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

About HDPE

The utilization of high-density polyethylene (HDPE) is widespread in CNC machining due to its exceptional qualities and versatility.

HDPE, derived from petroleum, belongs to the category of thermoplastic polymers. Its noteworthy feature is a remarkable strength-to-density ratio, making it an ideal choice for applications that prioritize strength while minimizing weight. Furthermore, HDPE exhibits impressive resistance against chemical substances, rendering it highly suitable for deployments involving exposure to harsh chemicals.

The material’s distinguishing characteristic lies in its low coefficient of friction. This attribute makes HDPE particularly advantageous in scenarios where components must smoothly slide against each other, minimizing wear and tear. Additionally, HDPE possesses exceptional resistance to moisture, positioning it as an excellent option for outdoor applications.

In CNC machining, HDPE stands out as a readily machinable plastic material capable of producing parts in diverse shapes and sizes. Gears, bushings, bearings, and a wide array of other products can be successfully fabricated using HDPE. The material’s appeal stems from its unique combination of strength, chemical resistance, and low friction.

High-density polyethylene (HDPE) emerges as an invaluable material in CNC machining, cherished for its remarkable attributes, encompassing strength, chemical resilience, and reduced friction. Its versatility and wide-ranging applications solidify its position as a go-to choice in various industries.

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.