What is Plastic Injection?
Plastic injection is a manufacturing technology for mass production of identical low-error plastic parts. In plastic injection, the polymer granules are first melted and then pressurized into a mold. The liquid plastic inside the mold cools and solidifies. Plastic injection materials are thermoplastic polymers that can be stained and filled by other additives.
Almost all of the plastic parts we use everyday are made using plastic injection technology: from auto parts and electronics to kitchen appliances.
Due to the popularity and widespread use of plastic injection, the cost of each piece is very low in high circulations. Plastic injection offers high reproducibility along with high design freedom. The main limitations of plastic injection are economical because although high-throughput plastic injection production is very cost-effective, relatively high initial capital is needed to start the process. Another limitation of plastic injection is the relatively high time it takes to get the piece to production (at least 3 weeks).
In this article we will first see how plastic injection parts are made and how plastic injection technology works. We also review the general features of this process that influence the design of a piece for plastic injection. We will go into the mechanics of plastic injection technology in more detail, examining the impact of this work on the cost of manufacturing with this technology, and consider its key capabilities and limitations.
Features of plastic injection system
A template is like a negative image of a photo: the geometry and pattern of the mold directly affect the shape of the plastic injection piece.
Most of the initial cost is usually spent on plastic injection molding: a typical mold starts at around $ 1- $ 1 for simple molds and relatively low circulations (between $ 2 and $ 1) and can go up to $ 6,000 for high-end molds. (1 thousand pieces or more).
This cost is due to the high expertise required to build a high quality mold that can accurately produce thousands (or hundreds of thousands) of pieces.
Plastic injection molds are usually made of aluminum or steel by CNC machine and then polished, polished and post-processed to high standards. In addition to the negative parts, plastic injection molds incorporate features such as injection system, internal water-cooling ducts, etc. that help speed the process.
Recent advances in 3D printing materials have made it possible to manufacture plastic injection molds with 3D printing.
3D printing plastic injection molds are much cheaper than conventional molds but are only used for low injection plastic (less than 2 pieces).
Production in these low circulations was previously impossible without the use of 3D printing in plastic injection because the cost of mold making is very high in traditional ways and the finished product cannot be economically marketed. An industrial mold for the production of tens of thousands of pieces of plastic. The right mold forms the core of the left mold. (Image is by Promolding.)