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Friday, 18 July 2014

Milling Machine Work Holding Devices

Milling Machine Work Holding Devices Points : Milling Machine Work Holding Devices, work holding devices for milling Work piece have to hold firmly with tightly on milling machine table for precise milling operation. The most generally use holding devices are various types of vices and holding devices used on a milling machine. Milling Machine Vises Milling machine vise is mainly general type of work holding devise use on milling machine.
1. Plain Milling Machine Vise
2. Universal Angle Milling Vise
1. Plain Milling Machine Vise Plain vise is use for holding work which has parallel sides. Vise is bolt directly to table by T-slots in the machine table. Plain vise can be accompanied through a swivel base. Swivel base is graduated in degrees with allows vise to swivel in horizontal plane. Swivel base give vise a greater degree of flexibility, but must be avoid while doing heavy irregular cutting operations as it reduces the stiffness of setup.
2. Universal Angle Milling Vise Universal angle vice is for machining operations relating compound angles is commonly used. Universal vise allocate the operative to tilt the workpiece 90° in vertical plane too as swivel it 360° in horizontal plane. In high production condition an air or hydraulically actuate vise can used. These vises are rapid acting. They also uphold reliable clamping pressures as of one part to next. Though, on mainly manual type milling machines vise is opened or closed by handle. As tightening a plain type milling machine vise is not needed to strike handle of the vise.
Milling Machine Holding Devices The most generally use holding devices are various types of holding devices used on a milling machine.
1. Circular Table
2. Collets
3. T-bolts and Clamps
4. Angle Plates
5. Parallels
6. Fixtures
7. Cutter Holding Devices
8. Direct Mounting to the Table
9. V-Blocks
1. Circular Table Circular table are presented in market in dissimilar shapes, designs, and specifications, except by the similar basic purpose. Circular tables are use for milling circular surfaces. On boring machines, circular tables are use for boring a sequence of holes. Circular table can be mount on machine table and use for make circular surfaces after centralization. Circular table are now presented in different inclinable forms for angular work. Indexing principles of circular tables are base on: (a) vernier principle, (b) dividing head index plate principles (C) optical scale principle. Vernier principle circular tables are mainly plentifully use on milling machines. These are calibrate accuracy tables use for precise work.
2. Collets Collet is an exact, time-saving cutter holding device use on milling machines. It is presented in different designs. The mainly usually use collet is spring-type collet. This is fixed on main spindle of milling machine by hand wheel draw sleeve with is operate by handle fitted on it. In intend, plain and spring collets are like to collets use on lathe machine. Screwed Cutters Extremely frequently, small cutters are giving by threaded holes at centre. These cutters are mounting on threaded nose of an arbor. Arbor is mounting on spindle in common way and the cutter is held on the other end for moving out milling operations.
3. T-bolts and Clamps T-bolts are use for hold work directly on milling machine. Milling machine table is providing by T-slots with the workpiece is held by the help of T bolts. Clamps are also called straps, are mild steel flats commonly 12-20 mm broad and 45-75 mm wide. They are giving by a slot or opening to allow T-bolt to pass through them.
4. Angle Plates Angle plate is L shaped part of Cast Iron or Steel to have tapped holes or slots to make easy the clamping of workpiece. Angle plates are use while parts require to contain machining operations perform at a 90° angle to axis of the table.
5. Parallels Parallels are part of steel bar stock precisely machines so that the opposite sides are parallel to each other. Parallels are providing in sets of two by the same dimensions. Parallels are use in order to provide clearance below the work so cutting tool does not break the machine table or vise base.
6. Fixtures Fixtures are particular work holding devices to be specially intended to hold an exacting workpiece. Fixtures are required, in a few cases, to hold odd-shaped parts which cannot be held any other method. Castings are generally a excellent example of parts which require to be fixtured. Fixtures can use in high production position. Use of fixtures reduces loading, locating, clamping with unloading time. Depending upon the intend requirements, different types of fixtures are use on milling machines.
7. Cutter Holding Devices Depending upon the devise of cutter, the following cutter devices are use on milling machine. Arbors Cutting have a bore are mount on arbor of a milling machine. A simplify vied of a milling cutter mounted on an arbor.
Some rules have to be followed as holding cutters on milling machine:
  1. Turn cutter in correct direction with protect it as of breakage by using suitable speeds and feeds.
  2. Keep the milling spindle head and tapers on milling arbors as of break.
  3. Use a accurate milling cutter equivalent to diameter of arbor.
  4. Clean all fitting surfaces previous to assembly.
8. Direct Mounting to the Table Work that is as well big or has an odd pattern is generally bolted directly to table. This process of work holding takes the most skill and capability. Direct Clamping using strap clamps-Stop block is use to support the work as well as stop the part from slipping.
9. V-Blocks V-Blocks hold and support encircling work for milling or drilling. V-Blocks come in various different sizes. On milling machines, V-Blocks are in general clamped directly to table. V-Block and a strap clamp being use to clamp a round element to table.

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