the POLCA simulation game

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Appendices

1. Nestor Introduction

2. Manual and Presentation

3. Internet Version of the POLCA Simulation Game

4. Simulation Games

5. The POLCA Simulation Game 6. Results Test Game

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Appendix 1. Nestor Introduction

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Let’s

POLCA!

Nestor introduction to

the POLCA simulation game

In this introduction the following subjects will be discussed:

• The need for POLCA

• The features of POLCA

• The implementation of POLCA o POLCA Cells

o POLCA Loops o POLCA cards o HL/MRP

• A POLCA case study

Click here to start the introduction.

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Let’s POLCA!

In today’s marketplace, there is an increasing demand for customized products.

Customers can select from a large number of options, or they can even order custom- engineered products. Besides this, there also is the pressure to produce faster and faster.

For high-variety companies, this creates some challenges. You can imagine that a company, which produces a high variety of products, cannot keep every item in stock.

The demand for one particular item can be very low; it can even be a unique order. On the other hand, companies have to deliver very quickly.

Manufacturing companies that have to supply such high-variety or custom-engineered products are struggling with questions like:

- When should we start producing, do we have to forecast production?

- What products should we keep in stock?

To answer questions like these, material control schemes have been developed. They can be classified as push, pull, or hybrid strategies. Push and pull strategies are mainly developed for the more stable production situations. To see what makes them not suitable for the high-variety markets, the basics of those strategies will be outlined shortly.

‘In a push system, activities are scheduled by means of a central system and completed in a line with central instructions, such as an MRP system. Each work centre pushes out work without considering whether the succeeding work centre can make use of it. Thus, in a push system, material is moved to the next stage as soon as it has been processed.

Work centers are coordinated by means of the central operations planning and control system. According to Slack, the main problem with push systems is that actual conditions differ from those that are planned. This can lead to idle time, inventory and queues.’¹ Suri adds to this that it is a waste of time and effort to work on products not needed yet by the next workstation.

‘In a pull system, the specifications of what is done are set by a workstation, which

‘pulls’ work from his preceding workstation. The customer acts as the only trigger for the movement. In a pull system, material is moved only when the next workstation wants it.’² Demands are satisfied from the removal of items from the output inventory buffers of workstations. The removed items then have to be replenished. To avoid long waiting times for customers, parts and finished products must be stored in buffers at every operation and for every product. This means that inventory is always needed to keep the process going.³ As we saw, these strategies cause excessive inventories when the product mix is broad. An example of a pull strategy is Kanban.

1 Slack, 2001: 326

2 Slack, 2001: 327

3 Gstettner, 1996: 3253

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In reactions to the shortcomings of push and pull strategies, hybrid systems where developed. Hybrid systems are more recent systems and are better suitable for high variety production environments. ‘They are material control strategies that combine features of push and pull. These systems recognize that in certain markets, the ones we have discussed, responding to the variability may provide competitive advantage.’⁴ In America scientist Suri recently developed the hybrid material control strategy POLCA.

This is a material control system designed with the discussed high variety situations in mind. POLCA is an abbreviation for Paired-cell Overlapping Loops of Cards with Authorization. What is exactly meant by these words will be explained in this introduction to the POLCA game.

Click here to proceed…

4 Krishnamurthy, 2004: 124

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Work smarter, not harder

The central, covering objective of POLCA is lead time reduction. All the principles of POLCA are pointed at this central objective. Focusing on lead time reduction namely has several benefits from which the most obvious one is that responding fast to customers promotes customer satisfaction. And, in reaction, the performance reputation may assist in taking orders away from competitors. In addition, if customers have an urgent need for products, companies might be able to charge a price premium.⁵

‘Less obvious, but more fundamental, is that implementing QRM and POLCA can improve the integration of the whole enterprise. The concept searches for ways of squeezing time out of the whole process, thereby uncovering sources of inefficiency, quality problems and wasted efforts.’⁶ According to Suri, ‘lead time reduction has a positive impact on quality, costs and waste reduction.’⁷

The characteristics of POLCA will be explained by elaborating on the word POLCA. We already know that POLCA is an abbreviation for Paired-cell Overlapping Loops of Cards with Authorization. What these words exactly mean by will be explained.

Paired-cell…

Underlying the POLCA system is a cellular organization. Employees and machines that produce a certain product family are placed in one cell. These cells are quite independent;

they have all the facilities needed to produce a product family. So, in principle it is not possible to share machines with another cell. To see an example of an organization that is divided into cells, you can click here. This example will be explained later.

POLCA only coordinates the flows between the cells. Within the cells the most suitable system for that cell is used. If the operations in a specific cell are routine like, for example Kanban can be applied.

In the POLCA system always two cells are connected. When for example cell 1 wants to start production, it only is allowed to do so if there is space in cell 2 when cell 1 will be finished. If not, cell 1 better starts working on another order. If there are no orders that do comply this rule, the people from cell 1 should not start working on other orders, but they can make themselves more useful by for example joining quality circles and thinking about ways to improve the production process. An important feature of POLCA namely is continuous improvement. The POLCA organization always looks for ways to improve their production, including lead times.

5 Suri, 1998: 31

6 Suri, 1998: xiv

7 This in contrast to Just-In-Time management. Here, waste is eliminated in order to improve quality, decrease costs, and reduce waste.

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Overlapping Loops of Cards…

The two connected cells are tied with a POLCA card. This card makes a loop when an order goes from cell 1 to cell 2. The card namely shares an order from the start of operation 1 until the end of operation 2. Then the card is turned back to the start of operation 1. When cell 1 is finished, cells 2 and 3 are the connected pair. To visualize this, the following picture is made. As you could see on the picture, the loops are overlapping. It shows the routing of a certain order.

POLCA uses Kanban-like cards to coordinate production. The difference between the two types of cards is that Kanban cards represent an order replenishment of a certain item and POLCA cards represent capacity. So a Kanban card is linked to a certain product (which is impossible for a company with a high variable product mix) and a POLCA card is linked to capacity. Click here to see an example of a POLCA card. If a POLCA card is available, then capacity to produce is available in a certain cell.

With Authorization

The POLCA cards are used at a quite detailed level. To get a more aggregated impression of the production process, the High Level Material Requirements Planning system (HL/MRP) is developed. This system oversees the whole production process and gives permission to start an order. This permission is given when all material to start producing is available and when it is the right time to start producing. The latter is because not all customers want their products as soon as possible, but at a certain point of time. Then it is useless to start producing earlier (and build up inventory).

We have seen that for a cell to start working on an order, there are two prerequisites:

- Authorization by the HL/MRP;

- Availability of a POLCA card.

This all sounds quite theoretical. To make it a little clearer, an example will be elaborated.

But first a little question. How does POLCA/Suri think to improve an organization?

a) Elimination of waste leads to better quality, lower costs and shorter lead-times b) Lead-time reduction leads to better quality, lower costs and reduction of waste

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First picture:

Second picture:

R1 D1

D2

P1

P2

P3

F1

F2

Pre-press Press Finishing DTP

D1/R1 Loop

R1/P1 Loop

P1/F2 Loop Pre-press

Complica -ted graphical computer

Simple graphical computer

s

One- colour presses

Two- colour presses

Four- colour

press

Finishing large size orders

Finishing small size orders

MSD Printing Company

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Third picture:

Answer a:

Wrong…

This answer is the principle of Just-In-Time Click here and try it again!

Answer b:

Very good!

(Answer a) is the principle of Just-In-Time) Click here to proceed…

MSD Printing Company POLCA Card

D1 / R1

Originating Cell: DTP Cell 1 Destination Cell: Pre-press Cell 1

Card Serial Number D1/R1-007

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An example – MSD Printing Company

In a small town in the east of the Netherlands a middle-sized organization, MSD Printing Company, serves the competitive local printing market. The company has a high variety product mix and is struggling with a high level of WIP and long lead times. Therefore it considers implementing POLCA. A POLCA team is established to prepare the implementation.

The implementation of POLCA can, as can be derived from the previous text, be divided into the following elements:

• The Cells;

• The POLCA Loops;

• The POLCA Cards.

• The HL/MRP.

Now the several steps of implementing POLCA at MSD Printing Office are elaborated to get a better understanding of the system.

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Forming cells

First, the organization is split into several cells. We will now look at the different parts of the MSD Printing Company.

At the printing company, in most of the cases a design has to be made for a certain product. This can be simple, or complicated and time consuming. Sometimes a customer already has a design. Than this phase can be skipped.

The department which makes the design and layout of orders and which makes dummies (prototypes) is called the DTP department. In the current situation all the computers are in the same room. At every desk are a lot of papers and other things.

In the company, the DTP department is, on the advice of the POLCA team, split into two cells: one cell for the simple orders and one cell for the complex orders. In the simple cell are only some simple graphical computers and a simple laser printer. In this cell the lead- time of an order is quit short, never more than one hour. The personnel of this cell doesn’t need to have a very thorough understanding of a lot of graphical programs. In the complex cell the more sophisticated graphical computers and printers are placed. Here work the higher educated DTP-ers.

We now have the following two DTP-cells:

The next cell is the pre-press cell. In this cell the metal plates are made for the printing department. In this cell works only one person. He makes the plates for both the complex and the simple products.

He also checks whether the plates are good. This means for example that there are no little black points on the plate. He doesn’t check the spelling and the page numbers etc.;

this is the responsibility of the DTP cells.

A feature of POLCA namely is that every cell produces a certain type of wound up product. The cell has the responsibility that that product is perfect. In this way a lot of rework and a lot of (double) checking is prevented for the other cells.

Pre-press cell:

Then the printing is on turn. MSD Printing Company has five presses (drukpersen). Two that are for one-color orders, two for two-color orders and one for the full-color orders.

The full color press of course can be used to print a one-color advertisement folder, but that is not very smart. This press namely takes a lot time to clean and set up.

The one-color presses are used very often and are the main bottleneck in the organization.

Complicated graphical computers

Simple graphical computers

Pre-press

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The POLCA team decides to split the printing department into three cells. One cell for the one-color presses, one cell for the two-color presses and one cell for the full-color press.

The team as well decides to acquire an additional one-color press.

One of the features of POLCA is that the capacity utilization is less important than the lead-time. The emphasis is on quick delivery and not on efficiency. According to Suri lead-time reduction namely leads to a more efficient organization, but efficiency does not lead to lead-time reduction. When you have enough capacity to satisfy demand, you will have a shorter lead-time and a better position in the market. Finally this will lead to more profit.

The next three cells are thus:

Finally there are some finishing operations. These operations include cutting, folding, stapling, putting together the pages of a magazine, gluing, and packing.

The machines and the tools for performing these operations are now spread over the organization. The POLCA team chooses to make two cells and puts all the required resources together in these cells. One cell is for the orders with large products like posters. The other cell has to perform operations for the smaller products like cards and books.

Finishing cells:

In total, this gives the following picture:

All the cells are given a certain number. Click here to see how this looks at MSD Printing Company.

One-colour presses

Two-colour presses

Four-colour press

Finishing large size orders

Finishing small size orders

Pre-press Complicated

graphical computers

Simple graphical computers

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Now we have finished the first step in implementing POLCA in MSD Printing Company, you know more about the features of POLCA. Please answer the following question.

What is NOT a feature of POLCA?

a) Concentrating on other parts of the lead-time than the run time b) Focus on lead-time reduction

c) Cellular organization d) Continuous improvement e) Focus on efficiency

f) Empowerment

Picture:

Click here to continue…

R1 D1

D2

P1 P2 P3

F1 F2

Pre-press Press Finishing DTP

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Answer a:

Wrong…

The waiting times in high-variety-product-mix and-demand companies are a much larger proportion of the total lead-time than run times are. Most material control strategies concentrate on the run time, but one of the basics of POLCA is the focus on decreasing

the waiting time part of the lead-time.

Click here and try it again!

Answer b:

Wrong…

Lead-time reduction is the central feature of POLCA. When introducing lead-time as the performance measure, this will, according to the developer Suri, have a positive impact

on quality, costs and waste reduction.

Answer c:

Wrong…

Underlying the POLCA system is a cellular organization. All employees and machines that produce a certain product family are placed in one cell. These cells are independent;

they have all the facilities and resources needed to produce a product family.

Answer d:

Wrong…

An important feature of POLCA is continuous improvement. The POLCA organization always looks for ways to improve their production and lead-times. If there is not an order

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to perform, the cell can join quality circles and spend time on thinking about improvements of the process.

Answer e:

Very good!

The centre of attention in a POLCA company is not on efficiency, but on lead-time.

According to Suri, focussing on efficiency very often leads to longer lead-times.

Not the efficiency in itself is a problem, but most measures of efficiency work counter to lead-time reduction.

It seems for example cheaper and thus also more efficient to buy resources in large quantities. But this leads to longer lead-times in the supplier’s factory. Which leads to longer lead-times in your factory, etc. This effect is called the ‘Response Time Spiral for

Purchasing from Suppliers’⁸.

Please look carefully at the following picture.

8 Suri, 1998: 270

4. Your supplier has long lead-times

2. The supplier’s factory receives many orders for large batches

1. You order a large batch of parts 3. Supplier runs each

order as a large batch through the factory

Your purchasing department wants quantity discounts

Other customers behave similarly Supplier uses cost-based

operating rules

Impact of manufacturing system dynamics (utilization ↑ Æ lead- time↑ )

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Answer f:

Wrong…

A feature of POLCA is that every cell produces a certain type of wound up product. The cell has the responsibility that that product is perfect. In this way a lot of rework and a lot

of (double) checking is prevented for the other cells.

According to the law of requisite authorization, you need to have some authorization when you have certain responsibilities. For a cell this means that they have to be

empowered enough to perform the tasks they are responsible for.

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High Level Materials Requirements Planning

We saw at MSD Printing Company that cells where formed and that these cells where connected through POLCA loops and POLCA cards. As a result, all cells are attuned to their former and their next cell. But, how does a POLCA organization plan the total, complete process of all the needed cells by orders?

This planning is performed by a HL/MRP system. The final element in implementing POLCA is making sure that there is a HL/MRP in the organization. HL/MRP is a covering system that oversees the whole organization. This system plans the timing of the production and makes sure that every thing needed is at the right cell. According to Suri, it has the following functions:

- Prediction of the need for, and ordering materials from external suppliers;

- Coordination of material delivery across internal cells.⁹

A POLCA organization uses a system for high-level planning and coordination of materials. Rather than looking at the details of replenishing materials and routing steps within each cell, the HL/MRP sees each cell as one step in the MRP logic. In this way, only a few steps have to be scheduled. According to Suri, this results in a simpler system than regular applications of MRP.

But do we need a simpler planning, don’t we have powerful computers that can easily handle complex routings? There are three reasons why a company can benefit from a simpler planning:

- ‘There are fewer steps to schedule and control. The ripple effects from 16 steps can quickly become unmanageable, while for three steps there is a good chance you can keep them under control;

- With the simpler planning, the cells can be given realistic and well-organized, clear targets as opposed to unreasonable ones, ones that would be soon be ignored;

- In the organization with HL/MRP the cells are more likely to keep their end of the bargain and deliver products on time.’¹⁰

9 Suri, 1998: 212

10 Suri, 1998: 217

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In a figure, the interaction of the HL/MRP and the cell planning systems looks for MSD Printing Company as follows:

The HL/MRP is driven by specified demand. This might be customer orders, sales forecasts (if possible), or a combination of both. Based on this demand, and using the cell lead times, the HL/MRP system develops delivery schedules for each cell. These schedules are given to each cell. In accordance to the schedules, each cell develops its own rough-cut lot sizing and work force policies to achieve the desired schedules. If the cell detects periods when it cannot meet the production targets, or when its lead times differ significantly from the ones being used by the HL/MRP system, it gives this feedback to the HL/MRP system. Based on such feedback, the HL/MRP system develops a modified schedule.

HL/MRP

Cell schedule

Actual lead times, any schedule infeasibilities

Cell decisions on lot sizing, manpower etc.

Demand

D1 F2

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Identifying the POLCA Loops

For every possible interaction between two pairs of cells there is a loop.

So for identifying the loops all possible combinations of sequences of routings have to be checked. If you take for example cell R1 (metal plates), than three loops are possible.

Namely loop R1/P1, R1/P2 and R1/P3. (P was the abbreviation of Printing Department).

It is not possible to pass a metal plate back to the DTP department, and it is also useless to pass a metal plate directly to the finishing department.

Think for yourself about the possible loops in MSD Printing Company. Click here to see the cells of the organization.

Now it is apparent how the loops are identified, we will make clear how the POLCA loops are used. We show an example. Assume that POLCA is already implemented at MSD Printing Company.

Imagine, one day the MSD Printing Company gets three orders:

• 65 birth tickets (geboortekaartjes);

• 25 large (A0-sized), two color posters for a supermarket;

• 400 full-color art magazines.

What should the company do with these orders? The first order is explained below.

When a pregnant couple comes to the MSD Printing Company, they can look into the birth ticket books of the company and then they can choose a birth ticket for their expected baby. These tickets are almost ready; the only thing that has to be done is to print some data (name, size, weight, visit times, poem etc.) on the card. But this can only be done when the baby is born. A feature of this type of orders is that the parents always want the ticket to be finished in maximum one day after the baby is born, so speed is very important in this case.

Today the father comes to the MSD Printing Company to tell the happy news. He has a baby, a boy, and he called him Thomas. He also gives the other data and wants the birth tickets to be ready as soon as possible. What has to be done now?

For this order the cards the parents choose two weeks ago were already ordered. The envelopes are given to them one week ago and MSD Printing Company has to print the data (in dark purple characters) on the birth tickets. What POLCA loops are needed now and in what sequence?

First, the layout of the cards has to be made. This is very simple and can be done in cell D1 (simple graphical computers), only the data have to be filled in. Then the people in cell D1 print the layout and give it to cell R1. In this cell the metal plate is made for the printing department. This plate is needed by the printing department to print the text on

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the cards. So now a D1/R1 loop has been made. (Click here to recall the picture of the cells)

After this, the printing department receives the metal plate from the pre-press department. When the printing cell is authorized to start and capacity is available, it starts to mix the right color of ink. Then the text is printed on the cards. Because only one color is needed the P1 cell can do this. The relevant loop is thus R1/P1.

When the ink is dry (technical waiting time), the finishing operations have to be performed.

Birth tickets are quite small, so the finishing operations will be done in cell F2. The relevant loop is from P1 to F2, thus P1/F2. Now the cards are cut on the cutting machine and placed in a box in which the final product will be given to the customers.

The loops are visualized in the picture below:

Note that when the birth tickets order is in one cell, there are always two loops overlapping in that cell, as you can see in the picture. Except for the first and the last cell.

Why this is will be explained later.

First, you have to solve the following problem. What are the loops needed for the other two orders? (Click here to recall the picture of the cells)

a) Posters: R1/G2, D2/P1, P2, F1 Art magazine: P3/F1, F1/D2, D2/P3 b) Posters: D2/R1, R1/P1, P1/F2 Art magazine: D1/R1, R1/P2, P2/F2 c) Posters: R1/P2, P2/D2, D2/F2 Art magazine: P2/R1, R1/P3, P3/F1 d) Posters: P2/R1, R1/D1, D1/F2 Art magazine: R1/G1, D1/P3, P3/F2 e) Posters: D1/R1, R1/P2, P2/F1 Art magazine: D2/R1, R1/P3, P3/F2 f) Posters: P2/R1, R1/D2, D2/F1 Art magazine: R1/D2, D2/P3, P3/F2

D1 R1 D2

P1

P2 P3

F1

D1/R1 Loop R1/P1 Loop

P1/F2 Loop

F2

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Picture:

Pre-press Complica-ted

graphical computers

Simple graphical computers

Pre-press Press Finishing DTP

MSD Printing Company

Click here to continue…

R1 D1

D2

P1 P2 P3

F1 F2

Pre-press Press Finishing DTP

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Answers a,b,c,d,f:

Wrong…

Tips:

A regular poster for a supermarket is quite simple. It can for example look like this:

This has the implication that the simple graphical computers can be used. Then the metal

plates are made which are given to the printing department. The poster has only two colors.

When the ink is dry, the posters go to the finishing department. Here the very big (size:

A0) posters are cut and packed.

Art magazines

Art magazines are very complicated to produce. They exist of several pages and have a complex layout. When the metal plates are made, the pages have to be printed on

the full color press. The stapling (nieten) folding (vouwen), cutting and packing can be done in the small

finishing cell because art magazines are not very large.

Only this week!

Grenadines

2,-

(kilo)

Star supermarket

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Answer e:

Very good!

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The POLCA Cards

When cell D1 wants to start to make the layout of the birth ticket there are two requisites we have seen earlier:

- Authorization by the HL/MRP;

- Availability of a POLCA card.

In the case a cell wants to start producing, it first needs the permission to start. This is given by the HL/MRP. When there is this permission, the cell needs capacity to be able to produce.

A POLCA card represents this capacity. When there is not a certain POLCA card available, a cell cannot start producing because the needed capacity is not there.

A POLCA card is always connected to a loop and not to a single cell. For the loop D1/R1 for example the card D1/R1 has to be available. This POLCA card joins the order from the beginning of D1 until the end of R1. At the end of the operations of cell R1, the card is returned to cell D1 to indicate that capacity is available in the loop D1/R1.

Consequently, at the beginning of cell R1, the R1/P1 card joins the order, etc.

The reason for this is that only when there is capacity in both the current cell and the next cell, the first cell is allowed to start. Because, why should you start if you will have to wait for the next cell? We have seen that it is better to put your efforts on something more useful.

So for example only if there is capacity in both cell D1 (DTP) and cell R1 (Pre-press) cell D1 is allowed to start making the layout of a birth ticket.

Because a POLCA card represents both the current cell and the next cell, the cards are overlapping. This we could see in the routing from the posters and the art magazines:

Posters: G1/R1, R1/P2, P2/F1 Art magazine: G2/R1, R1/P3, P3/F2

Only the first and the last cell are not overlapping because there exist no previous or next cells in that case.

Now we know what the use of POLCA cards is (reveal whether there is capacity), we need to know how the cards are made.

One important aspect is the appropriate ‘quantum’ of capacity that should be represented by a POLCA card.

It is essential that the optimum quantum is not too large and not too small. If the quantum were too large, then it would imply too few POLCA cards in the loop between two cells resulting in infrequent and possible ‘lumpy’ signals of available capacity to the upstream cell. On the other hand, if the quantum were too small, it would result in excessive

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POLCA cards in the loop, making it time-consuming to manage and keep track of them.

These two tradeoffs need to be considered while determining the quantum.¹¹

Another aspect is the number of POLCA cards in each loop. The number of cards can be computed by using the following simple formula:

NA/B = (LTA+LTB) x (NUMA,B / D) Where:

NA/B = Number of the POLCA cards in the POLCA loop going from cell A to cell B

LTA = Estimated average lead-time for cell A LTB = Estimated average lead-time for cell B

NUM_A,B = Total number of jobs (in terms of the quanta) that go from cell A to cell B during the planning period

D = Length of the planning period

Then finally the design of the POLCA cards is important. A POLCA card always has the same basic layout. An example:

The main information on the card consists of the acronyms for the paired cells for which the card is used. These are written in large characters.

The card is split into two colors. Each color is associated with a cell. And the card contains some more detailed information: the abbreviations are explained and the serial number of the card is projected.

To check you knowledge about POLCA cards, two final questions will follow. When you have answered them right, you can read the finishing conclusion on POLCA.

11 Suri, 2003: 8

D1 / R1

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1.

A great part of the orders at MSD Printing Company are family printing orders (familiedrukwerk: birth tickets, wedding tickets, etc.). These orders are quite simple and are mainly printed on the one-color presses in cell P1. The finishing operations always find place in the cell F2 (finishing small size orders). Every week 35 orders like this pass POLCA loop P1/F2. It takes on average three hours to print one order and four hours to do the finishing operations. The planning horizon is one week (40 hours).

How many POLCA cards should be in loop P1/F2?

a) 6 b) 7 c) 8 d) 9 2.

Recall the birth ticket order. We saw that the first POLCA card looks like this:

How does the next POLCA card look?

a) c)

b) MSD Printing Company POLCA Card d)

R1 / P1

Originating Cell: Pre-press Cell 1 Destination Cell: Printing Cell 1

R1 / P1

Card Serial Number D1/R1-007 MSD Printing Company POLCA Card

R1 / P1

D1 / R1

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1a,c,d:

Wrong…

The formula for determining the amount of POLCA cards in a certain loop is:

N_A/B= (LT_A+LT_B) x (NUM_A,B/ D)

Where:

NA/B = Number of the POLCA cards in the POLCA loop going from cell A to cell B.

Using the formula you need to calculate this parameter. All the other parameters are given in the case (respectively 3, 4, 35, 40).

LTA = Estimated average lead-time for cell A LT_B = Estimated average lead-time for cell B

NUMA,B = Total number of jobs (in terms of the quanta) that go from cell A to cell B during the planning period

D = Length of the planning period

Note: the answer has to be rounded up to the next integer value.

1b:

Very good!

Click here to proceed with question 2

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2a,b,c:

Wrong…

Every POLCA card is split into two colors. Each color is associated with a cell. So you know that each cell has his own color. On the first POLCA card you could see that cell

D1 is orange and that R1 is yellow.

This means that R1 on the next POLCA card has to be yellow.

2d:

Very good!

D1 / R1

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Summary

The purpose of the text was to give an introduction to the recently developed materials control system POLCA. Now the main facts will be summarized.

POLCA is a hybrid strategy and is mainly mend for companies that struggle with high WIP and long lead-times. This due to high variety in product mix and high variety in demand. POLCA is an abbreviation for Paired-cell Overlapping Loops of Cards with Authorization.

The central objective of POLCA is lead-time reduction. This lead-time reduction will lead to better quality, lower costs and reduction of waste.

Underlying the POLCA system is a cellular organization. Employees and machines that produce a certain product family are placed in one independent cell. POLCA coordinates the interaction between the cells. A cell is responsible for perfectly finishing the operations in the cell. Therefore, empowerment is a keyword.

Each cell is connected to its previous and its next cell (except of course for the first and last cell) by a POLCA card. This card represents capacity that is available and stays with an order during one loop from one cell to the next cell. Then the card is returned to this first cell. At every cell the loops are overlapping (also except for the first and the last cell). When no order is available to work on in one cell, the people of that cell join quality circles and work on continues improvement.

An HL/MRP oversees the whole system and decides when a cell is allowed to start working on an order. The HL/MRP sees each cell as one step in the MRP logic and is driven by specified demand. Like this, unneeded inventory build-up is prevented.

This is the end of the introduction. Thank you for your attention and success at the POLCA game.

Let’s POLCA!

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Appendix 2. Manual and Presentation

A. Manual

B. Presentation

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Appendix 2A. Manual

Let’s POLCA!

POLCA Simulation game

Manual

Team 1

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Table of contents

Case 3

Organization 3

Products 3

Process 4

POLCA 5

Game 6

Purpose of the game 6

Factory 6

Tasks 7

Cells 9

Orders 10

Revenues, costs, profits 11

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Case

Organization

The game takes place at Meubelmakerij

‘L’Intérieur’, set up in 1975. It is a company that produces special, customer- specific pieces of furniture. Each product is designed in dialogue with the customer.

The organization consists of a factory and a shop. The shop is opened only on Saturdays. Here the orders are accepted and the pieces of furniture are designed.

The factory consists of six departments and produces five days per week, from Monday to Friday. One shift consists of eight hours per day.

Products

‘L’Intérieur’ makes all kinds of luxurious pieces of furniture for offices, living rooms, bathrooms, dining rooms, etc. As a basis, the company uses a catalogue with approximately 500 standard products. Standard products are taken as a starting point and can be adjusted to the wishes of the customer. For example, color, form, size and type can be changed. A customer can also come up with an own design.

Consequently, the number of products that ‘L’Intérieur’ can make (the product mix) is in principle infinite.

Figure 2. Products

L’Intérieur

Figure 1. Factory

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Process

The process of making a piece of furniture starts when an order is placed. The design of this piece of furniture is discussed with the customer and added to the production planning by the planner. Because of the catalogue, a design never takes much time.

Hereafter real production starts. The wood that is necessary for the product is sawed in the sawing department of

‘L’Intérieur’. The sawing department will be called cell A.

When this is ready, several possibilities exist. For some pieces of furniture, it is necessary that holes are bored. This is done first, in cell B. Here is also milled (see figure 3). Thereafter, the wood is scoured.

This must be done after boring and milling because otherwise sanding would be needed twice. For some products, sanding is not necessary. Sanding happens in cell C. If the customer wants, the wood is painted and/or enameled. This confiscates much time because the paint or the lake must be dry. The painting department is called cell D. An order does not go along all cells.

However, an order visits along minimal one of the cells B, C and D.

Then the pieces of furniture are assembled. This takes place in the assembly cell, cell E. All pieces of furniture are assembled. ‘L’Intérieur’ delivers all pieces of furniture ready for use. The last step in the process is packing and sending. This happens in cell F.

The process looks as follows:

Figure 3. Production hall

Figure 4. Production process Sawing

Boring

Sanding

Painting

Assembling Packing

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POLCA

Since the establishment in the seventies, ‘L’Intérieur’ has been is a successful company. It has many customers, particularly because of the good quality of the products and the broad product mix. Quality and diversity are thus the core features of the strategy of the company. The last few years however, the company was less flourishing. The organization faced growing competition. This competition was focused especially on the delivery times. Quality remains important, but the customers are no longer patient enough to wait very long for their pieces or furniture. ‘The customers require an ever more rapid production’, the sale manager said on the board meeting of last April 25. He had read in a professional magazine about a new material control system, POLCA, and thought that it perhaps could be suitable for his company. In agreement with the production manager, it was decided to look whether POLCA can mean something for ‘L’Intérieur’.

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Game

To find out if POLCA indeed is something is for ‘L’Intérieur’, the POLCA simulation game is played. The game covers two months, May and June. In May the regular processes take place. In June POLCA will be introduced. Both months, revenues, costs, and profits will be measured. Now, the components of the game will be explained. In addition, it is explained how the revenues, costs and profit are calculated.

Purpose of the game

The learning goal of the game is to discover what the influence is of POLCA on the results of a company as ‘L’Intérieur’. The play goal is to make as much profit as possible. The winner will be the team that has gained the largest profit.

Factory

In the game, the factory will be projected by means of boards that represent the cells. This will look as follows:

Figure 5. Overview of the cells

E

C

D

Sales F

&

Planning

A

S S

B

S

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The factory of ‘L’Intérieur’ consists of six cells, as could be seen in figure 5. In each cell, one part of the production process will be completed. The cells have their own colors, and they have the following functions:

A: Sawing

B: Boring/milling C: Sanding D: Painting/enameling E: Assembling

F: Packing/sending

Cell has F has, beside packing and sending, a scheduling function. The cell stays in contact with the sale department and discusses acceptation of the orders. Cell F is therefore both the beginning point and the final point of the production process in the factory.

Tasks

Each player has the responsibility for one cell. He does the operations and he takes care of the transport of the orders to next cell. Thus, basically he has two tasks:

operation and transport. Below, the exact tasks per cell will be specified.

Sales & planning:

Sales & planning decides on the number of orders that will be accepted. Accepting orders goes by throwing two dices. With the first dice (see figure 6) is determined how many cells of the cells B, C and D will be visited. This can be one, two or three cells. With the second dice, it is determined which of the cells B, C and D will be visited. The colors on the dices correspond with the colors of the cells. Once thrown, means that the order must be accepted. All cells cannot be visited more than once.

Figure 6. Dices

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The routing and the number of the thrown orders are written on the plan board. As soon as an order is ready, the planner will eliminate it from the plan board. In addition, the planner administrates on which day the orders are accepted. This happens on the ‘Form Order Administration’.

Cell A:

As soon as the planner has given authorization to start with an the order, the production process starts. Each order requires one hour for sawing the required wood. There possibly is a set-up time of one hour necessary to set-up the machine for the next cell. How this is reflected in the game will be told later. If the wood has been sawed, the order is transported to next cell. On the plan board of the planner can be seen what the routing is of the order and therefore what next cell will be.

Cell B:

Each order that visits this cell needs four hours for boring and milling. When this is done, the order has to transported to the next cell. On the plan board of the planner can be seen what the routing is of the order and therefore what next cell will be.

Cell C:

Each order that visits this cell needs four hours for sanding. When this is done, the order has to be transported to the next cell. On the plan board of the planner can be seen what the routing is of the order and therefore what next cell will be.

Cell D:

It takes five hours to paint and/or enamel. This is including the time needed to dry.

Orders in this cell always will be transported to cell E.

Cell E:

Assembling the several parts takes two hours. When this is done, the order will be transported to cell F.

Cell F:

In this cell, the orders are packed and sent. In addition, the player from this cell has to administrate when the orders were sent. This has to be done on the ‘Form Order Administration’.

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Cells

Each cell is represented by a board. This board displays the number of hours it takes to do the operations for that cell. A one-color circle represents one hour production time. Set-up times are also reflected by means of a circle. On these circles is written ‘set-up’. Also these circles represent one hour of time.

The routing within a cell is reflected by means of a line. This line starts at the beginning stock of the cell and goes via operation circles and possibly set-up circles to the end stock. The orders run along this line. The stocks are also reflected by means of circles. The beginning stock (the stock of orders that must be still treated by the concerning cell) stands always at the left-hand side of the board (in figure 7 the red circle). The end stock always stands at the right-hand side of the board (in figure 7 the blue, green, and yellow circles). The color, with which the stock circles are colored, is the color of the originating cell, or the color of the destination cell.

Cell A is the only cell with a set-up time. Here, several routings can be distinguished, in contrast to the other cells. How the cell must be set up depends on the next cell. If the routing of the order is A C D E F for example, then cell A has to be set up for cell C because this will be the next cell after cell A. Setting up happens by placing a card on the set-up circle. Because of this, the circle disappears and it will cost a next order no longer the one hour set-up time. Setting up, moving the set-up card, costs one hour. In figure 7, cell A has been set up for cell C as the next cell. Transport costs no time in the game; the time that transports costs, can be neglected.

Orders

Set- up

A

Figure 7. Elements cell

One hour operation time Beginning stock of the cell

End stock of the cell

Line that shows the path to be followed in the cell

One hour set-up time Movable set-up card

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Orders are reflected by means of platforms with a rod. The beads that are on the rod show how far the order is progressed. Each bead stands for two hours of work. Therefore, each cell has four beads per day. At each step, thus each ‘hour’, one bead is added to the order. At the end of each day, a pink bead has to be added to the orders. An order which is ready for sending can look like this:

The platform has a slot. The planner places a card with the number of the order in the slot.

During the second round of the game POLCA has been implemented. Then POLCA cards are added to the orders.

With cards, the order looks for example as follows:

Figure 8. Meanings order

Order Operations

Figuur 9. Meanings cards

POLCA cards Order card Order

1

A/B B/C

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Revenues, costs, profit

Like every company, ‘L’Intérieur’ makes revenues, costs, and profits (or losses). The revenues are determined by the number of cells the order visits. The more operations needed, the higher the price of the product. Each visited cell means a revenue of €500,-. Is the routing for example A B D E F, then the revenues of this order are (€500,- x 5 =) €2500,-.

The costs coincide with the time it takes to produce a product. Customers find this very important we saw. When the factory takes a long time to produce, customers will be impatient and will not order by ‘L’Intérieur’ the next time. In addition, it takes time and space to store the products that are in the process. The money invested in material et cetera (tied-up capital) can also be used for other aims.

Therefore, the costs start when the product enters the company and the costs end when the product is delivered. The time this takes, is called lead time. Each day an order is in the company will cost the organization €100,-. Thus, when the order mentioned above takes six days to produce, then the profit will be (€2500 – (€100 x 6 =)) €1900,-. As told before, the team with the highest profits will win the game.

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Appendix 2B. Presentation