productivity improvement using mttr and mtbf...

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International Journal of Mechanical Engineering and Technology (IJMET)

Volume 8, Issue 7, July 2017, pp. 1338-1347, Article ID: IJMET_08_07_144

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=7

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

PRODUCTIVITY IMPROVEMENT USING MTTR

AND MTBF METHODOLOGY

Pulkeshian Daruka

Undergraduate Student, Department of Mechanical-Mechatronics Engineering,

The LNM Institute of Information Technology, Jaipur, Rajasthan, India.

Tushar Agarwal

Undergraduate Student, Department of Mechanical-Mechatronics Engineering,


Dr.Vikram Sharma,

Associate Professor, Department of Mechanical-Mechatronics Engineering,


ABSTRACT

There are manysmall-scale industries in India, but tough competition amongst

them have made their survival very difficult. This has led to reduced production. The

case study presented in this paper deals with the implementation of Kaizen in

automotive parts manufacturing industry situated in North India.Kaizen, is well tested

Japanese concept of continuous improvement to increase the productivity of man,

material and machine.

The methodology of Why-Why analysis, MTTR and MTBF has been used here to

implement Kaizen in an industry and compare the statistics of growth comparing it

before and after the implementation of Kaizen. Various Kaizen methods are listed

according to tools/machines, and improvement is estimated. The results have shown

savings in terms of money and time. The case study can motivate the practitioners to

implement kaizen in a small scale industry. Over the years lakhs of rupee have been

saved after the implementation of kaizen by reducing the use of resources.

Key words: Kaizen, Why-Why Analysis, Mean Time between Failures (MTBF),

Mean time To Repair (MTTR), Losses.

Cite this Article: Pulkeshian Daruka, Tushar Agarwal and Dr.Vikram Sharma,

Productivity Improvement Using Mttr and MTBF Methodology. International Journal

of Mechanical Engineering and Technology, 8(7), 2017, pp. 1338-1347.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=7

Pulkeshian Daruka, Tushar Agarwal and Dr.Vikram Sharma


1. INTRODUCTION

Today, in the era of high competitiveness, it has become difficult in India for small scale

industries to survive in the market. Small scale industries have a major impact on the

country’s economy. Technological and managerial advancement at regular interval is required

for these industries to survive. Lean implementation has been proven as one such tool which

has claimed to improve the working scenario of an industry. It improves the quality system

with proper documentation of it. It aims to reduce the losses of human efforts, machinery, and

inventory waste. It also helps to speed to market and to become responsive to demand of

customers while producing superior quality products in the most efficient, effective and

economical way. The implementation of lean principles started with the Toyota Production

System. Lean approach consists of various practices which helps to improve the productivity

in an efficient and economical way. In India, Small scale industries does not prefer to

implement this tool due to assorted reasons. It is an alarming stage for all the industry which

are lacking in terms of quality and cost.

In an industry, there are around 5 type of major losses, these are:

1. Overproduction: When number of item produced are more than requirement it leads to

overproduction. It can be at any stage of production and lead to wastage of resources, increase

in lead time and high storage cost.

2. Idle time: Delay between the process either due to human intervention, delay in order or

delivery or due to poor material flow between the processes.

3. Excessive transportation: Due to the poor layout of the shop floor lead to excessive

transportation of good adding no value to the final product. It also causes deterioration of

quality of goods due to poor handling.

4. Producing defective items: Higher production rate lead to high chances of defective items.

Defective product amalgamates to unnecessary cost to the industry as scrap and wastage of

useful resources. This can be reduced by appropriate employee involvement and continuous

process improvement.

5. Over inventory: Storing extra goods in an inventory both unfinished goods, finished goods,

raw materials and have excess WIP.

2. LITERATURE REVIEW

To address the issue of eliminating waste, Kaizen has been used as a lean implementation tool

in an industry. It a combination of two words Kai means “change for” and Zen means

“betterment” or continuous improvement1. Japanese manufacturers have been expert in

implementing Kaizen in the field of automobile industry. It was first linked to Toyota

Production System (TPS). TPS aims to improve the production by elimination of waste and

Kaizen has constantly helped them to achieve the aim. There is still the need of learning these

from the Japanese. Learning of Kaizen at an early stage has been the reason for their success2.

It strategizes for every individual employee of an industry to work together to attain customer

driven improvement. Kaizen is not just a theoretical concept it has its complete meaning in

the implementation part3.Womack et al. (1990) has used Kaizen as tool of the “Lean

Philosophy” which changed the manufacturing world4.Imai (1989) has marked Kaizen as a

tool for continuous improvement of different life styles related to personal, social, work etc5.

Existing production state and proposed state can be differentiated using value stream

mapping6. Value Stream Mapping (VSM) is efficient in eliminating the waste activities from

the different processes in industry7. Kaizen can be combined with VSM for removing wastes8.

It involves the use of skill full people so that task can be performed effectively and efficiently.

Productivity Improvement Using MTTR and MTBF Methodology


Henry Ford has implemented Kaizen and analysed standardization and innovation as two side

of the coin.

Every stage of an industry has scope of continuous improvement in processing methods,

working condition etc 9 and Kaizen can be employed to succeed. It motivates the employees

to eliminate the issues and difficulties faced during production of goods10. Kaizen can be used

to identifies the issue and eliminate problems related to either process or our general life too11.

Processes and services which not add to the final value of the product can be removed12. The

waste removal will help to allocate major resources to the production activity and increase the

productivity leading to profit Gain13-14. A cross functional team need to be established which

identifies the waste and eliminates it15. This would help to attain an edge over the competitive

market16. Kaizen in public sector industries such as Coal India, BHEL etc. aims to improve

customer satisfaction by empowering employment17-18.

3. IMPLEMENTATION METHODOLOGY

Kaizen has been implemented at an automotive parts manufacturing company situated at

Uttrakhand, India. It is a large scale industry with ISO 9001:2010 certification. The company

relies on the concept of lean manufacturing and shows perseverance to achieve every single

possibility of improvement through Kaizen. A step by step approach is followed to implement

Kaizen.

The research methodology is shown by means of flow chart in figure 1:

Figure 1 Research Methodology of Kaizen

From industry, past data related to the losses on certain key performance measures, their

cause and effect have been collected and analysed. Depending on the data, action plan for

each step is laid out which is then implemented in the manufacturing unit. After

implementation, data is collected again to verify the results and check the improvement status.

The Production process starts off with the moulding process. Recently used injection

process is injection moulding due to its accuracy and high production rate. Moulding and



press shop process occur simultaneously depending on the parts which need to be

manufactured. Their after parts move to pad printing process, where required prints are made

on the equipment. After the pad printing parts move for final finishing through powder

coating. A coating is placed on the equipment to increase durability and provide lustrous

effect. Once the part is ready and inspected it move to assembly floor for final assembly.

3.1. CASE STUDY

Implementation of Lean Manufacturing Methodology for Improvement in Powder Coating

Process:

A start up time loss occurs during the initial initiation of the machine at Powder coating

unit. This is mostly due to the waiting time for tank to get heat up. This cause a delay in the

production process leading to economical loss.

3.1.1. Methodology

a. Initial Phase

Production staff starts the heater at the starting of the shift.

b. Problem Status

Startup loss is 200min/month. Machine requires 30 min to start initially.

c. Kaizen Theme

To reduce startuptime loss.

d. Idea of Improvement

The ideas of improvement are achieved through Why-Why analysis which is done as follows.

Why-Why analysis

Why 1: Machine require 30 mins to start initially.

Why 2: Startup loss due to waiting to attain desired temperature in chemical tank.

Why 3: operator starts the heater in morning at start of the morning shift.

Why 4: No alternate solution to start the heater.

e. Root Cause:

No alternative method to start the heater before the shift starts.

f. Kaizen Activity

One member to be deputed to start the heater.

g. Final Stage:

Night shift maintenance person to start the heater before the morning shift starts.

h. Result analysis

Initial startup loss of 200min/month reduced to 0min/month.

Implementation of Lean Manufacturing Methodology for Improvement in Knob of a

vehicle

A knob pass movement was observed sticky in control switch (LH)due to which head

light is not working in pass condition. Due to which a number of complaints from customer

are received. Gap leads to rejection of parts after manufacturing leading to huge investment of

valuable resources in to dead stock was

a. Problem Status.

A knob pass movement was observed sticky in control switch.

b. Kaizen Theme



To Prevent customer complaints of head light not working during pass condition.

i. Idea of Improvement

The ideas of improvement are achieved through Why-Why analysis which is done as follows.

Why-Why analysis

Why 1: Head light not working in gap condition.

Why 2: Pass movement sticky

Why 3: Knob pass broken

Why 4: Breaking load found to be 5.50 Kgf which was less to accommodate in extreme

condition.

Why 5: Less wall Thickness (0.25mm) on pass wall.

j. Root Cause:

Low wall thickness

k. Kaizen Activity

Increase wall thickness.

l. Final Stage:

Wall thickness increased to0.50mm and 0.25mm radius provided at moving counter slot.

m. Result analysis

Zero Warranty failure after modification.

Comparison of both the case studies

Case study 1 derives out the benefits like reduced setup time and case study 2 derives the

change in parts design leading to less rejection rate.

MEAN TIME BETWEEN FAILURE (MTBF) is a reliability term used to provide the

amount of failures per million hours for a product. It is the most crucial information about a

product’s life span, and is required by the end user for decision making process. MTBF is

mostly followed by industries than by consumers. Most consumers are price driven and do not

consider MTBF and nor is the data often available. On the other hand, when equipment such

as media converters or switches need to be installed into mission critical applications, MTBF

becomes very crucial. In addition, MTBF may be an expected line item in an RFQ (Request

for Quote). Without the complete information, a manufacturer’s piece of equipment can be

disqualified.

MEAN TIME TO REPAIR(MTTR) is the time needed to repair a failed hardware module.

In an operational system, repair generally means switching a failed hardware part. Thus,

hardware MTTR could be presumed as mean time to switch a failed hardware module. Time

required to repair a product is too long then drivesup the cost of the installation in the long

run, due to down time until the new part arrives and the possible availability of time required

to schedule the installation. To avoid MTTR, many companies purchase spare products so

that a replacement can be installed quickly. However, customers will enquire about the turn-

around time of repairing a product, which can lead them to fall into the MTTR category.



Figure 2 Methodology for MTBF and MTTR Kaizen

Parts were analysed and root cause problem was determined. Depending on the issue, part

was selected, to perform the MTTR or MTBF kaizen. To reduce the MTBF and MTTR

several kaizens were implemented and data were recorded after implementation which are as

follows:

Table 1 Kaizen implemented and change in results

S No. Machine Kaizen Theme Work Done

Time Minutes Up Time

Minutes Before After

1 Moulding

Machine

SM-90T

To reduce MTTR of

Opening & Closing of

Bolt of Cylinder

Injection Unit

Provided Socket

Spanner for Bolt

full rotation

30 10 20

2 WDO

Blower

To reduce MTTR for

Shaft Key removal of

Blower Motor

Tapping done on

Shaft Key

30 10 20

3 Moulding

Machine

SM-50T

To reduce MTTR for oil

seal replacement of

injection cylinder

Provide Socket type

Allen Key for easy

removal of Allen

Bolts

15 2 13

4 Pad Printing

Machine

No. 1

To reduce MTTR for

relay replacement on

input board of Pad

Printing Panel

Replace Solder

Type relay board

with holder type

relay board

60 20 40

All the kaizens implemented in the parts to increase the efficiency and productivity are

mention in the above table. Comparing the data,we can see the increase in uptime of each

process leading to decrease in production lead time.



Figure 3 No. of Kaizen Completed

This graph shows the no. of points identified cumulative for kaizen and total no. of points

rectified during the respective month.

Figure 4 Methodology for MTBF

This figure shows the methodology followed to up level the parts which are the root cause

of the failure. Working condition for parts can be improved to prevent from damages or

improvements in parts designing, structure or material for corrective maintenance.



Table 2 Aim, improvement and saving in resources

S No. Machine Kaizen Theme Work Done MTBF Cost Saving

1 Moulding

Machine

SM-90T To increase life of Hydraulic Parts

Provide On

Line Hydraulic

filter in

moulding

Machine 2 years to 4 years Rs. 20,000/-

2 Moulding

Machine

SM-50T To increase life of Contactor

Solid State

Relay

provided in

place of

Contactor

12 month to 36

months Rs. 3,000/-

3

PCO Blower

Motor To increase life of relay

Electronics

Relay (Soft

Hard Motor

Protection

relay )

provided in

place of

Bimetallic

Relay

12 months to 24

months Rs. 2,400/-

4

DG Set 500

kva To increase life of Battery

Maintenance

Free

(Cummins

make) Battery

provided in

place of

Normal

Battery

12 months to 24

months Rs. 40,000/-

5 Moulding

Machine

SM-50T To increase life of Hydraulic Hose

Wire braded

hydraulic hose

provided in

place of

Rubber braded

hose pipe

12 month to 36

months Rs. 3,000/-

6

DM Pump To increase life of Pressure SW

Syphon

provided b/w

pipe & Power

SW to avoid

jerk

6 months to 24

months Rs. 1,500/-

7

RT Pump

To increase MTBF of Motor Spider

Coupling

Use PU Spider

in place of

Rubber Spider

12 months to 24

months Rs. 600/-

8

Seizer Lifter

To increase life of bearing in scissor

lifter

Gun Metal

bush provided

to support the

bearing

12 months to 24

months Rs. 1,600/-

9 Power Press

16T To increase life of Crankshaft

Gun Metal

bush provided

in place of

Brass bush

18 months to 36

months Rs. 4,000/-



The above table illustrates the machine where kaizen need to be implemented, to improve

the working scenario of the machines. These kaizens were implemented for the improvement

and total saving were recorded.

Figure 5 No. of Kaizen Completed

This graph shows the no. of points identified cumulative for kaizen and total no. of points

rectified during the respective month.

4. CONCLUSION

Competition prevailing effect on Indian business, has increased in recent times. In this study,

Kaizen have been implemented in an industry which had helped them to save both time and

money. The study shows the records of each kaizen implementation, its requirement, theme

and finally the net saving achieved by it. We tried to explain MTTR and MTBF and kaizen

which we have implemented to reduce the mean time.

A Why-Why analysis was made on certain problematic parts not just for monetary or time

saving but also a preventive step for maintenance. We were able to achieve zero warranty

failure due to knob pass movement and reduction in initial startup loss. This reduction in

processing time is always beneficial for the industries to achieve processing target within time

frame giving advantage over competitor.

This paper will encourage the managers to implement kaizen in Indian Manufacturing

firm, in India. It aims to cut down the cost of the products by eliminating waste at various

stages of processes. Such improvements are essential to survive in this competitive era to

secure the enlightened future of Indian manufacturing firm.

Further research can be done to reduce processing lead time using kaizen and decreasing

number of defects at final stage by Poke – Yoke. It will help to implement Kaizen and get

maximum benefit out of it.

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