Below are 2 Theory of Constraints games. The game from The Goal book and the job shop game. Both games do a great job of explaining Theory of Constraints concepts.
GOLDRATT’S Theory of Constraints GAME from The Goal book – The Dice Game
This activity is a variation of the game Goldratt described in his “novel”, the Goal (North River Press, 1992, pp. 104-112.). This variation can be used to illustrate many concepts in production management. We use it to reinforce the notation that reduction of variation in processes is more efficient and economical than increasing inventory, or work-in-progress in this case.
The game simulates a production line with 5 work stations. The product must pass through each of the 5 work stations in order from 1 to 5. We use pennies to simulate the process. The potential amount of work completed at each station in a given time period is a uniform distribution of 1, 2, 3, 4, 5, and 6. This random potential work is determined each period by the tossing of a die. Hence the average potential amount of work at each station and thus through the system is 3.5 units per period.
If the game is played for 20 periods for example, one might expect an average of 70 completed units. However, the actual work completed at each station is limited by the WIP. The game is played by starting each station with a WIP of 4. At a signal all stations roll their dice to determine their potential work. The actual work forwarded to the next station is of course the minimum of the number on the die and the number of items in the WIP. We use pennies to represent the item being produced (No actual work is done at each station as the pennies move along).
The first station’s WIP is always replenished to the 4 level. As the game is played, WIP begins to vary and eventually in some cases limit the amount of work done. We set up as many lines as we have students available. By the end of 20 periods no line will be near the expected level of 70 finished units. When asked to suggest adjustments that might allow us to reach the target of 70 units on average, many students will suggest increasing the WIP. We re-run the game starting with WIP’s of eight rather than four and production does tend to increase but still often below the 70 level.
Further discussion usually results in a suggestion that better results could be obtained by reducing the variation in the work. The game is played one more time flipping coins to determine potential production levels with heads resulting in 4 units and tails 3 units. The average work done is still 3.5 units. Going back to WIP’s of four, this run is the most successful.
You can download the PDF of the above game here:
Free Game from The Goal by Eliyahu M Goldratt pdf
Video on The Dice Game:
The JOB SHOP GAME, a Theory of Constraints Game
If you run a custom job shop — be sure to visit our Velocity Scheduling System site for tons of free content and to sign up for our coaching program for guidance on implementing The Goal concepts in your shop!
This simple game was developed by
James R. Holt, Ph.D., PE
Associate Professor Engineering Management
Washington State University
Feel free to use this game when you credit to the source.
Instructor Information
Objective of the Theory of Constraints Game
The student will be able to understand how Drum-Buffer-Rope (DBR) scheduling applies to Job Shop environments.
Overview:
The game is played by releasing up to 36 Orders, one at a time, into the shop and sending them through four different Work Centers (A – D) to make the product. The Orders are monitored to determine how long it takes to get an Order processed from start-to-finish (flow time). The flow days are recorded on a chart. The results are analyzed.
Background:
In a Job shop environment, machines are organized in a functional layout (machines with similar processing characteristics are grouped together in a Work Center). Each Order that is released follows a specific outing (a processing sequence) through the Work Centers. With the high variety of routings and loads (setup and run times), you have a complex environment which is extremely hard to schedule. The bottlenecks
(constraints) seem to constantly shift, making it difficult to determine when Orders will be completed. Even though Job Shop environments range from ‘High Variety / Low Volume’ (Unique One-of-a Kind, ex. a tooling shop), to ‘Lower Variety / Higher Volume’ (ex. a production shop where the parts for a set of products are made in batches on a regular basis), this exercise effectively demonstrates the applicability of DBR
to all Job Shop environments.
Work Centers & Capacity:
For this exercise, our Job Shop has four (4) Work Centers (A – D) and each Work Center has one machine. The processing capability of each Work Center is specialized, so you can’t use alternate routings.
Each machine has only enough capacity to perform one operation per day.
Products:
There are 36 Order cards and each Order card has a Product # (1 – 4) on it. For the student who works in a High Variety / Low Volume environment, there are four product TYPES represented by the Product # (1 – 4) [ex. four different types of tools]. Each Order card represents a UNIQUE PRODUCT [tool] within each product type.
For the student who works in a Lower Variety / Higher Volume environment, there
are four different PARTS represented by the Product # (1 – 4). Each Order card
represents a different BATCH of each part.
Routings:
The process Routing, which represents the necessary sequence of Operations (the
Work Center where each operation is to be performed) is on the Order Card.
Orders must be processed by the Work Centers in the same sequence as the
Routing.
Role Requirements:
The Instructor should assign students to the Scheduler, Work Center Operator, and Flow Control Monitor roles. The roles have the following requirements: Scheduler – This game requires the Scheduler to be able to add up the buffer count and determine whether to release an order.
Work Center Operator
– At the end of the day in scenario 3, the students will be required to indicate the number of ‘B’ operations that have not been completed on the orders in their queue. This will be indicated by either a closed fist for none, or the appropriate number of fingers.
Flow Control Monitor
– Must be able to calculate the flow days for each Order card by subtracting the Release Day from the Shop Day. Allow the students to select their own roles.
The Players & Duties:
Scheduler (One):
When the Instructor calls out “Shop Day …”, the Scheduler makes a decision to Release/Not Release an Order card according to the specific scenario instructions. When the Instructor calls out “Write…”, and the Order is going to be released, the Scheduler writes the Shop Day on the ‘Release Day’ line on the Order card. When the Instructor calls out “Pass…”, the Scheduler passes the Order card to the queue of the initial Work Center (the first Operation).
Work Center Operators (Four):
Each Work Center can only process a maximum of one Order per day. When the Instructor calls out “Shop Day …”, the Operator takes ONE Order card from their queue (if there are any Order cards in the queue),
writes the Shop Day in the appropriate ‘Routing Box’ on the Order card. When the Instructor calls out “Pass…”, the