Acrylic Polishing – The Techniques Used

Acrylic is known for its clarity, lack of color and excellent light transmitting properties. In both its extruded and cast form, acrylic can be polished to a far superior, glass-like finish than many other materials such as ultem, polycarbonate and polysulfone. This makes it ideal for lenses, light guides and other similar engineering components.

Acrylic is a stress-sensitive material that’s on the brittle side. Polishing necessitates special skill since the surface could crack or craze and it should always be annealed after machining to help prevent cracking during use.

PEP Connecticut Plastics offers professional, skilled acrylic polishing using a variety of techniques. There are four main techniques commonly used to polish acrylic – vapor polishing, flame polishing, buffing and direct machine polishing.

Vapor Polishing

Vapor polishing is a method using a solvent vapor, which flows over the surface of the acrylic, producing a more translucent finish. The end result depends on how good the original machine finish was prior to polishing, and it is essential the part is completely clean before starting with this procedure.

There are many benefits to using this method of acrylic polishing, including:

  • Smoothing out surface irregularities – especially important on medical parts as this ensures no debris sticks to the surface during sensitive procedures
  • Gives a shiny, polished look and a “water clear” finish
  • Enables light to pass through freely

Flame Polishing

As its name suggests, the flame polishing method utilizes a fine, high-temperature, hydrogen-based flame, which is “flowed” over the surface of the acrylic, actually melting it slightly. This method can be used on any shape or size of cut acrylic, but is most effective on flat, external surfaces. This is a high-speed technique requiring a great deal of skill, but, if done properly, can achieve some of the clearest finishes.

Buffing

The buffing technique is used mainly on the exterior surfaces of larger components and gives a good finish. A spinning wheel with a cutting compound is used in the buffing process, which leaves microscopic scratches on the surface of the acrylic, giving a slight haze or uneven finish.

Direct Machine Polishing

A specialty tooling is used to produce a polished finish with direct machine polishing. This is the most technical of all the methods, but it is capable of producing complicated surface profiles with virtually flawless finishes.