How is a plastic injection molded part made from a concept?
As we know, most of the products in market are designed by the product designers. But the product can’t come true directly from the computers or drawings, it has to be made by different manufacturing processes. Many plastic parts are made by plastic injection molding. Like all the other manufacturing processes, plastic injection molding is not as easy as eating a pie. It is also a complicated process which will use a lot of human intelligence. This manufacturing process could start from mold design, and then mold making, finally plastic injection molding.
1. Mold design
The mold designer will design the mold according to the drawing from the product designer. The mold designer should determine the mold base standard, mold core and cavity material, the cooling system, runner type and location, gate type and placement, parting line location, ejector system etc.. After confirming all these things, the mold designer will use CAD software to draw a 3d mold drawing and make a bill of material including all components the mold will utilize. On designing the injection mold, the designer should consider the shrinkage rate of the product material, the geometry, balance of the runner and cavity, balance of the cooling system and smooth ejection. There are also many questions the mold designer have to think about, how to deal with the inconsistent wall thickness, how to make the high glossy surface product, how to make the parting line invisible and so on.
Nowadays, the mold designer could get a lot of assistance from the CAD and CAM software. The designer uses the mold flow simulation software to see how the melted plastic flows in the mold and check the defects which will happen. The main duty of the mold designer is not only making mold drawings, but also the good design to avoid any possible problems in the future.
2. Mold making
The mold maker would make the mold after receiving the drawings and BOM sheet from the mold designer. Some of the mold components are standard parts, which should be purchased from other suppliers. Some components should be custom made by CNC milling machines, EDM, grinding machines and drilling machines.
The standard components are mold base, ejector pins and other things for guiding, locating and cushioning. The standard components should also be machined to hold the custom made components.
The custom made components are core, cavity, cold runner and slider. All there components have to be machined from the block. There are a lot of machining job to do for making there things. So the mold making process could last many days.
After all these components are finished, the mold maker will start to assemble the plastic injection mold and do the mold trial. Generally, we can get the golden samples after several mold trials and the mold could delivered to injection molder to start mass production.
3. Plastic injection molding
The injection molder will fix the finished mold into the injection molding machine, set the right parameters and start mass manufacturing. The robotic arms are used for taking the plastic out and put on the conveyor automatically. In order to keep high quality production, the quality system should be executed by the injection molder. Regular measurement checking report should be made by the quality inspector.
The main duty of injection molder is to keep the mass production running smoothly and make sure the parts measurements are within the tolerance. Due to the annual demand of the product, the plastic injection molding period could last long or short.
Summary
We can see that a plastic product concept should go through a lot of manufacturing process to become a real injection molded part. And all the process can’t be made by single worker, but a team. Only a good team could makes great plastic product.
Fengjin Mold is a professional plastic injection molding company provide mold design, mold making and plastic injection molding services, if you have any inquiries, please contact sales@fengjinmold.com
