Finishes

Only a limited range of surface finishes work on plastics. This is especially the case when CNC machining in polycarbonate because the material tends to scratch easily. Some possible finishes are listed below:

Vapor polishing: CNC-machined polycarbonate often comes out with tool marks on the surface. This is not ideal for applications that require optically clear components. Polishing, in general, is the process of removing tool marks or blemishes, and one of the more effective methods when it comes to polycarbonate is vapor polishing. This works by exposing the surface to a solvent that reacts and causes the surface layer to melt and flow. The process evens out the surface and fills in any tool marks. Scratch-resistant coating:: One disadvantage of polycarbonate is its propensity to scratch easily. Some coatings on the market help maintain the optical clarity of polycarbonate while improving its scratch resistance.

Cost-saving Design Tips Polycarbonate is a relatively inexpensive engineering plastic, however, to further save on machining costs, try the following:

Sub-assemblies: PC for machining is supplied in either sheet or bar stock. As such, when CNC machining in polycarbonate, it is important to design parts with standard sizes in mind. Large parts machined from a single block of polycarbonate can become prohibitively expensive. Instead, consider designing separate sub-assemblies that will later bolt together or get fused via plastic welding. Tolerancing: Achieving extra-tight tolerances with plastics like Polycarbonate can be challenging. We recommend only calling out tolerances tighter than +/- 0.005" for critical features to reduce the increased scrap, cost, and lead times associated with tight tolerances. Consistent features: Design with consistent features to reduce specialized tooling or tool switching.