24-11-2012, 05:16 PM
MILLING machining
Unit 3 milling machine .pptx (Size: 4.15 MB / Downloads: 37)
Process of machining flat, curved, or irregular surfaces by feeding the work piece against a rotating cutter containing a number of cutting edges.
Cutter rotates at high speed & bcz of multi point cutting edges it removes metal at very fast rate.
Machine can hold one/ more cutters at a time.
This machine produces accuracy & better surface finish, high rate & very close limits of dimensions.
Milling is a very versatile process capable of producing simple two dimensional flat shapes to complex three dimensional surface configurations.
Milling machines may be manually operated, mechanically automated, or digitally automated via computer numerical control (CNC).
Milling machines can perform a vast number of operations, some very complex, such as slot and keyway cutting, planing, drilling, die sinking, rebating, routing, etc.
Principle:
Work is rigidly clamped on table of machine & revolving multi teeth cutters are mounted either on spindle/ arbor.
As shown in dia. cutter revolves at high speeds & work fed slowly past the cutter.
Work can be fed in vertical,
longitudinal/ cross direction.
As work advances cutter teeth
remove metal from w/p
surface to produce desired
shape.
The milling process:
Typically uses a multi-tooth cutter
Work is fed into the rotating cutter
Capable of high MRR
Well suited for mass production applications
Cutting tools for this process are called milling cutters
Table is given straight motions in 3 directions:
For giving vertical movement to table knee itself, together with whole unit above it , slides up & down along ways, provided in to front of column.
For giving cross movement to table, saddle is moved towards/ away from column along with whole unit about it.