Do not use adaptor bushings to reduce size of the collet on a routing or

Do not use adaptor bushings to reduce size of the

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premature toot failure and associated production difficulties. Do not use adaptor bushings to reduce size of the collet on a routing or production basis. Tools will not perform properly in bushings over an extended period of time. Bushings are for prototype, experimentation, test and evaluation and not for production. Wherever possible, use a coolant when routing. Heat caused by action between the tool and piece part is enemy #1 to toot life. Heat is a function of surface footage per unit of time, thus, the more dense the material, the faster the feed rate to minimize heat. However a compromise must be reached between finish and heat. Tool geometry dramatically affects the tool life. Rake and clearance angles, as well as cutting edge length should be examined. Router bit breakage is most often caused by a misapplication of the router bit. Make sure to use the proper router bit. Tool Breakage In spite of the structural and metallurgical attributes, which are designed into industrial and professional router bits, breakage occurs. A detailed examination yields the following: Application related breakage: Cutting edge lengths should be as short as possible to accommodate length of cut required. Larger cuffing edge diameters require larger shank diameters. Spiral geometry can direct chip flow and expel chips to reduce heat. Changing the type of tool is the only solution when tool application becomes a problem. Tool quality shortcomings: Upon investigation an internal flaw in the steel or carbide can cause failures. These failures are normally random, however, if the flaw was raw material batch based, an entire batch may be a problem. The same is true for heat-treating. Too high a hardness can lead to premature edge failure. This is generally confined to one batch of tools. Geometry induced fractures usually are related to improper rake and clearance angles as manifested in the bit riding the cut. The resulting heat generated by friction shortens edge life, tends to create burn marks and may cause the chips to accumulate behind each cutting edge and culminates in fracture. A shank out of round prohibits effective colleting and does not permit the tool to turn in a concentric manner. The whipping action generated is catastrophic to bit life and failure by fracture is imminent. Router Collet Integrity A router bit is rendered nearly useless if the mechanics of gripping and rotating the tool are not made to the same accuracy as the tool. Overt signals such as breakage and dark markings on the shank of the bit should be immediately investigated. Inspect the collet for out of round or bell mouthed conditions. Operators often overlook inspecting new collets based on the assumption that a new collet is geometrically correct. Tool manufacturers are aware and openly share the subtle nature of this problem. Dirt, dust, bonding agents and sap can also affect collet performance, which occupy space and accelerate wear.
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  • Fall '19
  • Tools
  • Milling cutter, High speed steel, Cutting, Collet, Downcut Spiral

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