Extrusion can be an inherently expensive activity, and it is important to perform tool maintenance to minimize costs as much as possible. Extrusion processors need to be aware of the following factors to contend with in their attempts to be profitable:
• Materials usually cost more than labor:
• Running a product oversize to hold the minimum tolerance can waste valuable material.
• Downtime due to poor or damaged tooling is costly.
• It is expensive to keep an extruder running if it is producing scrap.
Appropriate tool maintenance addresses all of the above issues. New tips and dies are machined to a determined specification, ensuring concentricity and alignment. It is important to remember that minor misalignment of the tools may result in major problems in the final product.
Another adverse affect of unnecessary die adjustment is the stress introduced to the extrudate caused by unbalanced flow. The net effect is the final product retains memory of this imbalance and unpredictable die swell occurs.
Dirty, neglected, and improperly adjusted tools contribute to excessive material use. In turn, this complicates the die’s ability to maintain a minimum thickness tolerance. The excess material results in unnecessary costs that directly affect the profitability of the company and may in turn harm a valuable relationship with customers.
Maintenance and cleaning of tooling is necessary; and when you are fully prepared for it, easy. This is an important, controllable function that ensures a quality extruded product – one that meets dimensional specifications, maintains the specified minimum tolerance, and delivers an economically produced end product.
Preparing For Proper Maintenance
Use a dedicated work cart exclusively reserved and equipped for extruder head maintenance. This cart should have a supply of spare components and hardware. Create a clean, organized work area with soft and clean renewable work surfaces. The work cart should include:
• A vise with jaws of a soft metal, such as copper.
• Special equipment, such as tip-removal tools.
• Standard tools such as wrenches and soft-faced hammers.
• A supply of soft, clean rags.
• A spray bottle of cleaning solution.
Spare parts suggested by your tooling supplier, properly organized and stored. The operator’s manual contains a list of these.
• The repair and maintenance manual, which comes with your equipment.
• A small surface plate for a true, flat surface.
• A set of appropriate gauge and tip pins for initial tool location adjustment.
Make sure you have all the proper lifting aids available, including overhead hoists and hydraulic lifts. In most situations, the head and tooling are still at high temperatures, therefore lined gloves are needed when handling. Get help for moving heavy parts in awkward situations. Surfaces and edges are hard and therefore somewhat brittle, so dropping a part or striking parts together can result in damage.
Store you 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. Tools should be segregated so that they do not come into contact with each other. Clean all instruments thoroughly before storage.
For disassembly of tooling, it is imperative to use purpose-built tools to facilitate disassembly. These should be available from your supplier, but if they are not, consult with a reputable tooling house for replacement. The cost of these tools is easily offset by potential damages caused by improper equipment such as hammers and drifts.
(TO BE CONTINUED)
PART II – Extrusion Tooling Maintenance
In the next installment these important considerations in maintenance will be reviewed.
• Check your operators manual for guidelines – often overlooked
• Making timely repairs ¬– saves money & time
• Why and how to assemble tooling – a tool cart works best – see why?
Roger Guillemette, CEO
Glen Guillemette, President
Guill Tool & Engineering