Extrusion International 2-2020

28 Extrusion International 2/2020 EXTRUSION TOOLING cleaned thoroughly before storage. For disassembly of tools, it is impera- tive to use purpose-built tooling to facilitate disassembly. These should be available from your supplier. If they are not, consult with a reputa- ble tooling house for replacements. The cost of these tools is easily offset by potential damages, frequently caused by improper equipment such as hammers and drifts. Follow the guidelines outlined in your opera- tor’s manual. Individual tools may have specific recommendations, so contact your supplier if anything is unclear. Your supplier understands that optimum performance relies on proper care and maintenance. Here are some useful tips: 1.) Clean your equipment while it is still hot as the residue is easier to re- move. It helps to remove and clean one piece of tooling at a time in or- der to maintain elevated tempera- tures. 2.) When cleaning a dual compound crosshead, (plastic and rubber) clean the plastic tooling first; the rubber second. 3.) Never use steel tools such as scrapers or screwdrivers because these can scratch and mar the tool- ing. 4.) Don’t use open flames because this generates excessive heat es- pecially in thin sections, which can affect hardness, concentricity and tolerances of components. Recom- mended cleaning tools and materi- als include: a.) Brass pliers to grip material and aid in pulling b.) Brass scrapers available in dif- ferent widths for cleaning flat ex- posed surfaces c.) Brass bristle tube brushes that are available in diameters from1/16” to 1” in 1 /16” increments (ideal for cleaning holes and recesses) d.) Brass rods – different diameter rods are good for pushing material out of flow holes e.) Copper gauze for cleaning and polishing exposed round or conical surfaces f.) Copper knives for removing res- idue from recesses and other hard- to-reach areas. Also, polishing com- pound restores polished surfaces g.) Compressed air, which is more effective for releasing plastic, but also aids in rubber removal. Be care- ful not to force debris into recesses with compressed air h.) Cleaning solutions may be use- ful, so remember to use fresh, clean rags (used rags often have metal chips embedded in them, which may scratch polished surfaces) i.) Cleaning oven – for plastic only. Follow manufacturer’s recommen- dations. If no temperatures are spec- ified do not exceed 850 degrees F (454 degrees C). Don’t quench tool- ing to cool, as this could affect tool- ing hardness, concentricity and tol- erances j.) Purging compounds – several are offered to purge the extruder screw/barrel of residual polymer and rubber compounds Removing Excess Material for Optimum Machining Efficiency Clean parts are critical to extrusion tooling performance and quality manufacturing. This is especially true for the sealing and locating surfaces – that control uniformity of the production process. For gen- eral maintenance of the tools, be- fore storage or tooling changeover, a thorough cleaning and removal of the excess material assures the precision machining alignments required to produce end products to the precise tolerances. Equip- ment should be cleaned while it is still hot, since residual polymer and rubber will be easier to remove. Be sure to follow all MSDS recommen- dations when heating the tooling. Thermal gloves are used to protect the hands from the heated tooling surfaces. A brass scraper, as well as a brass or copper wool cleaning cloth are recommended because they are soft enough not to scratch the surface. Make Tool Cleaning Easier The quickest way to remove the die is to employ the pressure of the extruder to push it out. Clean the body by using an air compressor and brass pliers so that the mate- rial cools down which increases the melt strength, making it into one- lump versus an elastic, gummy-like substance that is harder to remove. Cleaning the body feed port using compressed air and brass pliers to simultaneously cool and remove the excess residue from the feed ports. This procedure is followed by brushing with a round brass brush that polishes the surface. The flow area of the 2” (51 mm) flange