Shahrukh Irani, Ph.D.

A custom fabricator isn’t Toyota. So how can a job shop adapt lean manufacturing for a low-volume, high-product-mix operation? It can start by revisiting the original principles of lean.

The value stream mapping tool, as used in lean manufacturing based on the Toyota Production System, can be difficult for custom fabricators and other job shops to implement. An alternative called value network mapping, however, can account for the highly complex environment of the high-product-mix, low-volume manufacturer.

Job shop managers may say that each product they make is different, but if they put their minds, video cameras, ERP data, spreadsheets, and business analytics tools to work, they probably will find repeating patterns in their order history.

Part 4 in a series, Dr. Irani describes how revenue plays a role when analyzing a job. Instead of focusing on a sample of products selected using a single criterion—quantity—the PQR Analysis brings revenue into the equation.

Incorporating the PR Analysis (relating product mix and routing similarities) into a PQ Analysis (relating product mix and quantities), creates the PQR Analysis.

The Product Quantity (PQ) Analysis method can be used to segment the product mix based on the annual production volume for each product, which helps determine the type of layout best suited for each product segment. For job shops, however, the tool may be insufficient, because it does not consider varying margins, revenue, routings, and repeatability of various jobs.

Dr. Shahrukh Irani offers an alternative to the value stream map in lean manufacturing. He calls it the value network map, and it’s tailored for the high-product-mix, low-volume world of the job shop.