{"id":2833,"date":"2026-06-23T13:50:45","date_gmt":"2026-06-23T05:50:45","guid":{"rendered":"https:\/\/www.cncmaven.com\/?p=2833"},"modified":"2026-06-23T13:50:45","modified_gmt":"2026-06-23T05:50:45","slug":"powder-coating-cnc-machined-parts-guide","status":"publish","type":"post","link":"https:\/\/www.cncmaven.com\/de\/blog\/powder-coating-cnc-machined-parts-guide\/","title":{"rendered":"How to Specify Powder Coating for CNC Machined Parts"},"content":{"rendered":"

Powder coating is a durable finish for aluminum and steel parts, but it is not just a color choice. The coating adds thickness, flows around edges, needs clean pre-treatment, and can interfere with threads, bores, grounding points, sliding fits, and assembly surfaces. A good powder coating specification tells the supplier what must be coated, what must stay bare, what finish quality is acceptable, and how the finished part will be inspected.<\/p>\n

This guide focuses on CNC machined parts and precision assemblies, where coating thickness and masking decisions can create real fit problems if they are handled after machining is complete.<\/p>\n

Where powder coating fits best<\/h2>\n

Powder coating is often chosen for brackets, housings, panels, guards, covers, outdoor hardware, and visible aluminum or steel components that need a tough decorative finish. It is usually stronger than simple wet paint for abrasion and handling, and it offers many colors and textures. It is not the right answer for every precision surface. Sliding fits, bearing bores, threaded holes, electrical contact points, sealing faces, and tight datum surfaces often need to remain uncoated or receive a different finish.<\/p>\n

\"Powder
Threads, bores, grounding points, bearing seats, and mating faces should be masked or controlled before powder coating.<\/figcaption><\/figure>\n

Coating thickness changes the part<\/h2>\n

Powder coating adds measurable thickness. Typical finished thickness often falls around a few mils, depending on powder type, application method, geometry, and cure. That thickness can be harmless on an exterior cover, but it can block assembly when applied inside a threaded hole, over a bearing seat, or across a close-fitting slot.<\/p>\n\n \n
Feature<\/th>Powder coating risk<\/th>Practical specification<\/th><\/tr><\/thead>\n
Threaded hole<\/td>Powder buildup can stop screws from starting or gall during assembly.<\/td>Mask with silicone plugs or call out post-coat thread chasing only when acceptable.<\/td><\/tr>\n
Bearing bore<\/td>Added thickness reduces diameter and affects roundness.<\/td>Mask the bore or machine after coating if the design allows it.<\/td><\/tr>\n
Mating face<\/td>Coating can create uneven stack-up or poor grounding.<\/td>Define bare metal zones, conductive contact areas, or flatness after finish.<\/td><\/tr>\n
Cosmetic outside face<\/td>Orange peel, thin edges, or handling marks can be visible.<\/td>Define color, gloss, texture, acceptable side, and packaging expectation.<\/td><\/tr>\n <\/tbody>\n<\/table>\n

Masking checklist for machined parts<\/h2>\n