CHAPTER 5

CUTT

ING

SPEED GROUP 4

CUTTING SPEED

I M P O R T A N T O F C U T T I N G S P E E D

C O R R E C T V S AV E T I M E & C O S T. C O N T R I B U T E T O Q U A L I T Y & S U R FA C E F I N I S H .

Introduction

CUTTING SPEED

- K E E P T H E C U T T I N G T O O L L A S T L O N G E R ( W I T H O U T S H A R P E N I N G R E P E AT E D LY ) .

- M A X I M I Z E T H E M A C H I N I N G P R O C E S S W I T H O U T D A M A G I N G T H E T O O L , W P & M A C H I N E .

CUTTING SPEED

T H E FA C T O R S :

V = C U T T I N G S P E E D I N M E T R E P E R M I N U T E [ M / M I N ]

N = S P E E D O F W O R K ( S P I N D L E S P E E D ) I N R E V O LU T I O N P E R M I N U T E [ R E V / M I N ]

D = D I A M E T E R O F T H E W P I N M I L L I M E T R E [ M M ]

Π = C O N S TA N T 3 . 1 4 2

R E L AT I O N B E T W E E N T H E FA C T O R S :

Basic factor in Turning

CUTTING SPEEDSpindle speed diagram / rpm graph

CUTTING SPEED

E X A M P L E :

G I V E N

V = 2 5 M / M I N

D = 1 0 0 M M

Π = C O N S TA N T 3 . 1 4 2

N = ?

Spindle speed diagram / rpm graph

Solution:N = 1000 X V

d X π

= 1000 X 25

100 X 3.142

= 25000

3.142

= 79.6 rev/min

CUTTING SPEED

T H E FA C T O R S :

- D I A M E T E R T O B E W O R K .

- D E P T H O F C U T.

- F E E D .

-T Y P E O F W O R K .

-T Y P E O F T O O L M AT E R I A L .

CUTTING SPEED

D E P T H O F C U T. F E E D R AT E .

CUTTING SPEED

Machining Time

D0= Original / initial diameter [mm]

D1= New / final diameter [mm]

d = Depth of cut [mm]

N = Spindle speed [rev/min]

L = Length of the workpiece

l = Length of tool travelled

F = Feed [mm/rev]

Fr = Feed rate [m/min]

V = Cutting speed [m/min]

T = Time taken by the tool [min]

CUTTING SPEED

Machining TimeThe turning operation reduces the diameter of the workpiece from D0 to the final diameter D1. The Change in diameter is determined by the depth of cut, d:

D0 - D1 = d [mm]

The feed in turning can be converted to a linear travel rate in mm/min by the formula:

Fr = N · F [mm/min]

The time to machine from one end to required length is given by:

T = l / Fr [min]

TO BE C

ONTINUE