Pioneering 4.0: Applying Lean Six Sigma in ultra-precision manufacturing

Published on by Precision Components. The reading time is approximately 8 minutes.

Applying Lean Six Sigma in an ultra-precision manufacturing environment can rightly be called pioneering 4.0. After all, how do you use a method that was originally intended for mass-volume effectively if you work on products and components with a high complexity and large variation in a low volume? Project leader Stephan Huijgen and Tim van den Hoogen took up the challenge at NTS Norma in Drachten. They now both have a Black Belt and are seeing the results of their efforts: fewer measurements, less variation and a growing enthusiasm among their colleagues, who now have also been trained in the methodology.

“Our start with Lean Six Sigma at NTS Norma in Drachten had several reasons,” says Stephan. “In addition to the fact that we ourselves strived for an even more stable process and fewer error costs, our customers also asked for it. In addition, Tim and I had a strong personal interest in the methodology. We wanted to know exactly what it entailed and what we could do with it in daily practice. For that reason we started the training a few years ago. We are now both Black Belts and we have set up Lean Six Sigma projects.”

Supported by NTS and the customer

“Applying Lean Six Sigma is widely supported, both by the management of NTS as by our customers. Our colleagues have also had a White Belt training and some of them are even Green Belts. A number of our customers are actively involved in this as well, they have their own methodologies. For example, one of our strategic customers asked for a risk analysis per product while they wanted to reduce the number of measurements from a cost point of view. The question then is: "How do you deal with this?" You always have to deal with a field of tension."

Saving costs versus insight and quality assurance

“Measuring less means saving costs,” explains Tim: “but measuring means insight and assured quality. It also provides insight into where the spread or variation is. You must first determine the process quality and improve it where necessary, and only then can you reduce measurements. Before we started applying Lean Six Sigma, the approach was measuring 100 percent and then we reduced the measuring moments on gut feeling. We now base that on statistics. By removing the variation, there is less chance of incorrect products and that means that more production capacity remains available. This results in a stable process and less frustration. ”

Applying Lean Six Sigma in an atypical environment

“Lean Six Sigma is a method that is usually applied to high volume products with low complexity,” Stephan continues; “in that respect, NTS is a bit of an odd man out. We are a jobshop environment. This means that we make high mix, high complexity, low volume products here. Our batches are often small (ranging from a few pieces to tens), but you do need a certain volume of measurement data to be able to analyze and improve the process. In addition, our products are also very complex. We therefore apply this method in an atypical environment. In that sense it is a complex organization, you can tell by only looking at the amount of materials that are used. Making a set-up is much more intensive than at a company that produces mass volume. ”

A critical look at suitable product flows

“At NTS Norma in Drachten we make around 2,000 different products at low level with very multidisciplinary teams every year. As mentioned, we therefore do not apply Lean Six Sigma to every product, but have looked critically at which products, modules or parts are suited for it. On the basis of among others production numbers, customer expectations and product value we selected 5 to 6 product flows that were suitable, which meant that our efforts would pay for themselves.”

Involving everyone and working according to a fixed structure

“It mainly concerns New Product Introduction projects that are likely to be made in higher volume in the future,” Stephan continues. In that sense, being Black Belt is an excellent addition to my role as NPI project manager. We involve everyone from the start of a project. The entire chain is essential, from the work planner to the operator and the measurement experts. To limit the variation in production, we work in accordance with a fixed structure as much as possible and use measurement data to make the process more stable. Moreover, applying statistics successfully is not a matter of doing it once. Securing the process is important. Everything should be done in the same manner as much as possible. The process should not vary. In practice it is often impossible to keep all variables the same, but there should not be too much variation. ”

A best practice

“A good example of a project in which we applied the method with good results is the product Pole,” says Stephan. “There were a lot of measuring hours concerned with the product. Therefore, it required a lot of capacity. The question was how do we apply measurement reduction. We saw a lot of variation in the measurement data of the reference plane. This variation in the first operation had to be reduced so that the operators of the second operation would no longer be affected by it. We discussed that with the operator and he had the idea of ​​using a different tool. We then compared measurement data of the reference plane made with the two different tools in Minitab. It turned out that the variation had been reduced considerably and that it had resulted in a stable process. Due to the reduction in variation, we could also reduce the number of measurements which meant that less capacity of the measuring chamber was needed. ”

Unique measuring chamber

“Ultimately, the reduction in measurements should also result in fewer numbers of (the same) products being measured and an increase in capacity of the measuring room, creating more space for other/ new products,” says Tim. “At NTS we have a measuring room that is quite unique in its kind in the Netherlands due to the combination of measuring equipment, the experience of the measuring specialists and the variety of small products with very accurate specifications. In addition to having the most advanced equipment, our measurement specialists are absolute experts. They regularly teach at STODT. It is therefore a unique combination of equipment, knowledge and expertise. We make high-precision products and components here, so measuring and reliable data are extremely important. ”

A selection from the registrations performed by the measuring chambre
  • Determine position
  • Measuring the circumference and the diameter / height and diameter with 3D measuring means
  • Neasuring holes
  • Performing roughness measurements
  • Cylindrical measurements
  • Optical measurements
Finally, we have a very detailed microscope.

“As a substantiation, it is important to us that the chosen or required measuring tool is suitable for measuring certain geometries. For this we use a so-called Measurement System Analysis (MSA) in which we determine by a Gage R&R study whether the chosen measurement tool is reliable enough to measure the relevant dimensions.”

The ultimate pursuit

“Ultimately, we want to move towards a situation in which we perform a Measurement System Analysis right from the start, collect measurement data from the first production orders and then determine a sample size. By measuring various parameters on the shop floor, such as temperature, vibration, humidity, etc., the operator behind the CNC machines, together with the measurement data, gains insight into the production process at all times. This means that adjustments can be made immediately in case of process variation. Then you can always do everything in the same way. It will take some time before we get there. We also have a Continuous Improvement plan. Within Lean Six Sigma you have the CIMM model that consists of five levels. We want to use the Continuous Improvement plan to reach the highest (5) level within a few years. "

Pioneering, puzzling, trying and enthusing colleagues

“Implementing Lean Six Sigma really means pioneering,” says Stephan; “We have to figure everything out ourselves, we cannot learn from others. Fortunately we have each other to brainstorm with and we Google a lot and try to gather information. Moreover, the group of enthusiastic colleagues is also growing. I like to make them enthusiastic. Tim adds: “This really feels like unexplored territory. It is fun to work on this because it is a puzzle and a challenge to solve it properly. The great and motivating thing is that we also see real results from our work. For example, we have developed a specific method to determine the sample size. The fact that you get so much freedom and opportunities for your personal development here is also what appeals to me about NTS. Often your scope is very small at a larger company, if you have the ambition you can try everything you want at NTS. You get the opportunities for it here.”

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