Putting inherent instability to good use.

Most proponents of lean manufacturing suggest that it removes or substantially reduces the need for IT support. Graham Hackwell, Technical Director of scheduling software solutions provider Preactor International, examines the case for pursuing IT-in the form of Advanced Planning & Scheduling (APS)-as the only way to create a truly lean factory.

The new Typhoon Eurofighter has been designed to be aerodynamically unstable to give it the agility it requires in dogfights. Because it is unstable it utilises a computerised fly-by-wire control system that has to respond rapidly to any events that affect the stability of the aircraft, while still allowing the pilot to execute the required. The parallels with manufacturing processes are quite striking, and deserve some extra consideration.

Lean manufacturing is about the reduction of waste. This can take the form of quality initiatives to reduce scrap and rework, but it also addresses the reduction of inventory in all its forms (raw materials, work-in process [WIP], finished goods, etc.) and the utilisation of manufacturing resources.

The ideal solution would be to "make to order", with no inventory and all resources working 100 per cent of the time. The challenge of lean manufacturing is how close to this ideal can we get?

The real issue here is stability. The Typhoon requires computerised control to remain stable when events such as air turbulence occur. In our manufacturing processes the events are more likely to be customer (demand) change, breakdowns, material shortages, etc. This raises the question of how do we achieve stability?

The answer lies primarily in inventory and capacity, because adding one or both to a manufacturing process makes it more stable in meeting delivery dates. For example if you have either a large finished goods stock, or significant excess capacity then you are buffered from changes in demand.

"The opportunity to what if your options on delivery promises across the whole order book can be likened to the manager having a crystal ball for the business."

Lean aims to strip out both inventory and excess capacity but in doing so it makes the process less stable, so in practice lean projects leave enough inventory and excess capacity to preserve the process stability. After all what is a Kanban other than in process inventory aimed at keeping the process running and stable?

The other side of this coin is that the more stable you make a process, the less agile it becomes. To give us the manufacturing agility we need to truly make to order and react to sudden changes in demand or loss of capacity, we, like the Typhoon, need a computerised control system.

Flying the factory

Of course, like the Typhoon pilot, our production management still wants to 'fly the factory' so the APS must highlight problem areas in advance. The planners and shop floor staff can then take the results into account whilst still striving to meet the overall goals of minimising waste.

In fact you can also liken the APS to the pilot training simulator used for the Typhoon.

You wouldn't want to try something completely new, directly on the aircraft in flight, so simulators are used instead. Preactor has a "what if" capability, so you can test the alternative strategies for dealing with, say, a breakdown, and then pick the one that meets your objectives.

The opportunity to what if your options on delivery promises across the whole order book can be likened to the manager having a crystal ball for the business.
Case studies are the best testament to establish the benefits of this approach. One manufacturer in the aerospace sector had embarked upon a lean project to great effect, but when it added Preactor APS, it achieved a further 30 per cent reduction in work-in process, and a 10 per cent improvement in utilization. This reduced their Takt time (the rate or time that a completed product is finished) considerably!

The message is clear, if you want to make your factory to be as lean as possible, yet agile enough to handle the random events that de-stabilize it, then just like the Typhoon, fly by wire is your only choice.

Graham Hackwell is Technical Director for the scheduling software solutions company Preactor International (PI). PI, is an independent company based in the UK. First formed in 1984 the company is one of the fastest growing companies specializing in advanced planning and scheduling software and, through its partnerships with other software vendors and system suppliers, offers implementation and software support all over the world.

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