Harnessing the power

Six sigma and lean manufacturing are a winning combination. Debbie Giggle discovers how companies are managing the two methodologies to gain a strategic advantage

The pioneers of the Wild West knew that if you harness two horses to your wagon instead of one, you can travel faster and further. But they also learnt that, if you haven’t tied the two together securely, they can end up wrecking your wagon, and possibly tearing you limb from limb. The same applies to pioneers of lean manufacturing and six sigma. With the pulling power of both of these methodologies at its disposal, a manufacturer can aspire to world class performance. But if the two approaches are insufficiently integrated the results may not be pretty.

The terminology of six sigma with its black belts and green belts has a distinctly combative ring. And lean manufacturing, with its focus on surpassing performance targets, also brings out a certain competitive spirit in those involved at the sharp end. It doesn’t take much imagination to understand what will happen if two teams, each championing a different methodology, find themselves going head to head. It could be a case of ‘this town ain’t big enough for the both of us’.
Yet, to survive in face of today’s competitive pressures it is crucial to harness the power of both these approaches.

“There is significant synergy between the tools of six sigma and lean manufacturing,” said consultant Mark McDavitt of Hosca, “so each informs and reinforces the aims of the other. But perhaps even more useful are the differences between the two. Tools such as the gauge repeatability and reproducibility study which arises from a six sigma approach will often have sufficient statistical rigour to enable manufacturers to tackle the real nitty gritty of a problem that has eluded them using lean manufacturing concepts.”

So are we saying that six sigma is real rough, tough problem-solving while lean is for wimps?
“Absolutely not,” continued McDavitt. “It’s a matter of horses for courses, and the ideal solution really is to have both at your disposal. Lean manufacturing is fantastic for raising the bar across the entire company and engendering the necessary environment in which to drive continuous improvement. Without the discipline which springs from the concepts of lean, the ability to use any of the six sigma tools effectively will be severely hampered. But once lean principles are in place, six sigma can then be used highly-effectively to tackle persistent quality or waste-based issues.”

There must be an art therefore in deciding which approach to use for which problem. According to McDavitt it sometimes happens that a six sigma approach will be applied to a problem that actually can be solved using good lean manufacturing practices. Apparently this ‘hammer to crack a nut’ situation is far from uncommon. But how well does the average operator actually understand the intricacies of the two different methodologies? Isn’t there a far greater risk that operators will become completely confused?

Paul Phillips is the lean and continuous improvement manager at Luxfer – a global manufacturer of high precision gas cylinders – based in Colwich, Nottinghamshire.
“As long as the person with responsibility for deciding the approach knows the differences between six sigma and lean it doesn’t matter how well-versed the operator is in the complexities of the theory,” he said. “In fact I find its far better to pre-select the tool you plan to use for a particular situation. Then focus the operators on the problem and explain the need. At that stage, discuss the tools you want to use to solve the problem. You might also build in some training to back-up the kinds of skills that will be required. Then, given the information and management support they need, the operators involved can get to work on understanding the root cause and solutions to the problem without getting too hung up on whether its a six sigma approach or a lean manufacturing tool. It all comes under one banner, that of continuous improvement.”

Luxfer has been using lean manufacturing tools for a number of years, right across the shopfloor, and has involved Hosca as an outside consultant, in addition to building its own skilled continuous improvement team. Its most recent decision to use a six sigma approach arose when a waste issue identified using lean manufacturing tools, proved to be particularly stubborn. While the team had been able to achieve some reductions in scrap rates in a billet cutting process, the scrap rate was still running at nine per cent which was unsatisfactory in the eyes of the team.

Luxfer brought in McDavitt from Hosca, a six sigma black belt, to look at other approaches. The process itself involves the cutting of continuous sections of extruded metal from an external supplier into billets of the correct dimensions. The team decided to carry out a gauge repeatability and reproducibility study to determine how to improve the percentage of cut billets which met the desired specification. From the statistics gathered using this method, the team was able to identify some technical changes to the process to enhance the overall quality of the operation. Through equipment enhancements and other measures, the scrap rate for this part of the manufacturing process has been reduced from nine per cent down to just 0.4 per cent.

“We’re still not satisfied with the scrap rate and intend to do more work,” explained Phillips, “but the improvements we’ve achieved so far have already cut waste significantly and improved profitability. Now that we have a deeper understanding of the process conditions at this particular point, we are in a much stronger position to take the scrap level down to zero. It also helps us to give accurate guidance to our supplier to make the kind of upstream changes that will help us to achieve this level of performance.”

The Luxfer example shows how well the two methodologies can work when harnessed together effectively. But what are the pitfalls of using the two in tandem?
The obvious one, it appears, is infighting. It is by no means uncommon for individuals, even very senior personnel, to throw their weight behind one or other approach. The motivation may be fear, the tried and trusted versus the new, or concern that control of a situation will pass from the company’s own hands into the hands of a consultant.

Ian Bettles of Smallpeice Enterprises, a company which specialises in leansigma training, said: “There is absolutely no point in pitching one set of tools against another. The synergies are innate. Hopefully most management teams will not allow this competitive situation to occur and will clearly link both methodologies to the company’s overall strategy to gain the maximum benefit. But it is true to say that integration of six sigma and lean is still relatively new and many organisations will be attempting it for the first time. I would have the following advice.

“Obviously it is good practice to have one set of people with both sets of tools. Be realistic however about the degree of expertise you wish individual employees to develop. Not every member of the team will feel equally confident with the sometimes complex calculations of data demanded by certain six sigma tools. In your desire to be even-handed you may unwittingly place certain individuals out of their depth, which of course could be demotivating. It may be far better to keep a certain degree of hierarchy in place so that, while all those involved have a thorough understanding of lean principles, their involvement in six sigma can be chosen (yellow, green or black belt etc) on a more individual basis.”

Careful consideration must also be given to the choice of measurement outcome.
Phillips advised: “Be clear at the outset whether you’re aiming towards PDCA or DMAIC outcomes for each project, otherwise you can run into conflicts further down the line. The underlying thinking must be clear, but I would say don’t get too hung up on terms – the different names for things. At the end of the day it doesn’t matter too much whether it’s a six sigma approach or a lean manufacturing one, as long as it gets results.

“The other important thing is to ensure that, as a management team, you are creating the right environment in which either, or both, methodologies can work at their most effective. There must be high level support for these tools, for example to finance suggested improvements wherever budgets allow. This also extends however to ensuring that the continuous improvement projects are communicated effectively, both to those that are directly involved, as well as to other employees. At Luxfer we avoided introducing six sigma to our personnel as ‘a new initiative’. People instantly assume that an initiative will have a set end-date, and that isn’t the case with six sigma or lean. They’re tools that you can come back to time and again to reach solutions.”

In summary then, it appears that manufacturers are finding that the two methodologies have clear synergy and experts believe the two should never be seen as mutually exclusive. For the pioneers of leansigma there may be pitfalls to watch out for and avoid, but the benefits of harnessing twice the ‘horse-power’ are definitely worth considering.