Cup Game

Push/Batch vs Pull/Kanban Manufacturing Simulation

The Cup Game is a quick simulation to demonstrate the advantages of Kanban/Pull manufacturing over traditional Push/Batch. The full simulation with discussion can take less than an hour, and requires only nine participants, although it is worthwhile if others are observing. This Game was originally developed by Mike Studley for ACT in England, and has been modified by HP and Lockheed, and now by Kevin Meyer and John Vermillion at Abbott in Salt Lake.

1. Setup

Materials

  • Small paper drinking cups (about 400)
  • Green, red, and yellow circle stickers (about 500 each)
  • 20 stickers different from above to use as “defects”
  • Small pieces of paper, approximately 3”x3” (such as Post-It notes, about 400)
  • Flipchart and markers

Set up a large conference room. Use flipchart paper to create stations for the following:

  • Warehouse station (does not need “In” box)
  • Assembly Station #1
  • Assembly Station #2
  • Assembly Station #3
  • Assembly Station #4
  • Final Inspection station (does not need “Out” box)

Flipchart #1: Introduction

  • Description of the Cup Game
  • Agenda:
  • - Introduction (10 minutes)
  • - Push Simulation (10 minutes)
  • - Push results discussion (5 minutes)
  • - Pull/Kanban=6 simulation (10 minutes)
  • - Discussion (5 minutes)
  • - Pull/Kanban=1 simulation (10 minutes)
  • - Discussion (10 minutes)

Flipchart #2: Roles

  • Warehouse person
  • Assembler #1
  • Assembler #2
  • Assembler #3
  • Assembler #4
  • Final Inspector
  • Material Handler
  • Engineer
  • Observer

Flipcharts #’s 3,4,5: Simulation Instructions

  • Instructions – see below

Create a “process instruction” by creating a final “product”:

  1. Introduction

Introduce the Cup Game and assign roles.

  1. Push/Batch Simulation

In this simulation, the assemblers cannot talk to each other to exchange quality information, and the Material Handler must be used to transfer all product between stations in batches of 6. Run the simulation for 10 minutes. The Material Handler can stage raw parts at appropriate stations ahead of time (he will be very busy moving product!). After the line is full and running, inject a “reject” unit (a non-standard sticker) at the Assembler #2 station. Since no one can talk about quality, this reject should make it all the way to Final Inspection. Continue to sporadically inject defects into the line. The line is unbalanced with Assembler #3 having to put three times as many stickers on the paper as the others. Each operator to work as fast as possible, and not to wait on the next station to finish, hence the “In” area of slower stations will fill up rapidly. Follow first-in-first-out principles with each batch.

Procedure:

  • Warehouse person counts out 6 cups and 6 pieces of paper and calls for Material Handler to move them to Assembler #1. Start working on the next batch.
  • Assembler #1 puts the paper into the cup and when done with 6 sub-assemblies, calls for the Material Handler to move the units to Assembler #2. Start working on the next batch, if available.
  • Assembler #2 puts the one green sticker on the paper and when done with 6 sub-assemblies, calls for the Material Handler to move the units to Assembler #3. Start working on the next batch, if available.
  • Assembler #3 puts the three red stickers on the paper and when done with 6 sub-assemblies, calls for the Material Handler to move the units to Assembler #4. Start working on the next batch, if available.
  • Assembler #4 puts the one yellow sticker on the paper and when done with 6 assemblies, calls for the Material Handler to move the units to Final Inspection. Start working on the next batch, if available.
  • The Final Inspector inspects each assembly and puts them into a “Pass” or “Reject” box.
  • The Engineer calculates cycle time (time it takes for one product to move from the warehouse through final inspection).

At the end of 10 minutes, stop the line. The Engineer then records on the flipchart the cycle time, productivity (units shipped per person), total WIP, and total shipped. The Final Inspector records on the flipchart the yield. The Observer then leads the group in a discussion of the simulation. Some questions:

  • Where was the reject unit noticed?
  • How much product is at risk due to potential risks?
  • How much product is tied up in WIP?
  • Where were the bottlenecks?
  • How stressed out is the Material Handler?
  1. Pull/Kanban=6 Simulation

In this simulation, the assemblers can talk to each other to exchange quality information, and each assembler can pull subs/parts from the previous station in groups of 6. Each assembler cannot make more parts until the downstream assembler has pulled the group of 6 subs from their “Out” area. Run the simulation for 10 minutes. The Material Handler can stage raw parts at appropriate stations ahead of time, but he will not have to do anything more except keep the stations stocked with raw parts. After the line is full and running, inject a “reject” unit (a non-standard sticker) at the Assembler #2 station. Since the assemblers can talk about quality, this reject should be immediately noticed at the following station, and removed from the line. Continue to sporadically inject defects into the line. The line is now balanced with each assembler putting on two stickers.

Procedure:

  • Warehouse person counts out 6 cups and 6 pieces of paper and moves to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #1 pulls the batch of parts from the Warehouse “Out” area and inserts the paper into the cup and when done with 6 sub-assemblies puts them in his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #2 pulls the batch of parts from the Assembler #1 “Out” area and puts the one green sticker and one red sticker on the paper and when done with 6 sub-assemblies, moves them to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #3 pulls the batch of parts from the Assembler #2 “Out” area and puts the two red stickers on the paper and when done with 6 sub-assemblies, moves them to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #4 pulls the batch of parts from the Assembler #3 “Out” area and puts one yellow sticker on the paper and when done with 6 assemblies, moves them to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • The Final Inspector pulls the batch of assemblies from the Assembler #4 “Out” area and inspects each assembly and puts them into a “Pass” or “Reject” box.
  • The Engineer calculates cycle time (time it takes for one product to move from the warehouse through final inspection).

At the end of 10 minutes, stop the line. The Engineer then records on the flipchart the cycle time, productivity (units shipped per person), total WIP, and total shipped. The Final Inspector records on the flipchart the yield. The Observer then leads the group in a discussion of the simulation. Some questions:

  • Where was the reject unit noticed?
  • How much product is at risk due to potential risks?
  • How much product is tied up in WIP?
  • Where were the bottlenecks?
  • How stressed out is the Material Handler?
  1. Pull/Kanban=1 Simulation

In this simulation, the assemblers can talk to each other to exchange quality information, and each assembler can pull subs/parts from the previous station in groups of 1. Each assembler cannot make more parts until the downstream assembler has pulled the group of 1 sub from their “Out” area. Run the simulation for 10 minutes. The Material Handler can stage raw parts at appropriate stations ahead of time, but he will not have to do anything more except keep the stations stocked with raw parts. After the line is full and running, inject a “reject” unit (a non-standard sticker) at the Assembler #2 station. Since the assemblers can talk about quality, this reject should be immediately noticed at the following station, and removed from the line. Continue to sporadically inject defects into the line. The line is now balanced with each assembler putting on two stickers.

Procedure:

  • Warehouse person counts out cup and 1 piece of paper and moves to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #1 pulls the batch of parts from the Warehouse “Out” area and inserts the paper into the cup and when done with 1 sub-assembly puts them in his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #2 pulls the batch of parts from the Assembler #1 “Out” area and puts the one green sticker and one red sticker on the paper and when done with 1 sub-assembly, moves it to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #3 pulls the batch of parts from the Assembler #2 “Out” area and puts the two red stickers on the paper and when done with 1 sub-assembly, moves it to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • Assembler #4 pulls the batch of parts from the Assembler #3 “Out” area and puts one yellow sticker on the paper and when done with 1 assembly, moves it to his “Out” area. Begin working on another batch when the “Out” area is emptied.
  • The Final Inspector pulls the assembly from the Assembler #4 “Out” area and inspects it and puts it into a “Pass” or “Reject” box.
  • The Engineer calculates cycle time (time it takes for one product to move from the warehouse through final inspection).

At the end of 10 minutes, stop the line. The Engineer then records on the flipchart the cycle time, productivity (units shipped per person), total WIP, and total shipped. The Final Inspector records on the flipchart the yield. The Observer then leads the group in a discussion of the simulation. Some questions:

  • Where was the reject unit noticed?
  • How much product is at risk due to potential risks?
  • How much product is tied up in WIP?
  • Where were the bottlenecks?

How stressed out is the Material Handler?

  1. Final Discussion

Discuss what happened. Specifically, notice the dramatic difference in WIP, risk WIP, productivity, and cycle time between the three simulations. With such an increase in cycle time and total shipped, how many assemblers can be removed and still make the same amount of product in the same amount of time?

How can this be applied to your current operation?

What is the next step?