manufacturnig process Marks 4 Q6 a A circular copper workpie

   manufacturnig process

(Marks: 4) Q6 (a) A circular copper workpiece 300 mm in diameter is \"faced\" using a lathe. The cutting tool If has a major cutting angle (k) of 600, the depth of cut is 10 mm and the feed per revolution is 0.1 mm. has a motor power 4kW, what is the maximum workpiece rotation per minute (rpm)? For this problem use Table I for undeformed chip thickness and Figure 1 to obtain the specific cutting [Note: Material Removal Rate (MRR) Pn/p], Where, P is the motor power, n is the efficiency of cutting and p is the specific cutting energy. Also note MRRuuming rfde Ndm L work dismis as 30 whaler 6 (Marks 2) (b) If in question 6a, you want to increase the production rate so you want to increase the RPM to above 500 rpm what changes will you make into the lathe. JustifylExplain in brief why.

Solution

solution:

1)here undeformed chip thickness is given by

t=fsinKf=.1*sin60=.0866

where specific cutting energy is approximately 2 GJ/m3

hence metal removal rate is

MRR=Power*n/p=4000*.7/2=1400 mm3/s

hence speed of turning is given by

MRR+pi*f*dc*N*dm

f=.1 mm

dc=10 mm

dm=300 mm

on putting value we get that

N=1.485446 rps

N=89.1267 RPM

hence speed of lathe machine is 89.1267 RPM

2)if we want to increase cutting speed the following things will increase

i) MRR

ii)cutting forces

iii)increase power input to lathe for operation

iv)tool strength has to increase as rubbing will increase