UNIT 4 MACHINING AND ROBOTICS

Question 1

Machining

Answer 1

process of removing the excess material from the work piece in the form of
chips, by forcing the cutting tool with one or more cutting edges.

continuous chips = ductile

discontinuous = brittle

• A secondary process

MACHINE TOOL major functions
-rigidly supports the work piece and cutting tool
-Provides relative motion between work piece and cutting tool
-Provides range of speeds and feeds

cutting tool removes the
material by moving i parallel to rotation => turning.

final object formed is a cylinder. achieved by rotating the work piece

Question 2

LATHE

Answer 2

WORKING PRINCIPAL OF LATHE:
a cutting tool that can remove material in the form of chips from the rotating work pieces to produce circular objects

oldest machine(mother of all machines)

(most common) work piece is clamped by centres (live (rotating) and dead centres(non rotating, fixed))

parts of LATHES
- BED: backbone, where all components mounted, made of cast iron due to good daming etc

HEADSTOCK (LIVE CENTRE):
box like casting mounted, has a spindle which rotates
mounted on left side

TAILSTOCK (DEAD CENTRE)
mounted on right side
movable part, (can house drills etc)

FEED ROD
long shaft used to drive the apron mechanism for cross and longitudinal power feed during turning. powered by the set of gears from the headstock.

LEAD SCREW
long threaded shaft geared to the headstock. Closing a split nut around the lead screw engages it with the carriage. The lead screw is used for cutting thread accurately and should be disengaged for other operations.

Question 3

CARRIAGE ASSEMBLY

Answer 3

CARRIAGE ASSEMBLY:
supports the cutting tool and enables controlled movement along and across the workpiece. and also feeds tool

MAIN PARTS ARE:

SADDLE: can slide back and forth along bed slide ways thus tool will move parallel to the spindle axis.

CROSS SLIDE: On the upper surface of the saddle, moves the tool at right angle to spindle axis.

either be operated by the by cross slide hand wheel or by apron mechanism.

COMPOUND REST: mounted on the upper surface of the cross slide. can be swiveled so that the tool can move at an angle to the spindle axis.

TOOL POST: mounted on the compound rest and carries the cutting tool.

Question 4

LATHE operations

Answer 4

Axis of rotation: straight line around which an object rotates or spins.

PLAIN TURNING

work held in spindle is rotated while the tool is fed parallel to the axis of rotation. The surface
generated is cylindrical

DONE IN 2 STAGES
Rough turning:
majority of material removal and done at high speeds

smooth turning:
done at lesser speeds
and involved in finishing the given job

FACING
operation for generating flat surface

feed is perpendicular to the axis of revolution.

tool should have a suitable approach angle so it wont interfere with the work piece during the tool feeding.