Focus on handling and raw material supply
Progressive automation solutions for a modern injection moulding processor
Redaction: Klaus Vollrath

Weidmann produces sophisticated multi-component composite injection-moulded parts for the automotive sector at the new location in Treuen. (Photo: K. Vollrath)

Production of sophisticated injection-moulded parts for the automotive sector commenced in the new plant of Weidmann Plastics Technology in Treuen just six months after the first sod was turned in November 2004. Today 17,000 parts are being produced with 12 injection moulding machines per day. An important partner for the automation Wittmann Kunststoffgeräte GmbH in Vienna.

Josef Bauer, Chairman of the Board of Weidmann Plastics Technology, Franziska Tschudi, Chairman of the Board of WICOR Holding AG, Ulrich Heide, Director of Weidmann Plastics Technology Deutschland AG and Works Manager Hans-Eberhard Jung (from the right) at the official opening on 9. 6. 2005 (Photo: K. Vollrath)

For automotive suppliers even miracles are not allowed to take much time: “Less than six months after the turning of the first sod in June 2004 we were already producing the first components”, remembers Hans-Eberhard Jung, Works Manager of the new injection moulding plant of Weidmann Plastics Technology (Germany) AG in Treuen. Series production of medium-sized components for the fresh air management of the 1 and the 3 series BMWs commenced by the middle of November. Production of components for the VW Passat has since commenced as well and additional components for Peugeot and Mercedes have already been firmly booked for the coming years. The twelve manufacturing cells currently built around the Krauss-Maffei injection moulding machines, the automation of which was largely provided by Wittmann, meanwhile produce as many as 17,000 parts per day. The products are highly sophisticated, many of the parts are manufactured using a 2-component process from two plastic components, while additional metallic insert components are moulded into some of them. In addition,  depending on requirement, they are also supplied with additional components such as sealing rings or foam rubber strips within the production cell. The know-how for design and configuration of these compact and highly complex fully automatic production cells, each of which produce completely finished parts per work cycle, counts among the special competencies of Weidmann Plastics.

The hall presents itself clean and neat with the injection moulding cells in formation. A removal /handling system is arranged above each of the cells (Photo: th)

View of the engine compartment of a BMW 116i. The injection-moulded parts for the fresh air management manufactured in Treuen are shown by the arrows (Photo: th)

Production start under time pressure…

“With regard to design & implementation we are under extreme time pressure. For this reason we require partners in whose competency and flexibility we can absolutely trust” Martin Eberle (Photo:th)
“Since last minute changes are part and parcel of the development of new motor car models we have to wait with the implementation in production technology as long as ever possible”, says
Martin Eberle, the Project Manager responsible for the development of production technology of the new plant. A direct consequence of this is virtually extreme time pressure in design and implementation of the production technology: Between starting shot and production start he only had five months. Since Weidmann obviously does not produce everything in-house but cooperates with suppliers in certain areas such as automation, confidence in their competence and flexibility plays a decisive role. With regard to the areas of handling, material supply and safety technology the company rely on Wittmann Kunststofftechnik AG, with which there has been close cooperation for many years. With such time pressure it is not possible to specify everything in advance but one has to be able to “count on the pals at the other end of the rope”. Not only does the installed equipment have to be highly productive, it must also be reliable enough to last at least for ten years of continuous operation around the clock even with changing materials and products without problems. Obviously the price level was compared with that of other market participants – and found to be quite acceptable. Added to this is that Wittmann proved to be extremely reliable also with regard to service.

View of the engine compartment of a BMW 116i. The injection-moulded parts for the fresh air management manufactured in Treuen are shown by the arrows (Photo: th)

Jointly accomplished in a team

View of the engine compartment of a BMW 116i. The injection-moulded parts for the fresh air management manufactured in Treuen are shown by the arrows (Photo: th)

“With such a project it is always the respective customer who decides where he wishes to define the interfaces of the cooperation”, says Werner Bürli, Managing Director of Wittmann Kunststofftechnik AG in Kaltbrunn (Switzerland). Since Weidmann handles its own mould construction and some downstream operations in-house, very close intermeshing of the work components was required. This took place in a small and therefore highly efficient team of two employees of Weidmann Plastics and 4-5 people from Wittmann who required altogether only six meetings between February and June 2004, among these two on site in Treuen. Everything else was accomplished through direct communication per telephone or e-mail. The most essential contributions of Wittmann were the gantry removal robots including basic programming and training as well as central storage, processing and feeding of the plastic resin. In addition to this the company supplied components for the robots and guardings and safety technology for the production cells among others.

Rear view of the injection moulding cell for water drain upper parts with handling unit and laterally positioned second injection unit. The detail picture shows the robot with servo-motor wrist and sprue cutters (Photo:K. Vollrath)

Quick handling for short actual times

Wittmann robots are supplied with a teachbox as standard. The colour-graphic user interface simplifies communication. This minimises operating errors and their consequences (Photo: Wittmann)

“In view of the complexity of the parts manufactured in Treuen and the quality to be guaranteed “off-tool” production is not even conceivable”, explains W. Bürli. Placing of in-moulding parts and removal as well as defined transfer of the finished injection-moulded parts are therefore performed on most stations with the help of efficient CNC-controlled gantry robots with up to  5 servo-motor axes. These systems developed by Wittmann are characterised among other things by high positioning speeds to remove the part from the mould as quickly as possible to allow for the next cycle. Great value is attached to operational safety: The efficient microprocessor control of the robots allows accurate track-guided coordination movement of all numerical axes. As a result the wide-ranging manipulators of Weidmann can be safely manoeuvred in very narrow conditions with maximum repeatability.
Special attention was also paid to the most efficient communication with the operator possible. For this reason all Wittmann robots are delivered with a teachbox as standard which has a colour-graphic user interface. This allows the user to graphically follow the process and enter commands directly in the desired position. This is based on the knowledge that operation has to be as simple as possible to minimise operating errors and their consequences. Additional advantages of the uncompromising graphic set-up are short training and programming times. Menu-guided plain text programming is also available for more experienced operators.

Ingenious raw material supply

Six of the total of nine Drymax desiccant dryers ensure a dew point below -60 °C (Photo:th)

“Up to 1,200 kg of resin must be provided for the production per hour” says W. Bürli. As a second major contribution Wittmann supplied the complete raw material logistics from the bin technology, conveyor and processing technology to the entire piping, while total conveying distances of up to 180 m have to be overcome. By way of the central conveyor and processing station arranged in the centre of the production hall up to 14 different resin flows are currently batched from hoppers and storage containers, processed and supplied to the various consumer locations. Special attention had to be paid to ensuring a constant drying process. Two DRYMAX dry air generators supply a total of nine drying hoppers of different sizes with process air, the dew point of which was lowered to -60°C. The smartflow flap present in each drying hopper regulates the air through flow rate as a function of material properties and throughput rate. This guarantees a constant drying process and prevents over-drying of the granulate. The material throughput through each drying hopper calculated on the basis of the conveying cycles also allows recognising undershooting of the dwell time specified by the material manufacturer, in this way preventing a potential source of error.

The “coupling station” allows the free linkage of supply and discharge lines for resin while electronic encoding of the connections prevents confusion (Photo: K. Vollrath)

A “coupling station” allows the user selectable connection of supply and discharge lines for resin while electronic encoding of the connections prevents confusion. A central control, which was derived from the proven robot control of Wittmann and which is characterised by similarly user-friendly graphic operator prompting, ensures coordination and control of all processes. Another essential feature of the automation concept is a networked system of four separate “line server modules”, each of which checks an independently functioning bus line on the blower station, filter and material separators. This concept makes it possible to maintain the supply intact with slightly restricted capacity even if a bus line should fail.

For further information, please contact:

Wilfried Hagn
Wittmann Kunststoffgeräte GmbH
Lichtblaustrasse 10
A-1220 Vienna, Austria
Tel. +43/1/250-39-129
Fax +43/1/259-71-70

E-mail:
Website:
 Werner Bürli
Wittmann Kunststofftechnik AG
Uznacherstr. 18
CH-8722 Kaltbrunn
Switzerland
 Tel: +41(0) 55 293 40 93
Fax: +41(0) 55 293 40 94

Short portrait: Wittmann Kunststoffgeräte GmbH
The company founded by Dr. Werner Wittmann in 1976 with head office in Vienna today operates as a global partner of the plastics industry for complete automation solutions connected with injection moulding machines. Many years of experience from the practical use of a complete program of peripheral devices from conveying, drying and dosing of the raw material and the tempering of the mould to the complex discharge handling including additional inserting, equipping or processing stations are utilised here.  An additional plus is the worldwide presence of the company with almost 50 subsidiaries in all key markets. Consequently the customer always has the same contact person from consulting to implementation and service. This also facilitates the porting across borders of applications  - an aspect which increasingly gains importance in times of global markets.

Short portrait: Weidmann Plastics Technology
Weidmann Plastics Technology, a corporate division of the WICOR Group with head office in Switzerland generated a turnover of approximately 208 million CHF in the year 2004 with 700 employees worldwide. The machine pool comprises more than 150 injection moulding machines ranging in the order of magnitude from 250 kN to 10 MN (25-1,000 tons), the processing capacity for plastics is around 8,000 tons per year. The product portfolio includes design and function series components for the automotive sector but also plastic components for medical technology, sanitary technology and sensor technology.
In the new plant in Treuen (Free State of Saxony) Weidmann will invest a total of 23 million Euro and create 140 new jobs. The cutting of the sod took place on 15 June 2004, production start was in the middle of November of the same year. At present parts for new models of BMW and Volkswagen are currently produced while additional products for Daimler Chrysler and Peugeot will be added in the year 2006.

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 Kunststoffgeräte GmbH
1220 Wien, Lichtblaustrasse 10
Tel.: 0043/1 25039-0 Fax: 0043/1 2597170
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