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Cutting tool (machining)

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In the context of machining, a cutting tool or cutter is any tool that is used to remove material from the work piece by means of shear deformation. Cutting may be accomplished by single-point or multipoint tools. Single-point tools are used in turning, shaping, planing and similar operations, and remove material by means of one cutting edge. Milling and drilling tools are often multipoint tools. Grinding tools are also multipoint tools. Each grain of abrasive functions as a microscopic single-point cutting edge (although of high negative rake angle), and shears a tiny chip.

Cutting tool materials must be harder than the material which is to be cut, and the tool must be able to withstand the heat generated in the metal-cutting process. Also, the tool must have a specific geometry, with clearance angles designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on the workpiece surface. The angle of the cutting face is also important, as is the flute width, number of flutes or teeth, and margin size. In order to have a long working life, all of the above must be optimized, plus the speeds and feeds at which the tool is run.

Contents

TypesEdit

Linear cutting tools include tool bits (single-point cutting tools) and broaches. Rotary cutting tools include drill bits, countersinks and counterbores, taps and dies, milling cutters, reamers, and cold saw blades. Other cutting tools, such as bandsaw blades, hacksaw blades, and fly cutters, combine aspects of linear and rotary motion

Cutting tools with inserts (indexable tools)Edit

Cutting tools are often designed with inserts or replaceable tips (tipped tools). In these, the cutting edge consists of a separate piece of material, either brazed, welded or clamped on to the tool body. Common materials for tips include cemented carbide, polycrystalline diamond, and cubic boron nitride.[1] Tools using inserts include milling cutters (endmills, fly cutters), tool bits, and saw blades.

Solid cutting toolsEdit

The typical tool for milling and drilling has no changeable insert. The cutting edge and the shank is one unit and built of the same material. Small tools cannot be designed with exchangeable insert

HolderEdit

To use a cutting tool within a CNC machine there is a basic holder required to mount it on the machine's spindle or turret. For CNC milling machines, there are two types of holder. There are shank taper (SK) and hollow shank taper (HSK).

Tool setupEdit

The detailed instruction how to combine the tool assembly out of basic holder, tool and insert can be stored in a tool management solution.

Cutting edgeEdit

The cutting edge of a cutting tool is a very important for the performance of the cutting process. The main features of the cutting edge are:

  • form of the cutting edge: radius or waterfall or trumpete
  • cutting edge angles (free angle and rake angle)
  • form and size of the chamfers

The measurement of the cutting edge is performed using a tactile instrument or an instrument using focus variation.

ReferencesEdit

  1. ^ Stephenson, David A.; Agapiou, John S. (1997), Metal cutting theory and practice, Marcel Dekker, p. 164, ISBN 978-0-8247-9579-5.