Machining is a critical manufacturing process for producing plastic parts and products. The machining behavior of plastics can vary widely depending on the material. Two of the most common thermoplastics, POM and nylon, have markedly different machining characteristics. Understanding these differences is imperative for efficient, high-quality machining.
POM Machining Characteristics: POM is renowned for its stellar machinability. It machines like a metal, holding tight dimensional tolerances without distortion. POM's thermal conductivity prevents localized heat buildup, allowing high speeds and feeds. This results in very low cutting forces, power consumption and tool wear. POM's crisp edges and ability to capture fine details enable precision machined components like gears or bearings. Surface finishes down to 0.2 microns are possible with POM machining.
Nylon Machining Characteristics: In contrast to POM, nylon is notoriously more difficult to machine precisely. Its lower thermal conductivity leads to melting, smearing, and gumming on cutting tools. Nylon's tendency to grab and stick to tools accelerates tool wear. Higher cutting forces are required, increasing power needs. The additional heat generated can limit cutting speeds and feeds. While dimensionally stable nylons are available, achieving tight tolerances is still challenging. The moderate surface finish of nylon usually requires post-machining operations.
Machining Recommendations: Adjusting parameters like tool geometry, feed rates, depth of cut and use of coolants can aid nylon machining. HSS tooling with sharp cutting edges and high positive rake angles perform better. Flood cooling is suggested to prevent melting. Roughing and finishing operations may need to be optimized differently for nylon versus POM. POM can often be machined in a single pass.
Application Examples: For precision components like gears or bearings, POM's stellar dimensional stability would be highly beneficial. Where dimensional accuracy is less critical, such as housings or enclosures, nylon may be suitable. In all cases, the plastic's machinability must be matched to the part requirements.
In summary, POM's excellent thermal conductivity and stability result in superior machining behavior over nylon. POM allows higher speeds and precision while reducing tool wear and power needs. Understand your plastic's machinability characteristics relative to your application requirements when selecting a material. With the right techniques, even challenging plastics like nylon can be machined successfully.
