Tailor-made solution ups speed and reliability

09 January 2009

Accuracy and speed were the essential requirements for a processing line at a window and door manufacturer. MKM International joined forces with NUM to custom build an appropriate solution.

Both robot machine heads on MKM's new aluminium processing line are controlled by the Axium CNC kernel
Both robot machine heads on MKM's new aluminium processing line are controlled by the Axium CNC kernel

A window and door manufacturer says it has increased production speed and eliminated human error on a singe-stage processing line for aluminium profiles. MKM International, special-purpose machinery builder, engineered the integrated single-stage processing line, with customisations to a standard CNC controller.

The automated end-to-end machining solution replaces an old multi-stage, semi-manual production process. Dual five-axis robot heads machine aluminium profiles of up to 9m long, on six sides and in a single pass. The new line is combined with bar code identification of materials.

An Axium CNC platform from NUM, controls the entire machining centre, including the 10 motion axes on the robot heads plus various sensors and actuators.

The control cabinet for the aluminium machining line, housing the Axium CNC kernel, drives and I/O
The control cabinet for the aluminium machining line, housing the Axium CNC kernel, drives and I/O

The manufacturer said it chose the Axium platform for its processing power and because NUM was willing to work with MKM on the control system and customise the CNC controller to optimise performance.

One modification is the development of an interface to a harmonic drive motor, which combines a hollow shaft servomotor with backlash-free gearing. The harmonic drive is exploited on MKM's 5-axis robot heads, and is claimed to provide the machine tool with a higher range of performance, fidelity of motion, and compactness compared with alternative approaches such as belts or planetary gearboxes. The resulting compactness of the robot head allows it to make very tight movements, while the stiffness of the system is designed to ensure that precision and accuracy is high.

The second major modification, again driven by a need for a compact solution, was the integration of a specialised third-party spindle motor with NUM's digital drive and designed-for-purpose high-speed bus.

A view of the human-machine interface developed for MKM's new aluminium profiling centre, using NUM's ActiveNC tool
A view of the human-machine interface developed for MKM's new aluminium profiling centre, using NUM's ActiveNC tool

When MKM first started discussions with the customer to specify the new type of machine, the original concept was for a single robot machining head and a 'flip over' work holder, allowing the head to machine all the faces of the profiles in two steps. However, as MKM gained knowledge of the process, they saw that providing two robot heads could increase productivity and precision.

NUM is MKM's CNC technology partner and the two companies have co-operated together on numerous special-purpose machine projects. After discussing the new aluminium processing concept, the parties worked out a way of controlling both heads using a single Axium CNC controller, as well as agreeing to modify the motor interfaces to optimise machining performance.

Manager of MKN International, Michael Koehler praised the support MKM received from NUM, saying: ‘NUM helps us compete with the largest machine tool builders, even though our products are often made in single or small volumes.


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