We have all heard of ‘Pull Systems’ and the revered Kanban process, developed by Toyota to control production and inventory of parts and assemblies in their ‘high volume, low variety’ environment. Used in conjunction with ‘supermarkets’, the flow of work in progress is controlled in terms of FIFO (First-in, First-out), and inventory levels are capped by the number of Kanban cards in circulation.
But what if your business environment is not ‘high variety, low volume’? What if the carrying costs of holding supermarket stock is too great, because individual part demand at SKU level is too low, or part costs are too high, or the risk of obsolescence is too great? Traditionally, these types of Job Shop environments have been run by MRP-driven Push systems. How do you introduce some form of Pull system in these circumstances, to prevent launching work before the downstream (Customer) processes are ready for it, especially when bottleneck operations move all the time? How do you prevent yourself getting knee-deep in WIP?
Quick Response Manufacturing is an approach to ‘low volume – high variety’ manufacturing environments, developed by Professor Rajan Suri of Wisconsin University. Its aim is to reduce the lead time to supply the Customer in Engineer/Make-to-Order environments. One of the tools in QRM’s armoury is POLCA – Paired Over Lapping Cards with Authorisation, which on first appearance are similar to Kanban. However, the neat thing with POLCA cards is that they signal to the Supplying process that the Customer process ‘has the capacity available’ to receive the next job. This is unlike Kanban, which is stock driven – and signals to the Supplying process to replace parts that have been consumed, usually from a controlled stock location called a Supermarket.
POLCA cards are paired, allowing an individual work centre to ‘pair’ with multiple Supplying and Customer work centres. This is ideal for Job Shop environments, where there are multiple product routings, and volumes cannot justify dedicated flow lines. They allow a sequence of different products to be pulled through a multi-routing environment. Therefore, POLCA controls the release and processing of works orders. It prevents the ‘flooding’ of works orders on to the shop floor, preventing WIP build up and supporting FIFO and lead time reduction.
In the 21st century marketplace, where faster response times and greater customer choice are driving ever shorter lead time requirements, POLCA is an important technique within Quick Response Manufacturing to aid manufacturers in meeting the challenge.
To find out more about how Industry Forum can support your journey of improvement, email us or phone +44 121 717 6600 to talk to our expert practitioners.
– November 2019 authored by Mike Scull
A Bit More About Mike
Mike Scull has over 30 years of manufacturing experience within the automotive, aerospace, electronics, off highway, white goods and apparel sectors. Joining Industry Forum in January 1998, Mike underwent training and mentoring in the implementation of Lean Manufacturing with Japanese Master Engineers from Toyota, Nissan and Honda. Mike’s current role at Industry Forum is Principal Consultant – Lean Manufacturing.
Mike is a Chartered Engineer (CEng MIMechE), and has a BSc (Hons) in Civil Engineering. He has professional qualifications including APICS Certified Supply Chain Professional (CSCP) and Certified Production and Inventory Management (CPIM), Certified Demand Driven Planner, PRINCE2 Practitioner and is a Certified Six Sigma Black Belt. He is also an Assessor for the National Manufacturing Competitiveness Levels (NMCL) programme.
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