IE知识综合论述(英文版)

1、Industrial Engineering :Work DesignPrepared by Ken Leung2002/9/261SMT Training for ProductivityWork DesignMethods ImprovementErgonomicsAssembly line balancingPrinciples of motion economyVarious type of chartsWork measurementTime studyActivity sampling2002/9/262SMT Training for ProductivityErgonomics

2、 DefinitionApply information about human behavior, abilities, limitations, and other characteristics to the design of tools, machines, system, tasks, jobs, and environments for productive, safe, comfortable, and effective human use. 2002/9/263SMT Training for ProductivityObjectives To enhance the wo

3、rk effectiveness and efficiency.Increased convenience of use Reduced errors Increased productivity To enhance human values.Improved safetyReduced fatigue and stressIncreased comfortGreater user acceptanceIncreased job satisfaction Improved quality of life2002/9/264SMT Training for ProductivityTwelve

4、 Principles of Ergonomics1. Work in neutral postureseg. Wrist rests for keyboard and mouse.2. Reduce excessive forceseg. Boxes with handholds for carrying.2002/9/265SMT Training for ProductivityErgonomics Principles3. Keep everything in easy reacheg. Keep materials within the “reach envelope” of the

5、 arm.2002/9/266SMT Training for ProductivityErgonomics Principles4. Work at proper heightseg. Heavy work should be performed lower than elbow height; precision work should be higher. 2002/9/267SMT Training for ProductivityErgonomics Principles5. Reduce excessive motions eg. Use power screwdriver.6.

6、Minimize static load eg. Use a pencil grip.2002/9/268SMT Training for ProductivityErgonomics Principles7. Minimize pressure points eg. Provide padding for hand grips.8. Provide clearanceeg. Provide visual access (carton delivery).2002/9/269SMT Training for ProductivityErgonomics Principles9. Move, e

7、xercise, and stretch eg. Change adjustments of the chair for those sit for a long time.10. Maintain a comfortable environment eg. Consider the quantity and quality of light at the workstation.2002/9/2610SMT Training for ProductivityErgonomics Principles11. Make displays and controls understandable e

8、g. Clicking is easier than memorizing commands.12. Reduce stress eg. Design task to fit people.2002/9/2611SMT Training for ProductivityAnthropometry DefinitionMeasurement of the human body and its biomechanical characteristics.Biomechanical refers to the mechanical (machine-like) capabilities of the

9、 human skeleton-muscular systems.Measures our sizes and how we move and move easily.Need of AnthropometryWe are not in the same size.Poor design for mechanical abilities of the human body can lead to discomfort or injury.Eg. Height of keyboard for a computer.2002/9/2612SMT Training for ProductivityA

10、nthropometric DataStatic measures are used to determine size and spacing requirements of work space, eg., height, weight, seat to elbow height, and wing span.Dynamic measures are used to match the dynamic characteristics of controls to user, eg., range of motion for various joints, and strength of f

11、ingers.2002/9/2613SMT Training for ProductivityAnthropometric DataThe anthropometric data is performed in normal distribution.50th percentile is the most of the population.5th and 95th percentiles are the extremes.2002/9/2614SMT Training for ProductivityHow to use anthropometric dataDesign for extre

12、mesA standard is to design to fit 5th or 95th percentiles of the population.Design for most of the population50th percentile of the population should be used.Make the design adjustable The design can fit 5th to 95th percentiles of the population.2002/9/2615SMT Training for ProductivityExamples Desig

13、n aimsDesign examples: Examples of measurements to consider:Users that the design should accommodate:Easy reach Shelving Arm length, shoulder heightSmallest user:5th percentileAdequate clearance to avoid unwanted contact or trapping Cinema seats Shoulder or hip width, thigh lengthLargest user: 95th

14、percentileA comfortable and safe posture Worksurface heights Elbow height, sitting eye height, elbow height (sitting or standing)Most of the users:50th percentileSpecial fitting Headphones Head circumferenceMaximum range:5th to 95th percentile (adjustable design)2002/9/2616SMT Training for Productiv

15、ityAssembly Line BalancingEqualize workload among the assemblies.Identify the bottleneck operation.Establish the speed of the assembly line.Determine the number of work stations.Determine the labor cost of assembly.Establish the percent workload of each operator.Assist in plant layout.Reduce product

16、ion cost.2002/9/2617SMT Training for ProductivityTable for Assembly Line BalancingNo.Operation R-ValueCycle time# stationsAvg. cycle time% LoadHrs / 1000Pcs. / hrA1Sub-assembly 0.2160.2110.211003.5285A2Assembly 0.2160.44130.1477010.595 Major items: operation description, R-value, cycle time, number

17、of stations, average cycle time, percent load, hours per 1000 pieces, and number of pieces per hour. An example is as follows.12345672002/9/2618SMT Training for ProductivityItems for Assembly Line Balancing TableR-value (plant rate): Takt time or time needed to produce a product.= effective producti

18、on time / required production volume.Cycle time:Standard time for operation.Collected from time study.# stations:= Cycle time / R-valueAverage cycle time:= Cycle time / # stations 12342002/9/2619SMT Training for ProductivityItems for Assembly Line Balancing Table% Load: Tell how busy each work stati

19、on is compared to the busiest work station.% Load = Avg. cycle time / highest avg. cycle time.Highest avg. cycle time (100% station) is the bottleneck.100% station is reduced by 1%, then we will save 1% for all stations.The less percent loaded, the more desirable to be sub-assembled or combined.5200

20、2/9/2620SMT Training for ProductivityItems for Assembly Line Balancing TableHours / 1000 : The hours per 1000 units produced.Choose the bottleneck station.= (Avg. cycle time / 60 mins) x 1000 For more than one workers at the station, “hrs/1000” = # workers x “hrs/1000” of bottleneck.Because everyone

21、 on an assembly line must work at the same rate.Pcs. / hr :Number of units produced hourly by one worker at the station.= 1 / “Hrs/1000” X 1000672002/9/2621SMT Training for ProductivityImprove Assembly Line BalancingCalculate the Line Balance rateReducing the bottleneck station.Combining the bottlen

22、eck station with an operation in front or behind.Combining other operations to eliminate one of them.2002/9/2622SMT Training for ProductivityExample: Original Line BalanceNo.Operation R-Value(mins)Cycle time(mins)# stationsAvg. cycle time (mins)% LoadHrs / 1000Pcs. / hr1Place bottom housing on line

23、and lubricate0.250.20010.200804.172402Assemble parts 3, 4, & 50.250.25010.2501004.172403Assemble parts 6 & 7 together and place sub-assembly in housing0.250.30520.153618.341204Drive 6 bolts holding sub-assembly in bottom housing0.250.60030.2008012.50805Get vent cover & cement in place assembly to bo

24、ttom housing0.250.19810.198794.172406Get top housing, apply cement & assemble to bottom housing0.250.29020.145588.341207Place in carton & in master carton (6 per) and aside to pallet0.250.62530.2088312.5080Total 131.354 Producing new plastic charger; 1200 units per 8-hrs shift (with 300 mins effecti

25、ve). 2002/9/2623SMT Training for ProductivityExample: Original Line BalanceOriginal line balance rate= total cycle time / highest cycle time station x no. of stations= 1.354 / (0.25 x 7) = 77.4%Pcs./hr = 60 / 0.25 = 240Improve the bottleneck station by combining with an operation in front or behind.

26、Combine and eliminate work steps.Re-design the jig & fixture.OperationsBottleneck or 100% load station2002/9/2624SMT Training for ProductivityExample: Improved Line BalanceNo.Operation R-Value(mins)Cycle time(mins)# stationsAvg. cycle time (mins)% LoadHrs / 1000Pcs. / hr1 & 2Place bottom housing on

27、line, lubricate, & assemble parts 3, 4, & 5020.225987.631313 & 4Assemble parts 6 & 7 together. Place in housing & drive 6 bolts holding sub-assembly to housing.0.250.90540.2269915.26655Get vent cover & cement in place in bottom housing.0.250.19810.198863.822626 & 7Get top housing, apply cem

28、ent & assemble to bottom housing, pack out.0.250.91540.22910015.2665Total 110.878 Improved line balance 2002/9/2625SMT Training for ProductivityExample: Improved Line BalanceImproved line balance rate= total cycle time / highest cycle time station x no. of stations= 0.878 / (0.229 x 4) = 95.9%Pcs/hr

29、 = 60 / 0.229 = 262Increase in output with decrease in no. of workstations. OperationsBottleneck or 100% load station2002/9/2626SMT Training for ProductivityPrinciples of Motion EconomyGuidelines for efficient and effective work station design.Summarized to 4 major elements:Elimination Combination R

30、earrangementSimplification2002/9/2627SMT Training for ProductivityElimination Eliminate all possible jobs, steps, or motions.Eliminate irregularities in job.Eliminate the use of hand as holding device.Eliminate abnormal motions.Eliminate the use of muscles to maintain a fixed position.Eliminate musc

31、ular force by using power tools.Eliminate danger.Eliminate idle time.2002/9/2628SMT Training for ProductivityCombination Replace with one continuous short motion.Combine tools, controls, and motions.RearrangementDistribute the work evenly between two hands.Shift work from the hands to the eyes.Arran

32、ge for a straight forward order of work.2002/9/2629SMT Training for ProductivitySimplification Reduce eye travel.Keep work in the normal work area.Shorten motions.Adapt handles, levers, pedals, buttons, etc., to human dimensions and musculatures.2002/9/2630SMT Training for ProductivityApplying the P

33、rinciples of Motion Economy1. Move both arms in unison or move them symmetrically, but do not move just one arm at a time.Eg. Take the cap off an ink bottle.2002/9/2631SMT Training for ProductivityApplying the Principles of Motion Economy2. To minimize body movement by limiting movements to body par

34、ts with low time rankings.The following illustration shows the correlation between arm movement and working time.2002/9/2632SMT Training for ProductivityApplying the Principles of Motion Economy3. Minimize fatigue by repeating motions with a natural feeling of rhythm and by making your curved moveme

35、nts as smooth as possible.Do as little holding or adjusting of materials as you can.Use stands or jigs to hold your materials or tools for you.2002/9/2633SMT Training for ProductivityApplying the Principles of Motion Economy4. Keep materials and tools in specified places in front of and around you.5

36、. Try to keep from fighting gravity with the materials you are handling; move them down, not up.Eg. Use a chute to transport the products by its own gravity.2002/9/2634SMT Training for ProductivityApplying the Principles of Motion Economy6. Try to set your chair or desk at the most comfortable posit

37、ion and make sure your lighting is bright enough and at a good angle.7. If you utilize your legs and feet, you can lighten the load on your arms and hands.2002/9/2635SMT Training for ProductivityApplying the Principles of Motion Economy8. Side-to-side eye movements are less tiring than up-and-down o

38、nes.9. Whenever possible, combine procedures, using your tools as extensions of your hands and feet. Try to combine two or more tools into one.2002/9/2636SMT Training for ProductivityVarious types of chartsUsed as record techniquesOutline process charts:Overview of a process with graphical represent

39、ation.Show principal operations () and inspections ().Assist in the plant layout design, design of product, or machinery processes.2002/9/2637SMT Training for ProductivityVarious types of chartsFlow process chart:Activities of men, material or equipment.Two or more subjects can be presented alongsid

40、e each other to show their interdependence.Activities are divided by 5 functions, operation (), transport (), storage (), delay (D), inspection ().Only the activities of particular subject, either man, material, or equipment, are recorded on a single chart.2002/9/2638SMT Training for ProductivityExa

41、mple,Flow process chart:Inspecting and markingincoming parts(original method) 2002/9/2639SMT Training for ProductivityExample,Flow process chart:Inspecting and markingincoming parts(improved method) 2002/9/2640SMT Training for ProductivityVarious types of chartsTow-handed process chart:Useful in sho

42、wing idle time by either hand.Activities of a workers two hands. Simultaneous movements by both hands appear opposite each other.Description of the activities represented by the symbols should be inserted.2002/9/2641SMT Training for ProductivityExample,Two-handed process chart:Cutting glass tubes(or

43、iginal method) 2002/9/2642SMT Training for ProductivityExample,Two-handed process chart:Cutting glass tubes(improved method) 2002/9/2643SMT Training for ProductivityVarious types of chartsMultiple activity charts:Consider on the activities of a subject in relation to one or more others.Show up clear

44、ly ineffective time within the process.Useful in finding the best sequence of carrying out the various parts of the work.Operation / machine chart shows the interrelationship of the operator and the machine.2002/9/2644SMT Training for ProductivityExample,Multiple activity chart worker and machine:Fi

45、nish mill casting (original method) 2002/9/2645SMT Training for ProductivityExample,Multiple activity chart worker and machine:Finish mill casting (improved method) 2002/9/2646SMT Training for ProductivityTime StudyMost common technique for setting time standards.Useful for repetitive work.Provide s

46、tandard rate of working.A means of assessing the amount of rest that should be associated with the job.2002/9/2647SMT Training for ProductivityTime Study: Procedures1. Select the job to study.2. Collect information about the job.3. Divide the job into elements.4. Do the actual time study.5. Extend t

47、he time study.6. Determine the number of cycles to be timed.7. Rate, level, and normalize the operators performance.8. Apply allowances.9. Check logic.10. Publish the time standard.2002/9/2648SMT Training for ProductivityTime Study: Focus PointsExtend the time studyCalculate average observed time.De

48、termine performance rating.Calculate normal time:- Normal Time = average observed time x performance rating Find out frequency (how many times a task is performed within a time period).Calculate unit normal time. 2002/9/2649SMT Training for ProductivityTime Study: Focus PointsDetermine the number of

49、 cyclesN = number of cycles R = range of the sample of observations (in minutes)A = required precision (+/- 5% or 10%) d2 = statistical constant (3.078 for 95% confidence level) x = average time (in minutes)2002/9/2650SMT Training for ProductivityTime Study: Focus PointsPerformance ratingRating is t

50、he process of adjusting the time taken by an individual operator to what could be expected from a normal operator.Four major factors: skill, consistency, working conditions, and effort.Effort is the most important.Effort is the operators speed, and is measured based on the normal operator working at

51、 100%.2002/9/2651SMT Training for ProductivityTime Study: Focus PointsRelaxation allowanceIt is the allowance for the periodic stops for personal needs or fatigue.Example: going to washroom; getting a drink.Contingency allowanceIt is a small allowance of time which may be included in a standard time

52、 to meet expected items of delays.Occurs infrequently or irregularly.Example: interruptions by supervisors; changing materials.2002/9/2652SMT Training for ProductivityTime study: ExampleStation No.OperationDescriptionFindings (sec)Required # cyclesAverage Time (sec)12345678910M15PWB 分割 & 蓋印123129138

53、14011911611210212113216122.25102127131125121118M1626 pin, 電容, 振盪器, 接地線焊接48.6551.1448.6950.8146.5049.1650.0048.2843.7852.061048.91M17電感焊接18.5919.0120.4020.1019.7518.2223.9722.0020.2521.691220.7520.2923.75M18PWB 目檢12.4714.7818.1319.0013.2415.4015.0918.4417.6216.812816.9210.5713.2913.699.7819.6215.0318

54、.7516.4023.0122.1915.0921.9725.3820.414.0916.9724.1612.34PWB 分割 & 蓋印PWB 分割 & 蓋印 Example: Hand soldering for PWB of MPF82C. Identify the operations. Time first 10 cycles for each operation. Calculate the required no. of cycles to be taken.2002/9/2653SMT Training for ProductivityDetermine No. of Cycle

55、s StationNo.OperationDescriptionFindings (sec)Required # cyclesAverage Time (sec)12345678910M15PWB 分割 & 蓋印12312913814011911611210212113216122.25102127131125121118 Take the follows as an example, consider first 10 findings. By N = 4R2 / A2(d2)2(x)2 R= (140-102) / 60 = 0.633 Avg. (x) = 123.2 / 60 = 2.

56、053 For 95% confidence level, A = 0.05, d2 = 3.078 N = 4 (0.633)2 / (0.05)2(3.078)2(2.053)2 = 16 6 additional cycles should be time taken.2002/9/2654SMT Training for ProductivityExtend the Time StudyStation No.Average time (sec)Performance RatingNormal Time (sec)FrequencyManpowerUnit Normal Time (se

57、c)M15122.250.9110.038113.75M1648.910.9546.461315.49M1720.750.918.681118.68M1816.92116.921116.92 Determine performance rating for each operation. Normal time = avg. time X performance rating eg. For M15, normal time = 122.25 X 0.9 = 110.03s Identify frequency and manpower for each operation. Unit normal time = normal time / (frequency x manpower) eg. Unit normal time = 110.03 / (8 X 1) = 13.75seg.2002/9/2655SMT Training for ProductivityEstab