What is meant by taper turning?

Definition of Taper :

Gradually increase or decrease in the diameter along with the length of job is called Taper.

Taper Turning :

Taper turning is a machining operation that is gradually increase or decrease in diameter from one part of a cylindrical work piece to another part is called Taper Turning.

Taper can be either external or internal.

If a work piece is tapered on the outside it has external taper; if it tapered on the inside, it has internal taper.

TAPER ELEMENTS:

D = Big diameter

d= Small diameter

l= length of the taper

L= Total length of job

α= Half taper angle

2α= Full Taper angle

Expression of Taper and its Conversion:

Taper can be expressed by –

·        Giving the big diameter, small diameter and the length of the taper.

Conversion: Tan θ = D-d/2L

·        Mentioning the included angle of the taper in degrees.

EX: 30° Taper angle

·        Giving the taper per feet.

EX: 5\8” TPF means in a 12” (one feet) taper length the difference in diameter is 5/8” TPF.

Conversion: Tan θ = TPF /24

·       Giving the taper in the ratio.

EX: Ratio 1:20 means for a taper length of 20 units the difference in diameter is 1 unit.

Conversion: Tan θ = Ratio/2

·       Mentioning by standard taper.

EX: MT 3

Classification of Taper:

Tapers are classified as two categories –

1) Self holding tapers

2) Steep or quick releasing taper

1) Self holding tapers:

Self holding tapers have a low taper angle the maximum taper angle of self holding taper is 10°.They will not have any locking device for holding the components assembled

In a self holding taperMT and BS taper are mostly used.

Examples:- Taper shank drill, reamers &sleeves.

2) Steep or quick realising taper:

Quick realising tapers have higher taper angles and they require locking device for holding. It is 3.5 inch per feet taper.

Examples:- Arbor of milling machine.