Injection molding is the process of creating plastic parts in mass quantities. This type of production is used when the same type of product is produced in large numbers (i.e. in the thousands or millions). For example, a plastic swimming pool for children needs to be sold to a large market of consumers. The plastic mold can be used repetitively to make large numbers of children’s pools cheaply.
Injection molding has several major advantages including:
- Economies of scale; the mass production capabilities of injection molding means that the cost per part is extremely low, especially relative to other production methods.
- Large quantities; creating a larger number of plastic products meets the demands of the market easily.
- Consistency; the injection molding process ensures that the output is consistent and that each piece containing plastic is the same. Consistency reduces the amount of errors.
Injection molding also has some major disadvantages:
- Waste; Large amounts of waste come from the sprue, runner and gate, all of which are crucial components of the production process.
- Expense: The initial outlay and technology required is significant. 3D printing and significant testing is takes time and costs money. The testing is extremely important as these tools make mass quantities and therefore must be accurate and efficient.
- Large required lead times: the testing and development phase will take a significant amount of time. The tools and technology must be up to standard and capable of handling large volumes of plastic.
- Difficult to change; interdependent tools and processes are hard to changes once they are developed. It is difficult to isolate and make changes of any elements without delaying the entire production process.
The initial outlay of plastic injection molding is expensive and the maintenance costs are significant. Furthermore, the process is not suitable for all producers. Nevertheless, plastic injection molding is the only viable option for cheap and consistent mass produced plastic goods.