Paint Masking
In a metal finisher’s perfect world all parts would be coated all over with whatever coating or coatings are specified. It would cut down on costs and would also reduce the risk of any quality issues. The reality is that in many instances masking is required to prevent coating systems from covering specified areas.
The reasons for masking are:
Electrical Contact
Tight Tolerances
Interference with Mating Parts
Electrical Contact
The ability to pass an electrical current through a metal part may be critical to the performance of the overall assembly in many instances. This can be done in several ways, but when the design calls for a surface to be left uncoated or a surface that has conductive coating in place, masking is required.
Tight Tolerances
Over the last 25 years the tolerances manufacturers can hold have grown tremendously. 3, 4 and 5 axis manufacturing cells are producing work you could only dream of a few years ago. This typically adds to the performance of the component and the overall assembly. Due to these tight tolerances masking is often required to protect those surfaces. Bores, through holes, splines and threads are traditionally masked from most coatings to avoid surface to surface issues.
Interference with Mating Parts
In particular with electrochemical plating or paint systems, the thicker coatings can cause alignment issues, problems with installation, as well as galling and fretting issues. Where there are possibilities of these, masking is often part of the coating process.
How do we mask?
Selective plating or painting is accomplished in a number of different ways. Tapped holes can be masked with a simple plug or threaded fastener. A contact face can be protected by the use of specialized tape, a liquid paint on masking system, or custom made fixtures. Some more sophisticated selective coating techniques involve machining discreet areas after coatings are applied and then a touch up procedure may be employed. In some instances the use of a laser has been used with great success.
More than just masking
The key to any masking effort is the ability to repeat the process with a successful outcome. Wolkerstorfer Co. prides itself on our ability to “create” the ideal masking scenario to meet the most demanding of applications.
