Tag Archives: Job Shop

Why Are Job Shops Always Such a Chaotic Mess? Part 2

May 26, 2020Material FlowJob Shop, Material FlowChristoph Roser

Ford Piston Shop 1917 — Ford piston shop 1917

Job shops are a mess. Period. The increased and uneven levels of inventory cause a host of other problems. In my last post I described how these inventory imbalances are caused by irregular material flow, how subsequent safety buffers increase inventory even more, and how this causes staff to change their workplace irregularly in a job shop. In this post I will continue the long list of ills in a job shop with staff changeover losses, extra searching and organizing, fluctuating lead times, and general un-plannability of job shops. Continue reading Why Are Job Shops Always Such a Chaotic Mess? Part 2 →

Why Are Job Shops Always Such a Chaotic Mess? Part 1

May 19, 2020Material FlowJob Shop, Material FlowChristoph Roser

Job shops have a strong tendency toward chaos. Even well managed plants struggle to maintain order in a job shop. This is due to the inherent nature of a job shop, and there are no good solutions to manage job shops. The only good way to improve a job shop is to turn it into a flow shop. I will talk more about such changes later in this short series, but first let me explain why job shops are always a mess. Continue reading Why Are Job Shops Always Such a Chaotic Mess? Part 1 →

Calculating the Number of POLCA Cards

August 28, 2018InventoryInventory, Job Shop, Material Flow, POLCAChristoph Roser

In my previous posts I explained how POLCA works and discussed the pros and cons of POLCA. In this post I will explain how to calculate the number of POLCA cards. While POLCA is overall a feasible method, I do have some critical comments on the method to calculate the number of POLCA cards. Continue reading Calculating the Number of POLCA Cards →

Advantages and Disadvantages of POLCA

August 21, 2018InventoryInventory, Job Shop, Material Flow, POLCAChristoph Roser

In my previous post I described how POLCA (Paired-Cell Overlapping Loops of Cards) is supposed to work. Now let me look at the advantages and disadvantages of the method. Overall POLCA is a valid method of managing job shops. If it is the right one for you depends very much on your production system. Continue reading Advantages and Disadvantages of POLCA →

What Is POLCA?

August 14, 2018InventoryInventory, Job Shop, Material Flow, POLCAChristoph Roser

POLCA stands for Paired-Cell Overlapping Loops of Cards with Authorization and was developed by Rajan Suri around 1990. It is sometimes mentioned alongside kanban and CONWIP as a production control system. Let me explain to you how POLCA works. In my next post I look at the pros and cons of POLCA. In my last post of this mini-series, I will show you the calculation for the number of POLCA cards, including some critical comments.

The similar-sounding word Polka is also a Czech dance music and textile pattern, hence the colorful illustration of the polka dots on the left (don’t worry, more technical diagrams will follow below). Continue reading What Is POLCA? →