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PRODUCTIVITY IMPROVEMENT ON COPY TURNING MACHINE, THROUGH CYCLE TIME REDUCTION
OUR ACHIEVEMENTS
We reduced the cycle time required for a valve on
CT machine from 24 seconds to 22 seconds.
The reduction of 2 seconds in the cycle time has
resulted in following changes.
Monthly turnover increased by Rs 5,62,500.
Yearly turnover increased by Rs 67,50,000.
AIM OF THE PROJECT
To increase the valve production from 950 to 1050 valves per shift on Copy turning machine by reducing the cycle time required by one valve to complete the seat turning & undercut operations. 
INTRODUCTION TO VALVE
INITIAL-CYCLE-TIME ON COPY TURNING MACHINE
The time taken to perform the entire operation on CT machine is 24 seconds which accounts to the production of 950 valves per shift of 6.5 hours.
CYCLE TIME TO ACHIEVE
In order to achieve a target of 1050 valves per shift, the cycle time has to be decreased to 22 seconds. This has to be done without having much effect on the machining time, so as not to have any effect on the quality of the valves produced.
INTRODUCTION
Operations performed on CT-81
a. Valve seat turning
The valve seat in an internal combustion gasoline or diesel engine is the surface against which an intake or an exhaust valve rests during the portion of the engine operating cycle when that valve is closed.
Valve seat turning
In Valve seat grinding the material behind the head of the valve is removed to some extent as per required angle.
b. Valve undercut
The undercut of valve is done for right positioning so it never emerges out of the valve guide. To state its advantages, due to undercut the weight of the valve reduces without having impact on the strength requirements of the valve.
Valve undercut
Valve undercut is the action of material removal from the stem of the valve near the valve head.
Valve seat turning and undercut operations
STEP BY STEP OPERATION ON CT-81
1.Valve from magazine falls into the V block.
2.The V block moves along the z axis towards the collect.
3.Now the gripper picks the valve in the V block and moves along the y-axis to reach the collet.
4.The valve is loaded into the collet.
5.Tools mounted on the bench, moves along the z-axis, towards the valve.
6.Now the seat grinding operation is carried out by Tool 1.
7.After finishing the seat grinding operation, Tool 2 carries out the undercut operation on the valve.
8.Now the valve gets unloaded into the bin.
STEP BY STEP OPERATION ON CT-81
METHOD OF APPROACH
We followed SEVEN steps of Quality Circle story:
Step 1: Identification of Problem
Step 2: Study Current situation
Step 3: Analyze data and find out route causes
Step 4: Choose solution (counter measures)
Step 5: Implement solution and Check results
Step 6: Standardization
Step 7: Conclusion
TIME TAKEN FOR THE THREE PHASES
WE OBSERVED THE TIME BEING TAKEN FOR THE THREE PHASES & OBSERVED THE STEPS CONSUMING EXCESS TIME.
PROBLEMS IDENTIFIED
THE CAUSES 2,3,4 AND 5 ARE DROPPED BECAUSE THEY ARE CONSIDERED NECESSARY TO EXIST SO AS TO PROVIDE DWELL TIME.
PROBLEMS IDENTIFIED
ARRIVING AT SOLUTION
Solution 1:
Program can be modified to change the path travelled by the tool. The changes should ensure the replacement of linear path with a displaced path.
Solution 2:
Replace the servo drive used for the movement of gripper with a pneumatic drive mechanism.
ORIGINAL PROGRAM
G28 U0 W0;
M32;
M72;
M31;
M12;
M28;
M10;
M70;
M23;
N1;
T0101
G50 S3000 M04;
G96 S120 M32;
G0 G40 Z23.0 M25;
M08;
G0 X20.182 Z4.4;
G01 X17.996 Z4.169 F0.12;
G01 X21.528 Z3.150;
G02 X25.246 Z2.076 A150 M71;
N2 T0102;
G50 S3000 M4;
G96 S100;
G02 X29.40 Z0.0 A135;
G00 G40 Z40 M27;
N3 T0203;
G50 S3000 M3;
G96 S100;
G0 X-50.0 M27;
G0 Z34.0 F0.2;
G0 X-8.0;
G01 X-5.95 Z32.644;
G01 X-5.38 Z32.644 F0.1 M26;
G01 X-5.32 Z15.200;
G03 X-6.9 Z10.191 R15 F0.2;
M09;
G28 U0.0 W0.0;
M05;
M13;
M11;
M61;
M01;
M99;
M30;
%
CHANGED PROGRAM
G28 U0 W0;
M32;
M72;
M31;
M12;
M28;
M10;
M70;
M23;
N1;
T0101
G50 S3000 M04;
G96 S120 M32;
M08;
G0 G40 X50.0 Z23.0;
G01 X17.996 Z4.169 F0.12;
G01 X21.528 Z3.150;
G02 X25.246 Z2.076 A150 M71;
N2 T0102;
G50 S3000 M4;
G96 S100;
G02 X29.40 Z0.0 A135;
G00 G40 Z40 M27;
N3 T0203;
G50 S3000 M3;
G96 S100;
G0 X-50 Z34 M27;
G0 X-8.0;
G01 X-5.95 Z32.644;
G01 X-5.38 Z32.644 F0.1 M26;
G01 X-5.32 Z15.200;
G03 X-6.9 Z10.191 R15 F0.2;
M09;
G28 U0.0 W0.0;
M05;
M13;
M11;
M61;
M01;
M99;
M30;
%
Implementing solution1
The traveling length of the tool is made to cut off up to some extent by changing the present linear path to a displaced path. This is achieved by making slender modifications in the CNC program.
Initial distance travelled by the tool =153mm
Reduced travelling distance of tool=115mm
Distance reduced = 153-115 = 38mm
Implementing solution2
By replacing the servo mechanism with pneumatic drive mechanism the time established is one second lesser than with the servo drive mechanism.
This is achieved because of the faster movement of the pneumatic drive and the halt is provided with the help of a stopper.
RESULT
As an outcome, there is a cut off of 2 seconds from the actual cycle time.
1 second is saved by making necessary changes in the CNC program for establishing a shorter path for the tool.
Another second is put aside by replacing the servo drive with pneumatic drive which is to be used to drive the gripper.
PRODUCTION IMPROVEMENT
CONCLUSION
Total time available 6.5 hrs*60*60 = 23400 seconds Per shift with 3 shifts per day.
Final cycle time=22 seconds.
Final output per shift=1050 valves.
Monthly turnover Increased by Rs 5,62,500.
Yearly turnover increased by Rs 67,50,000.