A compact automation is a mechatronic system that performs a whole series of consecutive production steps autonomously. ‘Compact’ refers to the small dimensions, in the millimetre and centimetre range, of the products to be processed. Designing and constructing such systems is one of the core activities of the Austrian machine manufacturer, STIWA. Its modular LTM-CI system has been optimised for small parts assembly. Linear and rotating micromotors from Faulhaber perform key tasks in these systems.
The valve consists of just a few components, and is only eight millimetres long. It is part of the antilock braking system of a large automotive supplier, and is required in seven-digit quantities every year. Production must run with a takt time of half a second in order to cope with this volume.
The individual parts are first fed from storage containers, separated using a shaker, and correctly positioned on a conveyor system ready for the first manufacturing step. The components are then transported to the respective station, where delicate grippers pick them up and join them together, or process them in some other way.
The machine that executes these complex movements in precise synchronisation is a compact automation of the LTM-CI series from STIWA. It is designed for products with a spatial diagonal of up to 30 millimetres, and is itself the result of drastic miniaturisation. Roland Schiermayr, departmental head of Automation Research and Development, explains: “A customer in the west of Austria produces dampers for a well-known furniture retailer that needs millions of these parts every year. The company wanted to buy a new production machine. The existing machine was 10 metres long – for the production of small components measuring just a few centimetres in length, and this was simply too much.”
The result of the development phase was an automation platform which, depending on the configuration and equipment fitted, has a length of 3 to 4 metres. A rigidly linked transport system forms the basis. “We can integrate up to 22 function modules, each measuring 90 millimetres in width, for different work steps,” explains Christian Mersnik, who was involved in development from day one. “These functions include, for example, pick-and-place laser welding with up to five degrees of freedom, screw insertion, press-in operations, labelling, and testing and measuring processes.”
Customers appreciate the uniform, smooth movements without impacts or vibration, which guarantee a stable process. With the LTM-CI, the cycle times have been reduced to just half a second, which brings with it a significant leap in productivity. The drives used in the actuators inside the machine make a major contribution to the smooth movement and the high speed. In earlier generations, electric motors of a completely different size class were used; for the compact automation, the developers discovered the Faulhaber linear motor, which now play a key role. It performs its task at up to 20 points in the system, including stopper units and grippers. One particular strength is its extremely high speed. This drive also delivers an enormous thrust: At just 12,5 mm wide and 19,1 mm high, it produces a continuous force of 3,6 Newtons. “When operating at full power, it can even manage 10,7 Newtons,” explains Schiermayr. “There is no other small linear motor with this power density available anywhere in the world.”
The engineers from STIWA heap equal praise on the brushless motor of the BX4 2250 series. In the portal handling of the compact automation, this motor drives the swivel units that move the tools or components to a specific position. When selecting a suitable drive, in addition to the typical strengths of the Faulhaber motor, the availability of an accessory part was also an important factor. Mersnik explains: “At this point in the system, we require an extremely high level of precision and repeatability. This is why it was important that Faulhaber was able to deliver this motor with a matching multiturn absolute encoder. The signals from this encoder are necessary to achieve the high production quality and for quality assurance.”
For STIWA, it is the longevity and long-term reliability of all components that make the real difference. This is because the company guarantees its compact automation customers fault-free operation of no less than 60 million strokes. The motors from Faulhaber have shown that they can meet extreme requirements. They help us to achieve our own peak values with minimum space requirements and the shortest cycle times,” concludes Schiermayr.
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