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Selection of chipbreaker

Apart from actually cutting the material , indexable inserts
with chipbreaker groove have two other functions -
Shaping and Breaking the chip . On modern day machines,
good chipbrekage and chip control are just as important
if disruptions to the machining process are to be avoided.
Chip shaping and breakage must therefore be just as
predictable as other factors such as tool life, cutting speed
,feed etc. The following factors are to be kept in mind
while selecting the chip control groove.
a) Cutting conditions such as speed ,feed and depth of
    cut.
   The thickness of chip will be proportional to the feed
   rate and chip width proportional to depth of cut . The
    cutting speed is inversely proportional to the chip
thickness.

b )Nature of work material such as alloying element
    ,hardness and condition of heat treatment.
    The thickness of chip and ease of curling are dependent on
    these aspects.Mild steel chips are thicker than those of
    hard steel.Hard steel chip are liable to curve more than
    those of mild steel .Thin chips may not curl. Chips of MS
    may not curl even if it is thick.

c) Profile of the Tool, such as nose radius and approach
    angle.
    The nose radius is relative to chip thickness, width and
    direction of flow . Small radius is preferable for
    fnishing while large radius is better for roughing . The
    approach angle will have influence on chip thickness
    and width . A smaller angle is preferable.

d) Shape of the chipbreaker groove such as width, depth
    and position of groove relative to the cutting edge.
    The Chipbreaker width should be proportional to the feed
    selected. Narrow at low feed and wider at high feed.
    The depth of the groove should be inversely proportional
    to feed i.e., deep at low feed and shallow at high feed. The
    entry angle should be inversely proportional to the chip
    thickness.

e) Friction at groove and cutting fluid.
    The grooves can be ground or mould. Ground grooves have
    lower frictional co-efficients. Effective range is wider when
    coolant is used. However it is liable to curl at low feed
    range.

Apart from the above, material to cut, mounting of insert in
the holder, machining method etc., also to be taken into
consideration for optimum shaping and breaking of chips.

The Chipbreaker used in WIDAX -KS system is an independent part as
against integral with insert in the case of WIDAX-LS and WIDAX-LR
systems. Chipbreaker used in KS system tool holder is most versatile. Whatever width of chipbreaker is desired, it could be obtained by a slight modification of the existing chipbreaker. It could be modified by simple grinding operation. Once modified the chipbreaker provides effective chipbreaking for 100 to 500 cutting edges. A narrow width of chipbreaker will shorten the chip length, where as a wider chip breaker width will give longer chips. The width of the chipbreaker depends upon the toughness of work material being machined, feed used and side rake of the tool used.

Chipbreaker profile

Widia has developed a comprehensive range of chipbreaker
grooves equal to any machining task. The various geometries are
designed and produced using state-of-the-art techniques.

Type T IMAGE 1page 30.jpg (13788 bytes)
Well known standard geometry depending on the Insert size,
good chipbreakage is achieved at depths of cut from 0.5 mm to
5 mm and the feeds of 0.1 mm to 0.5 mm.

Type R IMAGE 2page 30.jpg (10964 bytes)
Standard chipbreaker groove geometry for indexable insert
without a fastening hole; for use with clamp type toolholders.
WIDIA indexable inserts of this type have a positive geometry
and are thus outstandingly suitable for finish-turning operations
with small to medium chip cross sections from cutting depth of
1mm and feeds of 0.1 mm.

Type MU IMAGE 3page 30.jpg (14961 bytes)

Newly developed chip control geometry covering both rough
machining with medium chip loads and finish machining .with
low chip loads. Cutting edge geometry with positive rake keeps
cutting forces low. Ideal for internal machining and for turning
non-rigid work pieces. Designed for holders with screw type
clamping.