In today’s world of intense competition and ever-increasing pressure, not just to perform but excel, manufacturers have to make things faster and to a higher quality. And mistakes are no longer tolerated in virtually any modern factory. Sarah Coles looks at how quality is delivered under pressure
From a very early age we are given the wise tortoise as a role model. We are indoctrinated into the understanding that slow and steady produces the kind of accuracy and quality that ensures a world class performance. Of course, when times are tight, it’s easy to be tempted by the promise of the hare – producing more, in a faster time, and with fewer people. The question is whether manufacturers can achieve the best of both worlds and make efficiency and accuracy the bedfellows they are theorised to be.
The key to efficiency lies in operational equipment effectiveness (OEE). This depends on three things: the speed you run at, the availability and the quality. The first part of any process is therefore to identify your OEE, and whether increased efficiency lies in improving accuracy, upping the speed, or reducing downtime.
David Bailey, leader of the manufacturing practice of PA Consulting in the UK says accuracy and maintaining quality is key: “Any failure in the product is poor efficiency; anything that doesn’t meet specification is a failure, therefore you can’t have efficiency if you don’t have an accurate process.”
Quality is key to Lean manufacturing practices, as reducing defects is one of the seven muda (wastes) of Lean theory. The ideal is therefore to change the culture and processes within the organisation to drive out inaccuracy.
Darron SBO manufactures components for the gas and oil industries. It has 100 employees based in Rotherham. It needed to reduce waste through resolving quality issues. Gerald Smith, managing director says: “It was vital for us to improve our production planning process and reduce machine downtime and scrap if we were going to achieve both customer and shareholder demands.” The Manufacturing Advisory Service (MAS) worked with them to develop a ‘right first time’ culture. A number of Kaizen quality improvement teams were put in place to work on quality issues, and the culture of the business gradually shifted to promote accuracy. Teams now monitor and manage their own KPIs, and as a result efficiency has improved enough to substantially reduce the order backlog.
A key theory building on the Lean ideology is Poka Yoke, developed by Shigeo Shingo. His aim was for errors to be entirely squeezed out of the process by making mistakes impossible – otherwise known as fool-proofing or mistake-proofing. There are a number of techniques that can be introduced to work towards Poka Yoke. The process can include visual devices to prevent mistakes happening in the first place, or the machinery itself can be constructed so that it’s impossible to make a mistake. Bailey explains: “If you have a product with seven screws, on a typical production line it moves in front of the operative, he puts the screws in, and then it moves on and often has to be rejected much further down the line because they haven’t done it properly. With Poka Yoke there will be a solution, such as an automatic screwdriver which counts the screws and won’t allow the line to move on until all seven are done.”
Ying Zhang, a spokeswoman for RNA Automated Limited adds: “New technologies in flexible handling systems combined with bar code and camera detection systems are powerful allies with quality control and lean manufacturing.”
So automation is one way to remove error from the process. However, it is not always the most efficient, especially if you factor in budgeting requirements but even if you don’t. It can also depend on where the product is being manufactured. Bailey says: “If you are manufacturing in Germany with high labour costs you may be looking for automation. However if you are manufacturing in China, not only do you have lower wage costs, but you also have a culture where a worker can be expected to do the same operation day in day out and do it perfectly, so you get accuracy and efficiency without automation.” It also depends on the process itself. Bailey uses the example of a manufacturer who purchased a piece of machinery which would only assemble one of its products. By taking a piece of the machine out and replacing it with a manual process, it gave them the flexibility to put all their products down the Indeed, some Poka Yoke solutions are decidedly low tech. Secure Systems and Technologies employs 52 staff in Gloucester, making specialist IT equipment. Its USP was delivering quality with fast delivery times. As a result speed and accuracy were vital. It worked with MAS to introduce Lean methods, including Poka Yoke. It redesigned its manufacturing space to reduce clutter, to improve the passage of parts through production and reduce the number lost in the clutter. This created a 50% increase in capacity, an increase of throughput of 35%. Meanwhile, reworks fell from 48% of product manufactured to 10%.
However, accuracy alone is not enough; manufacturers also need to work on speed. Often they are nervous of the speed part of the equation. It remains one of the major untapped opportunities in increasing the output of the manufacturing plant, because those involved in the process are afraid to challenge speed constraints for fear of introducing quality problems.
Tom Edwards, a director at Newton Industrial Consultants points out that although there is a point in the process of speeding up the plant where problems start to occur with quality, it’s a question of where that point is, and your reaction to it. He says: “If you are producing 100 widgets an hour you can try running at faster speeds to discover when you hit your first quality problem. If you do it at 1050 you can either see that as a constraint so you stay below 1050, or you can see it as a problem to solve.”
A solution, Edwards says, will require buy-in from various parts of the organisation, including quality, production and engineering. But if they can all be persuaded of the financial benefits of increasing speed, they can work together to overcome these problems.
Sometimes increasing speed is surprisingly straightforward. Edwards worked with an injection moulding company making syringes for veterinarian practices. He was called in to improve efficiency at the plant, so started with a review of the process. He says: “There was a machine which assembled the syringes, which had a speed dial on it marked from one to 12. There was a big sign on it saying it mustn’t be run any faster than eight.” Edwards asked around the company and couldn’t find anyone who knew why, so they ran trials testing at higher speeds. He says: “Over three days we increased the speed 60% without any problems. It was only a few months later we discovered that the sign had been put up because there was a camera on the machine that checked whether the syringes had been assembled correctly, and it couldn’t work any faster than on level eight. The camera had been removed two years earlier. It was only the sign that remained.”
The third element to OEE is controlling down-time. The solution to equipment availability must be tailored to each process. Lean theory calls for a tighter production system with a just-in-time approach, where a complex process involving tens of thousands of components will shut down if one part of the process stops, otherwise these components will accumulate and create efficiency problems. However, Edwards says: “A simple two step process may be better served by the ability to allow a certain amount of accumulation in between, so that if the first machine stops the second can continue, and vice versa.”
In some cases, availability is a matter of scheduling. It means looking at the production process and the optimum balance of making each product just in time for the market, while also keeping changeovers to a minimum. In addition, Edwards points out, the schedule has to be right. He uses the example of making paint: “You want to go from light to dark. You don’t want to be making black and then have to changeover to making white.”
These three factors together often hold the solution to efficiency issues. Edwards says: “Typically you get a 20% improvement without having to do anything critical”. However, in some cases efficiency may require product redesign. Bailey says: “I was involved in a project to industrialise a product with a very high tolerance. To make it effective to manufacturer was a process of negotiation, talking to the designers to ask ‘can we change the way the product is designed to make its manufacture more efficient, without any impact on the end user?’” He says: “Look at car manufacture. The body in white is made to a high tolerance, so the parts can slip over one another and there is significant give. The car itself can be made to a high quality, but requires a degree of accuracy that is achievable reliably.” Many production processes lend themselves to continual design improvements to allow for a more tolerant build with subsequent generations of the product.
The right approach can therefore improve on all three elements of OEE: availability, accuracy and speed, to enable a manufacturer to do improve efficiency without harming quality. It is possible to get the best of both worlds of the hare and the tortoise. Like most fairy stories there’s a moral behind the mythology.