Vapor Polishing & Other

Connecticut Plastics has an expertise in a number of plastic polishing and acrylic polishing processes.

Each plastic polishing process is best suited for particular configurations and  plastic material types.

We can work with you to determine the plastic polishing processes and materials to best meet your design specifications. The procedures described in this section are intended as an overview of the plastic machining process and precise polishing capabilities our machine shop offers. Please contact us to discuss your specific plastic polishing requirements.


Common plastic polishing methods

Flame polishing uses a hot flame to flow a plastic surface. Operator skill is critical with this method. When done properly, flame plastic polishing produces the clearest finish, especially when polishing acrylic. Flat external surfaces are the most applicable configuration for this method.

Vapor polishing utilizes a chemical vapor which attacks the surface of the plastic, causing it to flow. Acrylic unfortunately does not respond to this polishing process as well as polycarbonate, polysulfone, and ultem. This process requires specialized equipment and handling to achieve the desired results. With precise machining by a skilled plastic machinist, an optical quality component can be achieved. Conversely, if the machining has been done improperly, vapor polishing can actually make the situation worse and the feature takes on an opaque white look. In extreme cases, plastic parts may immediately stress crack and are rendered unusable in the vapor plastic polishing process. This method can be used in polishing both internal and external features, including threads and drill holes.

Mechanical plastic polishing is the most common, easiest to do, and useful on any plastic. This method tends to leave very fine scratches on the surface and will usually look nice but is not acceptable for optical work. Buffing will degrade the surfaces of the two other methods above.

Direct machining is the most successful but technically difficult method to produce clear acrylic components. With this polishing approach, tooling and machine parameters are fine tuned to produce a polished acrylic part directly off the machine. Direct machining produces some of the clearest and most consistent acrylic components.

Buffing typically uses a cotton wheel with a cutting compound. Similar to flame polishing, it works well on large exterior surfaces. It has limited use in interior work and generally cannot produce a really consistent finish. Buffing is appropriate where focus is on aesthetics. When viewed at magnification, the buffing wheel actually produces fine multidirectional scratches, limiting its ability to produce true clarity.

One caveat: Plastic polishing, like painting, is all in the preparation. If the CNC machining is not done correctly, all the polishing in the world will not fix the components. Metal shops do not typically have the knowledge or skill to properly prepare the plastic component for polishing. Precision machined polished components completely processed at a single location tend to represent the highest quality.

In addition, all of the above methods require annealing to avoid stress cracks. Plastic and acrylic polished components without annealing will likely crack in operation.

Consider the advantages of choosing a machine shop that specializes exclusively in plastics for all of your plastic polishing and acrylic polishing needs. Success in polishing is strongly dependant on the quality and preparation of the initial plastic machining process .

Contact us at (203) 265-3299 to discuss your specific needs.