Process Industry, Lean and Six Sigma

Lean manufacturing basically developed out of discrete manufacturing with the goal of making it more continuous. This has resulted in continuous manufacturing (aka process industry) being challenged in how to look at their continuous flow as discrete flow so it can be more continuous!

While this seems like a circular argument, the brain contortions need to be focused on determining what is batch size in the process industry. Whereas the downstream packaging forces the nomenclature of a batch based on either a unit of time's production (IE one day) or a switchover of packaging material, this is often not the same batch size as the upstream, continuous process.

For many years now, batch sizes have been getting larger to fit "economies of scale", thus demanding that the required manufacturing equipment be larger and more powerful. In some companies, a batch could be considered to be anything produced in one year between annual overhauls or at least from one major upset to the next. Thus the true limiting step in batch processes is the batch size. And most companies feel they cannot change this as a lot of equipment capital and intellectual capital have been invested in the process.

There are several different ways a company can tackle continuous improvement under these circumstances and two popular methods are Six Sigma and Lean. Generally, Six Sigma is focused on the process itself; how to optimize process conditions, how to identify process upsets faster and how to control the process. It is also used in determining reasons for process upsets, setting up experiments for new technology or new products for the process. Lean is often used on the support systems; reducing changeover time when it does occur, improving maintenance through 5S and TPM, visual management, scheduling, capital project process and downstream in packaging and warehousing.

Unfortunately, in this age of flexibility, fluctuating demand and a more customer-focused agenda, true savings will not be made until the issue of batch size is dealt with. It is only from blending aspects of Lean and Six Sigma though, that the batch size will be able to be reduced in an optimal manner. You need to know how to measure the product quality, you need to know when your process is producing defects and you need to know how to be effective in your changes. More importantly, you need to take the time to make the financial calculations based on life cycle analysis and the changing markets to determine where your customer needs the batch size to be.

Learn how to improve your changeover times and to get your products to first grade as quickly as possible and reduce variation and your payback time for smaller tanks, pumps, filtration units, ovens etc will be short and well worth it. And your customer will be happier too!