tool's performance baseline matches your program's chemical and mechanical operating conditions.

Audit Note: These inputs must be locked before steel purchase to prevent T1 issues related to unmitigated resin risk or surface-finish loss.

Critical Input Audit Checklist (Selection Phase)

  • Resin Grade & Filler %: Verifying exact fiber content to assess localized abrasion risk.
  • Lifetime Volume Target: Aligning production scale with the proposed steel route and maintenance plan.
  • Finish Zone Definition: Cross-referencing SPI/VDI targets with steel ESR cleanliness requirements.
  • Gate Area Wear Exposure: Reviewing flow velocity to define hardened or replaceable insert strategies.
  • Part Geometry Risks: Reviewing shut-off sharpness, edge loading, and brittle-zone risk areas.
  • Corrosion Exposure: Analyzing PVC/FR outgassing risk and humid storage/transport protection.
  • Replaceable Insert Strategy: Designing wear-critical zones for localized maintenance without rebuilds.
  • Treatment Restrictions: Defining "No Weld" zones and nitriding or coating limits before PO.
  • Maintenance Assumption: Expected cleaning protocols and rust prevention SOP requirements.
  • Traceability Requirements: Defining level of steel certification and heat-treat documentation needed.

Verification Flow: This audit is integrated into our DFM and engineering review service to lock logic before machining.

Evidence Deliverables Aligned with Specification

Material Records

Source traceability and original certifications for core/cavity blocks.

Heat-Treat Evidence

Vacuum HT charts and hardness route uniformity testing by component.

PM Assets

Spare-part lists for wear areas and shutdown/storage SOP definitions.

Spec Alignment

Defined steel grade, HRC, and treatment matched to the mold spec sheet.

For documentation-heavy programs, review the quality documents and PPAP deliverables used for tooling validation.

Engineering Reference PDF: Injection Mold Steel Selection & Spec Verification Matrix

Engineering PDF preview of the mold steel selection matrix showing technical tables for resin and hardness alignment.
Technical Data Matrix: Engineering Alignment Reference

Audit Content: Technical Decision Matrix

  • Component-Level Selection: Quick-reference steel grades for core, cavity, and sliding pairs.
  • Heat Treat & Hardness Route: Specific HRC targets and dimensional stability risk notes.
  • Resin Behavior Mapping: Steel requirements for abrasive GF, corrosive PVC, and FR compounds.
  • Engineering Verdicts: Decision logic for P20 vs. 718 vs. H13 vs. 420 stainless.

When to use this reference during your project flow

RFQ Stage: To verify supplier steel callouts and ensure quote transparency.
PO Review: To confirm the correct hardness route and treatment limits before purchase.
Design Alignment: As a technical anchor during mold specification freeze meetings.

Audit Note: This PDF is a technical working reference. It is designed to align resin risk, component steel, and heat-treatment cautions before final mold specification approval.

Ready to finalize the technical spec? Use this verification matrix in tandem with our mold specification sheet template for injection molding .

Injection Mold Steel Selection FAQ

How do you choose injection mold steel?

Injection mold steel selection is based on balancing resin abrasion, corrosion risk, surface finish targets, and expected tool life. P20 or 718 fits standard lower-risk programs, while H13 is common for abrasive glass-filled wear. 420 or 1.2316 stainless is preferred for corrosion-prone cavity and core surfaces.

When is P20 no longer the right mold steel?

P20 stops being a safe default when the program involves glass-filled resin, corrosion-prone materials, high-polish cavity surfaces, or longer production runs where wear and finish retention become critical. In these cases, P20’s lower hardness and lack of corrosion resistance lead to rapid gate wear, pitting, and finish loss.

Is 420 stainless usually required for PVC mold cavities?

For PVC molds, 420 stainless or 1.2316 is often the correct baseline for exposed cavity and core surfaces. PVC generates acidic byproducts that rapidly pit non-stainless steels. Using stainless preserves critical finishes, prevents part sticking, and protects cooling circuits from clogging due to internal rust scale.

Which mold areas wear first with glass-filled resin?

Abrasive wear from glass-filled resins occurs first at high-velocity flow zones like gate lands, sub-gates, and sharp shut-off edges. These locations experience intense fiber wash, creating micro-grooves that lead to flash. These zones are often managed with localized hardened inserts rather than relying on a single cavity steel.

Injection Mold Steel Selection Summary

Key steel-selection rules to avoid overspec, under-spec, and preventable tool failure

RULE 01

Non-abrasive & Lower-Risk: For commodity resins (PP/ABS/PE) in low-to-mid volume programs, P20 or 718 is often sufficient. Hardened steel is usually unnecessary unless high-gloss targets or corrosion-prone storage conditions justify the added cost.

RULE 02

Glass/Mineral Filled Resins: Abrasive fillers often push gate lands and wear-critical areas toward a hardened H13 route or a dedicated wear-insert strategy. Treat these as local wear zones rather than relying on a single mold-wide steel default.

RULE 03

PVC / FR / Corrosive Risk: Exposed cavity and core surfaces often need 420 or 1.2316 stainless as a baseline. However, cooling circuits, storage control, and shutdown protocols must be reviewed separately to prevent systemic rust.

RULE 04

SPI A-1 / A-2 High Gloss: Mirror finishes usually push selection toward cleaner ESR-grade steel to avoid inclusions. Beyond material choice, success depends on polish sequence, rework limits, and strict cosmetic-surface handling.

RULE 05

Fragile Shut-offs & Side Actions: When geometry creates impact risk, toughness outweighs maximum hardness. S7 or tempered H13 is often reviewed as a better fit than a harder but more brittle steel to prevent edge chipping.

These rules are technical starting points for steel review, not substitutes for component-level callouts, hardness routes, and failure-mode analysis. The final mold specification must align resin behavior, finish target, and wear duty before PO release.

Upload Your Drawing for a Technical Steel and Hardness Review

Receive a component-level mold steel, hardness-route, and treatment-risk review summary before freezing your tool specification.

✓ Component-level cavity, core, and slide steel callout review.
✓ Hardness-route review with heat-treatment and post-EDM cautions.
✓ Corrosion, wear, and coating watch-out notes by localized risk.

Step 1: Upload

CAD Drawing, Resin Grade, Finish Target, and Expected Volume.

Step 2: Receive

Technical review summary for RFQ alignment or steel PO verification.

Upload CAD for Steel Callout Review →
100% NDA Protected Secure Engineering File Transfer

Review output includes component-level steel direction, hardness-route notes, and coating or corrosion watch-outs based on resin behavior and local geometry risk. This review is intended for RFQ preparation, steel PO checks, or mold-spec alignment before machining begins.