Machine Building Systems Ltd.

System built jigs cut costs and speed production

This company has production and product development facilities in France and Germany, with headquarters being in Marseilles.

It manufactures helicopters for civil and military use, built in series of up to 500 units, which are then individually fitted-out to meet customer specifications.

However, this required multiple processes including welding, straightening, sandblasting and finally painting.

With the complicated, heavy assembly jigs, this also involved complex, costly and time consuming procedures to achieve maximum rigidity while maintaining a high level of tolerance accuracy.

The need for rigidity also necessitated an enclosed construction which limited working access to inside the jigs.

In some instances threshold steps were required for use by personnel, adding to costs and reducing the productive assembly time available.

As part of a reorganisation of its assembly procedures, Eurocopter adopted the Item range of construction equipment, based on an impressive range of aluminium profiles and purpose designed fastenings together with an extensive range of building accessories.

These constructions were openly accessible, permitting easy and unrestricted access for all assembly work.

In addition, pipes and hoses for compressed air tools were no longer required to be run through a jig as the hollow sections of the construction profiles can be used as conduits for power supplies.

This leads to a less cluttered assembly with the convenience of power outlets being placed exactly where required.

The modular concept of the Item equipment, which provides a high degree of production flexibility, also means that design modifications can be undertaken to assembly jigs with minimum cost and time, very often without any interruption to helicopter component production.

What has proved to be particularly impressive is that the joints of the modular assemblies withstand even the high stress riveting operations.

Whereas the previous steel framed jigs needed constant retightening of bolted joints under the same conditions.

This is achieved because of the design feature of a slight inward angle on the profile groove flanks which results in a prestressed bolted joint capable of withstanding high loads and vibration.

In addition, the precision production of the Item extruded profiles has also enabled the company to maintain the level of close tolerance manufacture required in such a safety-critical environment.
Once again, a much more difficult proposition with steel based construction.

A CD-ROM design guide on the Item range, together with resultant reduced manufacturing times, has shown an overall saving of 15% on jig costs.

This, coupled with the more efficient assembly procedures and the pre-cut subassembly profile service provided by Item, means that 25% savings have been achieved on overall production.

At the current price for aluminium profiles, there is very little if any price disadvantage compared with steel frame assemblies.

Any perceived initial extra cost of the Item build components compared to the previous steel construction is very quickly recouped by the more obvious benefits and savings in design and assembly times as well as convenience and increased production potential achieved for the workforce.

A typical example would be to compare the cost of marking out, drilling and tapping an M8 hole in a steel frame with the 36p cost of a steel T-slot nut to suit the aluminium extrusion.

This can be inserted in seconds and relocated at will to suit changing requirements.

The flexibility of the design principle has also led to a more creative approach to other production machinery, using Item to create solutions that would not have been possible using steel based constructions.