Complete Guide to 3D Printed Masking Tools

Coating, painting, or metallizing processes can vastly improve both the functionality and appearance of parts used in any industry, but these processes often involve extra steps, one of which is masking. Masking is the strategic covering of certain areas on a part that need to remain free of any coating. That area may need to remain untouched for multiple reasons — because it will become an attachment area for an assembly, for electrical conductivity reasons, or because it might need to be coated in some other material or color, among others.

Traditional masking workflows include manually measuring and cutting masking tape, machining metal or plastic masks, or sometimes coating an entire part and then machining or scraping away the coating from the designated area. Taping workflows, though they use cheap materials, are extremely labor-intensive, and can add minutes of labor time per part on a production line. Machined masks can be repeatedly used but are expensive to manufacture, and the machining process confers some geometric limitations.

There are a few factors to consider when selecting a material option for producing masks. These factors are mechanical and chemical requirements, part fit, and production requirements.

The largest limiting factor for 3D printed masking is temperature. Some coatings, such as powder coatings, cure at temperatures above 238° C. To select the most appropriate 3D printing material for an application, consult the Technical Data Sheet to find the heat deflection point before using it in a coating process. For many lower temperature powder coating processes, Formlabs High Temp Resin for the Form 3+ or Form 3L SLA printers can withstand up to 238° C.

Some finishing processes, like media blasting or vibratory tumbling, are subtractive, so the use of masking tools is to keep the coating of certain surfaces protected, rather than bare. These processes are more abrasive, and the masks need to be made from materials that can withstand the forces of the media used, like ceramic pellets or walnut shells. For these instances, use a harder material such as Formlabs Rigid 10K Resin for SLA parts or Nylon 12 GF Powder for SLS parts.