Extrusion International 2-2022

30 Extrusion International 2/2022 EXTRUSION TOOLING maintenance of minimum thickness tolerance. Excess material results in unnecessary costs and these di- rectly affect the pro fi tability of your company and the relationships with your customers. The Important Final Step – Reassembly Working from your dedicated tool cart, follow the manufacturer’s in- structions for reassembly. Give each component a fi nal wipe down with a clean rag before installing. Even the smallest amount of grit, dirt and residual material must always be re- moved. Use mechanical or manual assistance for heavy and awkward components to avoid unnecessary mishaps. Reapply anti seize com- pound to all fasteners if required. Tighten fasteners to manufacturer’s recommended speci fi cations as well as in the recommended sequence. This fastening sequence should be speci fi ed in the manual and is generally in a star pattern. Tighten gradually until the proper torque is achieved to prevent distortion of the tooling. One of a die manufac- turer’s main goals is to form a con- centric cone as quickly and accurate- ly as possible in the primary section of the die – when the extrudate fi rst emerges from the die’s distribution capillaries. A properly designed and manufactured die has even distribu- tion close to the extrudate entrance point, but this effort is negated once the die is adjusted, shifting the ex- trudate off to one side. An eccentric cone is formed in the primary area, and a concentric cone exists at only one point in the process, rather than a smooth, continuous fl ow path with decreasing volume. A properly manufactured and aligned extruded head, along with well-maintained tooling should require little or no adjustment. Another adverse affect of unnecessary die adjustment is the stress introduced to the extrudate caused by unbalanced fl ow. The net effect is the fi nal product retains memory of this imbalance and un- predictable die swell occurs. Guill Tool & Engineering Co., Inc. 10 Pike Street, West Warwick, RI 02893, USA www.Guill.com Guill 812Three Layer Version03-Rework 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 brush- ing with a round brass brush that polishes the surface. The fl ow area of the 2” (51 mm) fl ange adapter should be cleaned by carefully using a brass brush. Examine all surfaces for any irregu- larities such as burrs and scratches since these must be repaired be- fore the head is reassembled. Most manufacturers recommend using a hand polishing stone to remove the offending burr. Follow stoning with a light application of 600-grit emery cloth if necessary, but avoid round- ing edges that are intended to be sharp. Flat sealing surfaces can also be cleaned using a stone, followed by a 600-grit emery cloth. Place the cloth on a clean, fl at surface, prefer- ably a surface plate, then apply fric- tion in a circular hand motion until the area is clean and even. The parts in question should all be hardened steel alloys and will not be adversely affected using these methods. In- conel, monel and Hastalloy® are typically not heat-treated, requiring special care and handling to avoid any damage. Don’t Overlook Repairs Tooling maintenance helps ensure a quality extruded product – one that meets dimensional speci fi ca- tions, maintains the speci fi ed mini- mum tolerance and is economically produced. Dirty, neglected and improperly adjusted tools contrib- ute to excessive compound appli- cations, which in turn complicate