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All five of these components are critical and should be regularly maintained. Another item not to be overlooked is the fact that collets should be replaced on a regular basis. Careful inspection on each tool change for metal damage such as bellmouthing or burrs inside. If damage is visible, the collet should be discarded and replaced. Also consider that even if there is no damage present, the collet can be worn out through metal fatigue. Insert the tool shank into the back of the collet, then into the front. If the grip in back is tighter the collet has lost it’s memory or is deformed from improper tightening. Heat is directly transferred from the tool to the collet. These heating/cooling cycles remove the original tempering of the steel. Collets are made from spring steel allowing them to have elasticity to grip the tool evenly. As the heating and cooling cycle is repeated this elasticity diminishes. This also occurs in a shorter time period on smaller size of the collets, especially in hand held air routers. Over time, a collet requires increased tightening to maintain the tool in proper position. As over tightening increases, the collets are distorted, creating eccentricities in the tool holder. Therefore, instead of over tightening older collets, and creating a number of other problems, they should be replaced every 400-600 operating hours. Old worn collets should be discarded to prevent re-use in the future, which can cause damage or inaccuracy. Often, the cost of a new collet can be offset by the cost of broken or underutilized tools in one shift alone. Proper positioning of the tool in the collet is critical. The tool should only be gripped on the shank portion of the tool. At no time should any portion of the flute fade out be inside the collet. Always Make sure the collet is snapped into the nut before tightening or a concentric grip will not be achieved. This as well as it will be hard to remove the collet after loosening the nut as it will be jammed into the taper. For Best Results Complete the following each time you change tools • Inspect for brown marking and clean with “Rust Free” Cleaner (#3321) and Brass Brushes (#33-10) • Spray on and clean off immediately. This cleaner is design to remove the oxidation easily and quickly without harsh abrasives. If using the brushes inside the collets only use brass or the collets can be “honed” out. • Do not let the “Rust Free” dry on surface. If a chalky residue forms reapply and clean off. Buff completely dry, and with the collets blow them out with compressed air. • Use a sparing amount of the T-9 anti-corrosive on a rag, then buff completely dry with a separate rag. Take Care not to touch the matching/mating surfaces of the taper or collets with your hands to prevent fingerprints from causing oxidation. We hope you will find this information informative and useful. We at Diversified Equipment & Supply strive to provide our customers with solutions in productivity. Only through proper performance tooling choices and proper routing techniques can your router provide you and your company maximum productivity. Author; Ross Gobble 2-27-04 DES
Successful Routing Through Proper Collet Maintenance
223 Blair Road Charlotte, NC 28227 Phone # 704-533-1891 EMAIL rossgobble@gmail.com www.desus.biz 11 Find out what we can do to help you with your CNC Router Needs
Collet maintenance is one of the most common causes of inadequate tool life or breakage. There are five and sometimes six links in the chain that make up this critical tool holding system called a collet. As a chain is only as strong as the weakest link, a router bit can only be as good as the system that holds it properly. The small amount of time spent to regularly inspect and clean the collet system will be more than offset in productivity increases reducing production costs. The six critical components are as follows: 1. Internal Collet Clamping Surfaces The most important is the inside of the collet. A brown resin build up often accumulates on the inside end of the collet. Resin migrates up through the slits in the collet and then deposits itself inside the collet. This resin build up, if not removed causes the collet to grip inconsistently on the tool shank. It prevents the collet from applying equal pressure throughout the entire grip range of the collet. This causes uneven gripping at the end of the collet which allows the tool to resonate inside, causing slippage inside the collet. Slippage then causes “fretting� a condition when brown resins are deposited on the shank of the tool. Resin buildup can be easily removed from the inside of the collet with Rust Free and a brass tube-type brush*. These brass brushes are non destructive, yet adequately remove along with the Rust Free the deposits high pressure air guns cannot. The one critical thing is the Rust Free is sprayed on and quickly brushed and wiped completely dry. Do Not Let Sit and allow to dry wet. 2. Internal Spindle & Collet Taper The inside taper of the spindle and toolholder is a critical surface which accumulates resin build up and should be cleaned regularly with each tool change to maintain. 3. External Collet & Toolholder Tapers The outside taper on the collet& toolholder, both large and small, require regular inspection and should be cleaned of all deposits each time the tool is changed. 4. Clamping Nut Surfaces The inside taper of the nut should be clean and free of burrs on the surface, which if present, not only skew the collet but can ruin a new collet. At times collets are replaced only to be ruined in the first use of a a bad collet nut. In addition, inspect threads for wear. 5. Thrust Bearings Some collet nuts also have an integrated thrust bearing connected to the inside taper. This bearing serves to reduce friction wear between the collet and nut as the nut is tightened. It is very critical, for if it is rough in movement, or worse yet frozen, it will cause run out or, out of tolerance conditions. These bearings should be kept in smooth operating condition. 6.Tool Holders Tool Holders such as ISO/BT 30, HSK 63F provide additional matching and mating tolerances that will in fact be prone to buildup especially in humid climates. "Fretting" or "Bronzing" will cause inconsistent gripping in the taper and reduce consistency of tool life and if ignored can cause spindle damage.
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*Supplied by Onsrud Cutter. Brushes & Rust Free
5. 6. BT/ISO 30 Toolholder
HSK 63F Toolholder