Machining

MACHINING PROCESS

LATHE• Lathe is the most general purpose machine tool.

• The work piece is held and rotated against suitable cutting tool.

• It has provision to hold the workpiece and to rotate it about an

axis.

• If the cutting tool is moved parallel to the axis of rotation of the

work, then a cylindrical surface is produced

• If the tool is moved perpendicular to the axis of rotation of the

work, then flat surface is obtained.

lathe

PARTS OF LATHE

FEED MECHANISM : LONGITUDINAL, CROSS FEED AND ANGULAR FEED

Tail stockchuck

Lead screw bed

carriage Tool post

SPECIFICATION OF LATHE• The overall length of bed

• Largest diameter of the work piece that can be rotated (height of live and dead center above the bed)

• Distance between the centers (max w/p length)

• Range of spindle speed

• Power rating of electric motor

• Diameter of lead screw and number and range of threads that can be cut.

OPERATIONS PERFORMED ON LATHE1. TURNING- Obtaining cylindrical surface2. TAPER TURNING

METHODS3. FORMING TOOL METHODE

HOLDING OF W/P - CHUCK AND LATHE CENTERS

2. TAIL STOCK SET OVER METHODE

The principle of this method is to shift the axis of rotation of the w/p at an angle to the lathe axis and feeding the tool parallel to the lathe axis.

The taper angle will be twice the inclination of the axis.

• 3. COMPOUND REST METHOD

Swiveling angle should be half of the taper angle

Turning

Taper turning

• THREAD CUTTING

Thread can be cut either on outside or inside of the w/p called external and internal thread respectively

Pitch- lead screw – gear adjustment

Thread cutting

• KNURLING

ROUGHENING A SMOOTH SURFACE

knurling

SHAPING MACHINE

Function- production of flat surface

Single point tool

Tool reciprocatesFrwd stroke—cut

PRINCIPLE PARTS OF A SHAPER

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RAMQuick return mechanism---ram

Slower cutting stroke

Faster return stroke

Shaping machine

Planer Machine• Planer Machines are used to

produce flat surfaces by a stationary single point cutting tool.

• The table on which workpiece is clamped moves against the tool.

• The feed is given to the cutting tool.

• Planer machine is capable of holding very large workpiece which cannot be accomodated by a shaper machine.

Slotter Machine• In slotter machine the

tool reciprocates in vertical axis.

• Cutting action is only during the downward stroke.

• It operates on the same principle as that of shaper

DRILLING MACHINE

• Drilling is the operation of

making holes in a workpiece

by forcing a rotating tool

called drill against it.

• Main parts are: Base

Column

Table

Drill Head

Drilling machine

OPERATIONS ON DRILLING MACHINE

1. DRILLING (a)2. REAMING (b)3. BORING4. COUNTER BORING (c)5. COUNTER SINKING (d)6. TAPING (e)

Drilling:It Is the Operation of producing circular hole using a drill by removing metal from the workpiece.Reaming:It Is the Operation of finishing a hole using a reamer.Boring:It Is the Opreation of enlarging a hole.Counter Boring:It is the operation of increasing the diameter of a hole for a certain distance.Counter Sinking:It is the operation of creating a cone shape at the end of a hole.Taping:It is the operation of cutting internal threads by means of a tool called TAP.

MILLINGUP MILLING

(Conventional Milling)DOWN MILLING(Climb Milling)

• Milling is the process of removing metal by feeding the workpiece against a rotating multipoint cutter. As the cutter rotates, each cutting edge removes a small amount of material from the workpiece.

In up milling the workpiece is fed

against the rotating milling

cutter.

In down milling the workpiece is

fed in the same direction of that

of rotating milling cutter.

Milling machine

Milling machines can be classified as

1. Horizontal Milling Machine

2. Vertical Milling Machine

Horizontal Milling Machine

Vertical Milling Machine

MILLING OPERATIONS

1. PLAIN MILLING 2. FACE MILLING

• 3. SIDE MILLING 4. END MILLING

• 5. T SLOT MILLING 6. ANGULAR MILLING

• 7. FORM MILLING 8. GEAR CUTTING

GRINDING

Grinding is the process of metal

removal in which the cutting tool used

is an abrasive wheel.

It is used for the following purposes

1. To remove small amount of metal

from workpiece.

2. To obtain better surface finish

3. To machine hard surfaces

4. To sharpen cutting tools

Grinding machine

TYPES OF GRINDING• 1. CYLINDRICAL GRINDING

Grinding wheelsMade of abrasive materials

bonded together.2 types1. Natural : sand stone,

emery, diamonds etc.2. Artificial : silicon

Carbide, Aluminium oxide, boron carbide etc.

• 2. SURFACE GRINDING 3. FORM GRINDING

NC Machines• It is the method of controlling

manufacturing operations by means of numerical instructions.

• A programme is prepared by the programmer after product drawing and process planning

• This programme is recorded in a magnetic tape and fed to the control unit.

• This unit sends signals to the machine through position command unit.

CNC Machines• It is the method of controlling

manufacturing operations by

means of a computer.

• A CNC code is generated by the

computer after product drawing

and process planning

• The computer send signals to the

machine as per the CNC code.