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Analyzing the Machine Utilization and Overall Equipment Effectiveness of Machine Shop

Authors:
  • J S S Academy of Technical Education, Bangalore

Abstract

The existing problem in manufacturing industries is finding out the causes for low productivity. Low productivity can be caused by factors like unplanned maintenance, tool failure, machine breakdown, operator absenteeism, inefficient planning. An Effective Solution to this problem is the calculation of machine utilization in the manufacturing industry. Overall Equipment Effectiveness optimizes the process and gives us the definite result that is expected. It is not confined to a specific industry or a specific problem, it is a global solution that increases the productivity and in the recent years proven to be a boon for manufacturing industrialists.
Analyzing the Machine Utilization and Overall
Equipment Effectiveness of Machine Shop
T S Nanjundeswaraswamy*,
* Assistant Professor, Department of Industrial Engineering &
Management,JSS Academy of Technical Education,
Bangalore,
Shreyas.R**,Shashank Kashyap**,
**Research scholar, Department of Industrial Engineering &
Management, JSS Academy of Technical Education,
Bangalore,
Abstract:- The existing problem in manufacturing industries is
finding out the causes for low productivity. Low productivity can
be caused by factors like unplanned maintenance, tool failure,
machine breakdown, operator absenteeism, inefficient planning.
An Effective Solution to this problem is the calculation of
machine utilization in the manufacturing industry. Overall
Equipment Effectiveness optimizes the process and gives us the
definite result that is expected. It is not confined to a specific
industry or a specific problem, it is a global solution that
increases the productivity and in the recent years proven to be a
boon for manufacturing industrialists.
Keywords: OVERALL EQUIPMENT EFFECTIVENES,
Productivity, Supporting delays, Nonproductive activities.
1. INTRODUCTION
Machinery is the central to the production process and
manufacturers strive to optimize how it integrates with
other machines and supervisory systems in their business
enterprise.
A. Effective Utilization
Effective utilization implies judicious and economic use of
the available resources, effective use of available resources
in the key productivity at the plant level and also to higher
living standards of the people.
B. Work Study
It is a generic term referred to the techniques of method study
and work measurements which is used in the examination of
human work in all its contents
They lead to the systematic investigation of all the factors
which will affect the economy of the situation being
reviewed in order to affect improvement.
C. Method Study
It is the systematic recording and critical examination of
existing and proposed ways of doing work, as a means of
developing and applying easier and more effective methods
and reduced cost.
D. Work Measurement
It is defined as the application of techniques designed to
establish the time for a qualified worker to carry out a
specified job at a defined level of performance.
E. Work Sampling
It is the statistical technique for determining the proportion
of time spent by the workers in various defined categories
of activity.
F. Performance Sampling
To measure working time and non-working time of a
person on a manual task, and to establish a performance
index or performance level for the person during his or her
working time.
G. Overall Equipment Effectiveness
It is a way to monitor and improve the efficiency of the
manufacturing process.OEE is one of the ways to optimize
the performance of the existing equipment and gives ability
to measure the machines for productivity improvement.
2. LITERATURE REVIEW
Overall equipment effectiveness (OEE) is a hierarchy of
metrics developed by Seiichi Nakajima in the 1960s to
evaluate how effectively a manufacturing operation is
utilized. It is based on the Harrington Emerson way of
thinking regarding labour efficiency. The results are stated
in a generic form which allows comparison between
manufacturing units in differing industries. It is not
however an absolute measure and is best used to identify
scope for process performance improvement, and how to
get the improvement. If for example the cycle time is
reduced, the OEE will increase i.e. more product is
produced for less resource. Another example is if one
enterprise serves a high volume, low variety market, and
another enterprise serves a low volume, high variety
market. More changeovers (set-ups) will lower the OEE in
comparison, but if the product is sold at a premium, there
could be more margin with a lower OEE.
OEE measurement is also commonly used as a key
performance indicator (KPI) in conjunction with lean
manufacturing efforts to provide an indicator of success.
International Journal of Engineering Research & Technology (IJERT)
ISSN: 2278-0181
Published by, www.ijert.org
NCERAME - 2015 Conference Proceedings
Volume 3, Issue 17
Special Issue - 2015
OEE can be illustrated by a brief discussion of the six
metrics that comprise the system. The hierarchy consists of
two top-level measures and four underlying measures.
3. PROBLEM DEFINITION
Under utilization of various manufacturing units due to
number of non-productive activities which in turn
decreases the Overall Equipment Effectiveness [OEE ].
4. OBJECTIVES
To determine the utilization of machines and overall
equipment effectiveness of machine shop by
analyzing the data obtained.
To determine the present condition of capacity,
utilization of machines and reasons for less OEE.
5. METHODOLOGY
A. DEFINITION OF OEE
OEE is a way to monitor and improve the
efficiency of the manufacturing process.
OEE is one of the ways to optimize the
performance of the existing equipment and gives
ability to measure the machines for productivity
improvement.
B. OEE FACTORS
OEE can be divided into the following three metrics which
will help to gauge the plants efficiency and categorize the
key productivity losses that will occur within the
manufacturing processes.
a. Availability
b. Performance
c. Quality
METRIC 1: Availability
Availability = run time ÷ total time
Definition: Percentage of the actual amount of production
time the machine is running to the production time the
machine is available.
Simple OEE: The total run time of the machine subtracting
all unplanned downtime.
METRIC 2: Performance
Performance = total count/ target count
By Definition: Percentage of total parts produced on the
machine to the production rate of machine.
Simple OEE: How well a machine is performing during its
operation.
METRIC 3: Quality
Quality = good count ÷ total count
By Definition: Percentage of good parts out of the total
parts produced on the machine.
Simple OEE: How many good parts versus bad parts a
machine has produced.
C. OEE LOSSES
1. Identification of manufacturing units
2.Collection of data and codification of activities
3.Designing formats for main sample study
4.Conduct pilot study
5.Analyse the findings and compare with the
target to be achieved
6. Suggestions for improvement
7.Check for feasibility of suggestions
8. Implementation and maintain
Loss category
OEE metric
Loss example
Downtime loss
Availability
Equipment
Failures
Tooling Damage
Unplanned
Maintenance
Process Warm Up
Machine
Changeovers
Material Shortage
Speed loss
Performance
Product Misfeeds
Component Jams
Product Flow
Stoppage
Level of Machine
Operator
Training
Equipment Age
Tooling Wear
Quality loss
Quality
Tolerance
Adjustments
Warm Up Process
Damage
Assembled
Incorrectly
Rejects
Rework
International Journal of Engineering Research & Technology (IJERT)
ISSN: 2278-0181
Published by, www.ijert.org
NCERAME - 2015 Conference Proceedings
Volume 3, Issue 17
Special Issue - 2015
D. FORMAT FOR DATA COLLECTION
6. DAY-WISE SUMMARY SHEETS
PRODUCTIVE ACTIVITIES:
TABLE 1.Productive activities
SUPPORTING DELAYS:
TABLE 2. Supporting delays
Activity
Present
Maintenance
7.09%
Inspection
9.03%
Tool Crib
4.79%
Want of Tool
4.18%
Want of Information
2.48%
Total
27.6%
NON-PRODUCTIVE ACTIVITIES:
TABLE 3. Non Productive activities
Activity
Present
Break Down
2.72%
Idle Late
4.36%
Idle Early
4.13%
Idle
4.36%
Operator
unavailable
6.06%
Not Working
6.67%
Want of Work
1.81%
Total
30.1%
7. CALCULATIONS
Calculating OEE,
Availability = run time/total time
This takes account of Downtime loss
Performance = total count/target count
This takes account of Speed Loss
Quality = good coun/total count
This takes account of Reject losses
OEE = Availability x Performance x Quality
Availability is estimated to be 42.3%
Assuming both performance and quality to be
100%
OEE = availability × performance×quality
= 0.423 x 1 x 1
= 42.3%
Activity
Present
Target
Working
31.46%
78%
Set-Up
5.09%
10%
Load/Unload
5.75%
1%
Total
42.3%
89%
International Journal of Engineering Research & Technology (IJERT)
ISSN: 2278-0181
Published by, www.ijert.org
NCERAME - 2015 Conference Proceedings
Volume 3, Issue 17
Special Issue - 2015
8. SUGGESTIONS
A. SUPPORTING DELAYS
Maintenance is repair or regular changing of
coolant/components.
Causes:
Regular Maintenance work carried during
shift hours.
Coolant, Lubricant,& consumables changing
done in shift hours
Suggestions:
Regular Maintenance should be done in break
times like Lunch & Overtime break.
Preventive Maintenance, coolant change,
should be done periodically.
Tool crib, it is operators going far from workplace &
searching for Tools, there by machine remains idle.
Causes:
Regularly used tools and fixtures not kept at
the workplace.
Tools store is far from shop.
Suggestions:
Regularly used tools, fixtures should be kept at the
workplace.
Tools store should be near to the Machine Shop.
Want of tool, is defined as machine idling due to non-
availability of required cutting / supporting / inspection
tools. Causes:
Poor planning activities of production planning.
Lack of job preparation.
Less co-ordination between Methods, Tooling,
and Planning Depts , while process planning.
Suggestions:
In Shop, Engineering Dept should be located.
Tools should be designed according to process’
feasibility of usage.
Establishing effective communication between
Methods, Tooling, & Planning Depts.
Mini Store with good quality & spares of tools
should be started.
B.Want of information, defined as machine waiting for NC
Programming, its corrections etc.
Causes:
For storage of large size programs extra computers
not available.
Designed CNC Programming may not be feasible
due to lack of interaction between programmers
and operators/supervisors.
Skilled Programmers not available.
Suggestions:
For programs storage, computer should be used.
Programmers should interact with their end user.
Training required for operators & programmers skills
improvement.
NON-PRODUCTIVE ACTIVITIES
Breakdown, defined as failure of machine due to some
components failed.
A. NOT WORKING
Causes:
Delay in rectification of the problem, operators are
idle throughout the shift.
Low quality spare parts, bearings used for replacing
worn parts.
Suggestions:
For regular maintenance, spare parts should be of good
quality readily available for immediate rectification.
Idle late, is defined as operators coming late after
Tea/Lunch/Break.
Causes:
Operators extending their break duration.
Suggestions:
Shop supervisors & Top management should manage
them to avoid these delays.
Canteen, Tea delays should be sorted out &
disciplinary action should be taken against late
comers without genuine reasons.
Operator unavailable is defined as operator not in duty or
has gone out of division with permission in work.
Causes:
Operators Absent with permission only, but machines
idle.
Absenteeism due to various other reasons.
Suggestions:
Supervisors should assign other operator to the
machines for which operators are on leave.
All operators should be trained on other machines to
become Multi-Skilled.
Causes:
Unknown reason.
Suggestions:
Supervisors should try to know the reasons for Not
Working even if all facilities are provided.
RESULTS
1. Minimizing the non productive activities by taking
appropriate measures.
2. Also reducing supporting delays ( inspection,
maintenance)
3. Increasing the machine utilization. Thus increasing the
overall equipment efficiency, increasing productivity.
International Journal of Engineering Research & Technology (IJERT)
ISSN: 2278-0181
Published by, www.ijert.org
NCERAME - 2015 Conference Proceedings
Volume 3, Issue 17
Special Issue - 2015
RESULTS AFTER IMPLEMENTATION OF THE
SUGGESTIONS
TABLE: 5Non Productive activities
Activity
Present
Target
Break down
2.40%
0%
Idle late
2.70%
0%
Idle Early
2.40%
0%
Idle
3%
0%
Operator Absent
6.70%
8%
Not Working
5.70%
0%
Want of Work
1.40%
0%
TOTAL
24.30%
8%
TABLE:6. Supporting Delays
CONCLUSION
OEE Calculations
From above results we can estimate OEE for the Machine
Shop
Availability can be estimated as 42.3% from working
percentage.
Even if Performance & Quality are 100%
OEE = AVAILABILITY × PERFORMANCE ×
QUALITY
= 0.531 × 1 × 1
= 0.531
= 53.1%
World Average OEE for manufacturing plants is 60 %,
And for World class manufacturing plants it is equal or
more than 85 % .
Table:7 Productive Activities
In terms of activity occurrences the machines were
working for 53.2% of the reading so OEE can be
estimated as 53.2%.
Inspection activity is7.5%, it should be reduced but
compared to Maintenance, 5.7% & not working
activity,5.7% it can be considered later. The Downtime
Loss due to biggest reasons is Inspection activity and
Maintenance.
Solution for Breakdown is only Preventive
Maintenance. Identifying PM Status should be carried
out for all machines & ensure strict adherence to future
PM Plans.
The main reasons for idleness are cultural & work
practices norms. Addressing these is a major task that
requires significant Management Commitment. Other
companies controlled it by taking following measures,
such as
Flow lines.
Disciplinary Procedures.
Checking in & out of Shop.
Making rest areas inside shop.
Lunch/canteen services inside the shop.
Management By Walk-Around. (MBWA)
REFERENCES
[1] Measurement of overall equipment effectiveness as a basis for TPM
activities - Õrjan Ljungberg, (Department of Operations
Management, Chalmers University, Gothenburg, Sweden)
[2] Closed-loop measurement of equipment efficiency and equipment
capacity -Leachman, R.C.
Dept. of Ind. Eng. & Oper. Res., California Univ., Berkeley, CA,
USA
[3] http://www.google.com
[4] http://Google images
[5] http://www.wikipedia.org
Activity
Present
Target
Maintenance
5.70%
1%
Inspection
7.05%
2%
Tool Crib
3.90%
0%
Want of Tool
3.00%
0%
Want of Information
2.50%
0%
TOTAL
22.60%
3%
Activity
Present
Target
Working
42.20%
78%
Set-up
6.04%
10%
Load/Unload
4.50%
1%
TOTAL
53.10%
89%
International Journal of Engineering Research & Technology (IJERT)
ISSN: 2278-0181
Published by, www.ijert.org
NCERAME - 2015 Conference Proceedings
Volume 3, Issue 17
Special Issue - 2015
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