Plain or Slab Milling Operation

Plain or Slab Milling Operation
Points : Plain or Slab Milling Operation, Sequence of Operations The production of a flat surface parallel to the axis of the cutter is known as plain or slab milling operation. Flat surfaces may be milled with a plain or slab milling cutter mounted on an arbor (peripheral milling) and an inserted tooth or shell face milling cutter. Sequence of Operations

1. Check and lubricate the machine, wipe the work table.
2. Mount the work directly on the table if possible. Use a vise if the work cannot be mounted directly to the table. Pivot the vise so that the solid jaw supports the work against cutting pressure.
3. Align the vise with a dial indicator. If extreme accuracy is required. Otherwise, a square or machine arbor will do. Angular settings are made with a protractor.
4. Remove chips and dirt from the vise bottom, jaws and from the parallels.
5. Place the parallels in the vise with the work on them tighten the jaws and tap the work on to the parallels with a mallet or soft faced hammer. Thin paper strips can be use to check whether the work is mounted solidly on the parallels.
6. Select an arbor that is as short as the job will permit. Insert the arbor and draw it in tightly with the draw-in bar.
7. When possible, the cutter should be wide enough to take in the entire width of the, area to be machined and the smallest diameter possible, but large enough to provide proper clearance.
8. Key the cutter to the arbor. Position it as close to the column as the work will permit.
9. Position and lock the arbor support into place. Tighten the arbor nut.
10. Adjust the machine to the proper cutting speed and feed.
11. Before start to cut check cutter rotation and direction of feed. Set the cutter by using a strip of paper, it should be long enough to keep your fingers clear of the cutter. Release it as soon as you feel the cutter “Grabing” at it.
12. Tighten all locks and feed the work into the cutter with a proper depth of cut. As soon as cutting starts, turn on the coolant and the power feed. Do not attempt to feel the machined surface while the cut is in progress or while the cutter is rotating.
13. Do not stop the work during the machining operation. To do this a slight depression to be made in the work surface.
14. Complete the cut. Stop the machine or cutter’ and return the work to the starting position. Never feed the work back under the rotating cutter.
15. Repeat the above operations if additional metal must be removed.

Squaring Stock A definite sequence of operations must be followed to machine several surfaces of a piece square with one another.

1. Machine the first surface. Remove the burrs and placed the first machined surface against the fixed vise jaw. Insert a length of soft metal rod between the work and the movable jaw if that portion of the piece is rough or not square.
2. Machine the second surface.
3. Remove the burrs and reposition the work in the vise then machine the third side. This side must be machined to dimension. Take a light cut and measure its thickness. Stop the machine before attempting to make the measurement. The difference between this measurement and the required thickness is the amount of material that must be removed.
4. Repeat the above operation to machine fourth side.
5. If the piece is short enough, the ends may be machined by placing it in a vertical position with the aid of try-square. Otherwise, it may be machined with a side mill.