Precision Masking of parts is common for  industrial sectors such as aerospace, motorsports, firearms / defense and medical fields. Precision masking is used to protect part features during the CBF (Centrifugal Barrel Finishing) part polishing / mass finishing process. CBF is a high energy isotropic finishing process that adds precision and speed needed in the mass finishing industry. Our CBF machines are used for polishing, deburring, and deflashing of parts. Tumbling them allows for uniformity and even polishing. But before we can tumble parts, we assess the surface of the parts that need masking. Part features are masked for various reasons. We mask external surfaces, internal, and/or a combination of both. An example of this would be a part that has through holes or threaded areas intended for bolts. Masking prevents holes and threads from being filled with the deposit. The following is a breakout of various reasons to use masking.

  • Part feature preservation – Threads, deep features, part radii, need to be protected during certain phases of the part polishing process. Laser etching, serial/part numbers, and unique identifiers also need to be protected with special products that meet the necessary temperature requirements.
  • Avoid excess edge radius – We have the ability to process a high volume of parts simultaneously to meet defined metal radius corner specifications. The part geometry and material type are different for all parts and excess radiusing can become a problem if the right techniques are not used.
  • Prevent media lodging – We use temporary plugs to ensure holes are preserved. For example, on small motors, the oiler hole or lubrication cavity can plug. By masking (using plugs), we ensure the holes in the part are protected to ensure proper fluid flow for hydraulic and lubrication applications.
  • Avoid shadowing – Shadowing occurs when the finished surface is not consistent across the surface of a part. It can be a result of improper selection of media or a result of masking challenges. If media gets lodged in the first step of the finishing process, then the second step could result in shadowing. If that happens, you won’t be able to smooth the surface to the desired finish.

Standard Masking Products

  • Caps
  • Plugs
  • Tape
  • Netting
  • Spiral Wrap
  • Thread Protectors

Custom Masking Solutions

It’s common for ISO Finishing to make custom masking solutions when the standard plugs and caps don’t  fit properly. Custom solutions are needed when products may have custom threads, unique part geometry or features that do not fit standard masking  methods. For example, if we have a medical part with a uniquely shaped hole, we’ll create a seal-tight masked part to fill it. We need a process that is consistent and repeatable during the polishing process, so  our team will  create custom plugs, caps, or fill material for products that have proprietary shapes.

When is Masking Applied?

Masking applications are unique to each project. We may need to mask the exterior first, then the interior or vice versa. It just depends on the needs of the customer, what the part is made out of, and the level of finishing needed. There are cases where we mask in the first few phases of polishing, then remove all masks for the final phase of finishing. Some parts need a specific finish in order to be coated properly.

About ISO Finishing

ISO Finishing specializes in vibratory finishing, high-energy polishing, and micro-precision surface improvement. Through our innovative finishing solutions and industry-leading delivery times, ISO Finishing has become the go-to finishing resource for Fortune 500 manufacturers to small business owners alike. Contact us today to learn how we can assist you with surface perfection and burr removal in your manufacturing process.

If you’d like to learn more about mass finishing or to request a free sample please contact our team.

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