Shenzhen Alu Rapid Prototype Precision Co., Ltd.

Creating an injection mold (also called an injection moulding tool) is a precision engineering process that typically costs from several thousand to hundreds of thousands of dollars, depending on complexity, size, number of cavities, and material (aluminum vs steel). Most companies outsource this to professional mold makers (like in Shenzhen/China, which is the global center for mold manufacturing).Here is the realistic industry-standard process step by step (2025–2026 practices):

1.Finalize the plastic part design + DFM analysis

Complete 3D model of the part (usually in STEP, IGES, or native CAD format) 

Perform DFM (Design for Manufacturability) check → look for:  

     Adequate draft angles (typically 0.5–2° per side)  

     No impossible undercuts (or plan sliders/lifters)  

     Uniform wall thickness (ideal 1.0–3.5 mm)  

     Proper rib/gusset design  

     Good locations for gates, ejectors, and parting line

Many mold makers provide this DFM report for free or low cost.

2.Mold concept & quotation stage  

Decide: 

   Single-cavity / multi-cavity / family mold  

   Prototype mold (aluminum, P20 steel, fast & cheaper) vs production      

    mold (H13, 1.2344, S136 stainless, very expensive)  

    Hot runner vs cold runner  

    Lifetime expectation (shots): 100 k → 5+ million

Mold maker creates preliminary 2D/3D mold layout + quotation (usually 3–7 days)

3.Detailed 3D mold design

Usually done in professional software:  SolidWorks + Moldflow (most common)  

UG NX (Siemens), Creo, CATIA  

Main elements designed: 

    Cavity & core inserts  

    Parting line / parting surface  

    Gate type & location (edge, sub, hot-tip, valve-gate, etc.)  

    Runner & gating system  

    Cooling channels (very important – bad cooling = bad parts)  

    Ejector pins / sleeves / blades  

    Slides, lifters, collapsible cores (for undercuts)  

    Guide pins / bushings / interlocks  

    Support pillars / plates  

    Venting slots / vacuum venting

Moldflow simulation (filling, warpage, cooling, sink mark prediction)

4.Material selection & ordering

Mold base (standard or custom – Hasco, DME, LKM equivalents very common in China)  

Insert steel grade  

Standard components (ejector pins, sprue bushing, cooling nipples, etc.)

5.Rough machining  

CNC milling of mold base & roughing of core/cavity blocks (large cutters, high material removal rate)  

Usually leaves 0.3–1 mm stock

6.Semi-finishing & heat treatment 

More accurate CNC milling  

Heat treatment (hardening & tempering) – most common for production molds  

Stress relieving

7.CNC high-speed finishing + EDM (spark erosion)  

High-precision CNC for most surfaces (Ra 0.4–0.8 μm possible)  

EDM for deep ribs, sharp corners, textured areas, small details that cannot be milled  

Sometimes wire-cut EDM for inserts or through-holes

8.Bench work (hand fitting & polishing)  

Hand lapping, stoning, diamond polishing  

Surface finish from #400 to mirror (#8000–12000) or texturing (VDI, Mold-Tech, laser texture)  

Fitting of moving parts (slides, lifters) – very skilled work

9.Assembly & fitting  

Assemble all plates, inserts, cooling circuit, ejector system  

Install limit switches, sensors (if required)  

Check mold opening/closing, ejector stroke, slide movement

10.Mold trial (T0, T1, T2 …) 

Install mold in injection machine  

First shots → usually many defects  

Adjust: injection pressure, speed, temperatures, cooling time, holding pressure  

Modify mold (steel safe changes first – add material instead of removing)  

Repeat trials until parts meet spec (dimensional, cosmetic, strength)

11.Final acceptance & delivery 

Last trial (FAI – First Article Inspection)  

Mold polishing / texture touch-up if needed  

Anti-rust treatment & packaging  

Delivery + spare parts (ejector pins, springs, etc.)

Quick Comparison Table – Mold Types