Digitale POLCA: no traffic jams in your factory

PROPOS is worldwide the first to introduce Digital POLCA, a powerful way of ‘ramp admittance’ or ‘access denial’ to avoid queuing in your factory. With POLCA your orders are guaranteed to keep flowing with positive aspects for your work in process (WIP) and lead-times. We will be glad to explain to you in a personal meeting the power and working of this system. Below you find an introduction.

When your company is characterized by producing different products in separate batches, the production orders will not always follow the same sequence of machines or production steps. In other words: the orders follow individual routings on your shop floor. In that case you run the chance of having high work in progress (WIP). There is a greater chance on mistakes to be made and on long and unreliable lead-times times. Your ERP system of planning module won’t offer you control over the situation.

The image below shows a schematic representation of a factory with a typical spider web situation. Orders can travel from A to G through different routes. It might look complex, but if you sit down and note all the different routes of the production orders at your company, you probably end with many more varieties. Also in less complicated situations you can easily lose control.

Spider web situation: high risk at access work in process and unreliable lead-times.

There are many reasons for the above problems to occur. Orders are difficult to predict in which way they move exactly over the shop floor. The precalculated set up or tact times might be incorrect. Your staff might be absent or be replaced with someone having less experience. Another reason might be a machine break-down. Summarized: your actual situation at the shop floor differs from your planned schedule.

The result is that you will never be able to predict which production order is where at what time and when it will be ready. At certain spots work will pile up. Orders will sit idle longer than expected. Mistakes in order sequence are being made. Lead-times and production costs blow up. The phantom of backorders is troubling you.

To solve this problem POLCA has been developed. POLCA is a production control system that stands for Paired-cell Overlapping Loops of Cards with Authorization. POLCA has been designed by Prof. Rajan Suri at The University of Wisconsin Madison. Like Kanban and Conwip belongs to the group of production systems. It is in fact a hybrid system, where the A (Authorization) is push and the loops of cards are pull.

By means of bi-colored cards POLCA ensures that departments or work cells, as Rajan Suri calls them, only can supply to the next cell when a capacity card for this cell is available.(signal: you may supply). In case the right card is not available the cell upstream is not allowed to supply. The system prevents excessive WIP at your shop floor. The result is that other orders released at the floor reach their destination quicker. POLCA creates a pull mechanism instead of pushing the orders.

POLCA is a powerful tool. Yet it has some practical disadvantages:

  1. it takes education and training for your staff before they are able to understand and practice the system in your factory

  2. dozens of cards have to be designed, printed and plastified

  3. POLCA bords have to be placed at every department or cell of your shop floor

  4. calculating the required number of cards for every route is an awkward job for many companies. In practice the number of cards is not adjusted frequently enough, resulting in a lower performance of the system

  5. it takes discipline of your workers to use the cards properly

  6. at changing circumstances in your factory a lot of work needs to be done to keep the system up to date

Therefore PROPOS has developed Digital POLCA. It combines the power of POLCA with the advantages of a digital system. Within PROPOS working with POLCA is not more than starting the Digital POLCA module and configuring it. Then PROPOS shows directly to the employees at your shop floor the capacity of the cells downstream. It ensures admittance to the next cell. Your orders will flow.

In this example PROPOS shows that for certain orders no downstream capacity is available.
It prevents start up of these orders.

Implementing and keeping POLCA up to date in your factory has become an easy and logical step with the Digital POLCA module of PROPOS!

First in the world!

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How your factory can congest

Do you want to see how also your factory can congest because of unpredictable circumstances? Click here for an example.

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