Plastics Technology - Dedicated to improving Plastics Processing.
Issue link: http://pty.epubxp.com/i/421920
Improve Your Foaming Process with Foamazol™ Chemical Foaming Agents for... Extrusion Molding Wire & Cable Wood-Plastic Composites Very fine cell structure improves appearance, eliminates sink marks, and increases strength. Experience, Service and Solutions If you're currently foaming or contemplating foaming for extrusion, molding, wire & cable, or wood-plastic composites applications, Bergen's Foamazol™ CFAs can improve your low-density foaming process and save you money. • Service – the right product…the right physical form…at reasonable cost…when needed • Custom Products – we'll work with you to develop the perfect CFA for your application • Solutions – endothermic, exothermic and endo/exo blends…various carrier resins…pelletized masterbatches…powders • Experience – extensive formulating experience ISO 9001:2008 Certified Contact Bergen International today! Bergen International LLC 411 State Hwy 17, Suite 100 Hasbrouck Heights, NJ 07604 Phone: 201-299-4499 Fax: 201-335-5909 Toll Free: 866-554-4951 "Your #1 Source for Chemical Foaming Agents" ABOUT THE AUTHOR: John Bozzelli is the founder of Injection Molding Solutions (Scientifc Molding) in Midland, Mich., a provider of training and consulting services to injection molders, including LIMS, and other specialties. E-mail john@scientifcmolding.com or visit scientifcmolding.com. the fnal step of bufng and polishing the screw with an appropriate bufng/cleaning compound such as Semichrome. 2. BURN-OFF: Another method is to burn of the residual resin and degraded material. This works and is easier than hand cleaning, but the temperatures the screw is exposed to in this burn-of process can sometimes cause it to warp, scorch, and/or change its hardness. 3. DRY-ICE BLASTING: A newer tech- nique, which works nicely, is to use CO2 pellets to "sand blast" the baked-on carbon or degraded resin. This requires new equip- ment with the right kind of CO2 pellet and pellet generator. It is also a manual method. 4. HIGH-PRESSURE WATER: Here's another newer approach. The process is clean, can be automated, and will do no damage to the screw (though some coatings may be compromised). We've all seen high- pressure washers used to clean decks, etc., but there are super versions of these things that cost more money and can produce a steam of fltered water at 20,000 to 50,000 psi. Some are used to cut and trim plastics and are expensive, but we do not need the sophisticated cutting capabilities. The point is that they cut plastic and will not cut the metal of the screw, provided there is no dirt in the water—hence the need for fltering. To start, buy, borrow, or rent an appro- priate waterjet cutting system. Mount it in a waterproof box with safeties that require the box to be closed before it can be powered on. Ensure there are adequate shields and bafes around the box and on the bottom to keep the water from cutting through. Provide supports inside and outside the box to hold the screw but allow it to rotate and move forward and backward. Don't forget a drain for the water! Ensure that no one can stick his hand in the waterjet stream to test how powerful it is. The box front panel should be hinged to allow screws to be placed inside. When the panel is closed, that engages the safety switches to allow the waterjet to be turned on. Provide a mechanism that both turns and pushes the screw slowly through the box. When ready, turn on the waterjet. As the screw moves through the box, the carbon and degraded plastic will be cut and blown of the screw. As the screw comes out the other side, provide an electric- or air-powered bufng wheel with an appropriate metal polish. This procedure will yield a clean and polished screw with minimum manpower, time, and efort. It isn't free, but it's so easy that it might become a yearly routine for all your presses. @plastechmag 27 Plastics Technology I N J E C T I O N M O L D I N G