Value Stream Mapping

Value Stream MappingProcess ImprovementBy: Romains Bos

ContentsWhat is a value stream?Value stream mappingDrawing the Current-State MapGuidelines on Lean value streamsKey questions for the future stateDrawing the Future-State MapAchieving the future stateConclusion

What Is A Value Stream?A value stream is all of the actions (both value added and non-value added) currently required to bring a product from raw material to the arms of the customerValue Stream

What Is A Value Stream?We pursue a value stream perspective because it requires us to work on the big picture, not just individual processes, and improve the whole, not just optimize the parts

Value Stream MappingValue stream maps are communications & planning toolsThey graphically depict the value streams within and across our facilitiesCurrent processes within a product family define the Current-State MapThe goal is to develop and implement the Future-State MapCurrent state definition and future state planning are interactive processes

Why Value Stream Mapping Is An Essential ToolIt describes more than just a single process levelIt captures more than just wasteIt provides a common language for talking about manufacturing processesIt makes decisions about process flows apparentIt ties together Lean concepts and techniquesIt forms the basis for an implementation planIt shows the linkage between information and material flowsIt is more useful than quantitative tools that tally numbers associated with processes

Some Key PointsHave one person lead the mapping effortProductionMaterial flowInformation flowStart mapping at the door-to-door level within your facilityFocus on a single product familyConsider both material and information flows

Step 1: Drawing The Current-State MapSince future state design begins with an analysis of the current situation, we must begin with a Current-State MapValue stream mapping uses a standard set of icons to represent processes and flowsThese icons are linked to fully describe an entire value streamBegin by mapping the door-to-door level of detail; if further detail is required later, you can zoom in at that time

Value Stream Mapping Iconsprocesssourcedata boxinventoryshipmentPUSH arrowdelivery of FG to customerFIFO lanesupermarketPULL withdrawalmanual information flowelectronic information flowinformationproduction kanbanwithdrawal kanbansignal kanbankanban postkanban arriving in batchesload levelinggo see schedulingkaizen lightning burstoperator

A Few Mapping TipsAlways collect information while walking the actual material and information flows yourselfBefore mapping, take a quick walk along the entire door-to-door value streamBegin at the customer and work upstreamBring your stopwatch and do not rely on standard timesMap the whole value stream yourselfAlways draw by hand in pencil on a large sheet of paper (such as 11 x 17 ledger sized)

Getting Started On The Current-State MapLets draw the Current-State Map for a fictional company that produces painted baseball batsSince value is defined by customer requirements, starting with the customer is the best first stepOur customer, Sporting Goods Inc., requires 180 bats per month (90 blue, 60 green, and 30 red)Well use the source icon to represent the customer, and a data box to capture Sporting Goods Inc. requirements

Drawing The Production ProcessAdding the basic production process is the next stepWe use a process icon and a data box for each process stepIndividual steps are generally defined by the accumulation of inventory between themIf continuous flow already exists between two or more steps, consider using a single process icon to represent themInventory icons are used to show inventory buildup before and after each process stepThe amount of inventory is indicated underneath each inventory icon

Typical Process DataCycle time the time between successive good parts of the same typeChangeover time the time between the last good part of type A and the first good part of type BUptime the percentage of time a machine is available for productionBatch size the typical size of production lotsPack size the typical size of customer lotsNumber of operators can also be represented by the operator iconWorking time total time available, usually in secondsScrap rate percentage of all parts that are rejected as scrapAny other product variation information

Drawing The Production ProcessThe complete production process might look like this for our fictional companyPainted bats are produced in three steps and then shipped to the customerThe production process should always flow from left to right when mapping, ending near the customerWHITTLINGPAINTINGTESTINGSHIPPINGSPORTINGGOODS, INC.11120 days8 days3 days5 daysC/T = 27 minC/O = 8 hrsUptime = 85%C/T = 45 minC/O = 15 minUptime = 99%C/T = 33 minC/O = 5 minUptime = 99%Staging180 pcs/mo - 90 blue - 60 green - 30 redBox size = 9

Two Special CasesSome value streams have multiple branches that merge at some pointDraw such streams one over the otherResist trying to capture every branch if there are many; the main ones will be sufficientSome process steps will accumulate inventory in multiple locationsCapture each inventory location with a separate inventory iconTotal the inventory in each location underneath the appropriate icon

Material MovementMaterial movement into and out of the factory is shown with shipment icons and solid broad arrowsNote that solid broad arrows are used only for the delivery of finished goods to a customerIndicate the shipment frequency within the shipment icon itselfSuppliers providing material are represented by source icons; any associated supplier data are placed in a data box

Material MovementThis is how material flow might be represented on our mapNote that the production process favors the bottom half of the map while the supplier and customer are on the top halfWe also have not drawn in every purchased part (like paint); only the main raw material is indicatedWHITTLINGPAINTINGTESTINGSHIPPINGLUCYSLUMBERSPORTINGGOODS, INC.2x per monthDaily11120 days8 days3 days5 daysC/T = 27 minC/O = 8 hrsUptime = 85%C/T = 45 minC/O = 15 minUptime = 99%C/T = 33 minC/O = 5 minUptime = 99%Staging180 pcs/mo - 90 blue - 60 green - 30 redBox size = 9

Information FlowValue stream maps capture information flows as well as material flowsInformation moves from right to left in the top half of the map spaceWe use line arrows to indicate information flow, and give them a lightning effect when the information is electronicAn eyeglasses icon is available whenever go see information is used to adjust schedules

Information FlowWHITTLINGPAINTINGTESTINGSHIPPINGLUCYSLUMBERSPORTINGGOODS, INC.Daily Ship ScheduleShop OrdersQuarterly forecastWeekly ordersMonthly orders2x per monthDailyPRODUCTION CONTROL11120 days8 days3 days5 daysC/T = 27 minC/O = 8 hrsUptime = 85%C/T = 45 minC/O = 15 minUptime = 99%C/T = 33 minC/O = 5 minUptime = 99%Staging180 pcs/mo - 90 blue - 60 green - 30 redBox size = 9

PUSH And PULLThe final piece of information that we need to gather is how material moves between process stepsIn most cases, processes will produce by PUSH, meaning that they produce according to a schedule that guesses what the downstream process needsWe represent these situations using PUSH arrowsTo qualify as PULL, parts must not be produced when no kanban signal exists, and no more than the kanban quantity may be produced when signalledPUSHPULL

PUSH And PULLWHITTLINGPAINTINGTESTINGSHIPPINGLUCYSLUMBERSPORTINGGOODS, INC.Daily Ship ScheduleShop OrdersQuarterly forecastWeekly ordersMonthly orders2x per monthDailyPRODUCTION CONTROL11120 days8 days3 days5 daysC/T = 27 minC/O = 8 hrsUptime = 85%C/T = 45 minC/O = 15 minUptime = 99%C/T = 33 minC/O = 5 minUptime = 99%Staging180 pcs/mo - 90 blue - 60 green - 30 redBox size = 9

Almost Done!Our value stream map now has basic pattern of all value stream maps:Material moves from left to right on the bottom halfInformation moves from right to left on the top halfA timeline will now summarize the production information on our value stream mapUsing a stepped timeline as shown below, sum the days that material sits in various inventories on the upper lines; this is typically about equal to the product lead timeSum the time that material is actually in process on the lower lines; this is typically about equal to the value added timeInventory time Process time

Example Current-State Value Stream MapWHITTLINGPAINTINGTESTINGSHIPPINGLUCYSLUMBERSPORTINGGOODS, INC.Daily Ship ScheduleShop OrdersQuarterly forecastWeekly ordersMonthly orders2x per monthDailyPRODUCTION CONTROL11120 days8 days3 days5 days20 days8 days3 days5 days36 daysC/T = 27 minC/O = 8 hrsUptime = 85%C/T = 45 minC/O = 15 minUptime = 99%C/T = 33 minC/O = 5 minUptime = 99%27 min45 min33 min105 minStaging180 pcs/mo - 90 blue - 60 green - 30 redBox size = 9

What Have We Accomplished So Far?We can now see the value streamWe can begin to recognize areas of wasteWe have developed a Current-State Map that:Focuses on customer requirementsIndicates material movement through process steps and inventoriesDepicts information flows into, out of, and within our production processHighlights the difference between value added time and lead time within our value stream

Before we move on to the Future-State Map, its important to review some guidelines on Lean value streams . . .

Guideline #1 Produce To Your Takt TimeIn order to produce finished goods one piece at a time, a process has to be capable of working at the takt time:Takt time is the average time between pieces when you just meet customer demandTakt time can be thought of as the beat of a factory; its the inverse of the demand production rateTakt time incorporates a customer happiness test:Meet the takt time and your customers are happyMiss it and theyre not!

Guideline #2 Create Continuous Flow Or . . .

Guideline #3 Use SupermarketsThere may be reasons why continuous flow is not possible:Some processes operate at very fast or very slow cycle times and require changeovers between productsSome processes are far away and moving one piece at a time is not realisticSome processes have long lead times or are too unreliable to couple directly to a continuous flow processSome form of pull system works best in these situations

Guideline #4 Schedule Only One ProcessFlowFlowSchedule Here!Schedule Here!

Guideline #5 Level The Production MixLeveling the production mix means evenly distributing your production over a time periodIt will allow you to respond to changing customer requirements within a short lead time while keeping inventory levels low along the entire value streamBut it will require an investment in changeover reductionvs

Guideline #6 Level The Production VolumeEstablishing a consistent production pace creates a predictable production flowTry to release only a small amount of material at a time to the scheduled process at a standard pitchOne way to calculate pitch is to multiply your takt time by your pack size; if your takt time is 15 minutes and your pack size is 4, your pitch would be 1 hour

Guideline #7 Make Every Part FrequentlyBy reducing changeover times for all of your production processes, you will be able to make each of your product types more frequentlyA typical initial goal is to make every part every day for higher demand part numbersFollow-on efforts should drive towards making every part every shift, every hour, and every pitchTotal available time each dayTime to run daily requirementTime remaining for changeovers

Step 2: Drawing the Future-State MapNow well begin to highlight and eliminate sources of waste by designing and then implementing a future stateOur goal is to build a value stream in which:Processes are linked to customers by continuous flow or pullProducts are produced only when requested by the customerAs a first step, we will take product designs, production technologies, and plant locations as given

Key Questions For The Future StateWhat is the takt time?Will you build to a finished goods supermarket from which the customer pulls, or directly to shipping?Where can you use continuous flow processing?Where will you need to use supermarket pull systems?At what single point in the production chain (the pacemaker process) will you schedule production?How will you level the production mix?What increment of work will you consistently release?What process improvements will be necessary?

Question #1 Takt TimeTo calculate our fictional companys takt time, we need to know daily demand and the available working time per dayDemand is 180 pieces per month, or 9 pieces per day (using 20 working days to a month)Available working time each day is 8 hours minus two 15 minute breaks

Question #2 Finished Goods Supermarket?Should our company produce to a finished goods supermarket or directly to shipping?Determining factors should include:How reliable are our future state changes going to be?How predictable and stable is customer demand?How easy is it to store our finished goods?Can we calculate a kanban quantity for storage and subsequent production?

Question #3 Continuous FlowThis percent loading chart displays the total cycle times for each of the steps in the painted bat production processSince all steps are below the takt time, we could create a single process staffed by three operators to produce bats by continuous flowLets constrain our process, however, by saying that the whittling step is unreliable and is occasionally supported by an external vendorFurther, lets choose to pursue getting the total painting and testing time below takt timeT/T = 50 minutes

Question #4 Where Will We Need Supermarkets?In-line supermarkets are basically identical to finished goods supermarketsOptions exist in the way that production is signaled at the upstream process:Production kanbans request an amount of material identical to that which was withdrawnSignal kanbans request production to a max level when a min point is reachedSequenced-pull kanbans request one unit of a specific type of product

Question #4 Where Will We Need Supermarkets?Because we separated the whittling step from the rest of production, we require a supermarket after whittlingIn order to minimize the effect of whittling changeovers, a min-max reordering strategy will probably work best; this calls for signal kanban controlAn additional supermarket is needed to accept raw materials from our supplierSuppliers usually cant switch over to kanban control on short notice; well use internal kanbans to control that raw material reordering

How Are We Doing So Far?At the point we have introduced pull for raw material and whittled bats, established continuous flow between painting and shipping, and set up more frequent supplier deliveriesThe chart below summarizes the resulting lead time improvements, indicating that a large amount of waste will be removed from our value streamThe next step is to work on information flow at our fictional company

Question #5 Where Should The Pacemaker Be?Since the production process must flow downstream of the pacemaker, our scheduling point should be Paint & TestWe cant schedule any further upstream because of the pull systems in placeThis single process step will regulate the entire painted bats value stream

Question #6 How Should We Level The Mix?Recall that we level the production mix to avoid batch processing at the pacemaker and downstreamBatching amplifies problems, creates longer lead times, and requires supermarkets to account for sudden surges in demandWe should therefore choose a daily production stream that alternates painted bats according to current customer demand

Question #7 What Should Our Pitch Be?Because it is relatively lengthy, the takt time itself can serve as a good pitch for our production processThis means that every 50 minutes, finished work will be removed from the production process and a new set of work orders releasedA load-leveling box will both pace the production process and ensure that our chosen mix is being produced

Question #8 Necessary Process ImprovementsAchieving our future state will require several process improvements:Changeover time reduction at the whittling process step to allow for smaller batch sizes Point-of-use storage and standard work in painting and testing to enable one person to perform both process steps within the takt timeAdditional changeover time reduction within the new Paint & Test step to promote continuous flowFuture process improvements within our value stream might include a maintenance plan to improve whittling reliability and establishing kanban control of raw material delivery

Achieving The Future StateBreak the implementation into steps:The primary focus should be on your pacemaker loop, the flow of materials and information between your customer and the pacemakerAdditional loops exist upstream from the pacemaker; those should be your secondary focusPick a starting point where your process is well understood by your people, where the likelihood of success is high, and where you can predict quantitative resultsFollow this general process:Develop a continuous flow based on takt timeEstablish a pull system to control productionIntroduce levelingPractice kaizen to persistently eliminate waste

ConclusionTo be competitive the value stream needs to flow in a way that serves the customer with the shortest lead time, lowest cost, highest quality and most dependable deliveryEveryone - management and employees - has a role to play in lean implementation, and should feel a benefit from itBenefits come in many forms: increased competitiveness, a better work environment, greater trust between management and employees, and - not least - a sense of accomplishment in serving your customer

And do not forget - value streams extend upstream and downstream of our facilities; we are just one piece of a system-wide value stream