Plastic Injection Molding


Injection molding is the most commonly and widely used manufacturing process for the fabrication of plastic parts in industry. It is an important method of thermoplastic and thermosetting polymers production.


In First Part China Limited, we can handle the plastic injection molding rapid tooling for both high-volume and low-quantity parts production. Using the technical maturity to produce high quality custom plastic molded parts for defense, automotive, medical, aerospace and consumer products.




Except a few thermoplastics, nearly all thermoplastics can be used to produce plastic injection molding.

Below are some commonly used materials:

ABS , Acetal , Nylon 6/6, PEI (Ultem), PET, Polyethylene, Polypropylene, Styrene (crystal clear and opaque), TPE



Tolerances vary depending on material, filler, tooling strategy, geometry etc. It is always recommended to identify critical dimensions and make these available at the quotation phase. The possible tolerance of a thermoplastic or a thermo set is ±0.200 to ±0.500 millimeters. In specialized applications tolerances as low as ±5 µm on both diameters and linear features are achieved in mass production. Surface finishes of 0.0500 to 0.1000 µm or better can be obtained. Rough or pebbled surfaces are also possible.




Injection molding takes a large proportion in plastic molding, more than half of the plastic mold production in the world are injection mold. Injection molding is widely used in producing thin-walled plastic parts. Variety of products are manufactured with injection molding, which vary greatly in their size, complexity, and application.



Some critical issues to clarify before searching for tooling are

1.The most important issue to consider is whether the production intent material is really a requirement or not, if it is, then understanding the available time and attention to the CAD model are both paramount.

2. The realistic leadtime that you seek. Speed will cost a premium, so an accurate appreciation of the available leadtime after making allowances for the time to raise a purchase order, is a necessity.

3. The number of parts required both initially and over the life of the tool. This is important as if the initial batch is small enough it may be more economic to meet each requirement from a different solution.

4. Critical dimensions and their associated tolerances as these may preclude some approaches immediately.


5. Textures, are they required and if so where and to what specification.


6. Changes will frequently occur and most suppliers acknowledge this. However, if there are recognised areas of high risk within the tool, these should be highlighted to the supplier. This may result in a different approach and save time later on, if changes are indeed required.


7. Materials, evaluating different materials (or fillers) may be a possibility so long as there is an appreciation of the effect this can have on shrinkage and hence dimensional accuracy.


If you are new to injection moulding it is best to involve a supplier from an early stage as this will ensure that the design matures as efficiently as possible and avoids any last minute delays.

Injection molding is used to create many things, one of the most common is the plastic housing. These housings are used in a variety of products including household appliances, consumer electronics, power tools, and as automotive dashboards. Injection molding is also used to medical devices, mechanical parts (including gears), and most other plastic products available today. When you want to manufacture high volumes of the same object with plastic, Injection molding may be the ideal choice for it.