What is it?

Precision masking is the process by which specific areas of a part(s) are protected by masking materials.  Masking materials include liquid masking chemicals, plugs, plastic fasteners, tape or die cuts.  Typical features that may require masking are threaded holes, dowel pin holes, electrical contact points or areas, dissimilar metals on a single substrate and any tightly tolerance feature(s).


What does it do?

Parts are initially designed, they’re typically prepared with the machinist in mind.  The designs often don’t factor in the plating process, thus forgetting to allow for the build-up of plating until the part is completely machined.  If critical dimensions are not adjusted during machining; the part will probably need to be selectively plated.  Properly utilized the masking procedure will achieve the desired results.  The masking process is typically flawless and fool proof.  It may come with its own set of potential problems anything is possible and we expect it. 
 
For example, masking polished surfaces is difficult because the masking material requires a degree of surface roughness for a mechanical bond.  A good analogy would be the difficulty of getting paint to adhere consistently to a high gloss finish.  Masking on these surfaces has a tendency to lift off at the edges.  
 
Plug masking, the most straightforward solution, also can pose challenges as plugs can and do leak; Sometimes even fall out during the plating process.  Part designers should endeavor to avoid the time and expense of masking whenever possible.  One way to accomplish this is to be sure to make allowances for coating build-up when the part is machined.  Another option is to allow for a secondary machining operation to remove the coating in the selected areas.  However we here at AMF have excellent capabilities when it comes to masking and can ensure to help you design an efficient and cost effective masking strategy.