This Java Script program simulates the matchstick experiment in Goldratt and Cox, The Goal. The experiment shows that a "balanced" production line is an illusion. The simulation shows how random variation in a production line with balanced capacity reduces its throughput below the theoretical rate, and causes inventory to collect in the factory.

For each workstation, a single die is rolled (1-6). The workstation can process that many pieces (if they are available in queue). The station will ship the lesser of the die roll and the number of pieces that are waiting to be processed. For example, if six pieces are waiting and the die roll is 2, the station will ship 2 pieces. If only three pieces are waiting and the die roll is five, the three pieces will be processed and shipped.

Each workstation starts with 4 pieces in stock. Therefore (in theory) the manufacturing line "should" be able to ship an average of 3.5 pieces per turn.
 

Directions: Click on "Roll Dice" to roll a die for each workstation (and production releases). Click on "Ship parts" to complete the transaction. Return to step 1. To start over, click the button above the table. When you start the simulation, a new window will open: INVENTORY CHART. It shows a bar chart of the inventory at each workstation. It can display up to 20 units. When this is exceeded, the following symbol will appear. It means, "Big pile of inventory."

"Big pile of inventory"

visitors since 21 December, 2003