Extrusion International 1-2023

34 Extrusion International 1/2023 EXTRUSION TOOLING pecially true for the sealing and lo- cating surfaces – that control uni- formity of the production process. For general maintenance of the tools, before storage or tooling changeover, a thorough cleaning and removal of the excess mate- rial assures the precision machin- ing alignments required to pro- duce end products to the precise tolerances. Equipment should be cleaned while it is still hot, since residual polymer and rubber will be easier to remove. Be sure to follow all MSDS recommendations when heating the tooling. Ther - mal 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 flow area of the 2" (51 mm) flange 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, flat 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. Inco - nel, monel and Hastalloy ® are typi- cally not heat-treated, requiring spe- cial care and handling to avoid any damage. Don’t Overlook Repairs Tooling maintenance helps en- sure a quality extruded product – one that meets dimensional speci- fications, maintains the specified minimum tolerance and is economi- cally produced. Dirty, neglected and improperly adjusted tools contrib- ute to excessive compound appli- cations, which in turn complicate maintenance of minimum thickness tolerance. Excess material results in unnecessary costs and these di- rectly affect the profitability of your company and the relationships with your customers. The Important Final Step – Reassembly Working from your dedicated tool cart, follow the manufactur- er’s instructions for reassembly. Give each component a final wipe down with a clean rag before in- stalling. Even the smallest amount of grit, dirt and residual material must always be removed. Use me - chanical or manual assistance for heavy and awkward components to avoid unnecessary mishaps. Re - apply anti seize compound to all fasteners if required. Tighten fas - teners to manufacturer’s recom- mended specifications as well as in the recommended sequence. This fastening sequence should be spec- ified in the manual and is generally in a star pattern. Tighten gradually until the proper torque is achieved to prevent distortion of the tool- ing. One of a die manufacturer’s main goals is to form a concentric cone as quickly and accurately as possible in the primary section of the die – when the extrudate first emerges from the die's distribution capillaries. A properly designed and manufactured die has even distribution close to the extrudate entrance point, but this effort is negated once the die is adjusted, shifting the extrudate off to one side. An eccentric cone is formed in the primary area, and a concen- tric cone exists at only one point in the process, rather than a smooth, continuous flow path with decreas - ing volume. A properly manufac - tured and aligned extruded head, along with well-maintained tool- ing should require little or no ad- justment. Another adverse affect of unnecessary die adjustment is the stress introduced to the extru- date caused by unbalanced flow. The net effect is the final product retains memory of this imbalance and unpredictable die swell occurs. Guill Tool & Engineering Co., Inc. 10 Pike Street, West Warwick, RI 02893, USA www.Guill.com Guill 900 W-Stripe