Introduction to OEE and TPM. The background. The background. Overall Equipment Effectiveness and Total Productive Maintenance.

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1 Introduction to OEE and TPM Overall Equipment Effectiveness and Total Productive Maintenance The background OEE = availability x performance rate x quality rate Where: availability = (planned run time downtime) x 100 planned run time Performance = (units produced x design cycle time) x 100 actual run time Quality rate = (total output defects) x 100 total output or (parts right first time)x100 completed cycles Notice: The background OEE is a severe measure. It is the result of three factors. If each factor was 90%, the result would be 72% OEE is directly related to the 6 big losses Breakdown losses Setup and adjustment losses Idling and minor stoppages Reduced speed losses Process defects Reduced yield 1

2 The Effect of the Six Big Losses on Equipment Operating Time TOTAL AVAILABLE TIME Operating Time Net Operating Time Valuable Operating Time Equipment Defect Losses Speed Losses Downtime Losses Six Big Losses 1. Breakdowns 2. Setup and Adjustment 3. Idling and Minor Stoppages 4. Reduced Speed 5. Process Defects 6. Reduced Yield Breakdown (equipment failure) Caused by chronic and sporadic breakdowns. Sporadic breakdowns are usually obvious and easy to correct something broke. Chronic breakdowns are often ignored or neglected after repeated unsuccessful attempts to correct the problem Breakdowns account for a large percentage of total losses. Therefore a lot of effort is put into avoiding them. Eliminating them is difficult, but possible, and must be done to maximise equipment effectiveness. Conduct studies to increase reliability and reduce time needed to correct problems Aim to reduce breakdowns to zero Investment may be necessary upfront Attitudes must be changed, so breakdowns are no longer seen as inevitable Setup and Adjustment Losses during setup and adjustment result from: Downtime Defective products They occur when production of one item ends and the equipment is adjusted to meet the requirements of another item Many companies now working towards Single Minute Exchange of Dies (lecture 9) Adjustment is doubly expensive not producing good product, and using material. 2

3 Idling and Minor Stoppages Minor Stoppages occur when production is interrupted by a temporary malfunction for example product blocking a chute, then clearing under their own weight Idling occurs when the machine is sitting waiting for either material or manpower to allow it to work These small problems often have a large impact on OEE They may be easy to remedy They are usually difficult to detect They are hard to quantify zero minor stoppages is an essential precondition for automated production. Reduced Speed The difference between the equipment design speed (rated speed) and actual operating speed Typically overlooked Largest obstacle to equipment effectiveness in many operations Many reasons for slow running: Mechanical problems Defective quality History of past problems Fear of overtaxing or abusing the equipment Optimal speed simply not known Alternative view increasing operating speed can reveal latent defects in equipment condition Process Defects Losses in quality caused by production equipment split into two types 1. In general, sporadic defects are easily and promptly corrected by returning equipment to normal conditions 2. Causes of chronic defects are difficult to identify, quick fixes rarely solve the problem, so defects get ignored or neglected Defects resulting from improper equipment adjustments should be counted as chronic defects. Reducing them requires thoughtful investigation and innovative remedial action. Complete elimination of defects is the goal 3

4 Reduced yield Yield or startup losses are quantity losses that occur in the early stages of production from beginning to stabilisation Yield losses vary with Suitability of manufacturing conditions Maintenance level of equipment and tooling Technical skill of operators In practice, the numbers are often surprisingly high. Tools to tackle reduced OEE Actually what this course is about: 7 wastes identification FMEA 5S Process Variability Reduction Quick Change Over Quality control And today s topic: Total Productive Maintenance TPM TPM = Total Productive Maintenance (or Total Preventive Maintenance) Aims at zero breakdowns (and zero defects) Evolved out of Preventive Maintenance Has much in common with TQM 4

5 PM vs TPM Preventive Maintenance Centred in specialist maintenance function Concerned with: maintenance records and information Prediction of failure Condition monitoring Optimal maintenance timing Total Preventive Maintenance Like PM, plus it recognises everybody has a role to play Requires: Culture Commitment Communication Teamwork Systems and tools TPM considerations In TPM we extend the boundary of consideration from the machine to include: The operator, The product The process The environment Aim at prevention of breakdowns Spread the load out from the specialist maintenance function Make maintenance and problems visible not buried in a computer Management by fact Why Productive? We wish to gain productivity, not merely maintain TPM is like TQM but lower profile TPM is also like JIT Rely on thinking worker Aim at waste reduction Emphasise simplicity and visibility Today TPM encompasses energy management, safety, education and training 5

6 Central concepts of TPM 5S/5C/CANDO At its worst when new Visibility Red Tags Visual checklists Use of all senses Ownership Bottlenecks Failure Modes and Scheduled Maintenance Condition Monitoring Information Systems Design and Administration, and Benchmarking 5S/5C/CANDO The place to start with TPM See lectures 6 and 7 for details. Note 5S has a hidden agenda Pride in the workplace. Aims to move away from Maintenance is somebody else s responsibility to It s everybody s business, every day At its worst when new Provocative. Why should it be worst when new? Not yet quality capable Standard procedures not worked out Failsafe (Pokayoke) devices not yet added Operating and failure modes not yet known Losses not yet measured and understood Vital internal elements not visible or monitored 6

7 Visibility Make what s happening clear for all to see Maintenance records kept by the machine Problems noted on charts by the machine Replace (where possible) solid metal guards with transparent ones Make leaks or drips visible Red Tags Common form of visible TPM Maintenance Concerns written on Red Tags Red Tags hung on prominent board on shop floor Remain on the board until action is taken Usually covers concerns that the operators can t deal with Visual Checklists Monitoring is very important to TPM, so checklists are common. Status compared to written standards Checklists developed by operators Include photographs or drawings Checklist looking good not as important as effectiveness 7

8 Use of all Senses Most human s come to work with hidden extras which aren t used The brain get operators to think Senses: Smell Hearing Touch Sight Vibration detection We are especially good at detecting changes Report it, record it, act on it. Ownership Principle is: If you are responsible or you own it, you ll look after it better. Uptime will improve Pre-flight checklists at start of shift Learn to do simple maintenance tasks Keep stock of inexpensive consumable parts to hand Lubricate Keep records Bottlenecks An hour lost at a bottleneck is an hour lost to the system - E. Goldratt Should get first priority for Analysis Maintenance activities Keep especially good maintenance records at bottlenecks 8

9 Failure Modes and Scheduled Maintenance Classic Preventive Maintenance assumes Bathtub curve Therefore routine maintenance scheduled just before expected upturn in problems Now know not all equipment has this pattern Some may not have high early failure rate Some may not have sudden wearout Some may exhibit continuous incline, etc. Need to know the failure mode to plan the maintenance to prevent it Talk to the operators they know the failure mode Aim to improve, not just maintain Condition Monitoring Specialist function in TPM In some environments, an important means to reduce cost (heavy, rotating machinery) Methods include: Vibration detection Temperature monitoring Bearing monitoring Oil analysis IT systems available to help Information Systems Always important in PM Still important in TPM Scope increased from machines to include: Operators Safety Energy issues Must also allow for workplace data recording 9

10 Design and Administration, and Benchmarking TPM starting to be seen in offices Computers Printers Fax machines Projectors Also tidy desks, filing cabinets, and break rooms Best companies cater for TPM in product design Benchmarking (as usual) is useful Example 1 Company A makes gizmos. The Manufacturing Director is hard drivi ng, customer focused and quality conscious. The Quality program is well established and the reject rate for the machine manufacturing gizmos is 1%. Among other things, this has been achieved by providing the trained operators with enough rest time to avoid fatigue. There are three 10-minute breaks during the shift and a 30- minute lunch break. On average, 5 setups are made on each shift with very careful adjustment by experienced operators. The mean time for a setup and adjustment is 28 minutes. Because of the director s quality focus, machine output has been limited to 210 pieces per hour. He believes slowing the machine improves quality. The designers say the machine will produce 300 pieces per hour. Calculate the Overall Equipment Effectiveness for this machine. A. Gross Available Time (480 min/shift) minutes B. Planned Down Time minutes (for maintenance, breaks, etc) C. Running Time (Net Available Time) minutes (A-B) D. Downtime Losses minutes (breakdowns, setups, adjustments) E. Operating Time (C-D) minutes F. Availability (E / C) x 100 % G. Output during Operating Time pieces H. Theoretical Cycle Time minutes/piece I. Performance Efficiency [(H x G) / E] x 100 % J. Rejects During Operating Time pieces K. Rate of Quality Products % L. OEE (F x I x K) x 100 % What would you recommend the company does to improve the situation? 10

11 Solution A. Gross Available Time (480 min/shift) 480 minutes B. Planned Down Time 60 minutes (for maintenance, breaks, etc) C. Running Time (Net Available Time) 420 minutes(a-b) D. Downtime Losses 140 minutes (breakdowns, setups, adjustments) E. Operating Time (C-D) 280 minutes F. Availability (E / C) x % G. Output during Operating Time 980 pieces H. Theoretical Cycle Time 0.2 minutes/piece I. Performance Efficiency [(H x G) / E] x % J. Rejects During Operating Time 10 pieces K. Rate of Quality Products 99 % L. OEE (F x I x K) x % What would you recommend the company does to improve the situation? Example 2 Shift arrangements are: Five working days per week Three shifts of 8 hours each working day 30 minutes break each shift Measurements for a one week period are: 7 breakdowns, totalling 21 hours 16 setups, averaging ½ hour each Total output is 102,000 pieces, of which 2,000 are scrap Machine s designed production rate is 1,800 per hour What are the Availability, Performance, Quality and OEE figures for this machine? Example 2 worksheet Availability = available planned time actual downtime x 100% available planned time Available planned time = = Actual downtime = = Therefore, Availability = - x 100% = % Performance = total output x 100% machine design rate x actual operating time Actual operating time = = Therefore Performance = x 100% = % Quality = total output defectives x 100% total output Therefore, Quality = - x 100% = % Overall Equipment Effectiveness = Availability x Performance x Quality x 100% Therefore Overall Equipment Effectiveness = x x x 100% = % 11

12 Example 2 solution Availability = available planned time actual downtime x 100% available planned time Available planned time = (24 1 ½) x 5 = hours Actual downtime = = 29 hours Therefore, Availability = x 100% = % Performance = total output x 100% machine design rate x actual operating time Actual operating time = = 83.5 hours Therefore Performance = x 100% 1800 x 83.5 = % Quality = total output defectives x 100% total output Therefore, Quality = x 100% = % Overall Equipment Effectiveness = Availability x Performance x Quality x 100% Therefore Overall Equipment Effectiveness = x x x 100% = 49.4 % Coursework 1 Background The company manufactures a range of specialist radiator and heat exchangers. A Key component of all products is the metallic core tubing. Every product range contains these items. The company produces these tubes on a single machine. Due to the criticality of this equipment it is important to increase its ef fectiveness. The process itself entails two raw material types, depending on product (brass or tin). Reels of raw material are loaded to the rear, and fed through the machine. The raw material is then folded, welded and cut to the required length, so producing the finished component. Current situation The company has designed a data collection chart and instructed operators to collect data. Currently there is one week s worth of data collected. No corrective action has been taken. All breaks are covered (the machine is planned to run continuously) The shift starts at 8am and finishes at 4pm A set -up is defined as a change of material or cutters (or both) Speed is recorded digitally and reported as an average over the shift. The tasks 1 Calculate the daily availability, speed, quality and OEE figur es (state any assumptions made). 2 Pareto analyse the losses. 3 propose actions to improve the situation. 12