International Journal on Mechanical Engineering and Robotics (IJMER)
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Enhancing Overall Equipment Effectiveness of HMC Machines Through TPM and 5S Techniques in a Manufacturing Company
1Mohammedasif Mulla, 2Ramesh C.G
1M.Tech (Mechanical), 2Assistant Professor Dept. Of Mechanical Engineering, Sir M Visvesvaraya Institute of Technology, Bangalore- 562157
Email- [email protected], [email protected]
Abstract – In the today’s era of intense global competition, manufacturing industries are determined to improve and optimize their productivity in order to remain competitive.
Overall Equipment Effectiveness (OEE) of a machine plays an important role where performance and quality of the product are of key importance to the company. The OEE intended at minimizing the breakdowns, increasing performance and quality rate and thus improving the effectiveness of the machine. The main objective of this paper is to realize the root causes for problems occurring on Horizontal Machining Centre (HMC) machines. The fish-bone diagram helps to identify the causes for bottleneck problem in machine. The TPM and 5S techniques were used to take the corrective action and to improve the OEE of machine. A multi fixture has been designed using CATIA V5 R20 to reduce Manufacturing Lead Time (MLT).
Machine history of first two months was analyzed and the main reasons for low OEE were identified. The result obtained after implementing remedial measures showed that the availability increased from 67.73% to 70.78%, performance from 60.63% to 63.91% and hence OEE has been improved from 40.08 to 44.41%.
I. INTRODUCTION
In this age of agile manufacturing the global competition characterized by both technology push and market pull has forced the companies to achieve worldclass performance through continuous improvement in their products and processes [1].
The Overall Equipment Effectiveness (OEE) has been recognized as a fundamental method for measuring equipment performance. The OEE measure attempts to identify and measures losses of important aspects of manufacturing operations such as availability, performance, and quality rate [2]. Total Productive maintenance (TPM) is an innovative approach to maintenance by operators through day to day activities [3]. TPM is a methodology to increase the performance of the machines. The TPM results in maximum effectiveness of equipment, tidier, neat and clean work place [4].
A. Scope of the Study
The scope is to improve the effectiveness of machines and identify the machine which is having lowest effectiveness. Further the work is to analyze the root causes for bottleneck machine problems for selected machine and finding the solution in order to improve the OEE.
II. PROBLEM DEFINITION
In a manufacturing company enormous losses occur in the shop floor. These losses are due to the operators, maintenance personnel and process, part setting time, tool setting time problem and non availability of required components in time. There are also other losses like breakdown of the machines, material shortage, start- up loss and bottle necks in the process.
Total Productive Maintenance (TPM) is the answer to solve the above said problems which helps in benefiting the growth prospects of any organization. TPM works to eliminate the “six big losses” that are formidable obstacles to equipment effectiveness such as Equipment failure, Setup and adjustment, Idling and minor stoppages, reduced speed, Process defects, and reduced yield.
The overall goal of TPM is to raise the OEE.
OEE=Availability x Performance x Quality
Availability =Operating Time/Planned Production Time Performance = Ideal Cycle Time / (Operating Time / Total Pieces)
Quality = Good Pieces / Total Pieces
III. OBJECTIVES AND METHODOLOGY
A. Objective
The objective of this paper is to inspect the manufacturing losses, prioritizing the root causes with the help of time study and fish-bone diagram and finally suggesting the solution to overcome these problems.
The work is carried out in fallowing steps.
Observation of Horizontal Machining Centre.
Investigate the machine which is having lowest OEE based on monthly data.
Identify the root causes for the low OEE by using Fish-bone diagram.
Find the best solution to increase the performance machine.
Implementation of solution to improve the effectiveness of the machine.
B. Methodology
OEE is a way to monitor and improve the efficiency of a manufacturing process. This paper presents a systematic way to investigate the root causes for low OEE and arrive at the solution of machine bottleneck problems.
The methodology has been representing in Figure 3.1.
Figure 3.1: Methodology
Problems were identified while observing HMC machine. Time study helps to determine the performance of each machine. The work focused on the machine which is having low OEE. Data processing and analysis facilitates to identify the bottleneck problems in each machine. Fish-bone diagram is used to find the bottlenecks of the machine. After identifying the root causes it is found that many losses were occurring
because of non standardization of procedures to perform and non availability of tools at required time. TPM and 5S techniques were implemented to improve OEE of the TMC 1250-HP HMC machine. It is found that two components were the most frequent machined part on HMC machine and taking too high setting time for operations. To decrease the MLT a multi-fixture has been designed.
C. Calculations
The method used is to analyze the present OEE of the machine and compare it with world class OEE in manufacturing. And then implement the TPM and 5S technique to improve the OEE. The first step is to collect the data using time study and calculating the OEE in terms of Availability, performance, and quality of the component. There are three shifts in company with each shift of 8 hours.
Figure 3.2: Histogram shows percentage reduction HMC machine
The histogram clearly represents the OEE values of HMC machine, the availability was 67.73%, performance was 60.3% and hence OEE was 40.08%
which has far below world class OEE of 85%.
IV. ANALYSIS
Root cause analysis is a problem solving method used to identify the root cause nature of the problems. The completed representation of low OEE and low performance has shown in figure 4.1 and 4.2. In this, errors which may be responsible for affecting the low OEE is considered, i.e. Man, Machine, Material and Method.
Figure 4.1 and 4.2 shows the cause and effect diagram which indicates the aspects to take the corrective action.
0 20 40 60 80 100
A P Q OEE
Series1 67.73 60.3 98.15 40.08 67.73 60.3
98.15
40.08
Percentage
OEE of HMC machine
Fish bone diagram Study of existing
system
Problem Identification
Identify the root causes
Total productive maintenance (TPM)
and 5S Techniques
Design and development of
Multi-fixture Data processing and
Analysis Literature Review
Implementation
Time study
Catia V5 R20
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Figure 4.1: Analysis for low OEE
Figure 4.2: Analysis for low Performance The reasons for low OEE were listed. A systematic approach to increase OEE to acceptable level was attempted using TPM and 5S technique. From the root cause analysis for reduced OEE, the bottleneck machine problems were identified and fallowing remedies has been suggested in order to improve the Effectiveness.
V. MODEL CONSTRUCTION AND SOLUTION
The TPM and 5S technique has been used to improve the OEE, such as Autonomous maintenance, Preventive maintenance, planned maintenance, cleaning with meaning. However a TPM and 5S approach will teach operators to identify the root causes.
A. TPM Implementation Plan
Figure 5.1 TPM Pillars a) Autonomous Maintenance
Autonomous maintenance, a pillar of TPM, guides operators in the day-to-day activities of keeping equipment in order. It consist of preventive, predictive and occasionally breakdown maintenance activities which are done on daily basis by operators themselves.
The justification for the change in division of labour is that operator knows their equipment better than anybody.
Provide basic training to operators of the industry about safety equipment structure and functions of machines.
Make cleaning plan for each parts of the machines.
Removing unnecessary articles around the machineries of the industry.
The initial clean up include fibre dust, oil, etc. and has to be removed and minor defects of the machineries should be detected.
Tentative standards of cleaning will be set for the machines.
Mastering the inspection skill of the operators of all machines.
b) Training
Setting policy and priority measures to train the operators in the plant.
Establish training system for the maintenance men in all HMC machineries.
Understand the right method of cleaning, lubrication and inspection.
Provide training for skill upgradation for inspection and routine restoration.
Provide maintenance skill training to leaders of the operating sectors.
c) TPM Office
Providing awareness about office TPM to all support departments such as quality control, and marketing departments of the industry.
Initial cleanup of every offices of the industry.
Clean dirt, dust and strains in the work place.
Identify all documents in lockers and desks.
Classify documents in accordance with nature of work.
Safety and environmental factors.
Allocate articles in the right place.
Encourage the participation in the activities.
B. 5S Technique a) Sort (Sieri)
The first pillar of 5S helps to clearly distinguish the items needed in a work area from those no longer needed. In company, various items have been sorted out on the basis of priority of use. Low priority denotes the less frequency of use while high priority shows the items used daily/frequently.
b) Set in Order (Siton)
The second pillar of 5S helps to keep the needed items in the correct place to allow for easy and immediate retrieval. The correct place, position, or holder for every tool, item, or material must be chosen carefully in relation to how the work will be performed and who will use them easy identification.
c) Shine (Sieso)
The third pillar of 5S helps to keep work areas, all work surfaces and equipment clean and free from dirt, debris, oil, etc. in company, all the persons from managers to operators were engaged for cleaning their table, chair and cabin.
d) Standardize (Seiketso)
The fourth pillar of 5S defines the standard activities, procedures, schedules and the persons responsible for keeping the workplace in a clean and organized manner.
In company color-coding and standardized coloration of surroundings were used for easier visual identification of anomalies in the surroundings.
e) Sustain (Shitsuke)
Sustain is the last pillar of 5S and drives the organization to be disciplined in maintaining these new standards and procedures and in continuously improving the 5S state of the workplace.
Figure 5.2 Set in order (Sieri)
Figure 5.3 Shine (Sieso)
Figure 5.4 5S score board C. Design of Multi-Fixture
To reduce the operator losses and to improve the performance of two components the design of multi- fixture approach is used. The proposed fixture will fulfilled production target and enhance the performance of these two components.
Modelling software Catia V5 R20 is used to draw the multi-fixture and its clamping elements. After implementing the TPM, 5S and design of multi-fixture, again time study has been conducted and calculated OEE.
Figure 5.5 Histogram shows percentage increment of HMC machine
After implementation of TPM, 5S technique and design of multi-fixture, it is found that the OEE is increased by
0 50 100
A P Q OEE
Series1 70.78 63.46 98.15 43.87 70.78 63.46
98.15 43.87
percentage
OEE after Implementaion
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4.33%. It should be noted that the change in the maintenance policy in the company changed their availability and performance of the machine and hence the OEE is improved at desirable level. The improved result is shown in Tables 5.1.
Table 5.1 Performance result of two components
Description Before
Implementatio n (min)
After Implementa tion (min) Part setting time 75.64 32.83 Tool setting time 71.08 31.01 Loading/Unloading 105.24 55.76
Inspection 94.06 39.15
Others 73.14 21.8
Total operator losses
419.16 180.55
Spindle running time 394.258 225.976
Actual time 711.116 313.58
Standard time 300 300
Performance (%) 42.18 95.66
VI. RESULTS AND CONCLUSION
A. Results
The total operator loss of two components has been reduced to 60.09%, performance can be increased from 40.02% to 92.78%. Realization of multi fixture reduces 103.735 min of setting time thereby reducing the MLT and in turn improving the OEE of HMC machine.
Figure 5.6 Histogram shows the before and after implementation of HMC machine
B. Conclusion
A great knowledge about OEE improving techniques such as TPM, 5S and design of multi-fixture has been accumulated. It is obvious that OEE provides many benefits and with proper implementation, OEE can serve as a tool to elevate the company’s competitiveness in the industry. The OEE is simple nevertheless powerful performance measurement tool, as a result it is implemented in manufacturing Company.
The TPM and 5S techniques were used to improve the availability, performance and quality of the machine.
Though TPM, 5S technique, design of multi-fixture were focused, the availability and performance were improved significantly by minimizing the equipment deterioration and failure.
After the implementation of TPM, 5S techniques and design of multi-fixture, the availability of machine has been increased from 67.73% to 70.78%, performance from 60.63% to 63.91% and the OEE of TMC 1250-HP HMC machine increased from 40.08% to 44.41%.
VII. COPE FOR FUTURE WORK
The present work is to improve the effectiveness of machine which is having lowest OEE by implementing the TPM and 5S technique. From the implementation of these techniques it can be conclude that the implementation approaches in all machines will help to achieve higher OEE. It would be beneficial for the future researcher to conduct the time study and find out the root causes of all machines in order to improve the performance of machine. Future study is the formulation of new OEE by incorporating the element of profitability or costing. OEE lacks in any notion of machine profitability and costing. It would be beneficial to the industry if new OEE is formulated.
Accordingly, the potential for ease of TPM and 5S technique could be further investigated. The result obtained after implementing the continuous improvement of TPM, 5S approach may reach to world class OEE (85%).
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