When it comes to manufacturing plastic parts for your product, many manufacturing methods are available for you to consider. The two most common ones are plastic machining and molding.
The question for you is, how do you tell which approach makes more sense for your custom plastic prototyping?
It’s important to distinguish between these two options to discover which technique is most cost-effective for your needs. In this article, we compare the differences between these two methods to reveal the criteria required for material selection, speed, volume, and design.
What is Plastic Molding?
Plastic (injection) molding involves fabricating plastic parts through the injection of molten materials, also called thermoplastics, into tools or molds. This process starts by melting plastic in a barrel and forcing it through channels to form the desired part. As soon as the part cools, it’s removed from the mold. Then the same process is repeated for the rest of the parts.
What is Plastic Machining?
Plastic machining uses computer-controlled applications to remove material layers from a solid plastic block at a time. This process generally starts with a single material block and allows for different materials with a few limitations.
Similarly, information is obtained from a similar digital file, enabling the changes of files during production. These computer files are broken down into a chain of commands and fed into a mill or lathe tool to produce the final product.
What is the Difference Between Plastic Machining and Molding?
Plastic machining and molding have various distinctive differences. So before you start manufacturing your plastic parts, consider these characteristics.
- Material – Plastic machining usually offers a wide selection of materials for part creation. However, this process can lose accuracy on softer materials but works best for harder, high-performing materials. On the other hand, molding offers a limited choice of materials. Some materials like rubbers and other flexible substances would be impossible to machine but can easily be molded.
- Speed – Plastic machining is the fastest method when producing low-volume parts. For example, plastic machining could be your ideal option if you need ten pieces in about two weeks. On the contrary, molding requires time to produce a large volume of plastic parts that are tolerant. This can take some weeks to a few months based on the volume of parts needed. For instance, if you need 60,000 units in five months, you may need to opt for molding.
- Volume – The most crucial aspect of mass production is cost reduction. Plastic machining is cheaper when manufacturing only a few plastic parts. While you may get volume benefits, this can only be to a limited extent. Don’t expect the level of cost reduction to be commensurate with the increase in quantity.
On the other hand, the cost per part of molded parts is relatively cheaper. Although you may pay a higher upfront cost for these parts, the price is distributed across the pieces to determine the actual average cost.
The reason your cost can be higher upfront is due to the investment required to create the actual mold itself. Molds can range from a few thousand dollars well into the six-figure dollar range.
Ultimately, this means the higher the volume of parts you produce, the cheaper the production cost.
- Design – Plastic machining allows for flexibility in design, while molds are sometimes impossible to accommodate changes in structure.
Plastic machining and molding are both viable plastic manufacturing techniques. However, they both have distinctive characteristics and differences that you need to consider before deciding what method best suits you. Ensure you understand how each method works and the benefits you get from using either of the processes.