Ultra-efficient lightweight design
 |
|
MuCell reduces the component weight by ten percent. |
SuK Kunstofftechnik GmbH in Kierspe produces around 30 million housing parts each year for door locks, which are mainly found in BMW and Daimler models, but also in VW, Ford and PSA. The platform strategy of the automotive groups causes the volumes of individual components to rise, presenting suppliers with new challenges in certain areas: they have to combine excellent product quality with production that meets the highest standards of efficiency and availability.
Every day, 400 pallets packed with high quality plastic parts leave the plant. In 2007 Martin Witulski purchased the plastics processing firm Schütrumpf & Kückelhaus (founded in 1973), whereupon he renamed it SuK and embarked on a consistent path of growth. After several expansions, a completely new and significantly larger plant was acquired in Kierspe at the end of 2010. The next major phase of expansion is planned for the coming year. Even in 2009, when many processing businesses reported falling sales, SuK grew by more than 30 percent. The company achieved turnover of 21.3 million euros in the last financial year with 133 employees. SuK has focused on technologically sophisticated parts from the outset. As processes are continuously optimised, potential efficiencies are identified and quality is enhanced. "There is no future in simple parts in Germany as a location for industry. We have to specialise here," believes Managing Director Witulski. The door lock components are quite clearly one of the company's specialities. Another speciality is multi-component parts, which are produced for customers in the automotive, electronics and plant engineering sectors.
The plant has 52 injection moulding machines. Five of them fully utilised around the clock, seven days a week, producing lock components for BMW and Daimler. SuK customers are leading manufacturers of automotive lock systems. SuK has been an integral part of the BMW and Daimler project since 2011. Kierspe developed the pre-series moulds, and was heavily involved in optimising the design and processes before series production commenced in April 2014.
Lighter yet dimensionally constant
 |
|
From left to right: Managing Director Martin Witulski, Production Manager Sven Wieland, Technical Manager Rainer Heller, Christof Born from ENGEL Deutschland, Commercial Manager Gabriele Taferner and Production Manager Kyriakos Schoinas. |
In terms of product development, the challenge was to reduce component weight compared to previous models while further reducing unit costs. The weight had to be reduced by means of MuCell. "Even in earlier roles I was developing MuCell processes for automotive customers”, says Witulski. At that time we were the first in Germany to get a MuCell system from Trexel." Today, SuK buys the production cells as a complete package from ENGEL, including tailor-made automation solutions.
Each lock module consists of three individual parts: the 'housing', the inner cover and the external cover. All three parts are geometrically complex, although the inner and outer lock covers are particularly demanding, as this is where the mandrels and the bushings sit that are required for mounting the door lock. Let's take the example of Daimler. Two step mandrels, one large and one small, are inserted into the mould and overmoulded with PBT in the MuCell process. The manufacturing cell for this comprises an ENGEL victory 180 injection moulding machine, a 2+2-cavity mould – in which two parts are formed for the left and right door in parallel –, two ENGEL viper robots – sizes 6 and 40 – and an automatic box changing system. A fully automated process is the precondition for highly efficient series production. For each shot, the smaller ENGEL viper 6 positions four small and four large step mandrels on the lay plate. Here the large ENGEL viper 40 picks up the entire set, places the metal inserts in the cavities and takes the four finished parts. The quality of finished parts is also checked as part of the ongoing process. There are sensors in the gripper that monitor the end of the flow path of the component.
Saving valuable seconds
 |
|
Barrier-free access to the mould area makes manual intervention easier. |
Automation is one key to the high efficiency of the process; reproducible component quality is another. Foam injection moulding ensures that even tight areas and undercuts are reliably filled. Moreover, the cooled components do not show any sink marks or warpage. "Dimensional stability is required for automated assembly," explains Production Manager Sven Wieland. "Another point is even more important, however. If the parts are not a perfect fit, this can result in unwelcome noises that are unacceptable these days."
Last but not least, the precision of the injection moulding machine's clamping unit also contributes to high reproducibility. However, the decision to opt for a tie-bar-less ENGEL victory machine was taken for quite different reasons. "Tie-bar-less technology has enabled us to use a significantly smaller machine and thereby keep our investment and operating costs low," reports Rainer Heller, technical manager at SuK. The automation also benefits from barrier-free access to the closing unit.
"The fact that the robot can access the mould area from the side shortens the cycle time by 2 to 3 seconds," according to Wieland. "If we have to plan a contingency of two to three seconds in any new enquiry, we might not even get shortlisted."
 |
|
An ENGEL viper 40 and an ENGEL viper 6 robot working hand in hand. |
The example of door lock component production shows how many different efficiency factors have to be considered to be successful in large-scale, automotive production. "For every application we decide together with ENGEL what the ideal solution should be like”, stresses Witulski. “The fact that ENGEL is a family-run business is an advantage for us. The channels are short, and our contacts at the Hagen subsidiary have considerable scope to make decisions."
Focus on Industry 4.0
Early on, Martin Witulski started thinking about the time after his retirement from professional life to ensure longterm success. Many possibilities were evaluated, and the company was finally sold to Luxshare two years ago. Based in Dongguan, China, Luxshare focuses on cable assembly and connectors with the goal of expanding the automotive division further. "Our technological expertise is an important add-on for Luxshare," says Witulski. "For us, it is now much easier to work the very rapidly developing Chinese automotive market." SuK and Luxshare now tackle many new challenges together. Witulski has no doubt MuCell will continue to grow in importance worldwide. In terms of flexibility, SuK is happy to look beyond the confines of its own sector. "An online mail order company can supply to Berlin and the surrounding area within two hours. We want to learn that lesson. Aside from quality, speed will be decisive in terms of competitiveness in the future." Industry 4.0 should help with this in mind. "We want our customers to be able to view the status of their orders online at any time. Another project will be about monitoring our production via smartphone."
