College of Technological Studies                                 Dept. of Mech. Prod. Tech.

Production Technology (MEP232)                      Final Exam – Summer Term 01/02

Time allowed (Two Hours)      Marks=  60

Student Name:

Question ONE : CNC (15 Marks)

(a) [Five Marks]

In a milling CNC machine the table is connected to a leadscrew of pitch 10 mm. Pulses are sent in a rate of 1000 ppr. It is required to move from the point p1(10,350) to the point p2(50,500). If motor rotates at 20 rpm, determine:

i) Number of pulses to both X  and Y motors. ii) Time consumed for Y-motor to reach the second point.

iii) Table feed speed for Y direction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(B) [Five marks]

 In Point-To-Point (PTP) drilling CNC machining it is required to drill three holes at the points P0(0,0) P1(100,300), P2(200,400) P3(250,150). Draw a sketch indicating the tool path (P0►P1►P2►P3►P0). Also, calculate the total machining time if feed in all directions is 30 mm/sec.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 ( C) [Five marks]: Write a DYNA program for the part shown if cutter diameter is 20 mm and if Feed in all direction is 30 mm/min.

Text Box: Y

 


Text Box: 200

 

 


Text Box: R20

 

 

 

 


Text Box: R50

Text Box: R5

 

 

Text Box: 100

 

 

Text Box: ZText Box: XText Box: 150 Text Box: XText Box: 80Text Box: 60

100
 
Text Box: 120


 


Seq. No

Dyna Command

 

Seq. No

Dyna Commands

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Question Two : Milling Operation (20 Marks)

Cutter

Workpiece

Operation & Cutting Conditions

·          Coated Carbide Inserts

·          Cutter Diameter (Dc)= 5 cm.

·          Teeth (inserts) Number (Z) = 24.

·          Cutter width (b) = 0.12 cm.

·          Hard Alloy Steel (Ks=35 kp/mm2)     

·          30 slots on cylindrical rod.

·          Slot Dimensions 500*25*31 mm.

·          Machinability Index (RI)=0.5.

·        Type: slotting

·        Rough Speed (Vc): 3600 m/hr.

·        Feed Speed (F) =  450 mm/min.

 

Part (A):    Operation Sketch ( 3 Marks)

 

 

 

 

 

 

 

 

 

 

 

 

 

Part (B) Machining Time (7.5 Marks)

 

 


a) Metal Removal Rate (MRR) =

 

 

 

 


b) Feed Power (HP) =

 

 

 

 

c) Rough Machining Time (Tr) =

 

 

 

 

 

d) Finish Machining Time (Tf) =

 

 

 

e) Total Machining Time (T)

 

Part (C) Cutting Forces and Power (5 Marks)

 

a) Main Cutting Force (Ft) =

 

 

 

 

 

b) Total Cutting Force (Ft – total) =

 

 

 

 

 

c) Total Radial Force (Fr – total) =

 

 

 

 

 

 

d)Consumed Power (P) =

 

 

Part (D) Load Curve (4.5 Marks)

 

 

 

 

 

 

 

 

 

 

 

 

 

Question Three : Grinding Operation (15 Marks)

Cutter

Workpiece

Operation & Cutting Conditions

·          Grinding Wheel

·          Diameter (Dg)=260 mm.

·          Width (b) = 75 mm.

·          Hard Alloy Steel block of dimensions 600*50*50 mm.

·          Removed Thickness (h) =2.2 mm. 

 

·        Work speed (Nw)=3600 ds/hr

·        Wheel Speed (Vg)=950 m/min.

·        Rough & Finish depthes= 0.04 and 0.006 mm respectively.

·        Max Torque on wheel shaft = 9000 Kp.mm.

 

 

Part (A): Operation Sketch (2 Marks)

 

 

 

 

 

 

 

 

 

 

 

Part (B) Speed, Feed, and Depth of Cut (3.5 mark)

 

a)   Rough Workpiece Speed (Vw) =                                                                           m/min.  

 

b)   Finish Workpiece Speed (Vwf) =                                                               m/min

 

c)    Rough Wheel Speed (Vg) =                                                                                   m/min

 

d)   Finish Wheel Speed (Vgf) =                                                                                 m/min

 

e)    Max. Relative Speed (Vrmax) =                                                                          m/min

 

f)     Rough feed (Sr) =                                                                                                  mm         

 

g)   Finish feed (sf) =                                                                                                    mm

 

 

Part (C) Machining Time (3.5 Marks)

 

a)   Number of rough passes along depth (itr) =

 

 

b)   Number of  finish passes along depth (itf) =

 

 

c)    Number of rough passes along width (iBr) =

 

 

d)   Number of Finish passes along width (iBf) =

 

e)    Rough Machining Time (Tr) =                                                                                  min

 

f)     Finish Machining Time (Tf) =                                                                                   min

g)   Total Machining Time (T) =                                                                                      min


Partt (D) Cutting Forces and Power (3 Marks)

 

 


a)   Cutting Force (Pz) =

 

 

 

 

 

 

 

 

b)   Wheel Motor Power (Pgm) =

 

 

 

 

 

 

 

c)    Workpiece Motor Power (Pwm) =

 

 

 

 

 

 

 

 

 

Part (E) Draw TWO Sketches indicating both of Internal Cylindrical and External Floating Cylindrical Grinding Operations (3 Marks)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



Question Four : Broaching Operation (10 Marks)

Cutter

Workpiece

Operation & Cutting Conditions

·          Internal 4-bit Pull Broach

 

·          Hard Alloy Steel Block    

·          Slot Dimensions: 400*20*12 mm.

·          Specific Energy (Ks):30 kp/mm2

Broach Sliding Speed range (0.08 to 0.1 m/sec).

Rough Depth (tr) =0.6 mm.

Semi-Finish Depth (tsf) =0.4 mm.

Finish Depth (tf) = 0.2 mm.

Mechanical Effeciency ( ζ ) =0.85

 

Part (A): Broach Dimensions & Operation Sketch (2 Marks)

 

 

 

 

 

 

 

 

 

Part (B) (3 Marks)

 

a)   Rough Pitch (Pr) =

 

 

 

b)    Semi-Finish Pitch (Psf) =                                    Finish Pitch (Pf) =

 

 

 

c)     Number of Involved Teeth (Zir) =

 

 

 

d)   Involved Thickness (hir) =

 

e)    Number of rough teeth (Zr) =

 

 

f)      Number of semi-finish teeth (Zsf) =

g)   Number of finish teeth (Zf) =

 

 

h)   Rough length (Lr) =

 

 

i)      Semi-Finish length (Lsf) =

 

 

j)      Finish Length (Lf) =

 

 

k)   Effective Broach Length (Le) =

 

 

 

l)      Total Broach Length (Lb) =

 

 

 

 

 

 


Part (C) Cutting Forces and Power (3 Marks)

 

 


Cutting Force (Pz) =

 

 

 

 

 

 

Consumed Power (P)=

 

 

 

 

Minimum Motor Power (Pm) =

 

Part (C) Draw a sketch indicating the hydraulic driven broaching machine (2 Marks)

 

 

 

 

 

1