Metalworking has been practiced since prehistoric times and involves shaping and modifying metals. Turning is a metalworking process where a cutting tool is moved parallel to a rotating workpiece to cut off material. Turning operations include facing, parting, grooving, and threading. Automated lathes like turret lathes and CNC lathes were developed to increase the speed and precision of metalworking processes and enable mass production. While manual machines are still used for small production runs, CNC lathes are now widely used due to their programming flexibility and ability to perform complex operations.

1. ABOUT MACHINES.
By :
D.JOTHILINGAM

2. Metal Working
 Metalworking is the process of working
with metals to create individual parts,
assemblies, or large scale structures.
 It therefore includes a correspondingly
wide range of skills and the use of
many different types of metalworking
processes and their related tools.

3. PRE HISTORY
 Metalworking predates history. No one
knows with any certainty where or
when metalworking began.
 The advance that brought metal into
focus was the connection of fire and
metals.
 Not all metal required fire to obtain it
or work it.

4.  Metalworking was being carried out
by the South Asian inhabitants of
Mehrgarh between 7000–3300 BC
 Around the date 2700 BC, production
of bronze was common in locales
where the necessary materials could
be assembled for smelting, heating,
and working the metal.

5.  Iron was beginning to be smelted. Iron
began its emergence as an important
metal for tools and weapons.
 The Iron Age was dawning.

6. Metal Forming processes
 Sand casting
 Forging
 Sintering
 Sheet metal

7. OTHER PROCESSES
 Cutting
 Drilling
 Tapping
 Grinding
 Broaching
 Shaping
 Welding
 Brazing
 Soldering
 Filing
 Milling
 Turning
 Honing

8. TURNING PROCESSES.
 Turning is the process whereby a single point
cutting tool is parallel to the surface.
 It can be done manually, in a traditional form
of lathe, which frequently requires continuous
supervision by the operator, or by using a
computer controlled and automated lathe
which does not.
 This type of machine tool is referred to as
having computer numerical control, better
known as CNC. and is commonly used with
many other types of machine tool besides the
lathe.

9. Turning operations
 Turning is one of the most basic
machining processes. That is, the part is
rotated while a single point cutting tool is
moved parallel to the axis of rotation.
 Facing is part of the turning process. It
involves moving the cutting tool at right
angles to the axis of rotation of the
rotating workpiece.

10. Turning operations
 Parting is used to create deep grooves which
will remove a completed or part-complete
component from its parent stock.
 Grooving is like parting, except that grooves are
cut to a specific depth by a form tool instead of
severing a completed/part-complete
component from the stock.
 Drilling is used to remove material from the
inside of a workpiece. This process utilizes
standard drill bits held stationary in the tail stock
or tool turret of the lathe.

11. Turning operations
 Screw cutting both standard and non-
standard screw threads can be turned on
a lathe using an appropriate cutting tool.
(Usually having a 60, or 55° nose angle)
Either externally, or within a bore.[1]
Generally referred to as single-point
threading

12. Workholding Methods
 Three-jaw chuck: Used with a variety of
diameters of round stock.
 Four-jaw chuck: Used mainly for holding
irregular shapes.
 Collet chuck: Primarily used for small round
workpieces.
 Faceplate: A faceplate, drive dog, and
mandrel may be used to turn workpieces such
as gearblanks.
 Drive center: Use hydraulic or spring-loaded
teeth that "bite" into the end of workpieces and
can be used when the entire length of the
workpiece must be machined.

13. Tooling
 The various angles, shapes, and sizes of a single-
point cutting tool have direct relation to the
resulting surface of a workpiece in machining
operations.
 Different types of angle such as rake angle, side
rake angle, cutting-edge angle, relief angle,
nose radius exist and may be different with
respect to the workpiece.
 Also, there are many shapes of single-point
cutting tools, such as V-shaped and Square.
Usually, a special toolholder is used to hold the
cutting tool firmly during operation.

14. Dynamics of turning
 The relative forces in a turning operation are
important in the design of machine tools.
 The machine tool and its components must
be able to withstand these forces without
causing significant deflections, vibrations, or
chatter during the operation.
 There are three principal forces during a
turning process: cutting force, thrust force
and radial force.

15. CUTTING FORCE
• The cutting force acts downward on
the tool tip allowing deflection of the
workpiece upward. It supplies the
energy required for the cutting
operation.

16. THRUST FORCE
• The thrust force acts in the longitudinal
direction. It is also called the feed force
because it is in the feed direction of the
tool. This force tends to push the tool
away from the chuck.

17. RADIAL FORCE
• The radial force acts in the radial
direction and tends to push the tool
away from the workpiece.

18. WHY AUTOMATE COMES…,
Although it requires less-
skilled labor, the engine
lathes do need skilled labor
and the production is
somewhat slow.

19. WHY AUTOMATE COMES…,
Moreover, it can be
accelerated by using a
turret lathe and automated
machines.

20. About AUTOMATE machines
 In a turret lathe, a longitudinally
feedable, hexagon turret replaces the
tailstock.
 The turret, on which six tools can be
mounted, can be rotated about a
vertical axis to bring each tool into
operating position, and the entire unit
can be moved longitudinally, either
manually or by power, to provide feed
for the tools

21. HOW AUTOMATE COMES…,
Machine tools of the
"automatic" variety had
already reached a highly
advanced state by the World
War I era.

22. HOW AUTOMATE COMES…,
 When World War II ended, the
digital computer was poised to
develop from a colossal
laboratory curiosity into a
practical technology that could
begin to disseminate into business
and industry

23. ABOUT CNC TURRET LATHES
 Today, most CNC lathes have turrets, and
so could logically be called turret lathes,
but the terminology is usually not used
that way.
 Horizontal CNC lathes, with or without
turrets, are generally called CNC lathes or
CNC turning centers or turning centers

24. HISTORY OF CNC MACHINES
 The first NC machines were built in
the 1940s and 50s, based on
existing tools that were modified
with motors that moved the
controls to follow points fed into
the system on paper tape.

25. Late-19th through mid-20th centuries:
key to mass production
From the late-19th through mid-20th
centuries, turret lathes, both manual
and automatic (i.e., screw machines
and chuckers), were one of the most
important classes of machine tools for
mass production.

26. Mid-20th century to present: transition
to small runs and second operations
 With the development and dissemination of
CNC lathes
 manual turret lathes began to lose their
position as the key to mass production of
turned parts.
 However, they did not become obsolete; the
focus of their use simply shifted from the
main turning operations of mass production
to small runs and second operations

27. STATUS OF AUTOMATED
MACHINES
 Similarly, cam-operated screw machines and
chuckers did not disappear; they simply
shifted to a different niche.
 They still often compete with CNC machines
in terms of unit cost per part produced,
depending on the difference in overhead.

28. THANK YOU