IE Work Design: Productivity and Safety Dr. Andris Freivalds Class #2

IE NEED FOR SAFETY – 5 Myths, misconceptions –Safety doesn’t sell –Catastrophic failures main concern –Safety slows operations –Safety is human (operator, user) problem –Cheaper to pay insurance (McWane??) –Making product safer increases costs

IE NEED FOR SAFETY – 5 cont’ AMOUNT OF SAFETY COSTS

IE IE 419 – Work Design Productivity –Productivity tools: PERT, Worker-machine charts, line balancing, plant layout –Work measurement: MTM-2, MOST, Work sampling Safety –General safety principles: how to recognize & analyze problem, select & apply remedy –Quantitative analyses: JSA, fault-tree, cost-benefit –Legal aspects: Workers Comp, OSHA –Hazards: recognize & control specific hazards

IE PRODUCTIVITY TOOLS Methods Study = Systematic recording of existing and proposed ways of doing work in order to improve productivity (to improve the job for the operator) 1)Select project 2)Get and present data 3)Analyze data 4)Develop ideal method

IE Fig. 2.1 – Steps in Methods Study

IE #1 – Select Project Pareto analysis aka: rule 80% of problems from 20% of jobs Focus on the 20% Plot in descen- ding order as cumulative proba- bility distribution DesignTools

IE #1 – Select Project Gantt Chart Horizontal bar chart of activities, shaded if done A snapshot of the status of all activities Focus efforts on those that are behind schedule

IE METHODS STUDY (Next?) 2)Get and present data 3)Analyze data 4)Develop ideal method All of these overlap Use special charts Quicker, efficient, for IEs Focus on productivity improvement

IE PERT and CPM (pp ) PERT = Program Evaluation and Review Technique (1950s) –Booz Allen for U.S. government & military –Time has uncertainty –Minimizing time is main goal CPM = Critical Path Method (1950s) –DuPont for large scale projects –Time is specified –Trade-off between cost and completion date

IE BASICS Set of well defined jobs (activities) Totality of which defines a project Jobs start/stop independently of each other Jobs are ordered in specific (technological) sequence Forms a graphical network diagram Allows computational estimates

IE GOALS/QUESTIONS How long if every job works out ideally? (optimistic estimate) How long if everything goes wrong? (pessimistic estimate) With average conditions → likely result How can project be shortened at least cost? (trade-offs)

IE RULES/PROCEDURES #1 1)List jobs and estimated duration time 2)Draw network diagram a)Arcs or vectors to depict jobs b)Arrows to indicate direction (progress) c)Numbered nodes to indicate events d)Events = start and end of jobs

IE RULES/PROCEDURES #2 3)No two jobs can be identified by same nodes 3 a) b)Dummy jobs take no time, no resources c)Only to show dependency Job A Job B Use Dummy Job Job A Job B Job C Job D Dummy Job Job B Job A

IE RULES/PROCEDURES #3 4)Show precedence relationships (IP) clearly a)Jobs B & C both required for Job D b)Job C not required for Job D (but needed further on) A C B DE A C B DE

IE RULES/PROCEDURES #4 Time = estimated duration of each job –Earliest start time (ES) = such that IP hold –Latest start time (LS) = without delaying project completion –Earliest finish (EF) = ES + time to complete job –Latest finish (LF) = LS + time complete job Critical jobs = jobs which delayed, delay project Float (slack) = difference between ES and LS; time that noncritical jobs can be ↑, without delaying project Critical path = longest path of critical jobs, determines duration of project; zero float

IE Ex #1- CRITICAL PATH (Travel Times) Two PSU profs (Allen, Booz) drive to Washington DC for a meeting with their contract sponsor (U.S. Army) Prof. Allen leaves State College at 8 AM –drives to Philadelphia (KP, 3 hrs) –get materials from subcontractor Lockheed Martin (0.5 hr) –then onto Washington DC (2.5 hrs) Prof. Booz leaves State College 8 AM –drives to Pittsburgh (3 hrs) –meets 3 rd prof (collaborator) for lunch (2 hrs) –then onto Washington DC (4.5 hrs) What is earliest they can meet for dinner?

IE Ex. CRITICAL PATH - 2 Allen Booz

IE Ex. CRITICAL PATH – 3 Network Table ActivityNodesIPTime A - drive(SC, Ph)-3 B – pick up(Ph, LM)A0.5 C - drive(LM, DC)B2.5 D - drive(SC, Pi)-3 E - lunch(Pi, Lu)D2 F - drive(Lu, DC)E4.5

IE Ex. CRITICAL PATH – 4 Network Diagram PiLu 3 2 SC Ph LM DC Critical Path = = 9.5 Earliest dinner: = 5:30 PM

IE Ex. CRITICAL PATH - 5 Critical path = 9.5 hours Earliest dinner is 5:30 PM Allen can leave 3.5 hrs later (11:30 AM) –Or drive more slowly, sightsee –Flexibility or slack in time = float Practically: If Booz shortens lunch to 1 hr, then could meet a 4:30 PM

IE Ex #2 – CPM and FLOAT ( Building a House) 7 major steps in building a house (months): 1)A - Design & obtain financing (3) 2)B - Lay foundation (2) 3)C - Order materials (1) 4)D – Build house (3) 5)E – Select paint (1) 6)F – Select carpet (1) 7)G – Finish work (1)

IE Ex #2 – CPM and FLOAT A 3 C 1 B 2 D 3 E 1 F 1 G 1

IE A 3 C 1 B 2 D 3 E 1 F 1 G 1 #1 #2 #3 #4 Critical Path =

IE A 3 C 1 B 2 D 3 E 1 F 1 G 1 Forward Pass ES = max (EF i ) EF = ES + t

IE A 3 C 1 B 2 D 3 E 1 F 1 G 1 Backward Pass LF = min (LSi) LS = LF - t

IE JobLSESLFEFFloat A (1,2) B (2,3) C(2,4) Dum (3,4) D (4,6)55880 E (4,5)65761 F (5,6)76871 G (6,7)88990 Float = LS – ES = LF – EF A 3 C 1 B 2 D 3 E 1 F 1 G 1 0,3 3,5 3,4 4,5 5,5 5,8 5,6 6,7 6,7 7,8 8,9 Critical path = all with 0 float =

IE A 3 C 1 B 2 D 3 E 1 F 1 G 1 Crashing – Expediting job, reallocation of resources to shorten project duration