QUALITY MANAGEMENT

For a number of years, Nedschroef has seen autonomous growth rates of approximately 10 percent annually despite strong domestic and international competition. “We are achieving these growth rates by concentrating on “three” major targets for our group,” says Nedschroef’s Vice President Ron Deelen, who is responsible for their Business Unit Bolts. “First of all, it’s quality, secondly, it’s delivery on time, and thirdly, it’s giving the right price to our customers. These targets are subject to continuous improvement to maintain our market share in the future.” Part of this concentrated effort, as Ron understands it, is that Nedschroef has incorporated the latest innovations in process monitoring and data collection technologies.

Continuous improvement generates growth

“Quality, in recent years, has been the main objective when automotive customers rated their suppliers,” recalls Ron, proudly describing the results of Nedschroef’s efforts towards defect free products. “While 10 years ago, fault rates of maybe 500 – 800 ppm (parts per million) were acceptable, our production today is expected to deliver less than 50 ppm. In fact, in the meantime we are achieving effectively 0 ppm based upon the registered number of rejects.”
In a mass production environment such as the fastener industry, special efforts are needed to meet established targets. Nedschroef, just like other manufacturers in this industry, is faced with a multitude of possible cold forming defects which can lead to inferior products. The defects can roughly be divided into two groups, systematically- occurring errors and randomly-occurring errors.
“In the past, we had a good handle on those systematically-occurring errors such as tool failures by applying the usual statistical quality inspection routines,” says Ron Deelen, “but that’s no longer sufficient.” More headaches are caused by random errors. A classic example within this group is a defect called a rotated head or cauliflower head, which often occurs on multi-die cold formers when the headed blank accidentally rotates during the transfer from one forming station to the next.
The entire Nedschroef group applies in-process envelope monitoring techniques to cope with systematic faults as well as process-related random errors (Fig. 1). “We view process monitoring as the only option to guarantee a reliable and economic check of all manufactured parts at the high rates of production typical for our industry,” Ron explains their chosen route. “In the past, I was skeptical as far as process monitoring systems were concerned, but a recent major development has changed my point of view. That’s why all 10 plants within our group have decided to use the systems made by Schwer + Kopka.”

Quality comes first

Ron Deelen speaks highly of Schwer + Kopka’s Prozzy-technology which transfers the responsibility for a correct setup of the monitoring parameters from the machine operator to the electronic “brain” of the monitoring system. He really became convinced that perfect monitoring quality could now be accomplished, independent of the individual skills of the machine operator. The performance of the monitors is consistent on all machines, for all products, and on every day of the year. The Prozzy-technique ensures that the width of the envelope (sensitivity) is calculated by the normal allowed variation of the forming process. The envelope is tuned perfectly to the individual force characteristics of each forming operation, using tight limits during stable phases for added sensitivity, and looser limits during unstable phases to prevent unnecessary machine stoppages (Fig 2).
In addition, special monitoring routines for certain types of errors can be selected from the unique puzzle-menu via the push of a button (Fig. 3). The “rotated head” fault has an existing puzzle module which automatically zooms in to the fault relevant section at the beginning of the force curve, and activates the required tight sensitivity to detect this type of fault reliably (Fig. 4).

Establishing monitoring parameters automatically

But there is another aspect which contributes to the high level of acceptance of the monitors at Nedschroef: cold forming machines typically are rather complex systems with mechanical drives, and do not offer computer-controlled settings aside from a few exceptions in the areas of wire feed and ejector positioning. Hence, setting up a new job is a time-consuming procedure requiring an experienced operator, before a quality product will be produced by the machine.
“Too many setting options are available to the operator when adjusting a set of tools!” Mr. Deelen believes. “In order to achieve repeatable set-ups and, as a result of that, a uniform and superior quality, we need the easy-to-understand feedback we are getting from our process monitors such as wave forms, stability and consistency factors, data from previous runs of the same part, and the like.”
Nedschroef today views the monitoring systems installed on all their machines as a basic prerequisite to achieve their ambitious quality goals. Ron emphasizes the importance of the significant investment made into this technology this way: “This is the only feasible way if we want to meet the quality expectations of our customers from the automotive industry, and, at the same time, preserve the jobs of our employees.”

Using Captured process data to improve machine set-ups

As mentioned earlier, besides the quality aspect, having the correct customer pricing is one of the strategic success factors for the Nedschroef group. Obviously, the right price is largely depending upon effective control of the manufacturing costs.
“Our production profit and loss sheets contain four major items which we managed to improve greatly by using process monitoring technology,” says Deelen. “In recent years, we reduced the labour content in our manufacturing cost by eliminating all types of losses. In addition, machine cost went down due an increased number of machines served per operator, and improved quality at the same time. Overall output increased considerably while cost remained consistent, which in fact meant less cost per part. Thirdly, scrap rates have gone down, and, finally, cost for tooling and maintenance dropped drastically because those previously common tool crashes are no longer an issue thanks to the protection provided by our process monitors.”

Cost saving technology offers market advantages

The cost improvements described above are not just intangible “gut feelings,” but are proven facts thoroughly supported by a systematic collection of machine performance data. Nedschroef has installed the MES-system SK-go! also developed and supported by Schwer + Kopka. All production machinery, whether equipped with a process monitor (such as the cold formers and the thread rollers), or non-monitored (in the sorting and packaging department), are connected on-line to a central server computer. This concept has been expanded to all Nedschroef production plants with a total of more than 250 machines on-line. Even the remote plants, in Johannesburg and Barcelona, are integrated into the network and report their performance factors to the central data base.
Ron points out why Nedschroef has taken this route: “Only if you know where waste is happening in your organization, you will be able to initiate proper and successful remedial action. I would not know how else we could get the transparency we now enjoy from our data collection system. This vital information helps us to identify weak points and bottle necks in our technical and organizational procedures. Furthermore, we rely on a timely and as accurate as possible reporting system for machine down time reasons. We allow a buffer of just 2 minutes were we do not insist on getting a down code reported. If a machine is down for longer than the allowed buffer, it will automatically be locked until the operator has selected the proper down code from the given list shown on the screen of his process monitor or his machine data terminal.”

Thorough collection of production data creates transparency

The detailed database makes it quite easy for Nedschroef to verify if an improvement measure is producing the expected results. In the beginning, the available data is screened to determine if and where potential improvements are obtainable. Once measures are put into effect, the collected performance data clearly shows if the objectives have really been met (Fig 5).
“We are thoroughly analyzing the data on a daily basis and use the facts in our communication between the responsible staff from the different plants,” explains Ron. “When discussing a certain problem, we all have the same objective information on hand, no matter where our desk happens to be. Via video or telephone conferences, we often manage this way to quickly come up with solutions everybody agrees to. And you wouldn’t believe the impact on each plant generated by the fact, that our group management has an on-line view into the current production situation of every factory even from thousands of miles away!”

No strategic changes without ongoing success checks

It is evident that Nedschroef’s dedication to the thought of continuous improvement has more steps planned to further improve the utilization of their process monitoring and data collection systems. The near future has the following objectives on the agenda:
– Interfacing the data collection system with the company’s quality control system (CAQ) to introduce the more economical run-time-triggered SPC inspection intervals rather than today’s purely time-based procedure
– On-line documentation and traceability of the relevant monitoring parameters
– Automatic report generator to replace some older, manually-produced performance tables
– Report all tool changes via the data collection system to provide in-depth tool consumption and tool life reports
The use of modern productivity tools allows a European manufacturer such as the Nedschroef group to produce high-quality fasteners even in countries with high labour costs. Simple cost reduction strategies are not enough. The effective utilization of all production resources available will ultimately help companies like Nedschroef achieve economic optimization.
“For example, we love to spend money to service and maintain our machinery, which in turn gives us long, trouble-free times of quality production,” explains Ron Deelen speaking of the Nedschroef philosophy. “It’s our daily job to minimize down time, pinpoint weak spots, and optimize cost. The usage of process monitors on all machines, and the transparency gained from the data collection system are our major market instruments to offer our customers attractive market prices despite high pressure on the cost side.”

Even more improvement in the future

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