Mould & Tool Making
Every injection moulded or vacuum formed part begins with a precision-engineered tool. At Custom Molding Company, we design and manufacture injection moulds in P20 and H13 tool steel from our Johannesburg facility — delivering the same engineering quality as US and European toolmakers at 40–60% lower cost, driven by the structural USD/GBP to ZAR exchange rate advantage.
We also provide mould repair, maintenance, and refurbishment for existing tools, whether manufactured by us or sourced elsewhere. Our toolmakers work from your CAD data or reverse-engineer from physical samples.
CNC machining of a P20 tool steel injection mould cavity — Johannesburg, South Africa
Tooling Services
Our toolmaking capability covers the full lifecycle of an injection mould — from initial concept and DFM review through to first-off sampling, production validation, and ongoing maintenance.
| Service | Description |
|---|---|
| Custom Mould Design | Full mould design from your part CAD, including cavity layout, gating strategy, cooling circuit design, ejection system, and side action / lifter design where required. |
| Steel Selection & Procurement | P20 pre-hardened steel for medium-volume production; H13 hot-work steel for high-volume, glass-filled, or mirror-finish applications. See our P20 vs H13 guide. |
| Prototype Tooling | Soft-steel or aluminium prototype moulds for design validation and functional testing before committing to production tooling. Typically 1–2 week lead time. |
| Multi-Cavity Tooling | 2, 4, 8, 16, and 32-cavity family moulds for high-volume production. Balanced runner systems and matched cavity dimensions ensure consistent part weight and dimensional accuracy. |
| Mould Repair & Maintenance | Cavity weld repair, gate refurbishment, cooling channel descaling, ejector pin and sleeve replacement, parting line re-grinding, and general preventive maintenance. |
| Mould Transfer & Qualification | Acceptance of customer-owned moulds for production at our facility. Includes mould audit, trial shots, and dimensional first-article inspection before production sign-off. |
P20 vs H13: Choosing the Right Tool Steel
The choice of tool steel is one of the most consequential decisions in a tooling project. It directly determines mould longevity, surface finish capability, and total cost of ownership. Our engineering team conducts a formal steel selection review on every project.
| Property | P20 Tool Steel | H13 Tool Steel |
|---|---|---|
| Hardness | 30–36 HRC (pre-hardened) | 44–52 HRC (after heat treatment) |
| Shot Life | 100,000 – 500,000 shots | 1,000,000+ shots |
| Best For | ABS, HDPE, PP — medium volume | Glass-filled resins, PC, high-volume, SPI A1/A2 finish |
| Lead Time Advantage | No heat treatment required — 5–7 days faster | Requires post-machining heat treatment |
| Relative Cost | 12–18% lower than H13 | Higher material + machining cost, offset by longer life |
Read the full technical comparison: P20 vs H13 Tool Steel Guide →
The Toolmaking Process
- DFM Review: We analyse your part CAD for draft angles, wall thickness, undercuts, and gate locations before any machining begins.
- Mould Design: Full 3D mould design including cavity, core, runner system, cooling circuits, and ejection system.
- Steel Procurement: P20 or H13 steel block procurement and incoming inspection.
- CNC Roughing & Finishing: High-speed CNC machining of cavity and core blocks to ±0.01 mm tolerance.
- EDM (Spark Erosion): Electrical discharge machining for fine detail, sharp corners, and deep ribs that CNC cannot reach.
- Bench Fitting & Assembly: Manual fitting of all mould components, including side actions, lifters, and ejector pins.
- Trial Shots & First Article: Initial moulding trials with dimensional inspection and cosmetic review. Adjustments made until first-article approval.
- Production Release: Mould signed off for production with documented process parameters.
Get a Tooling Cost Comparison
Send us your part CAD and annual volume. We'll provide a full P20 vs H13 tooling cost comparison against your current US or UK quote.
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Landed Cost Arbitrage Calculator
Compare standard US/UK manufacturing against our quality-assured South African facility.