the goal

The GoalA Process of Ongoing Improvement

Eliyahu M. Goldratt and Jeff Cox

The GoalCharacters:Alex Rogo Plant ManagerJonah Physicist/Production ConsultantBill Peach Division VP of ManufacturingBob Donovan Plant Production ManagerLou ____ - Plant ControllerStacey Potazenik Production Control ManagerRalph Nakamura data processing manager

The GoalSetting:City of Bearington location? Pennsylvania, Ohio, Indiana manufacturing town

UniCo Corporation Manufacturing Plant probably 15 years oldother impressions?

The GoalIntroduction: Whats your first impression of the manufacturing plant?

Plant out of controlVP of manufacturing expediting an orderNew robotsControlled chaosGood at fighting firesExcellent at getting order filled when pressedLots of inventory

The GoalAlex travels to corporate meeting with a bunch of corporate speak.

Alex begins daydreaming.

The GoalAlex/Jonah Chance Meeting in Airport

Alex Robots increased productivity by 36% in one departmentJonah Are plant inventories down? : NoIs employee expense less? : No Shipping more product?: NoAlex Must keep robots running to maintain efficiencies.Jonah Then Inventories must be sky high and orders must be late.

The GoalAlex/Jonah Chance Meeting in Airport cont.Jonah In your own words, what is productivity.Alex Accomplishing your goals.Jonah Correct, then what is the goal of your company?Alex To be more productive? : No To produce products? : No To increase market share?: NoJonah How can you be productive? You dont know the goal.

The GoalWhat does Alex determine The Goal is?To make money!!

How do you know you are making money (Alex and Lou)?

Net profit (Income-Expenses) Return on InvestmentCash Flow

Why are each of these important?

The GoalHow do the making money measures translate to the production environment? (Jonahs translation)Throughput Is the rate at which the system generates money through Sales Inventory all the money that the system has invested in purchasing things which it intends to sell.Operational Expenses all the money the system spends in order to turn inventory into throughput.

The GoalWhat was the common word in all three measurement definitions? Money going into the systemMoney stuck inside the systemMoney flowing out of the system

The GoalThroughput Is the rate at which the system generates money through Sales Inventory all the money that the system has invested in purchasing things which it intends to sell.Operational Expenses all the money the system spends in order to turn inventory into throughput.

Where do the following fit?Raw materialsDirect laborIndirect laborTooling, machines, buildingKnowledge gained by employees

The GoalAlex meets Jonah in New York seeking help to determine steps to take in achieving the goal:

Jonah Do you run a balanced plant? Do you have any idle workers and is it good or not?Alex We try to keep all our employees productive

The GoalJonah Impossible to perfectly balance capacity to demand, there even exists a mathematical proof showing if you did, inventories go through the roof?Alex Hows this possibleJonah Due to two phenomenon:Dependent events a series of events must take place before another begins.Statistical Fluctuations the length of events and outcomes are not completely deterministic.The combination of these phenomenon are the issue.

The GoalDependent events Statistical Fluctuations

Q. - Where does Alex first come to grips with this (i.e. sees this first hand)?

A. During the boy scout hike.

The GoalAnalyzing the boy scout hike

Observations: the walking speed of individuals fluctuateAll may have the same average walking speed, but gaps continue to lengthen, why?There is no limit to how much an individual can slow down, but your top speed is dependent on the person in front.Fluctuations are accumulating over time, and the slow fluctuations tend to accumulate faster because they are not limited like the fast ones.

The GoalBoy scout hike > Manufacturing PlantObservations: Each boy is an operationThe product is walk the trailEach boy/operation is dependent on the one in front.A sale is when the last operation/boy walks the trail.Throughput is the rate at which the last person walks the trail.Operating expense is the energy output of each boy.Inventory (material inside the plant) is the distance between the first and last boy.Fluctuations in operating speed is causing inventory to increase and causing throughput to decrease. Attempting to reduce gaps is increasing operating expense.

The GoalPlay the matches game?

Setup: 5 players, 5 bowls, matches, 1 dieDump all matches in bowl #1Roll one die (starting with player #1) and pass that many matches from your bowl to the next person down the linePass die to next player who rolls die and moves that number of matches from their bowl to next player, cannot pass more matches than what is in your bowl.Continue for each player, with last player handing die back to player #1.

What is the average number rolled on a die?After 20 rounds, how many matches should the last player produce?

The GoalBack to the Boy scout hikeAfter lunch the boy scouts self-arrange so that the fastest is up front and so on until Herbie is at the rear.Q. What was the result?A. Line got even longer.Q. Did throughput improve (completing more miles)?A. No, completed miles still dependent on last scout walking the trail, plus inventory has increased.

Observation: however, everyone is always walking (no one is idle). But goal is not being achieved.

The GoalContinuing with the Boy scout hike

Q. How does Alex fix the boy scout hike?A. Puts kids in order from slowest first to fastest last. The line then stays compressed (i.e. inventory has gone down and progress has improved because Herbie is setting the pace and doesnt have to exert energy to catch up).Q. How do they further improve throughput?A. Off-loaded Herbies backpack. In oherwords, they improved Herbies throughput so the entire boy troops throughput improved.

The GoalAlexs First Chance to Test the Boy Scout Theory

Hilton Smyths order needs 100 parts by end of dayParts require 2 operations, fabrication then weld by robotEach department averages 25 units per hour, with robot working at almost exactly 25 unit pace.Start fabrication at noon, transferring parts on the hour, every hour.

Fabrication(25/hour)Weld(25/hour)Transfer(once/hour)


Expectation:

Hourly Part Count



Realization:

100 90Hourly Part Count


The GoalQ. So what have they learned to this point?

A. Have more capacity at downstream operations.

The GoalQ. What does Jonah suggest they do next?

A. Distinguish between bottleneck and non-bottleneck resources.

Definition:Bottleneck any resource whose capacity is equal to or less than the demand placed upon it.Non-bottleneck any resource whose capacity is greater than the demand placed upon it.

The GoalJonah then suggests balancing the flow of product through the plant with demand from the market. Not to balance the capacities of operations with demand.

Q. What determines the flow of product through the plant.

The bottleneck resources.

The GoalThe next step for Alex and company is to identify the bottlenecks (i.e. find Herbie).

Q. So how do you find a bottleneck in a manufacturing plant?

A. Go out on the floor and find the operation with the most inventory sitting in front of it.

Q. Is having a bottleneck a bad thing?

A. Not necessarily, all plants have to have a bottleneck.


Q. Once the bottleneck is identified, can you simply move the machines/operations around like Herbie was moved to the front of the line?

A. No, production steps often cannot be reorganized.

Q. So how do you solve the problem of moving Herbie to the front?A. Find more capacity for the bottleneck, dont try to move them. Have enough capacity to meet demand.


Q. How do you find more capacity?Make sure it is never idle (focus your attention on it).Increase cycle time on the machineAdd another duplicate machineOutsource to another vendorReduce the demand (process change)Inspect part quality before bottleneck (make sure bottleneck only works on good parts)Ensure process controls on bottleneck are good so bad parts arent producedDont let it work on parts that arent needed.

The GoalBack to the story:

Q. Where does Alex and company find the bottleneck?They find two bottlenecks, NCX-10 and Heat Treat

Q. What is thier first approach to improving the flow through the bottlenecks and ultimately improving productivity.1. Move QC in front of bottlenecks.2. Make a list of all late jobs and what components from those jobs flow through the bottleneck machines. They then create a schedule/list in due date order and instruct the bottleneck operators to only work on those jobs in that order.


Q. Does this scheduling system work (e.g. get late jobs completed while always keeping bottleneck running)?A. No, because the late job components are not always waiting in front of the bottleneck machines.

Q. What do they do to rectify this?A. Create a red tag (parts that travel through the bottleneck) / green tag system for all jobs throughout the plant such that any job with a red tag which arrives at a machine is given priority. If they are in the middle of a run, then if the run takes longer than 30 minutes to complete, stop that job and start the red tag job. If no red tags, then ok to process green tag jobs. If more than one red (or green tag), then process job with lower number on tag.


Q. What do they do next to further off-load the Herbies / bust the bottleneck?Gold tags placed on parts that have traveled through the bottleneck everyone extra careful not to damage.Dedicate personnel at NCX-10 and Heat Treat even though they are idle much of the time, just dont let machine idle. Send out some portion of heat treat parts to vendor in town.Found old equipment (that is less efficient) to run in parallel to NCX-10.Fully load furnace when possible (e.g. mix batches).Reduce setup time with new fixtures.Were able to process some parts differently so heat treat wasnt required.


Q. What were the results of these bottleneck busting tactics?New monthly shipping record from old record of 2 million to new record of 3 million.57 customer orders shipped versus old record of 31.WIP Inventories reduced 12%.

The GoalWhat happens next?

The bottlenecks are apparently expanding material is backing up at the milling machines, and non-bottleneck parts (green tags) are not reaching assembly even though all bottleneck parts (red tags) are available at assembly.

The GoalWhat happens next?

Jonah revisits plant and discusses relationship between bottleneck(X) and non-bottleneck(Y) machines.

Y X 3) Y A 4) Y Product AX Y X S X Product B S E M B L Y

The GoalJonah believes the new bottlenecks are not real bottlenecks, but self-created bottlenecks. Why?

Material is being released to the plant just to keep the non-bottleneck machines busy. This improves these machines efficiency measures, but does not help the goal.

Jonah: A system of local optimums is not an optimum system at all; it is a very inefficient system.

Lesson: Do not try to make non-bottlenecks work all the time. They should be idle some of the time!

The GoalSo how do you go about fixing the problem of keeping the non-bottleneck machines working at the same rate as the bottleneck?

Recall the boy scout hike: Herbie is in the middle of the line and cannot be moved, so how do you keep the kid in the front walking at the same pace as Herbie?

Alexs kids: use a rope and a drum.

Rope: Attach a rope from Herbie (bottleneck machine) to the kid at the front (assembly). The length of rope represents inventory. Drum: Herbie tells the kid at the front to slow down or speed up (beats the drum). Need some kind of signaling or communication between assembly and the bottleneck.

The GoalHow is the rope and drum concept implemented in the plant?

Identified it takes about 2 weeks from when parts are released to the floor until they get to bottleneck.Setup system that monitors when inventory is processed at the bottleneck. Material required 2 weeks later is then released to the floor.Non-bottleneck parts are released according using the same principle but tied to assembly.BottleneckMaterial Release2 weeks lead timeCommunicate release

The GoalWhat is the result of this new release system?

WIP is down.Revenues are up.Efficiencies dropped initially, but have come back up.The backlog of orders is completely gone (satisfied customers).

How does management respond?

HappySomewhat skeptical success will lastWants 15% more revenue next month!!

The GoalIn order to improve by another 15% what does Jonah suggest as the next logical step?

Cut batch sizes for non-bottleneck parts in half.

What is the impact of reducing these batch sizes?

WIP for non-bottleneck parts reduced by half.Significantly reduce time parts spend in plant. Leads to increased responsiveness (from 6-8 weeks to 3-4 weeks).

What about the time to handle increased number of setup? Doesnt matter if occurs on non-bottleneck operations.

Process TimeSetup TimeQueue TimeWait for Assembly TimeTime parts spend in the plant

The GoalAlso to help get the 15%, Alex calls the marketing/sales manager and bets him he can reduce lead time to fill orders. What does Alex expect to gain by reducing lead times to ship from what used to be 4 months to 4 weeks?

Increased sales!!The bottleneck had moved to customer demand. Quick response on promised due dates should translate to a competitive advantage.

The GoalEverything is going good now except it looks like part costs are going up. However, in reality all costs have gone down. How can this be?

The accounting rules:Cost per part = raw material + direct labor + burden costBurden cost is all the indirect labor costs.Burden = direct labor x burden factor

Cost per part has risen because more setups are occurring because of smaller batch sizes.

However, workers were idle, so the increased number of setups didnt really increase costs.

The GoalWhat other performance measure made them not look as good as they actually were.

Answer: Inventory

Inventory is counted as an asset on the balance sheet. When the plant worked hard to reduce inventories to improve their throughput and responsiveness, it looked as if their assets had fallen.

The GoalSacred Cows Slaughtered:

Worker efficiencyOptimal batch sizeReleasing work to the floor to keep people busyAccounting rules

The GoalWhy Alexs plant was successful:

Change in Focusfrom the cost world to the throughput world

CostThroughputInventoryThroughputInventoryCost

The GoalWhat process did they use to shift their focus to the throughput world?The Theory of Constraints

Step 1: Identify the systems constraints (NCX10 and oven)Step 2: Decide how to exploit the systems constraint (dont take lunch break on bottleneck machines)Step 3: Subordinate everything else to the above decision (red tags and green tags)Step 4: Elevate the systems constraint (bring back old Zmegma machine, outsource heat treat)Step 5: Warning!! If in a previous step, a bottleneck has been broken, go back to step 1 (material release system, marketing), but do not allow inertia to cause a systems constraint (red and green tags eventually caused problems).

The GoalFinal words from Alex on how to be an effective manager:

Help people to identify:what to change?what to change to?how to cause the change?

The GoalFinally some Philosophy:

What approach did Jonah use to help Alex and the plant succeed? Find the answers/solutions by asking questions, the Socratic approach. Let others convince themselves of the answers, dont just give it to them.

Also used a common sense approach which went against common practice. In other words, think!!

the goal

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