HITEC University Taxila Department of Electrical Engineering

Heavy Industries Taxila Armored Personnel Carrier Factory Taxila Cantt

Nisar Ahmed Rana

nisarahmedrana@yahoo.com

1/1/2008

Performance Measurement of Ramp Door

Introduction and Background

This case study was conducted at RAMP DOOR one of the products produced in APC

Factory for M113 APC in year 2008. Ramp door is used in Special Vehicles. The purpose

of the study was to improve manufacturing performance and enhancement of

productivity. At the time of the study FAB shop employed 100 employees. The APC

Factory had turnover around 90 million rupees per year. In the case study different

defects were also discussed which are the barrier in the productivity of the Ramp Door.

During study a survey was carried out in which a structured interview of the supervisor

and worker was carried out. Direct observation of manufacturing plant was also carried

out in a visit of one day.

Objective and Methods

This case study was initiated to study the manufacturing process of ramp door of M113.

Our goal was to increase the performance and thus enhance the productivity. The

company has specified three major objectives to be reached.

Productivity: Increase the output from production process.

Efficiency: Increase the effectiveness of the product.

Quality: Deliver product to the right quality and high degree of excellence

This case study involved some interviews of employees. Also some documents were also

studied. In this case study Overall Equipment Effectiveness is used as tool to measure its

performance and productivity. The reason behind the use of this tool was that we are

dealing with internal business process only. We haven't external customers. So it is most

effective and reliable tool for this case study.

Internal Business Process

Manufacturing Process:

Plates and blocks for Ramp door came from CRD shop and manufacturing process starts

in Fabrication shop. The main manufacturing process of this product is done in this shop.

The process of ramp door manufacturing consists on different steps. The whole process

is given in flow chart below.

In the fabrication shop different plates are fixed in a fixture and welding starts. Ramp

door consists on 1 inner plate 2 side plate and two hinges. 2 spacers are made to

support the outer plate. 2 housing are also made to lock with APC. First of all different

hinges, housings, spacer and two side plates are welded with inner plate. After welding

and cooling it is sent to Press Machine to straighten it and remove any defect.

After this outer plate is fitted in fixture and welded. First of all hinges and spacers of

inner plate are welded with outer plate. On the outer plate one seal ledge is fitted. Then

the outer plate is welded with inner plate. After completing welding process the ramp

door is again sent to press machine for pressing. Then it is sent in CRD shop for drilling.

After that different minor assemblies are fitted and it is sent to door matching which is

also completed in this shop.

Parts of internal door also came from CRD shop and welding process starts in FAB shop.

First the inner plate of the door is fitted in fixture with minor assemblies and welding

starts. Then it is sent to pressing machine. Outer plate is fixed and welded on inner plate

after pressing. After door matching inner door is fitted in Ramp door. After pressing it is

sent for hull matching. If hull matching is successfully completed, Different assemblies

are fitted and welded. Finally it is fixed in hull after final inspection. Stage inspection is

also made by expert quality control staff.

Overall Equipment Effectiveness

Item Data

Shift Length 8 hours = 480 min.

Short Breaks 0 @ 0 min. = 0 min.

Meal Break 1 @ 30 min. = 30 min.

Down Time 15 minutes

Ideal Run Rate 0.0013793

In one day 0.6% of a Ramp Door should be completed. So ideal run

rate per minute should be 0.0013793.

Total Pieces 0.5 pieces

Reject Pieces 0.05 pieces

Planned Production Time

= [Shift Length - Breaks]

= [480 minutes – 30 minutes]

= 450 minutes

Operating Time

= [Planned Production Time - Down Time]

= [450 minutes – 15 minutes]

= 435 minutes

Good Pieces

= [Total Pieces - Reject Pieces]

10% pieces are rejected

= [0.5 – 0.05]

= 0.45 good pieces

Availability = Operating Time / Planned Production Time

= 435 minutes / 450 minutes

= 0.9667 (96.67%)

Performance = (Total Pieces / Operating Time) / Ideal Run Rate

= (0.5 pieces / 435 minutes) / 0.0013793

= 0.8333 (83.33%)

Quality = Good Pieces / Total Pieces

= 0.45 / 0.5 Fuel Cell

= 0.9000 (90.00%)

OEE = Availability x Performance x Quality

= 0.9667 x 0.8383 x 0.9000

= 0.7250 (72.50%)

Comparison with world class OEE:

OEE Factors World Class OEE OEE of Ramp Door

Availability 90.00% 96.67%

Performance 95.00% 83.33%

Quality 99.90% 90.00%

OEE 85.00% 72.50%

Process Improvement

Firstly ramp door was completed in fabrication shop. Outer portion is first completed

then the internal door is completed. After completing they should be sent to pressing.

Then door matching is carried out. After fitment of internal door in Ramp door it is sent

to assembly shop for hull matching and finally fitted in hull.

Results

In this case study performances as well as quality are at low level as compared to

international OEE factors. Performance is at very low level. During study following

factors were identified to have major drawbacks on performance issues.

High Delay Time: High delay time exists between the requirement and supply of

one shop from other and it is not delivered according to schedule.

Low Labor Productivity: The value adding time of the operators in the assembly

was at an unacceptable level compared to total time.

There are some other minor performance losses in the factory which also be

finished.

The factors which were affecting quality are:-

Unskillful Workers: When a worker is not properly trained to do a specific job and

he is assigned to do it. He will pay his role in declined quality.

Negligence of Workers: When a worker is assigned a task or a wrong job and forced

to do it in time. He will not care for quality. Only right job should be for right person.

Conclusion

In our calculated OEE availability is at a good rate in comparison with world class OEE.

Performance and quality are less then the world class OEE. Need is to improve

performance and quality. No manufacturing organization can afford such a big lose in

quality. Performance is also affected by quality.

Quality can only be improved by strict quality control at each stage. If quality is

controlled the performance can automatically increase. Financial losses also occur due

to declined quality. Also skilled worker should be incorporated to do job. Only right

person should do right job. If a person can’t do a job better he should be assigned

another job. One of the reasons in reduction of quality is to increase availability.

Availability is not a big factor as quality is. When a worker is assigned a task and

imposed to do it in time he will not care for quality.

Performance is reasonably affected by quality. When quality is decreased the rate of

work also decreases. The reason behind it is that worker has to spend extra time in its

repair. Also the working process is very slow in the FAB shop. After welding workers

have to wait for a long time for cool down process. Also there is a delay time in each

process. After welding of Ramp door some time they wait for internal door. So there

should be strong co-operation in different shops so delay time can be reduced.