从成本管家到杰出的服务供应商

在诸如山高这样的刀具制造商的支持下，位于Dingolfing的BMW 2/1工厂的内部刀具技术部门已经有了长足的发展

    就像山高的钻削系统Crownloc和BMW Dingolfing那样，一个刀具制造商的发展目标和他们的客户的需求如此地协调一致，这是很少见的。 Without knowing about the problems confronting the Bavarian showpiece company, the Swedes developed a drill system which leaves nothing to be desired, at least with regard to the specific task in hand.  Pure coincidence?  Hardly. Seco is one of those companies which gladly take up the challenges inspired by the market and try to convert them into profitable products; and CrownLoc has proved to be a remarkable success for the Swedes.

When Robert Pfaffenberger took on responsibility for the Department of Tool Technology, Procurement, Tasking and Process Management at the BMW Dingolfing plant just two years ago, the enthusiasm of the staff was somewhat restrained. This had nothing to do with any technical or human failings on the part of the new boss, but rather with his former position as Manager of the Steering link-Transfer Line; in that capacity he had presented the tool technologists and manufacturing methods experts of the already stressed department with many a knotty problem. But now the somewhat dubious reaction has absolutely disappeared, because whatever fears may have arisen then, both Department and boss have in the interim blended into a success-oriented and successful team - and nothing succeeds in bringing people together than success. The tool technology specialists have developed from being what might have been regarded simply as a costs factor into respected service providers for the Mechanical Manufacturing Division. When challenges arise (and as Pfaffenberger says, "We don't have problems - only challenges"), the experts bring in the suppliers with their own applications technicians, and so come up with the answer even faster. This approach has also made it possible to avoid having a dedicated tool management arrangement, because it has proved feasible for the tool costs for this specific component to be cut from 3.60 to 1.78 DM. "Our client - the Manufacturing Division - would nowadays react against internal tool technologists or the tool maintenance unit being replaced by a tool manager", says Pfaffenberger, and "despite the obvious disadvantage of high overheads, our efficiency has enabled us to show that we have a costs advantage over a tool manager." This is due not least to the high standards of knowledge and ability of the staff. 
One of these specialists is Jürgen Halwax, who within the Tool Technology Department is an acknowledged specialist on the chassis. His main tasks include, among others, the ongoing optimisation of all the processes which determine the cycle times. What this means is, if the processing and machining times can be reduced on machine A then virtually in the same breath the task arises of reducing the time on machine B, which in turn makes it possible to reduce the cycle times on transfer line C. And once all that has been done, everything starts all over again.
 
This would not be possible without some assistance from outside specialists, who as a rule are drawn from the ranks of the tool manufacturers. As far as Jürgen Halwax is concerned, this support is very important, because "with the one hundred and more machines which I have to look after it is impossible to find the right, or at least the best, solution for all the challenges which come up." In the course of time, a handful of manufacturers has crystallised from the large number of possible suppliers, whose products are equally as impressive as their service. As Jürgen Halwax says, "we work with a small and very restricted group among tool suppliers. They are those people who are above average not only when it comes to the product side of things, but also with regard to service." And among them are Seco Tools.
To take just one example: Axle steering links are safety-determinant components, with a tensile strength in excess of 1100 N/mm2, made of 38 MnSiVS5. This is a material which is not exactly one of the easiest to machine. And at Dingolfing, these axle steering links have up to now (and will be for the foreseeable future) be machined on a Mauser transfer line which is not exactly new; in fact, it has been considerably converted. One of the weaknesses which this has incurred involves two drilling operations; for one of these, with the larger diameter (17.2 mm drill hole for the ABS sensor), only 700 holes could be drilled with a carbide metal drill, a figure which is simply an irritation, especially since after every regrinding operation the drills had to be measured and adjusted in the tool setting, which traditionally tends to be the bottleneck in every larger machining operation.
Jurgen Halwax describes the problems involved with the drill holes like this: "The steering links are forged. That means that the blanks differ in contours and dimensions, and are also slightly spherical on the surfaces which are to be machined. This leads to the tool being forced away from the ideal position when it engages. Because solid carbide tools represent an inherently rigid system, this is a burden which leads to increased wear." No wonder, then, that Jürgen Halwax's ears pricked up as soon as he heard of a drilling tool of which the shaft is made of steel, so making it considerably less susceptible to this type of stress, and the drill crown of which can be changed rapidly and without any elaborate adjustment while still in the machine.
Right from the very first tests with the Seco CrownLoc, the results were convincing. As Jürgen Halwax puts it: "Without changing anything with regard to the cutting data, we achieved clear improvements at a single stroke. And as well as that, the numbers also went up, in small diameters from 1,200 to 2,800, and for large diameters from 700 to 2,600 units." The conclusions that can be drawn from this are clear, when more than 850,000 axle steering links are being produced every year.
Hermann Lepschy, Team Leader for the Automobile Industry South section in the Seco External Service Division, expresses his views: "With the CrownLoc we are offering a system which saves the customer all the handling and logistics associated with regrinding. As well as the substantial gains in volumes, this was definitely the reason why we were able to win through at BMW against a well-established competitor. With a solid carbide drill which achieves savings of the order of only 5-10 percent, Seco would definitely not have been in the running for BMW."

The cutting data vary; with a diameter of 13.6 mm, 70 m/min at 1590 min-1 f = 0.16, with a diameter of 17.2, 60 m/min at 1060 min-1, and 0.3 mm feed. While it would have been entirely possible to have activated some additional reserves in this situation, according to Robert Pfaffenberger, "it would make no sense to stretch the limit ranges of the tool to their utmost, because the machining operations are not determined by cycle times, and in this case it is the advantage gained in downtime which is the determinant factor."
But this is still not enough.  Robert Pfaffenberger puts it like this: "The whole business of regrinding and readjustment during tool changes is done away with, which means total savings of 32 percent with small drill holes and 41 percent for large ones." And there's more still:  "Calculated over the year, just on 80 hours are involved with changing and adjusting the drills, time which can now be saved thanks to using the CrownLoc drill."  Something else which should be borne in mind is that "thanks to the enormous improvement in downtime, the useful service life of the transfer line has increased by the order of just over two percent.  It goes without saying that, given this situation, the higher tool procurement costs are no longer the determinant factor.  That's why the pure tool costs are only of peripheral interest to me.  The real factor is the cost per component."
Another factor which counts here is that a prime aim at Dingolfing is to make use solely of tools which no longer need any adjustment effort. Gabi Stoffels-Lunkenheimer, the Seco Product Management member responsible for drills, puts it like this: "Early on in the development of the tool one of the most important aims was established as being the elimination of regrinding costs." Measurements taken internally at BMW have also revealed that the changeover precision values indicated by Seco are even improved in actual practice.
All that is in fact changed, then, is the drill crown, while the body of the tool remains in use through a large number of crown changes. Jürgen Halwax says: "By using Seco drills we keep gaining more and more experience. So far there have been no signs of wear apparent on the body, and that means we have still not had to replace one single shaft because of wear. Our research has shown that the changeover mode with Seco is at the present time far and away the most stable available, as well as being designed in such a way that the drill head can be replaced while it still in the machine without the basic body having to be removed from the device."
Claes Moller, Manager of the Development Department in the Seco Drilling Centre at Norrk?ping, points out that: "The basic bodies are provided in gradations of one millimetre, while the crown itself can be provided in gradations of one hundredth of a millimetre; that means that with one basic body 100 different diameters can be covered." Gabi Stoffels-Lunkenheimer adds some details: "As well as that, there are three different geometries to be selected per diameter, and that in turn means that 300 different crowns can be supplied per basic body."
The use of CrownLoc drills has in the interim also been the subject of trials at BMW at other machining stages. Robert Pfaffenberger is certain that the goal they have set themselves, of reducing tooling costs by 10 percent, can only be achieved with innovative tool concepts, and it can be achieved even though the price per tool may have perceptibly increased. This apparent contradiction is explained by the enormous boost in performance which can be achieved with modern tool technology.

The experience gained with the Service Team from Seco has been entirely positive, and Robert Pfaffenberger attributes this in particular to the vast range of experience available from Seco personnel. "The technicians from Seco are partners with whom we can search for solutions together, and who can virtually always deliver the improvements they have promised."

About Dingolfing
The Dingolfing facility, with some 21,000 personnel, is the largest production plant within the BMW Group. As well as vehicles from the 3, 5, 7 and 8 Series, the plant also manufactures chassis units for production at other BMW plants. BMW Dingolfing has so far won no less than five internationally contested awards, and in 1992 the independent "Engine and Chassis" Division, part of Plant 2.1, won first place in the German national "Factory of the Year" contest.

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