To successfully choose a surface treatment that matches the CNC machined part of the design requirement and application, here are some factors to carefully evaluate:
Material
Usually, the materials of machined parts respond differently to specific CNC machining surface finishing. Aluminum parts, for instance, are compatible with anodizing and powder coating for enhanced aesthetics and corrosion resistance. At the same time, passivation is typically usable on stainless steel parts for corrosion resistance and improved lifespan, and steel is compatible with black oxide, or galvanizing.
Functionality
Every CNC machined part has a specific purpose or application. Hence, a compatible surface finish must be chosen based on different functions to meet design and performance requirements. You may have to choose a surface finish like plating, or anodizing for parts exposed to corrosive substances or environment.
Also, case hardening or thermal finishing methods like tempering or annealing may be suitable if the part is exposed to high-wear applications. Electroplating machined parts with conductive coatings like copper, silver, or gold might be suitable for improved conductivity in electronic components.
Aesthetics
The desired appearance of the CNC part determines the choice of a surface finish. Surface finish treatments offer an extensive range of visual effects from matte and satin to high gloss finish. CNC machining finishes like polishing and electroplating give a high gloss finish, while powder coating, bead blasting, and sandblasting offer a uniform matte or satin finish.
Cost
Precision surface finishing processes often vary in terms of costs. For example, powder-coating parts will cost more than regular paint. But it is cost-effective for larger production runs. Hence, balancing all parameters, including costs, time, and function, would be best to achieve the best results.
Lead Time
Some CNC machining finishes take longer than others to achieve. For instance, you may need to choose a quicker metal surface finish, like polishing, when working with a shorter lead time. However, you may want to use a high-quality finish like anodizing if you have more time and need parts with a more precise and polished surface finish.
