System solutions in workpiece clamping technology

23 / 11 / 2021

When it comes to thermoforming in industrial plastics processing, the name Illig comes up immediately. Because in thermoforming, and especially in packaging technology, the 750-employee Illig Maschinenbau GmbH & Co. KG, D-74081 Heilbronn, is one of the world's leading manufacturers. With the machines and tools as well as peripheral equipment from Heilbronn, customers in 80 countries around the world process thermoplastics and produce sophisticated to high-precision moulded parts from them. The origins of the company go back to a repair workshop founded by Adolf Illig in his parents' garage in 1946. Just 10 years later, the development of a vacuum forming machine laid the foundation for today's technology company. This was followed by automatic vacuum forming machines for the production of lids directly from the printed film roll, and further innovations were added, such as automatic compressed air high-speed machines with integrated additional functions (punching, etc.). In the following years, groundbreaking developments such as the RDM series, which as packaging machines integrate the forming of containers as well as the dosed filling of the same and ultimately the sealing, underlined the continuing high innovative ability of the constantly growing company. Impressive examples include in-mould labelling production lines for margarine cups made of PP (polypropylene) or fully aseptic forming, filling and sealing machines as well as automatic reelers and bottle formers.

Important success factor: in-house production!

Other elementary building blocks for the company's success are production with a very high degree of in-house manufacturing and uncompromising quality as well as efficient service; whereby production plays a decisive role, as Volker Marquardt, Head of Production, explains: "Although the basic machines and many peripheral components are largely standardised, almost every order is a customised solution. Consequently, our focus is on small-part production from batch size 1 and batches of up to about 200 pieces. This applies to small parts with a length of 3 mm as well as to large parts with a length of 2,500 mm. We work highly flexible and strictly demand-oriented in 2 to 3 shifts and have therefore divided the mechanical parts production into the production units (FE) turning, milling, sheet metal/welding, large parts machining and QA." The trend towards function-integrated components is also leading to an increased shift of workpieces towards milled parts at Illig, which is why capacity problems arose there on the one hand and replacement purchases were pending on the other. In order to get a grip on the variety of machines and controls as well as clamping devices and special clamping fixtures that had grown over the years, Volker Marquardt and Matthias Senghaas, foremen of production unit 3, decided to get their act together and look for an integrated system solution. This consequently included the machine concept with workpiece magazine for automatic loading as well as setup parallel to machining time and thus also necessarily the workpiece clamping technology. The evaluation of CNC machining centres and workpiece clamping technology turned out to be quite complex, not least because of the high requirements due to the range of parts and the milling performance required for this, as well as flexibility, accessibility, reduction of set-up times, openness for new machining/milling strategies or also clamping technology handling and long-term accuracy. 

Important success factor in manufacturing: System-capable workpiece clamping technology

Matthias Senghaas commented: "The intensive tinkering with the system capability has paid off. Because instead of two CNC 5-axis machining centres coupled with a workpiece magazine as initially planned, we ultimately only had to procure one CNC machining centre coupled with a larger workpiece magazine. Namely, because in connection with the highly developed and, above all, absolutely system-capable workpiece clamping technology from Gressel, a far-reaching flexibility of use, utilisation and set-up could be achieved, which was not initially recognisable to us as a consequence. We were not convinced by the clamping technology on offer until we became aware of Gressel clamping technology at an in-house exhibition. The well thought-out and truly system-compatible clamping systems, plus the large variety of exchangeable components and clamping jaws, as well as the simple clamping force adjustment via the sleeve and the fast opening/closing movement with only 160┬░ angular opening/closing travel, convinced us just as much as the precise and, at the same time, weight-optimised design." In order to be on the safe side, the machine operators of the 20-man milling department were fully involved in the decision-making process from the very beginning, e.g. by having one and the same team, consisting of programmer, operator and foreman, carry out extensive function and milling tests with all delivery aspirants in order to obtain reliable findings. In the end, the decision was made in favour of the workpiece clamping technology from Switzerland, namely from Gressel AG, CH-8355 Aadorf.

A workpiece clamping system for all applications

The responsible Gressel distribution engineer for Germany South, Frank Scheurer, on the special "sporting" challenges of this long-term project: "We have 32 pallets with 630 x 630 mm in the system here. Small parts have to be clamped on them individually or several times, and of course comparatively large, heavy workpieces up to a maximum total pallet weight of 550 kg. The clear requirement was to be able to change over clamping fixtures in 5 to 6 minutes during machining, because the shortest machining times are 6 minutes, while the longest times can be 15 times that. The milling tests were all carried out on recurring workpieces, and it quickly became apparent that, compared to the past, the handling was much simpler, safer and faster and, above all, the machining accessibility was greatly improved compared to the standard and special clamping devices offered by competitors and those used in the past. Standardised clamping technology even for bulky parts made of different materials, fast and reliable clamping, trouble-free clamping due to closed spindle, few manual operations during changeover, no more time-consuming clamping of specially contoured parts, compatible accessories such as base body or tie rod extensions, in order to be able to efficiently machine all workpieces possible on the CNC machining centre, in terms of working/travel paths and collision interference circles, with just one clamping system - we were and are able to meet all of Illig's requirements with our system-capable clamping technology solutions and bring about extensive standardisation. "

50% increase in productivity also thanks to system-capable workpiece clamping technology

The test phase towards the end of 2013 was followed by a continuous expansion and upgrading phase, which brought further deliveries of both basic systems and clamping jaws and accessories every few months. Focused on the three basic clamping systems double, single and centric clamping vice duogrip, 5-axis power clamping grepos 5X and 4-fold clamping tower (equipped with double clamping duogrip), Gressel supplied three different system jaws (stepped jaw with grip 3mm, 5mm and 8mm) for all clamping systems in order to be able to carry out both unfinished and finished part machining on all clamping systems and to only have to change the jaws for this. Including the aforementioned clamping towers, 32 + 4, i.e. a total of 36 pallets of equipment, have been set up today, so that the flexible manufacturing cell can work fully automatically in the 3rd shift from the magazine. This is not the only way that the wishes of the demanding customer Illig have been "more than fulfilled", as Volker Marquardt appreciatively expressed: "With the pallets completely equipped with flexible clamping technology and, further, the multiple clamping towers, we cover more than 90% of our parts spectrum and can produce highly flexibly into the night. With the selected clamping systems duogrip 125 and the 5-axis power clamp grepos 5X, we have different sizes in the system, but this does not matter at all because of the possibility of free exchange of the compatible jaw systems among each other. In fact, all jaws can be used everywhere and we get by with the range of accessories to such an extent that we hardly need any special solutions. Today, we even go so far as to accept 5 mm material allowance on certain workpieces, because we can then machine the parts completely and with high precision on five sides without interruption and, above all, without retooling. With the multiple clamps we also increase the machine utilisation, which is why the machine-clamping technology combination realised here is our model for all future new acquisitions. Viewed as a whole, the consistent implementation of the new production concept has resulted in an enormous increase in productivity of around 50% compared to the past and can therefore rightly be regarded as a success story".

The picture shows the workpiece magazine of the flexible manufacturing system in production unit 3 at Maschinenfabrik Illig GmbH & Co. KG.

Here you can see some of the standard components from the Gressel AG clamping technology range and accessories that are used in full at Illig GmbH & Co. KG: adapter plates, tie rod extensions, standard jaws, grip jaws.

Here you can see the 5-axis power clamping vice grepos 5X with special interchangeable jaws for clamping round material, from which a cubic milled part is produced highly efficiently in one work process, whereas this used to be produced in multi-stage turning/milling operations.

The 5-axis power clamp grepos 5X with prepared adapter plate for clamping a raw casting that is completely machined on 5 sides in one clamping.

The picture shows two parallel 5-axis power clamps grepos 5X with extended base bodies as well as extended tie rods, mounted on a pallet as a special clamping unit for clamping large aluminium plates.        

Here you can see a 4-fold clamping tower on a pallet, equipped with four duogrip type double clamps for clamping a total of eight workpieces.

From right to left Ahmet Ceylan, programmer and operator of the Flexible Milling System, Volker Marquardt, Head of Production, and Matthias Senghaas, Foreman Production Unit 3, all from Maschinenfabrik Illig GmbH & Co. KG, and on the far left Frank Scheurer, Distribution Engineer Germany South at Gressel AG and responsible for the customer Illig Maschinenbau GmbH & Co. KG.

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