Measuring loss Antti Salonen

Transcription

1 Measuring loss Antti Salonen

2 Setting up measurements Why shall we measure? What isn t measured can t be controlled

3 Setting up measurements Co-ordination; Monitoring; Diagnostics Forward-looking prediction and insight Provide feedback and build understanding Focus on: systematic thinking, fundamental structural change and organisational learning A framework for understanding and alignment with top-level objectives of the organisation

4 Setting up measurements Basic questions: Why is measurement required? (Purpose.) What should be measured? (Finding factors that are important.) How should it be measured? (Methods.) When should it be measured? (Timing and time frame.) Who should measure it? (Owner of the process versus independent party.)

5 Sources of loss Planning related loss Man hours Scheduled man hours Machine hours Scheduled work hours Planning related stops Break downs Poor leadership Planned man hours Planned work hours Change over Poor methods Poor line balancing Poor logistics Control and adjustments Net operative man hours Effective man hours Value adding man hours Available operative time Net operative time Value adding operative time Tool change Start-up Short stops, Idling Speed loss Scrap and adjustments Energy consuption Effective energy Material consuption Effective material Tool consuption Produced quantity Energy loss Raw material loss Tool loss

6 Scheduled working time Planned production time Available operative time Unplanned stopps Planning related stopps Failures and breakdowns Change-over and adjustments Planning factor = Scheduled time Planning related stop time Scheduled time Availability = Planned prod. time Unplanned stop time Planned prod. time Net operative time Speed loss Idling and minor stoppage Reduced speed Performance rate = Bought CT x items produced Available operative time Value adding operative time Defects Defects and rework Start-up losses Quality rate = Items produced - Defects Items produced Overall Equipment Effectiveness (OEE) = (Planning factor) x = Availability x Performance rate x Quality rate

7 System loss Conveyor systems between equipment Over- all computer systems like MPS Mal functioning buffer systems Power outs Failures in central systems e.g. central lubrication

8 Equipment 1 2 System availability A sys = A 1 x A 2 x..a n Availability 93% 96% 3 93% 4 95% 5 91% System availability 71.8%

9 System availability loss A 93% A 84% A 93% A 96% Conveyor full Conveyors empty

10 System cycle- time loss True CT: 40 s. True CT: 40 s. True CT: 44 s. True CT: 40 s. Theoretic CT: 40 s. Theoretic CT: 40 s. Theoretic CT: 40 s. Theoretic CT: 40 s. Conveyors full Conveyor empty True cycle time of system: 44 s.

11 System capacity Bought capacity (with an assumed A T of 98% and CT = 40s): C sys = (3600/40) x 0.98 x 0.98 x 0.98 x 0.98 = 83 u/h CT: 40 s. CT: 40s. CT: 40 s. CT: 40s. A T : 98% A T : 98% A T : 98% A T : 98%

12 System capacity Bought capacity (with an assumed A T of 98% and CT = 40s): C sys = (3600/40) x 0.98 x 0.98 x 0.98 x 0.98 = 83 u/h CT: 40 s. CT: 40s. True CT: CT: 40 s. 44s. CT: 40s. True A T : A93% T : 98% True A T : A84% T : 98% True A T : A93% T : 98% True A T : A T 96% : 98% True capacity, based on the actual data, presented above: C sys = (3600/44) x 0.93 x 0.84 x 0.93 x 0.96 = 57 u/h

13 How to measure? Start by asking if OEE Bigures are available! If so, check: DeBinitions Measurement method Reliability

14 Data sources? Operators journals / log books Manual measuring e.g. stop watch Documentation of previously performed studies Combine multiple data sources! Systems data (e.g. MRP, CMMS, etc) Interviews

15 Data sources? Operators journals / log books Manual measuring e.g. stop watch Documentation of previously performed studies Combine Inform multiple the operators! data sources! Systems data (e.g. MRP, CMMS, etc) Interviews

16 What s essential? Achieved output Planned output = OEE

17 Data sources? Error sources?

18 Random events? Stop causes Availability: 36.8 % Hours Component refill Shaft damage Set-up change Feeder error Other Software error Meeting PM

19 Random events? Stop causes 9 8 Very rare failure 7 6 Hours 5 Availability: 53,1 % Component refill Shaft damage Set-up change Feeder error Other Software error Meeting PM

20 Too short time span? Kuggfräs, Tillgänglighet % One week s measures Scheduled time Quality control Set-up time Short stops Break downs Misc. Available time

21 Alternative data sources? Milling: - MTBF: 113,25h - MTTR: 6,01h Grading: - MTBF: 117,4h - MTTR: 3,0h A sys : 92,6%

22 100 16,0% Adjusted graph ,0% 8,0% 70 2,4% 0,6% Schemalagd Scheduled tid Kvalitetskontroll Waiting for Failures AU Omställning Change over Småstopp Small stops Kassationer Scrap Available Effektiv time tid time quality assurance 65 %

23 Validity/Reliability Let the staff verify your findings!

24 Loss in manual labor Man hours Planning related loss Poor leadership Poor methods Poor line balancing Poor logistics Control and adjustments Scheduled man hours Planned man hours Net operative man hours Effective man hours Value adding man hours

25 Loss in manual labor Methods: Time studies Frequency studies Pre-determined Motion Time System Time formulas

26 Man hours, Frequency studies Performing a Frequency study First! 1. Define study object, e.g. operations time Check that measuring is approved 2. Assess the activity s share of total time, based on e.g. experience or a pre-study by the union and the operators. 3. Define the accuracy of the study in terms of confidence and risk levels Then inform the operators of the 4. Calculate the aquired number of observations 5. During the purpose study, new calculations of the of study. sample size may be performed in order to refine the study

27 Man hours, Frequency studies Necessary sample size: n = number of samples c = degree of confidence* z = percentage error p = probability of activity * C = 1.96 is commonly used for 95% confidence

28 Man hours, Frequency studies Activity Observations % Deviation Z Cost (SEK) Value adding: Assembly Value adding total: Semi productive Fetch material Prepare assembly Fteching tools Inspection Administration Getting information Cleaning Semi productive total: Waste Adjustments Searching for material Waiting for material Searching for tools Waiting for tools Searching for information Personal time Fetching material outside station Helping colegue Waste total:

29 Result: Distribution 28% 40% Value adding Semi productive Waste 32%

30 Loss in Change-over Internal Common and procedure external work Disassemble Clean old tools Fetch new tools Re-assemble Adjust new tools Produce Product A Down time for set-up change Produce Product B Stop time

31 Loss in Change-over Internal Common and procedure external work Fetch Adjust Disassemble Internal Clean External old tools External Re-assemble new tools Internal Internal new tools Produce Product A Down time for set-up change Produce Product B Stop time

32 Loss in Change-over Fetch new tools Internal Common and procedure external work Clean old tools Disassemble Re-assemble Adjust new tools Produce Product A Down time for set-up change Produce Product B Stop time

33 Loss in Change-over Fetch new tools Clean old tools Disassemble Re-assemble Adjust new tools Produce Product A Down time for set-up change Produce Product B Stop time

34 Loss in Change-over Further reading: Muchiri, P., Pintelon, L., (2008), Performance measurement using overall equipment effectiveness (OEE): litterature review and practical application discussion, International Journal of Production Research, Vol. 46, No. 13, pp Mali, Y.R., Inamdar, K.H., (2012), Changeover Time Reduction using SMED Technique of Lean Manufacturing, International Journal of Engineering Research and Applications, Vol. 2, Issue 3, pp