Chapter 24 Flashcards
Milling
A surface is generated by progressive chip removal. Multiple tooth tools are typically used
Milling cutter
The cutting tool in milling.
Interrupted cutting
Equally spaced peripheral teeth will intermittently engage and machine the workpiece.
Milling categories
Peripheral milling, end milling, and face milling.
Peripheral milling
The surface is generated by teeth located on the periphery of the cutter body. Surface parallel with the axis of rotation of the cutter
Slab milling
Performed on horizontal spindle milling machines.
Fm
Table feed rate in inches per minute
Feed per tooth
Fc
Width of cut
The width of the cutter or the work, in inches, designated by a W.
Face milling and end milling
The generated surface is at right angles to the cutter axis.
Face milling
Done on both horizontal and vertical spindle machines. Mainly the end surface of a milling cutter is used to create a flat surface.
End milling
Cutter can cut on both the sides and ends of the tool.
Horsepower
The maximum amount of material that can be removed per pass is usually limited by the available power.
If machine power is lacking for milling do:
1 use a cutter with a positive rake as this can be more efficient. 2 use a cutter with a coarser pitch. 3 use a smaller cutter and take several passes.
Up milling
Called conventional milling as it is a traditional method of milling. The cutter rotates against the direction of feed of the workpiece.
Climb milling
Called down milling. The cutter rotation is in the same direction as the feed rate.
Chip formation in uo milling
Chip is very thin at the beginning, then it increases in thickness. It is maximum where the tooth leaves the work.
Cutter in up milling
Éliminates the effect of looseness in the feed screw and nut of the milling table, but increases looseness in the work from the fixture so greater cramping forces are needed. Chips can cause surface finish to be poorer.
Down milling chip thickness
Maximum thickness cours close to the point of contact between tool and work. Pulls the workpiece into the cutter, must elongate looseness in the feed screw. This cutting process is smoother with a greater surface finish.
Milling surface finish
An interrupted cutting process. Positive rake angles tend to life the workpiece, while negative takes compress the workpiece.
Column and knee construction
Most basic milling machines are of this construction.
Column
The column is the main supporting frame for all parts and contains the spindle with the driving mechanism. Provides motion in three mutually perpendicular directions: 1 through the knee, moving on the ways. 2 through the saddle, moving transversely on the ways of the knee 3 through the table.
Ram type milling machine
Most versatile and popular milling machines, using the knee and Colin design. Suitable for light duty milling drilling reaming and so on.
The ram
Supports the head and permits positioning of the spindle with respect to the table.
Bed type milling machines
Has ruggedness and the capability of making heavy cuts with versatility. Table is mounted directly on the bed and only had longitudinal motion.
Bed type milling machine skill required
After set up, little skill is required to operate them, permitting faster learning time.
Simplex milling machines
Bed type milling machines with single spindles. They are made with both horizontal and vertical spindles.
Duplex and triplex type
Bed type machines made with two or three spindles.
Some milling machines are equipped with what
Automatic controls so that the operator only had to load and unload the workpiece into the fixture
Stand alone machines
A fixture can be located at each end of the table so that one workpiece can be loaded while another is machines
