Every month the Plastics Network gets a variety of misc. questions.  Starting this month, I am going to start posting and answering as many as I can,  even though some may appear to be elementary in nature.

*Vapor Polishing…of all the topics, I get a lot enquiries daily on the subject of Vapor Polishing. Many have wanted information on how to purchase vapor polishing equipment. I have researched this several times and know of no company that actually produces vapor polishing equipment. Most companies in the business already, pretty much have designed and built their own equipment to fit their specific needs. If anyone out there knows of any companies that manufacture vapor polishing equipment, please post their contact information here.

*Can you melt Acetal? ….Yes. It’s crystalline melting temperature is 329F for Copolymer Acetal and 344F  for Homopolymer Acetal.

*What to expect when machining Acetal?…it is easy and very free machining. Use plenty of clearance and rake on your Turning, Boring and Cutoff tools. Good grade of carbide is all you need. See my post on “Machining Characteristics of Acetal” for more detailed information regarding machined, molded and extruded in stresses and how to deal with them. I have a lot of hands-on plastic machining experience so, feel free to ask me questions not covered on our posts.
*Difference between Injection Molding and Extruding Plastics?…as far as physical properties go, when extruding plastics a material with a higher molecular weight is preferred and when molding the opposite is true in order to get material to flow through the small gates and runners under high pressure.  Injection molded plastics are typicallly packed in the mold under considerable pressure which will typically give injection molded plastics a little higher physical properties. When extruding a  material, it is conveyed through the barrel via a screw which goes through a Feed Zone followed by a Compression and then a Metering zone prior to exiting the die. And, when processed correctly good properties are achieved but typically a little less than a part that has been molded. Most applications will never know the difference in it’s actual application.Also, Good mixing is accomplished through both processes, which is important when processing filled materials. This is a topic that could be easily expanded on..if there are any remaining questions regarding this topic, please ask.
*Plastic”Manufacturers Representative”…several enquiries have come to The Plastics Network regarding Manufacturers Representative in the Plastic Industry. Reps in the plastics industry are typlically segemented as to their expertise so, it is important to ask some questions. One segment calls on only OEM’s and even within that group there are subgroups depending on market focus ie: Automotive, Medical, General Industial, Aerospace etc. Another segment only calls on Plastics Distributors with commodity oriented products ie: Stock Shapes, Sheet and related products and most of these Reps come from a variety of Industrial Backgrounds and not just the Plastics Industry. Another segment calls on the Plastics Processors such as Injection Molders, Extruders, Blown Film, Thermoformers etc. …selling Raw material, mold bases, tooling and other support equipment for the plastic process industry.


*Listing IAPD Manufacturers Reprsentative…IAPD has a listing of Manufacturers Representatives in their Magazine. If you let me know what region you are looking for Reps, I wil give you a listing for that area or you can contact IAPD for a listing. IAPD(International Association Plastics Distributors)
*Is Plastic Copolymer or Homopolymer?  depending on the material it could be either so you need to be specific on this question as to what material you are referring to . For example, Acetal has both Copolymer and Homopolymer grades depending on the specific manufacturer.
*Vapor Polishing source in Canada?…I have posted in the comment section of the Topic “Vapor Polishing” various companies that perform vapor polishing in various parts of the country as they become known. If anyone knows of any good companies that vapor polish in Canada please leave information in the comment section. I have had several enquiries.
*PEEK Machining characteristics?…Unfilled PEEK machines very nicely using just a good grade carbide. Small quantities can be machined dry or with  coolant, and is farily stable as far as holding good tolerances. For filled materials such as Carbon or Glass fiber filled…different story. You will have to flush with a good water soluable coolant and Diamond or Similar tooling. Be careful to keep the heat generation down caused by the tooling and use plenty of coolant and make sure your tooling is sharp. Fairly tight tolerances can be held with the filled materials due to the very low thermal expansion achieved by using a filled material.
*Definition “Continuous Use Temperature“…usually a material’s temperature at which it can operate continuously under a load for a  given application. Most material data sheets give a Heat Destortion Temperature (HDT) at both 64psi & 264psi which can be a good indication of how a given material will function under load under various temperatures. This is only a guide and reference as nothing will replace a test to duplicate your actual operating conditions and is always recommended prior to final selection of a material.
*Flame retardant Antimicrobial ABS…compounders such as RTP or LNP can put Flame Retardant and Antimicrobial additives in a building block approach to achieve the desired material for your application. I recommend contacting either company for a suitable compound to meet your requirements. www.rtpcompany.com 

Plastic Machining Coolant?…any good “Water Soluable Coolant” is what you want to use when machining plastics.