The Complete Guide to CNC Machining High-Density Polyethylene (HDPE)

About HDPE

High-density polyethylene (HDPE) is one such material that is commonly used in CNC machining due to its desirable properties.

HDPE is a type of thermoplastic polymer that is made from petroleum. It has a high strength-to-density ratio, making it an ideal material for applications where strength is important, but weight must be kept to a minimum. Additionally, HDPE is highly resistant to chemicals, making it an excellent choice for applications that involve exposure to harsh chemicals.

HDPE is also known for its low coefficient of friction, which makes it ideal for use in applications where parts need to slide against each other without excessive wear. It is also highly resistant to moisture, which makes it an excellent choice for outdoor applications.

In CNC machining, HDPE can be easily machined to produce parts of various shapes and sizes. It can be used to make a wide range of products, including gears, bushings, and bearings, among others. Overall, HDPE is a versatile material that is highly valued for its excellent combination of strength, chemical resistance, and low friction.

Consider wall thickness: HDPE is a relatively flexible material, so it is important to consider wall thickness when designing parts. Thicker walls will add rigidity to the part, while thinner walls will increase flexibility. You will want to balance these factors depending on the intended use of the part.
Avoid sharp edges: HDPE is prone to stress cracking, so it is best to avoid sharp edges and instead use radii or fillets wherever possible. This will help to distribute stress more evenly throughout the part and reduce the risk of cracking.
Use gentle angles: HDPE has a low coefficient of friction, which means that parts with sharp angles may be more prone to sticking. To avoid this issue, use gentle angles wherever possible.
Consider support structures: Because HDPE is flexible, it may require support structures during the CNC machining process to prevent warping or bending. Keep this in mind when designing parts and consider adding support structures where necessary.
Leave adequate tolerances: HDPE can shrink or expand slightly during the CNC machining process due to changes in temperature. Leave adequate tolerances in your design to account for this potential variation.
Avoid undercuts: HDPE is a relatively difficult material to mold, so avoid designing parts with complex undercuts that would require complex machining processes.