Interconnected engineering service creates tangible added value

Customised support characterises the collaboration it had with drive specialist Kollmorgen on its new production module for the medical sector. Kollmorgen´s direct drive solution allows exact synchronicity and concentricity with maximum precision up to 2µm, and is more cost-effective.

One of the founding concepts of the service company MEquadrat AG is networked thinking and the creation of new machines and systems that meet its customers´ needs through consistency in the software used, the sophisticated mechanical and electronic components, and the associated increase in the degree of automation.

It is clear for Stefan Nyffenegger, a member of the executive management team at MEquadrat AG that the interlock between the mechanics, electronics, and software is the key to innovative products and higher productivity. “We also break new ground with our unconventional approach, as can be seen with the current project for a machine module that is designed for processing thin-walled material in the medical sector.”

The two-sided and torsion-free clamping of highly sensitive glass and aluminium tubes is a particular challenge for the production module developed and constructed in Root. The product diameter ranges from between around one millimetre to 20mm, with very thin wall thicknesses of around one-tenth of a millimetre. Cutting and joining processes are carried out on the sensitive hollow rod material. The high speed for the material clamped on both sides in the process requires absolute precision in terms of the synchronicity.

Developing the overall module in such a compact manner in accordance with the customer´s strict specifications required a highly meticulous and extremely precise drive system for the spindles in the work piece feeder mechanism and for the relevant process steps with the clamped product.

Stefan Nyffenegger highlights: “With the KBM kit motor solution from Kollmorgen we have found the perfect solution for our needs, as the product can be guided through the drive in a fluid process thanks to the large hollow shaft.”

MEquadrat already had the idea of selecting a direct drive as they were designing the drive system. Their intention was to use an existing modular design in order to meet the precision requirements and to guarantee implementation on a time and cost-efficient basis. But tt became apparent that a rotor and a stator with the full functionality of a servo drive should be used as a result of the compact packing density and complexity of this assembly.

The company teamed up with Kollmorgen and decisions at the implementation stage for this project were made very quickly. The synchronicity however remained a problem. Key Account Manager at Kollmorgen, Martin Zimmermann, and his colleagues provided their full support: “When MEquadrat only requested the rotor and the stator for the feeder unit in this project, we knew that a mechatronics engineer would need to focus on the motor in greater detail. You have to have confidence when trying new things like in this project, which requires mutual and absolute trust.”

Aside from the time pressure and the extreme requirements related to precision in the functional specifications, there was another additional crucial challenge related to the medical technology: “The drive solution must be free from abrasion and lubricant, and we weren´t able to carry out any experiments at the implementation and commissioning stages for the mechanics and software”, says Nyffenegger. All of the components provided in this machine module therefore had to be tested and shown to be absolutely reliable.

The interaction of the direct drive with AKD Drives and the controllers from National Instruments (NI) enables extremely precise positioning. The cycle times in the current regulator are around 670ns, and are just 62.5µs in the speed regulator. Nyffenegger stresses: “This allows us to achieve optimum synchronicity in line with these high dynamic requirements. As such this drive combination represents the optimum price-performance ratio.”

A crucial thing here that the two synchronised axes achieve extremely precise concentricity of 2µm, Nyffenegger adds: “We´re talking about accuracy ranges that are otherwise only seen in spindle axes in large production plants.”

‘AKM’ drive with single-cable solution and SFD feedback were selected for the linear axis in the machine design. The components now just needed to be put together and everything fitted perfectly.

The resolver method as a single-cable solution is one of the drive expert´s specialties aimed at making optimum use of the robustness of the resolver. Nyffenegger stresses: “The wiring required in the AKM motor is also minimal here as a result. Highly compact cable carriers can also be used which really are sensational for tight spaces”.

AKD one-cable package (controller & servo motor) is used for the components in the liner drive for the feeder mechanism. The major benefit with this is that the system comes from one source. Nyffenegger emphasises: “This way I don´t need to worry about any screw fittings or pins that do not fit. We just had to plug it in and get started, which also made the implementation time very short.”

Martin Zimmermann adds: “Our specific part in the project related in particular to our comprehensive recommendation as to how the customer can achieve its objective in an optimised and most cost-effective manner.”

One thing is clear for Stefan Nyffenegger: “We were also able to discuss ideas directly with the Kollmorgen product developers, and put forward our requests related to the shaft and hub connections. Sitting down at a table and discussing in order to find solutions, or discussing the design details on the phone, provided us with the assurance that everything would work correctly with the drive, and that we would be able to get things right the first time on this project.”

The design phase alone for the machine took just three months, which he believes is extremely efficient. “The Kollmorgen part such as the installation of the axes and connection of the motor with full configuration and testing was completed within two days. This drive concept which was really customised to our needs worked out brilliantly for us. It fulfilled its objective, worked straight away, and met all of the requirements that we set ourselves for our customer.”

Benefits of Use:

• High flexibility of the coordinated components.
• Integrated hollow shaft for special application predestines integration of a clamping system which maintains its clamping force even at 3000rpm.
• Direct drive without any play or redundant mechanical parts allows exact synchronisation and concentricity with the utmost precision up to 2µm and is thereby hard-wearing.
• EtherCAT on board for simple implementation and integration (hardware and software) - also in LabVIEW.
• Comprehensive support from Kollmorgen from design through execution to commissioning.
• Easy conversion to different diameters.
• High process stability when increasing the degree of automation, achieving higher productivity levels, leading in turn to increased profitability.