The world's largest builder of double-decker bus bodies is making full use of the power and flexibility of Radan's latest CADCAM software to design and manufacture one of the most advanced ranges of single and double decker vehicles ever built. It has no fewer than 56 workstations running Radan products.

Since becoming part of the automotive engineering specialist Mayflower Corporation in 1995, the Scottish based Walter Alexander has made a complete review of its products. This has resulted in the launch of the ALX range of three single and two double decker low-floor all-aluminium body structures.

The company, which employs 900 people at its Falkirk factory, builds around 20 bodies a week onto customer-supplied chassis. These come from its sister company Dennis as well as from Mercedes-Benz, Volvo, DAF and Man. Alexander was the first to introduce aluminium bodies to the bus industry in the 1960s.


As well as finished buses and coaches, the Falkirk factory also manufactures body kits for shipment to its Belfast assembly plant and to factories in the Far East. It has been exporting buses, either fully built or in kit form for local assembly, for over 20 years and these continue to account for a significant proportion of sales. A recent joint venture agreement with Thomas of North Carolina has widened this activity to the USA. Initially complete buses will be provided with the intention of supplying kits in the near future.

All five new bodies in the ALX range have been designed using New Radesign and New Radraft software, as are the many variants of the designs for customers wanting changes in height or length or in position of door ways, size of seats and windows and so on.

Radan software also plays a big part in generating the data needed to create the part programmes used to machine the mainly-aluminium body components and panels. These include punched sheet metal parts, programmed using Radpunch and New Radbend, as well as the extruded sections which form the structural body components.

Radan's involvement with Alexander began five years ago when Radpunch and Radbend were purchased for programming two Amada Pega CNC turret punching machines. Not only has the use of CNC machines grown since then but so has the application of Radan to cover the complete task of body design and detail drafting.

Today the company's 56 workstations all run Radan software; 34 stations are used for design and drafting in the engineering department in Falkirk, three are in the CNC programming office on the shop floor, there are five in the company's assembly plant in Belfast and six in a satellite design office which has been set up at Leyland in Lancashire. There are a further 8 workstations at the vehicle panel manufacturer Mayflower Vehicle System (MVS) in Coventry.

All the workstations in the engineering department - which has separate design groups for single decker, double decker and prototype products - are networked together and to the outside world. As well as a local link with the CNC programming office, there are ISDN links to Belfast and Leyland and to Radan's offices in Bath, Cheadle Hulme and nearby Stirling.

Three workstations in the Falkirk engineering department runs Radan's latest version of New Radesign. This is a fully integrated product which allows designers to create 3D solid models of complete bodies and sub-assemblies and then have the detail drawings automatically created from these.

There is automatic two-way data exchange between the solid models and the detail drawings. Any changes to a design will result in a modified assembly or detail drawing, with a new set of updated drawings generated from the approved design. Data for machine programming is also then based on this design.

This integration gives assurances that when individual features such as fixing holes are designed into one component there will be corresponding features in any mating component. Also with any deletion or repositioning of a feature on one part all the other affected parts are also modified.
As senior design engineer Richard Murdoch puts it `We don't want the 2D part drawing changed without a corresponding change made to the 3D model. Using New Radesign and New Radraft we can drive all the changes from the design model. The aim is to have all the parts in one directory and be made from the same design data.'

This new level of integrity has contributed to improvements in accuracy and speed of body assembly. Prior to investment in CADCAM and in CNC machines for punching, milling and drilling, these operations relied heavily on the use of bench drills, jigs and fixtures and hand fitting skills during body assembly.

Today the integration of the design to manufacture process, from CAD design to CNC machining, provides a level of accuracy, repeatability and freedom from error that has seen the elimination of any need for these older methods. As a result bodies are being assembled more quickly and using less parts.

With the ALX bus bodies the numbers of parts needed in their construction has come down typically by 20 per cent compared to previous models. The time taken to build a body has also reduced dramatically so that it now takes approximately half the time to build the ALX 200 single decker compared to its predecessor.

That the use of CADCAM at Alexander began on the shop floor, for programming the Amada machines, has been a factor in its successful integration. With expansion from machine programming, into 2D design and drafting and now to 3D solid modelling, the needs of component manufacture has always been a priority.


Data generated by Radan during design is currently used to programme three Amada and one Safan CNC turret punching machines. This programming is carried out using Radpunch and New Radbend which run on the two workstations in the programming office.

Similar data is also used to programme four Unisign 4-axis CNC vertical machining centres used for milling and drilling cut-outs, slots and holes in aluminium extrusions up to 9-metres long. Radan data can be passed electronically to the Edgecam system that has been purchased to programme these machines.

Big benefits are being gained by Alexander as it continues to develop its use of CADCAM and CNC into an integrated design and manufacturing system. The company says that; `Production facilities in Falkirk and Belfast enable the company to retain leadership in applying modern manufacturing thinking to the traditional craft of body building.'

Radan is playing a key part in that thinking.