Why injections are so expensive


Why is the mold so expensive If you have ever considere […]

Why is the mold so expensive

If you have ever considered injection molding plastic parts, your first question may be why injection molds are so expensive? Injection molding is the most expensive part of the project and may significantly increase the cost of small batch production. The main factors that affect the cost of the mold are the size and complexity of the parts, the materials used and the number of parts produced.


What is injection molding?
Injection molding is the process of heating plastic particles to their melting point and then injecting them into a cavity (mold). When the plastic cools, it hardens into the shape of a cavity, thereby forming a part.


Why are molds so expensive?
The injection mold is subjected to thousands of pounds of pressure per cycle. As a result, the mold must be made of very durable materials that can withstand repeated use without deformation. The most common choice for injection molds is steel, which depends on the number of parts that must be manufactured and the materials that must be injected into the mold. (For example, glass fiber-filled materials cause a lot of wear during the injection process, so the mold must be made of higher quality steel.)

Another factor that determines the cost of the mold is the complexity of the parts to be manufactured. The more complex your parts, the more complex and expensive the shape. After the mold is made, it is difficult and often impossible to change, which prevents you from changing the design.

CNC machining or injection molding
Although the initial cost of injection molds is relatively high, at a certain volume, injection molded parts are cheaper than machined parts. This crossover may occur between 100 and 5000 parts, depending on the part. However, there are several other situations in which CNC machining is a better choice than injection molding.


Speed-Creating injection molds can take weeks to months. If you need fast parts, then CNC machining is the perfect solution.
Best Tolerance-When you need tight tolerances, plastic processing is unmatched. At Reading Plastic, we have successfully manufactured plastic parts with a tolerance of +/- .001. "


Material selection-Not all plastic materials can be injection molded, which limits material selection. CNC machining provides more material options, including high performance and special plastics.


Design flexibility-Design features that are difficult or costly for injection molding are easily adapted by machining. It is also easy to change the design using machining, which allows you to provide customized parts that meet the specific needs of customers.