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How Are Plastic Injection Molds Made

No matter how complex the mold is, in general the process flow of mold manufacturing is basically as follows:

Drawing review → Material preparation → Processing → Mold base processing → Mold core processing → Electrode processing → Mold parts processing → Inspection → Assembly → Flying mold → Mold trial → Production

1. Mold base processing


A/B board processing

Panel processing

Ejector fixing plate processing

Bottom plate processing

2. Mold core processing

Flying edge

coarse grinding

Milling machine processing

Fitter processing

CNC rough machining

heat treatment

fine grinding

CNC finishing


Wire cutting (slow wire cutting)

Save model

3. Mold parts processing

Slide processing

Pressure block processing

Divider cone gate sleeve processing

Insert processing

Mold base processing details

1) The numbering should be uniform, and the mold core should also be numbered. It should be consistent with the number on the mold base and in the same direction. It can be aligned during assembly to avoid errors.

2) A/B plate processing (ie, moving and fixed mold frame processing).

a. A/B board processing should ensure that the parallelism and verticality of the mold frame are 0.02mm;

b. Milling machine processing: screw holes, water holes, ejector holes, machine nozzle holes, chamfering

c: Fitter processing: tapping, trimming burrs.

3) Panel processing: The milling machine processes the boring machine nozzle hole or the material nozzle hole.

4) Processing of the ejector pin fixing plate: Milling machine processing: The ejector plate and the B plate are connected with a return pin. The B plate is facing up, and the ejector pin hole is drilled from top to bottom. To countersunk the ejector pin, the ejector plate needs to be turned over and the bottom is upward. Correction, first use The drill bit is used for rough machining, and then the milling cutter is used for finishing and chamfering.

5) Bottom plate processing: Milling machine processing: marking, correction, boring, chamfering. (Note: Some molds that require strong pulling and ejection need to add a strong pull and ejection mechanism, such as drilling screw holes on the ejector plate)

Mold core processing details

1) Rough machining of flying hexagons: Processed on a milling machine to ensure verticality and parallelism, leaving a grinding allowance of 1.2mm.

2) Coarse grinding: Large water grinding process, grind the large surface first, then clamp the small surface with a batch grinder to ensure the verticality and parallelism are 0.05mm, leaving a margin of 0.6-0.8mm on both sides.

3) Milling machine processing: first calibrate the milling machine head to ensure that it is within 0.02mm, calibrate and press the workpiece, first process the screw hole, thimble hole, threading hole, countersunk hole for inserting needle, machine nozzle or material nozzle hole , chamfer the diverter cone hole and make a water carrying hole, and mill the R angle.

4) Fitter processing: tapping, typing.

5) CNC rough machining: leave a margin.

6) External fever site HRC48-52.

7) Precision grinding; large water grinding process to be 0.04mm negative than the mold frame, ensuring that the parallelism and verticality are within 0.02mm.

8) CNC finishing.

9) EDM.

10) The accuracy of wire cutting (slow wire cutting) is plus or minus 0.005. Generally, one cut is made and one is trimmed.

11) Save mold, ensure smooth finish, and control the cavity size.

12) Process the inlet gate and exhaust. Generally speaking, the gate opening of zinc alloy is 0.3-0.5mm, the exhaust opening is 0.06-0.1mm, the gate opening of aluminum alloy is 0.5-1.2mm, the exhaust opening is 0.1-0.2, and the plastic exhaust opening is The air opening is 0.01-0.02, try to be wider and thinner.

plastic parts manufacturers

1) First, the milling machine roughs the six sides;

2) Precision grinding six sides to size requirements;

3) Milling machine rough processing hanging table;

4) The hanging platform is finely ground to the size requirements and slidably matched with the mold frame;

5) The milling machine processes the slope to ensure that the slope is consistent with the pressing block, leaving a margin for flying mold;

6) Drill water transportation and slant guide holes. The slant guide column hole should be 1 mm larger than the guide column and be chamfered. The slope of the slant guide column hole should be 2 degrees smaller than the slope of the slider slope. The inclined guide column holes can also be processed together with the mold base after the mold is completed and the upper mold is closed, depending on different situations.


Contact Us

Contact: plastic injection molding Company

Phone: +86 181 6575 9852

Tel: +86 755-27164277


Add: Northwest of Huihao Industrial Park, No. 1, Chuangwei Road, Guangming District, Shenzhen