school

2.  We can put different shapes on the High
speed tool bits to cut different shapes on
the workpiece

3.  The shape of the tool and the angles of its ground
faces will depends on:
 The operation to be performed
 The material which has to be machined
 The power & rigidity of the lathe
 The amount of material to be removed
 The quality of finish desired.

4. Tool holders
 Used for holding
cutting tool bits
 Available in Right
hand, left hand and
straight

6.  Carbon Steels
 High Speed Steel (HSS)
 Stellite
 Carbides
 Diamond

7.  Carbon steels start to soften at a temperature of
about 180o
C. This limitation means that such tools
are rarely used for metal cutting operations. widely
used for woodworking and they can be used in a
router to machine aluminum sheet up to about
3mm thick.

8.  HSS tools are so named because they were
developed to cut at higher speeds. They are
tough and suitable for interrupted cutting and are
used to manufacture tools of complex shape
such as drills, reamers, taps, dies and gear
cutters. Tools may also be coated to improve
wear resistance.

9.  A non-ferrous alloy of chromium and cobalt, so
hard that it cannot be forged or machined except
by grinding, it is usually used in the form of a
tipped tool.

10.  Also known as cemented carbides or sintered
carbides .Have high hardness over a wide range
of temperatures and high thermal conductivity.
Can be shaped only by special grinding wheels
and is always used in the form of a tipped tool.

11.  The hardest known substance is diamond. It is
most suited for light uninterrupted finishing cuts at
almost any speed and is mainly used for very high
speed machining of aluminum - silicon alloys,
composites and other non - metallic materials.

12.  Solid Tools
 Made throughout in one material. Normally HSS or
carbon

13.  Tools made by brazing or welding a piece of HSS
to a high tensile steel shank.

14.  Have a tip of cemented carbide, etc, brazed to a
blank of high tensile steel.

16.  Tool bits are held in holders at an angle of about
15°

17. Cutting
Tools
 Can be High Speed
Steel held in tool
holders
 Can be also
Ceramic (Tungsten
carbide) bits held
directly in toolpost

18.  Clearance angle
 Ensures only the cutting edge of the tool
touches the work
 Too much clearance causes chatter

19.  Rake Angle
 Allows the chip being cut
to flow out
 Changing the rake
changes the power used
in cutting and the heat
generated
 Large rake = soft ductile
materials
 Small rake = hard brittle
materials