CHAPTER 5 ENHANCING OVERALL EQUIPMENT PERFORMANCE

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1 75 CHAPTER 5 ENHANCING OVERALL EQUIPMENT PERFORMANCE 5.1 INTRODUCTION OEE is being used as a powerful equipment performance measurement tool by many industries. Nevertheless, any performance measurement tool or methodology achieves the improvement only with a considerable effort, the effort being primarily spent on maintaining the functionality and quality of the equipment. The maintenance department is often under pressure to maintain the availability of equipment, while primarily concentrating on the production needs. This chapter explores and details the ways and means of using OEE m methodology as a performance measure in enhancing the overall equipment performance. The OEE m methodology has been validated with a case study conducted in a manufacturing company. 5.2 CASE STUDY To understand the practical applicability and the capability of the developed methodology, it was implemented to shot peening machine in an industry. The case study is explained in the forthcoming sections.

2 Shot Peening Machine The reasons for selecting the shot peening machine for the case study are, breakdowns, high leakage of shots, poor performance among other shot peening machine, old machine, no proper maintenance schedule, dusty and dark atmosphere, poor housekeeping and safety Working Principle of Shot Peening Machine Fatigue failures are easily recognized and usually start from a focal point on the surface. These focal points are stress raisers such as fillets, holes, keyways, seams, tool marks, scratches or structure variations. Shot-peening is process of cold forming the surface of a part by means of a propelled stream of round hardened steel shot. The result of this process is a uniformly dimpled surface, the roughness being determined by the shot size and the peening intensity. This process is used to improve the fatigue properties of the part by the introduction of compressive forces in the surface layer. The presence of this surface compressive force serves to retard the initiation and growth of fatigue cracks. The size of the shot used is related to the size of the smallest fillets/openings that the shot must penetrate and the peening intensity required. The peening intensity is monitored regularly by the use and measurement of almen test strips. The peening intensity is normally selected from military specification S-13165A, based on the material strength and the section thickness. The recommendations are based on the lowest peening intensity capable of producing the desired surface compressive stress. The intensity may be considered excessive in thin parts if the tensile forces in the core material outweigh the beneficial compressive forces induced at the surface. Shot peening increases the fatigue life in the order of 400 % to 1200 %, depending on the extent of peening stress imparted.

3 77 In shot peening, particles are discharged on to the component at velocities up to 60 m/sec. The intensity with which the particles hit the surface and which is transmitted to the component is a function of their kinetic energy and the angle of impact. The portion of its energy that is used to do work causes each particle to deform the surface plastically, the rest being dissipated in heat. Thus, after peening, the surface will be covered in shallow depressions. It might be thought that these depressions would actually decrease the fatigue strength by acting as stress raisers. However, they are very shallow with a radius considerably greater than their depth. In addition, when the component is correctly peened, these depressions cover the whole surface (100% coverage) and share the intensified stress amongst them rather than carried by single stress raiser. Advantages of shot peening process are listed below: The result of this process being beneficial residual compressive stresses. Residual stresses of N/mm 2 can be induced. The major reason for shot peening is to improve the fatigue performance of the component by generating a compressive residual stress surface in the shear surface region of the material. The reason for most of the fatigue failure is that the applied tensile stress cause a crack to form at the weakest point and as the load cycle is repeated it propagates to a point where the remaining area of good material is insufficient to carry the load and fails. Thus residual compressive stresses induced by shot peening improve the resistance to fatigue failures.

78 The shot peening machine is shown in Figure 5.1. The details of enhancing the performance of this equipment, according to the developed frame work (Refer Figure 4.

4 78 The shot peening machine is shown in Figure 5.1. The details of enhancing the performance of this equipment, according to the developed frame work (Refer Figure 4.6) are discussed in the following sections. Figure 5.1 Shot peening machine 5.3 SMALL GROUP TEAMS Front line small group teams or manufacturing teams were developed similar to SGA of TPM, from production and maintenance departments involving production supervisor, maintenance engineer, technicians and equipment operators. These teams execute the implementation within the working areas.

5 Identification of Machine The SGA team and management identified the shot peening machine as a pilot case study based on its poor performance. The OEE m methodology is implemented to this equipment, to improve its performance Condition of the Machine before Improvement In a manufacturing environment, vital factors such as quality, delivery schedules and productivity depend greatly upon the operating condition of the production equipment. The data was collected for equipment breakdown and leakage of shots, to know its operating condition. The equipment was also inspected for safe operation and environment, both were in poor condition, along with no proper maintenance schedules. 5.4 EQUIPMENT RELATED LOSS Prior to adopting OEE m methodology, only maintenance department was responsible for the equipment operating condition. Thus the company was continually plagued by a variety of losses, such as equipment breakdowns, leakage of shots, retooling adjustments, replacement, idling and minor stoppages, speed reductions and equipment failures. The following are the reasons for selecting the shot peening machine. More breakdowns (No proper maintenance) High leakage of shots Dusty and dark atmosphere Poor house keeping Poor safety

6 Frequent Failure Equipment breakdown was very frequent and no effort has been made to come up with any lasting solutions. Table 5.1 shows the details of equipment breakdowns during the observed time period. On an average the breakdown was hours per month, leading to low availability of the equipment. Figure 5.2 shows the details of month wise breakdown events. Table 5.1 Details of equipment breakdown Breakdown event Time in hours Chain sprocket teeth worn-out 4.5 Bearing replacement 24 Segment plate replacement 15.5 Minor vibration 2 Elevator drive is slipping, plate replacement 4.5 Endless belt replacement 34 Wear / tear of blades and liners 33.5 Total hours 118 Breakdown in hours May June July August Month September October November Figure 5.2 Details of equipment breakdown

7 Leakage of Shots The equipment was facing a large quantity of leakage of shots leading to reclaim and quality losses (Figures 5.3 and 5.4). Figure 5.5 shows details of leakage of shots for a period of seven months, an average of kgs per month. Figure 5.3 Leakage of shots Figure 5.4 Shots spill out through feed funnel

82 Leakage of shots kg/month 350 300 250 200 150 100 50 0 May June July August September October November Month Figure 5.5 Leakage of shots 5.4.3 Dusty and Dark Atmosphere Figures 5.6 to 5.

8 82 Leakage of shots kg/month May June July August September October November Month Figure 5.5 Leakage of shots Dusty and Dark Atmosphere Figures 5.6 to 5.8 shows how the slight defects were ignored or overlooked for long period of time. The section of equipment of shot peening machine, surrounding is not clean and properly arranged, improper illumination around the equipment, leading to dusty and dark atmosphere. It can be observed some patches have been put on the equipment. Figure 5.6 Dark and dirty surroundings

9 83 Figure 5.7 Patches around the machine Figure 5.8 Dust entry solenoid valve Conveyor belt damage Figures 5.9 (a) and (b) shows the damaged conveyor belt, due to belt getting shifted and springs struck during processing.

10 84 Spring struck Belt damage (a) Spring struck in the belt Belt cut (b) Belt cut at the edge Figure 5.9 The belt damage

85 5.4.5 Poor Safety Figure 5.10 shows absence of protective guards around rotating chain and sprocket drive gears, leading poor safety and operating condition. Figure 5.10 Absence of protective guards around the chain and sprocket 5.

11 Poor Safety Figure 5.10 shows absence of protective guards around rotating chain and sprocket drive gears, leading poor safety and operating condition. Figure 5.10 Absence of protective guards around the chain and sprocket 5.5 EVALUATION OF OEE m BEFORE IMPROVEMENT The data was collected based on factory working cycle, one shift of eight hours (480 minutes) each for fifty two shifts. OEE m of the equipment is evaluated based on the data collected. The details of the data collected are shown in Table Planned Production Time From equation (3.2) the planned production time is calculated by subtracting planned down time from shift time hours. P ( ) minutes (5.1) t

12 86 Table 5.2 Data for OEE m evaluation before improvement Sl. No. Item Before improvement 1 Shift time (52 shifts, 8 hrs each) minutes 2 Short breaks (2 Nos, 15-minutes each) 1560 minutes 3 Long/Meal break (30-minutes) 1560 minutes 4 Planned downtime 3120 minutes 5 Unplanned equipment downtime 5570 minutes 6 Equipment stop time 2935 minutes 7 Ideal rate (components / minute) 35 8 Output pieces Rejected pieces Operating Time The operating time is obtained by subtracting unplanned down time from planned production time, using equation (3.3). O ( ) minutes (5.2) t Availability Using equation (3.1) the availability of the equipment is calculated by dividing the operating time by planned production time. Ot Availability % P t (5.3) Running Time Running time is the difference between operating time and stop time and is calculated using equation (3.5) as, R t ( O ) ( ) minutes t - S t (5.4)

13 Usability Usability of the equipment is obtained dividing the running time by operating time and is evaluated from equation (3.7) Usability % (5.5) Performance Efficiency The performance efficiency of equipment is calculated by using the equation (3.4) and is calculated as, Performance efficiency % (5.6) Quality Rate The quality rate is calculated by subtracting the output during running time by rejects and then dividing by the output from equation (3.6) Quality rate % (5.7) Modified Overall Equipment Effectiveness The OEE m of the equipment before improvement is the calculated using the equation (3.8) and is obtained as, OEE m ( ) % (5.8) The details of calculated values are tabulated in Table 5.3 and the analysis of OEE m and its factors is represented in Figure 5.11.

14 88 Table 5.3 Details of OEE m calculation and its factors Sl. No. Item Before improvement 1 Planned production time minutes 2 Operating time minutes 3 Running time minutes 4 Availability (percentage) 74.5 % 5 Usability (percentage) 81.96% 6 Performance efficiency (percentage) 67.97% 7 Quality rate (percentage) % 8 Modified overall equipment effectiveness (OEE m ) % Percentage Availability Usability Performance efficiency Quality rate OEEm Figure 5.11 OEE m and factors before improvement

15 EARNING CAPACITY OF THE SIX BIG LOSSES BEFORE IMPROVEMENT The equipment earning capacity due to the six big losses as defined, through an incremental improvement in OEE m, can be evaluated by using the following relations. The expected theoretical output is calculated is obtained by using equation (3.9) and is calculated as, Eto / p components (5.9) From equation (3.10) the expected theoretical value added by the equipment is calculated by multiplying the expected theoretical output by equipment value addition per product, rupees ten, as, E Rs / (5.10) tva The actual value added based on the OEE m of equipment is calculated using equation (3.11), A ( ) Rs / (5.11) va From equation (3.12) the total loss due to the six big losses is obtained as, L ( ) Rs / (5.12) m Using equation (3.13) loss per hour is evaluated by dividing total loss by the planned production time as, L hr Rs / (5.13) 364

16 90 If the company reaches the world class level, of 85 % OEE m then the increase in equipment earning capacity (amount) is given by the equation (3.14), and is obtained as, ( ) E c Rs / (5.14) ( ) Thus an incremental increase (one percent upraise) in OEE m of the equipment will increase an earning capacity of the equipment and it can be evaluated busing equation (3.15) and is obtained as, E Rs / (5.15) IC ( ) 5.7 IDENTIFYING THE SCOPE AND AREAS FOR IMPROVEMENT The analysis of OEE m factors indicates that the availability is 74.5%, usability is 81.96%, performance efficiency is 67.97% and with quality rate of 94.9%. The product of availability and usability is 61.06%, indicating the total utilization of the equipment being the least among all other OEE m factors. This leads to focus for the improvement in the usability and availability of the machine and exist scope for performance efficiency that will have a major impact on overall performance of equipment. It can also be noted that availability is one factor needs more focus, as this will lead to exposure for other factors requiring improvement. Also the equipment breakdown data analysis indicates poor performance and low availability (38.4%) of the machine. The cost of six big losses shows that loss per hour is Rs.12532/-. The analysis reveals that an incremental improvement (one percent upraise) in OEE m value will result into an additional equipment earning capacity of Rs.75149/-.Thus justifying the improvement to be taken up on the equipment.

17 Locating the Strategies for Improvement The strategy for improving the machine performance is to reduce the breakdowns and other down time events. The total downtime, contributes to % of the available time for production. The major focus for enhancing the performance should be on the following: 1. Reduction in breakdowns 2. Leakage of shots from funnel 3. Prevent belt damage and shifting 4. Shots falling on ground 5. Planned maintenance Thorough One Time Cleaning Small group team members carry out the cleaning activities. The fundamental purpose of initial cleaning is to touch, see and listen to the equipment and become aware of abnormalities, which can be fixed. During this activity, the group members realized how cleaning away the long accumulated dirt is way of inspecting equipment. This method of initial cleanup leads to identifying the abnormalities on the equipment, such as missing bolts, missing washers, lubricant leakage, and so on. Team members took off every removable equipment cover and reached all the places they had never seen or touched before, to clean even hard-to-clean areas. The purpose and process of cleaning is, To eliminate forced deterioration. To bring back the machine to best condition. Ownership of machine by operators through daily activities of cleaning, lubrication, inspection and tightening (CLIT).

18 Tagging of Abnormalities Cleaning is inspection of a machine and identification of abnormalities. As soon as abnormalities are identified by team member, a tag was put on the machine indicating the problem with a brief description of the defect. Team members used tags to identify the items that are required for production at the work station. Team members also provided an action path for appropriate storage or disposal of items not required at the work station and such items were sent to the holding area for further evaluation. The abnormalities detected, were the deviations from the normal operating conditions that have an effect on the quality of the product or cause deterioration and consequent failure of the equipment. The sample of tags is shown in Figure The tagging on the machine indicating the abnormalities identified by the SGA teams is shown in Figure TPM JISHU-HOZEN STEP NO LOCATION OF MINOR DEFECTS DETECTED EQUIPMENT NAME CONTROL NO DETECTION DATE DETECTOR RED TAG DESCRIPTION OF MINOR LOSSES TPM JISHU-HOZEN STEP NO LOCATION OF MINOR DEFECTS DETECTED EQUIPMENT NAME CONTROL NO DETECTION DATE DETECTOR WHITE TAG DESCRIPTION OF MINOR LOSSES THIS SHEET SHOULD BE ATTACHED TO THE EQUIPMENT THIS SHEET SHOULD BE ATTACHED TO THE EQUIPMENT Figure 5.12 Red and white tags

93 Figure 5.13 Tagging on the machine 5.7.

19 93 Figure 5.13 Tagging on the machine Classification and Listing of Abnormalities At the end of initial cleaning and tagging the group was able to identify 240 abnormalities in the equipment, the detailed classification is and is represented graphically in the Figure The CLIT abnormalities identified were 125 in number, which corresponds to % of the total defects. Defects identified with respect to safety aspects corresponds to 21.67% and the remaining were categorized as others corresponding to 26.25%. This indicates the abnormalities related to CLIT have the greatest impact and also these defects leads to accelerated deterioration of the equipment. Accelerated deterioration is wear and tear that is unnecessarily promoted when dirty spots are not (or cannot be) cleaned, when area needing lubricant are not lubricated, or when overload and over vibration is ignored or unnoticed.

20 94 Classification of abnormalities Cleaning Lubricating Inspection Tightening Safety Others Figure 5.14 Classification of abnormalities 5.8 WHY-WHY ANALYSIS Why-why analysis helps to structure brainstormed ideas towards problem root cause. When the team needs to explore possible root causes and represent them on single diagram. 1. State the problem to be analyzed 2. Ask why i.e., what are the first level of causes of the problem? 3. Write each cause 4. For each cause, ask, why again and write the answers in the next column, linked to the previous answer 5. Keep asking, why until no more answer can be suggested 6. Use the causes listed, especially those on the last level of the diagram, generate the possible solutions

21 95 Root causes were identified by the team members and eliminated by the 5-why method of root cause analysis. The root causes identified and eliminated by this method are discussed in the following sub sections Case-1 - More Time Consumption for Unloading of Shots The manual operation of opening and closing of door consumes excessive time and is difficult. This was originated by the tool manufacturer. The team members developed a mechanism for ease of operation and less time consumption. Opening was provided at the hooper, toggle clamps valves fixed, providing chute and flexible hose pipe fast and easy removal was provided. Table 5.4 shows how the root cause was identified and solution was developed for the problem identified. Table 5.4 Why-why analysis case-1 Question: Time consumption for unloading of shots Answer: Modified hooper by providing opening using toggle clamp. Toggle Clamp - Door with round opening Why Answer Action why? Unloading of shots why? - More time consumption why? Manual operation why? Originated by manufacture More time consumption Manual operation Originated by manufacture Change the design why?- Change the design Easy removal Modified hooper by providing opening using toggle clamp

96 5.8.2 Case-2- Leakage of Shots from Funnel Falling of shots from funnel was identified and the root cause for this was less funnel height.

22 Case-2- Leakage of Shots from Funnel Falling of shots from funnel was identified and the root cause for this was less funnel height. During opening of cylinder the spillage of shots used to take place due to less height of funnel. Design of funnel was changed, by increasing the height of funnel thus eliminating the falling of shots. Table 5.5 gives the details of elimination of root cause. Table 5.5 Why-why analysis case-2 Question: Leakage of shots from funnel Answer: Funnel height has been increased Why Answer Action why? Shots leakage from funnel why?-during the opening of cylinder flap spillage of shots, due to funnel height less. why? Design defect During the opening of cylinder flap spillage of shots, due to funnel height less. Design defect Design modified why? Design modified To prevent shot leakage Funnel height has been increased

23 Case-3 - Wear and Tear of Segment Plate Excessive wear of side mild steel plate was taking place due to impact of shots. The plate was designed by the tool manufacturer. The design was modified by using a mild steel plate coated with polyeuroethelene, thus helping to increase the life of the plate, by reducing the wear and tear. Table 5.6 shows the root cause identified for wear and tear of segment plate. Table 5.6 Why-why analysis case-3 Question: Wear and tear of segment plate Answer: Less wear and tear, life of plate increased. Why Answer Action why? Wear out of side MS plate why? - Wear out due to impact of shots on plate why? Due to usage of MS material why? Design and manufacture by supplier why? Change of material Wear out due to impact of shots on plate. Due to usage of MS material Design and manufacture by supplier Change of material MS plate coated with polyeurothelene Less wear and tear, life of plate increased.

24 Case-4 - Endless Belt Shifting Due to load being applied on the belt, it gets shifted, necessitating it to be adjusted frequently. There was no provision in the equipment to arrest the movement of belt in either direction. A split type of stopper was provided at both ends thus preventing the shifting of belt. Table 5.7 shows the details of identifying the root cause. Table 5.7 Why-why analysis case-4 Question: Endless belt shifting Answer: Now avoided belt shifting. Why Answer Action why? Shifting of endless belt why? - Due to load, belt shifts frequently. why? No provision to arrest the belt shifting why? Provided split type of stopper at both sides Due to load, belt shifts frequently. No provision to arrest the belt shifting Provided split type of stopper at both sides. To prevent belt shift. No shifting of belt Case-5 - Handling of Main Door Difficult and Time Consuming Manual opening of main door is time consuming and difficult for the operator. This was designed originally by the manufacturer. The design was changed and modified from manual to pneumatic operation. The detail of root cause elimination is given in Table 5.8.

25 99 Table 5.8 Why-why analysis case-5 Question: Handling of main door Answer: Conversion from manual to automatic Why Answer Action why? Opening and closing of door is difficult and time consumption why? - Manual opening and closing consumes the more time Manual opening and closing consumes the more time. More time consumption and strain to operator why? More time consumption and strain to operator Originated manufactures by why? Originated by manufactures Change of door design. why? Change of door User friendly and Modified manual design reducing loading time. operation to pneumatic cylinder system Case-6 Shots Fall on Ground during Unloading The gap between door and main frame resulted imperfect seating. The design was changed and toggle clamp provided for proper seating between door and main frame. Table 5.9 shows the details of root cause analysis.

26 100 Table 5.9 Why-why analysis case-6 Question: Shots fall on ground during unloading. Answer: Door seating changed and toggle clamp closing provided. Why Answer Action why? Shots fall on ground during unloading. why? - Leakage from door edges why? Gaps between door and main frame Leakage from door edges Gaps between door and main frame Seating is not perfect why? perfect Seating is not Poor seating system originated by manufacturer. why? Poor seating system originated by manufacturer Changing the door seating system and clamps provided for closing Door seating changed and toggle clamp closing provided. 5.9 AUTONOMOUS MAINTENANCE The team members sought to prevent accelerated deterioration by focusing on standards for maintenance. They listed everything that needed to be done to prevent accelerated deterioration, then drafted standards to guide their own autonomous maintenance activities. The operators themselves developed provisional autonomous maintenance manuals for CLIT, for the equipment. This deepened their concern for their equipment and sharpened their equipment related expertise, thus helping to develop the equipment consciousness among the operators. Tables 5.10 to 5.15 show the CLIT manuals developed by the team members.

27 Table 5.10 CLIT standard - 1 Machine: Shot-peening Module /Cell/dept : Main factory Illustration Classification Place/ part/ section CLIT standard Cleaning, lubrication, inspection and tightened During Standard Method Tools and handling Cycle Operation Stoppage Cleaning Body No dirt Visual D - Lubrication Roller bearing 4-stroke - M - Inspection Inspection FRL condition connection Solenoid Valve Fitment Visual M - Air leak Visual M - Inspection Mill belt size Match mark Visual D - Inspection Mesh tray condition No leakage of shots Visual D - Inspection Limit switch Function Visual D/M - CLIT : - D: DAILY, W : WEEKLY, M: MONTHLY 101

28 Table 5.11 CLIT standard - 2 Machine: Shot-peening Module /Cell/Dept :main Factory Cleaning, lubrication, inspection and tightened CLIT standard Illustration Classification Place /part /section Standard Method Tools and handling Cycle During Operation Stoppage Cleaning Rotor housing No dirt Visual D - Inspection Control cage Match mark - D - Inspection Feed funnel Bolt match mark Visual D - Inspection Pneumatic cylinder Opening /close Visual D/M - Inspection Rotor housing Vibration normal Visual D/M - CLIT : - D: DAILY, W : WEEKLY, M: MONTHLY 102

29 Table 5.12 CLIT standard - 3 Machine: Shot-peening Module /Cell/Dept : Main factory Illustration Classification Place/ part/ section Cleaning Hopper system No dirt Cleaning Machine top No dirt Standard Inspection Toggle clamp Function Inspection Spindle shaft Match mark CLIT standard Cleaning, lubrication, inspection and tightened Method Visual manual Visual manual Visual manual Visual manual Tools and handling Cycle Inspection Bolts/ Nuts Match mark Visual D - During Operation Stoppage D - D - D - D - Inspection Rear end cover No oil leakage Visual - 103

30 Table 5.13 CLIT standard - 4 Machine: Shot-peening Module /Cell/Dept : Main factory Illustration Classification Place/ part/ section Standard Method CLIT standard Cleaning, lubrication, inspection and tightened Tools and handling Cycle During Operation Stoppage Cleaning Elevator casing No dirt Visual D - Left top Inspection Chain and sprocket No slack condition Visual D/M - Lubrication Plumber black 5-stroke Grease M - Safety Guards In place Visual D - Inspection Elevator motor belt Condition hit noise Visual D/M - CLIT: - D: DAILY, W : WEEKLY, M: MONTHLY 104

31 105 Table 5.14 CLIT standard - 5 Sl. No. Machine Maintenance: CLIT Standards Check point Machine What to check? Stationary 1 Around the machinery Surrounding is clean 2 Shots on floor No shots / No leakage 3 Machine Clean 4 Any shots on machine (leakage) No shots 5 Refuse discharge No good shots 6 Shots Any contamination 7 Mill conveyor belt Condition/wear/tear 8 Chain and sprocket Condition/slack 9 V belt Physical condition/tension 10 Dust collector Empty Table 5.15 CLIT standard - 6 Machine Maintenance: CLIT Standards Sl. No. Check point What to check? Machine Stationary 1 Shaker Shaking 2 Elevator belt Any hit noise / condition 3 Blast wheel Vibration 4 Mill belt Shifting 5 Ammeter Functioning

106 5.9.1 Activity Boards Activity boards as visual controls were used and located in the work area for easy accessibility.

32 Activity Boards Activity boards as visual controls were used and located in the work area for easy accessibility. The display of activity boards, information pertinent to the team progress, tasks, etc., is shown in Figures Figure 5.15 Visual display boards 5.10 DESIGN AND DEVELOPMENT OF ONE POINT LESSON Team members were given skill specific lessons each lasting no longer than five to ten minutes. Table 5.16 shows the types of OPL developed. Among them the trouble shooting type, where-in actual trouble shooting cases, helps the members to discover abnormalities early and respond appropriately. In all twenty five OPL were designed and developed by the participants. These lessons were of great help in expanding the knowledge and overcome their limitations one point at a time. These onepoint lessons become part of the operator training documentation. The details of the OPL designed and developed, is given in Appendix 1.

33 107 Table 5.16 Types of one point lesson Type Basic knowledge Trouble examples Improvement examples shooting Description Fill in gaps and confirm fundamental knowledge Strengthen specific skills or areas of knowledge needed to prevent recurrence of problems Teach people how to take effective countermeasures against abnormalities through actual case studies 5.11 SAFETY AND ENVIRONMENT This framework for implementing OEE m methodology is meaningful without strict focus on safety and environment concerns. Ensuring equipment reliability, preventing and eliminating human error, create the systems for managing health, safety, and the environment. It creates systems to ensure zero safety and environmental accidents. An emergency switch is provided in front of the main door as well as on control panel, is shown in Figure Protective guards are provided around chain and sprocket drives (Figure 5.17). The Figure 5.18(a) to (d) shows the space provided for location of parts and spares. Figure 5.16 Emergency switch

34 108 Figure 5.17 Protective guards (a) Location of Ladder (b) Location for dust bin (c) Location for V belts (d) Loading and unloading component trolley Figure 5.18 Locations of parts and spares

35 EVALUATION OF OEE m AFTER IMPROVEMENT The details of the OEE m calculation after improvement are discussed in the following sections. The details of the data collected after improvement is shown in Table Table 5.17 Data for OEE m calculation after improvement Sl. No. Item After improvement 1 Shift time (52 shifts, 8 hrs each) minutes 2 Short breaks (2 Nos, 15-minutes each) 1560 minutes 3 Long/Meal break 1560 minutes 4 Planned downtime Unplanned equipment downtime Output Rejected pieces Ideal rate (products / minute) Planned Production Time From equation (3.2) the planned production time is calculated by subtracting planned down time from shift time hours. P ( ) minutes (5.16) t Operating Time The operating time is obtained by subtracting unplanned down time from planned production time, using equation (3.3). O ( ) minutes (5.17) t

36 Availability Using equation (3.1) the availability of the equipment is calculated as the ratio of operating time to planned production time Availability % (5.18) Running Time Running time is the difference between operating time and stop time and is calculated using equation (3.5) as, R ( ) minutes (5.19) t Usability calculated as, Usability of the equipment is obtained using equation 3.7 and is Usability % (5.20) Performance Efficiency The performance efficiency of equipment is calculated by using the equation (3.4) and is calculated as, Performance efficiency % (5.21)

37 Quality Rate The quality rate is calculated as a ratio of difference between outputs and rejects to the output of equipment and is obtained using equation (3.6). Quality rate % (5.22) Modified Overall Equipment Effectiveness The OEE m of the equipment after improvement is the calculated using the equation (3.8) and is obtained as, OEE m ( ) % (5.23) The details of calculated values are tabulated in Table 5.18 and the analysis of OEE m and its factors is represented in Figure Table 5.18 OEE m and its factors after improvement Sl. No. Item After improvement 1 Planned production time minutes 2 Operating time Equipment stop time Running time Availability (percentage) % 6 Usability (percentage) 89.23% 7 Performance efficiency (percentage) 78.15% 8 Quality rate (percentage) % 9 Modified overall equipment effectiveness (OEE m ) %

38 Percentage Availability Usability Performance efficiency Quality rate OEEm OEE and factors Figure 5.19 OEE m and factors after improvement 5.13 EARNING CAPACITY OF THE SIX BIG LOSSES AFTER IMPROVEMENT The equipment earning capacity/ability due to the six big losses as defined, through an incremental improvement in OEE m, can be evaluated by using the following relations. The expected theoretical output is calculated is obtained by using equation (3.9) and is calculated as, E to / p components (5.24) From equation (3.10) the expected theoretical value added by the equipment is calculated by multiplying the expected theoretical output by equipment value addition per product, rupees ten, as, E tva Rs / (5.25)

39 113 The actual value added based on the OEE m of equipment is calculated using equation (3.11), A va ( ) Rs / (5.26) obtained as, From equation (3.12) the total loss due to the six big losses is L m ( ) Rs / (5.27) Using equation (3.13) loss per hour is evaluated by dividing total loss by the planned production time as, L hr Rs.7527 / (5.28) If the company reaches the world class level, of 85 % OEE m then the increase in equipment earning capacity (amount) is given by the equation (3.14), and is obtained as, ( ) E c Rs / (5.29) ( ) Thus an incremental increase (one percent upraise) in OEE m of the equipment will increase an earning capacity of the equipment and it can be evaluated busing equation (3.15) and is obtained as, E Rs ( ) / IC (5.30)

40 CONCLUSION The process of recording data information must remain simple, but effective for future analysis. By utilizing existing performance data, such as autonomous maintenance, equipment breakdowns, losses, safety and so on. this method provides information for daily decision making. With the application of this methodology operators and management become aware of what constitutes waste and losses and how such activities could be controlled and managed more effectively. Maintenance of the equipment contributes to production losses, as defined by the availability and usability factors of the OEE m calculation. Traditionally the equipment suffered from lack of operator knowledge and training, poor planned and autonomous maintenance, etc. This method helps to improve maintenance activities with systematic approach towards eliminating the accelerated deterioration. It also gives an opportunity to the operators to raise their skills and know-how to foster improvement suggestions.

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