To get the very best edge finish on plastic there are the following options:-
• Lasering – the process of cutting plastic using a laser beam should automatically give a polished edge, although the quality of the finish is dependent on the laser; power of the laser and the skill of the operator. I spent days/months lasering different materials (normal acrylic; white acrylic; black acrylic; mirrored acrylic; frosted acrylic and PETG) to ensure I can obtain the very best edge finish. A huge benefit of lasering is that everything that is cut whether is a straight line; any shape; or a hole; all come off with a polished edge.
Not all plastics can be lasered due to different melting points and do to different fumes – any plastic with a chlorine content i.e. PVC can give off lethal gases.
• Diamond polishing – this is the process of passing plastic over either a vertical or horizontal rotating head containing a synthetic diamond to remove material and a real diamond to polish. If the machine is balanced correctly the finish should be virtual perfect and better than lasering; however, inferior machines or damaged heads can lead to a visible swirling pattern on the surface. The other big
• Flame polishing -
• Buffing – using a twin wheel low powered buffing machine, with one of the mops being a robust dense wheel used with an abrasive paste and the other mop being a softer lint with a softer paste.
• Vapour/Chemical polishing – this is the method of using chemicals to polish the edge of plastics either by applying to the edge directly or by using the vapours therein. This process is rare/difficult and expensive as the material needs cleaning and annealing properly after the process.
So which of these offer the best results for all the different plastics?
Acrylic is the only plastic that can polished using any method.
Most companies that have lasers will not cut PETG mainly because they have not invested the time to get the finish correct; however, a great edge finish can be obtained if the operator gets the feeds and speeds right (on thicker material you get a very slight bronzing). When I started my business I had no customer so in the growth period I spent hours and hours concentrating on cutting PETG to ensure we obtain the very best finish.
Polycarbonate is quite a difficult material to polish as it doesn’t react well to heat polishing i.e. lasering or flame polishing. The heat caused by the friction of buffing also is not ideal. Diamond polishing is an option if run at a high speed, for slower speeds can cause a smear on the edge. Therefore the best option for polycarbonate is chemical polishing.