Presentation on theme: "Flow Time Analysis (Ch 4 of MBPF)"— Presentation transcript:
1 Flow Time Analysis (Ch 4 of MBPF) And a cautionary tale
2 Flow Time Analysis Inputs Processing System Outputs T Flow time = processing time + wait time (total time in the box)Theoretical Flow Time is the time to process a typical flow unit assuming NO waiting.
3 Flow Time AnalysisTotal amount of time for a flow unit to flow from the entry to exit point of a processIncludes delays and workIncludes value added and NVA activitiesShortening flow time often “good”Decrease response time (Dell computer)Reduce inventory (less $ tied up in WIP)New product/service development (auto)Robust to short product life cyclesFast feedback on quality problemsAn indicator of overall process excellence
4 Process Flow ChartingFlow charts are graphical representations of processesMay capture inputs, outputs, activity network, resources used, locations visited, decisions or business logic, buffers and delaysMany tools available, we’ll use iGrafx Process as it is bundled with our MBPF textVery good flow charting engineNumerous templates for various kinds of common business diagramsAlso has a relatively easy to use and pretty powerful process simulation capability. We will use this.
5 To learn iGrafx Process, start by doing the Tutorial on “Creating Process or Swimlane Diagram” which you can find in the iGrafx Tutorials menu or iGrafx Help menu. This tutorial does NOT cover the simulation features of iGrafx but instead just gets you started building process diagrams. We’ll learn the simulation features as we move along in the semester.
6 Process Flow Charts Using PowerPoint or iGrafx Process Wait/BufferActivities/SubprocessesStart/End EventsDecisionUse AutoShape - FlowchartPPT not the best tool in the world for DFD’s and other diagrams.Visio much better.Demo using PPTUse connection toolActivity Precedence
7 Old Medical Transcription Process DiagnosisPlan of carePhysician dictatesinto tape recorderStart ExamTranscribe into word processorPrintReportPhysicianreviewsreportWaitWaityesColor here for resource involvedEasier to see non-value added activitiesSend report to medical records dept.Changes?End Processno
9 Process Flow Charting in Practice Multi-disciplinary teamHave each team member do own flow chartWhy?Group facilitator or group tries to reach consensus on process flow chartYellow sticky notesExamine and revise by groupExamine partsDon’t get buried in detailsGenuine disagreement may occurMore flow charting resourcesA Fresh Look at Flow ChartingFlow Charting Help PageFlow Chart Overview
10 Other Process Description Tools Swim lanes or Service System MapsEnhanced flow charting technique using bands to delineate department participation in process stepsVariants can use color or other features to represent more process informationiGrafx Processes are of this typeProcess Activity ChartsSee next slide and Excel file ProcessActivityChart.xls
11 Example: X-rayExample on p109 of Business Process Modeling, Simulation, and Design
12 Finding Theoretical Flow Time Sequential Process
13 Finding Theoretical Flow Time Sequential & Parallel Path 1: (T1=80)Path 2: (T2=90)T* is the length of longest path through the processThe path associated with T* is called the Critical PathActivities on the Critical Path are called Critical Activities
14 Finding the Critical Path If process is “simple”, we canenumerate all the possible pathsCalculate their lengthFind the longest pathIf process is complex, may be too many paths to enumerateVarious algorithms exist for thisSee Appendix of Chapter 4 in MBPF for Critical Path MethodSame method as used to find critical path in project management networks (e.g. MS Project)
15 Observations about Critical Path Delaying an activity on CP will increase T*Activities NOT on CP can be delayed to some degree without increasing T*Speeding up activities on the CP will decrease T*Speeding up activities NOT on the CP will NOT decrease T*The CP can change as we change the activity timesWe are still assuming the activity times are known deterministic quantities (no randomness)
16 Flow Time Measurement The Direct Method Observe the process over some specified, extended period of timeTake random (or exhaustive) sample of flow unitsCalculate flow time, T, for each by (tend – tstart)Calculate average T over sampled flow unitsExample: CalcFlowTime.xls
17 Flow Time Measurement The Indirect Method Observe the process over some specified, extended period of time, tMeasure number of flow units, N, processed over the time period, tCompute throughput, R=N/tAt random points in time, count the number of flow units in process. Compute the average of these counts (we’ll call it I)Use Little’s Law to estimate T=I/RLet’s revisit CalcFlowTime.xls
18 Actual Flow Time vs. Theoretical Flow Time Most processes have numerous delaysEstimate avg. delay times and treat as activitiesValue added vs Non-value added activitiesSee Example 4.7 (p86) for X-ray process exampleProblem 4.1 in MBPFT* = 55TA = 70Flow Time Efficiency = T*/TA = 55/70 = .786Many real processes have very low Flow Time Efficiency
19 Levers for Managing Theoretical Flow Time We are ignoring waiting/delays for nowThree broad methods for reducing T*Eliminate: Reduce work content of a critical activityWork in parallel: Move some work content off of the critical pathSelect: Modify the product mix
20 Eliminate Roots in scientific management and industrial engineering Some combination ofEliminate NVAs (“work smarter”)Classic BPR example: Ford Accounts PayableReduce # repetitions of task (“less rework”)Build quality into process (poke-yoke)Statistical process controlDesign for manufacturabilityWorkforce trainingIncrease speed (“work faster”)IncentivesBetter technologyMore resources
21 Work in Parallel Move work off CP to non-critical activity Move work off CP to “outer loop”Pre or post processingExamples: pre-authorization, pre-admission testing, pre-registrationUsually requires process redesignOften some enabling communications technology required to facilitate parallel workExample: concurrent engineering facilitated by CAD and high bandwidth networks allowing transfer/sharing of large electronic files
22 Reengineering/Redesign The fundamental rethinking and radical redesign of business processes to achieve dramatic improvements in critical contemporary measures of performance such as cost, quality, service and speed.Reengineering the Corporation, Hammer and Champy, Harper Business (1993)
23 Process Reengineering A 1st Look Radical rethinking/redesign of processesClean sheet of paperBenchmark best practicesCommitment from top leadershipQuestion unconscious assumptionsValue added vs. Non-value added activitiesWhy redesign business processes?How to go about redesign?What is role of information technology?Relationship to continuous improvement, total quality management?Isn’t reengineering just another word for layoffs and downsizing?
24 BPR Life Cycle Process Analysis Idea Generation Design and Implement Establish a goal and Define ScopeGenerate StrategiesEvaluate and SelectDesign and ImplementSustain
25 Why Redesign? Current process “broken” (or may not exist) No one seeing big pictureNo one questioning business assumptionsIncremental improvement efforts insufficientGo beyond perspective of “how we do things”Processes critical to business success
26 Classic Reengineering Principles Organize around outcomes, not tasksHave output users “do” the processTreat geographically dispersed resources as though they were localLink parallel activities instead of integrating resultsPut decision point where work performed and build control into the processCapture information once, and at the source“Reengineering Work: Don’t Automate, Obliterate”, Hammer and Champy, Harvard Business Review (July-Aug 1990)
27 IHI: Redesign the System (p42-53) Do tasks in parallel – info gather during waitsUse multiple processes – ED fast trackMinimize handoffs – reduce unit transfersSynchronize – surgery starts at incisionUse pull systems – pull asthma from ED to clinicMove steps closer together – registering ED patients in treatment areaUse automation - PACSConsider people to be the same system – self-scheduling of surgery by surgeon officeUse multiple processing units – increase staffingExtend the time of specialists – nurse aideConvert internal steps to external – outsource transcription
28 The 5-step BPR Framework Develop the Business Vision and Process ObjectivesIdentify the Processes to be RedesignedUnderstand and Measure the Existing ProcessIdentify IT LeversDesign and Build a Prototype of the New Process“The New Industrial Engineering: Information Technology and Business Process Redesign”, Davenport and Short, Sloan Management Review (Summer 1990)
29 The Fad That Forgot People Reengineering didn’t start out as a code word for mindless bloodshed. It wasn’t supposed to be the last gasp of Industrial Age management. I know because I was there from the beginning. I was one of the ‘creators’.The Fad That Forgot People, Davenport, T.H., Fast Company, November 1995.
30 BPR – What Happened? Started as real people with real problems The Fad That Forgot People, Davenport, T.H., Fast Company, November 1995.BPR – What Happened?Started as real people with real problemsFord Motor Co., Mutual Benefit Life, HPSynthesis of 3 conceptsTechnologyBusiness processesClean-sheet-of-paper approachCompanies did stuff, academics and consultants started to “model make”Davenport, Hammer and Champy wrote “bible” articles and books
31 The Feeding Frenzy Early successes were trumpeted The Fad That Forgot People, Davenport, T.H., Fast Company, November 1995.The Feeding FrenzyTop managers + big-time consultants+IT vendors = $$$Early successes were trumpetedProjects labeled “BPR”People always looking for “magic solution”Consultants started packaging BPR servicesBig $$$ contractsExecutives needed to justify $$$ spentLayoffs quickest way to realize savingsIT firms selling hardware, software AND reengineering consulting
32 Reality Bites Massive layoffs labeled “reengineering” The Fad That Forgot People, Davenport, T.H., Fast Company, November 1995.Reality BitesMassive layoffs labeled “reengineering”Alienation of good employeesTreated as interchangeable cogs in corp. machine25 yr old MBA’s making $80K as BPR “experts”Major project failuresConsultants start repositioning for next waveAnd sell BPR to “rest of the world”
33 The Good Stuff Focus on business processes The Fad That Forgot People, Davenport, T.H., Fast Company, November 1995.The Good StuffFocus on business processesIT only useful if it helps people do workA Lesson: The bigger the hype, the greater the chances of failure.Techniques and tools of BPR can still be useful
34 The Next Big Thing Remember the lessons of BPR The Fad That Forgot People, Davenport, T.H., Fast Company, November 1995.The Next Big ThingRemember the lessons of BPRDon’t drop all your current approaches for the “handsome newcomer”Don’t listen to most charismatic advocates, listen to most reasoned advocatesTalk softlyCarry big ruler to measure real results
35 Defining Characteristics? Statistical process controlTotal quality managementBusiness process reengineeringTheory of constraintsLean production methods6-SigmaLean/6-SigmaOperations research & management science
36 Process Capacity Recall flow basics R=flow rateT=flow timeO=occupancyProcess capacity = Maximum sustainable flow rate of a processA resource pool is a set of interchangeable resourcesO = RT (Little’s Law)