Extrusion International 2-2020

27 Extrusion International 2/2020 since there are many such surfaces in a quality tool, cleanliness is criti- cal. Checking of the tools for any de- formities is also important. Burrs, scratches and scrapes are usually a result of careless handling and/ or storage of equipment. Double and triple-layer extrusion heads pose an even greater challenge for maintenance. The number of seal- ing and centering surfaces multi- plies and can magnify the results of dirty tools. During changeovers, the head may be disassembled in order to change compounds and/ or tips and dies. Foreign matter is usually introduced at this point and residual materials must be thor- oughly removed. Physical tool dam- age often occurs during this phase, due to mishandling and poor stor- age techniques. These are highly precise parts, but can also be heavy and bulky to remove by hand. Use of a dedicated work cart exclusively reserved and equipped for extruder head maintenance is recommend- ed. This cart along with a supply of spare components and hardware is easily justified, especially when ex- amining the potential cost savings that result from well-maintained tools. The following should be consid- ered: 1.) Maintain a clean, organized work area with soft and clean renewable work surfaces 2.) Use a vise with soft jaws, such as copper 3.) Use special equipment, such as tip removal tools, etc. 4.) Standard tools include wrenches, soft-faced hammers, etc. 5.) Maintain a supply of soft, clean rags 6.) Use cleaning solutions in spray bottle 7.) Use spare parts as suggested by your tooling supplier, properly orga- nized and stored 8.) Keep handy your equipment’s re- pair/maintenance manual 9.) Have a small surface plate to pro- vide a true flat surface 10.) Use a set of appropriate gauge and tip pins for initial tool location adjustment 11.) Make sure you have all the proper lifting aids available, includ- ing overhead hoists, hydraulic lifts, etc. In most situations, the head and tooling will still be at elevated tem- peratures, therefore lined gloves are needed when handling. Today, tubing manufacturers com- pete with companies all over the world. To be a successful and prof- itable company, quality and effi- ciency are essential. This is especial- ly true in extrusion, where material costs are usually much higher than labor costs. Like a racing car stuck in the pit, many extruders sit idle because of poor or damaged tool- ing, plus excess maintenance time. Overhead costs add up and losing money is the result. Some start up quickly and make scrap, whereas others start up and run a product oversized to hold minimum toler- ance. They waste 10 to 20% of the material, which can run from 50 to 90% of the product cost. The tool- ing supplier goes to great lengths so that tips and dies are machined to a determined specification, en- suring perfect concentricity and alignment. The material is then dis- tributed in the proper location as part of the finished product. Understanding Maintenance Procedures: Get Organized Before You Start Example 1: In this example, with an improperly centered tool, a calculat- ed out-of-tolerance area of 0.059 in 2 (38 mm 2 ) was derived. When the two surface areas were compared, the calculated material waste was 11.8% of the finished product. The formula is % wall = min. wall thick- ness, max. wall thickness X 100. Ex- ample 2: Alternatively, if the % wall can be increased from 80 to 95%, a savings of about 12% of total cost can result. Savings will vary depend- ing on the designs, of course. Get help for heavy parts and awk- ward situations. Surfaces and edges are hard and therefore somewhat brittle, so dropping a part or strik- ing parts together can result in dam- age. Store your tools properly in a dry, clean area – a dedicated spot for each tool is best. These areas should have soft surfaces and each instrument should be covered after cleaning. Also, tools should be seg- regated so that they do not come into contact with each other. And tools and all instruments should be