Injection Mold Manufacturing Process

image of plastic injection mold makingIf you are a product designer or plastic industry related business person, you should have some basic knowledge on how a plastic injection mold is manufactured, which will help you better know your project status, easier control your product quality, even better for engineering communication.
Injection mold is widely used to make plastic parts in the world, but its technology is still a little bit complicated for most of us. Here below we would like to share some main process of mold making technology.

Stage One : Mold design

A good mold starts from a good mold design, it determined mold structure, quality, and lifetime. Therefore mold design is very important for any mold manufacturing. Most of mold manufacturer accumulated few mold designers who have rich experience in mold design and mold making, otherwise it could be a potential risk for their company.

Normally it takes 3~5 days to completed a full mold design including 3D, 2D, and EDM process drawing. These drawings should be reviewed and approved by clients, so they would know how the mold would be. As well the clients would give comments and requirement towards those drawing.

StageTwo : Mold material and standard accessories preparation

After mold design is finalized, we must prepare all of material and accessories so as for mold making.To obtain short time of mold manufacturing, any of mold manufacturer outsource the mold material and standard accessories from professional suppliers. Like mold base, mold material, hot runner, injection pin, nut, etc.

Those mold material and accessories have different standard, for example, in China, we use Chinese local mold accessories supplier’s product named “LKM”, in Europe and US, they might use Hasco, DME, HEB,STRACK, and OPITZ standards.

StageThree :Mold core and custom accessories manufacturing

1.CNC rough machining

This process is to remove the most of additional material to obtain a desired profile or shape, so that these workpiece can be accurately machined by other manufacturing process. Rough machining process can shorten the time of other process. Normally the rough machining process will only leave 0.2~0.3mm remaining material, just like a shell on the ideal shape

2. Heat treatment for steel
As soon as the rough machining process is done, we must send those workpiece for heat treatment that will remove the internal stress which resulted during machining, On the other hand, the purpose of heat treatment is also to get certain hardness and internal balance, we can also call it hardening process. For a certain number of hardness, it depends on customer’s requirement and the lifetime of mold.
3. precision machining

When we get back the workpiece from heat treatment supplier, it’s time to machine the mold accessories in accurate geometry, since it has precision requirement and harder steel, the manufacturing process is much slower than tough machining process,  

These process could be completed by CNC, EDM, Wire cutting, or metal graving machine. It’s also a time and energy costly process. All of piece must be well-achieved, otherwise there would be some trouble for next manufacturing or injection molding.

Stage Four : Mold assembly and mold trial

After all of mold components or accessories prepared, the mold maker should collects them in a particular area so as to move forward to mold assembly process.

Mold assembly takes 1~2 hours to complete, in this stage, all the components should be correctly assembled and fitted together. Otherwise it’s easy to result in some molding defects like flash, unfull-filling, or bubbles.

If everything is successfully done, we can be happy to expect for a mold trial. Most of time, there will be some defects happens during our first mold trial.(T0), but it doesn’t matter, we can fix those defects after the mold trial.


Stage Five : Texture and job sign off

After the mold is tested and tweaked successfully, we can send the mold for texturing or logo marks. As well as some package accessories should be added outside of the mold. Then we can say good luck, we will sign off the mold to clients.