CNC controller boosts machine capabilities

Replacing the control system on one of its milling machines has allowed vehicle convertor Brotherwood Automobility to bring in-house a number of production jobs that were formerly subcontracted.

By retrofitting a Heidenhain four-axis TNC 370 control system to a Bridgeport Interact, knee-type milling machine, disabled vehicle convertor Brotherwood Automobility was immediately able to bring in-house a number of production jobs that were formerly subcontracted.

The upgrade has also transformed the Interact into a key machine in the company's ongoing product development strategy.

Clive Brotherwood, manufacturing manager at the world-leading vehicle conversion specialist, says the new control "has not only regenerated the production capabilities of what was a sound and reliable machine tool, but it has also created an invaluable resource for prototype production".

Explaining that the machine, which is used by 18-year-old apprentice Olly Hole, is applied "to everything and anything we can use it for", including prototype production, Clive Brotherwood points out how application of up-to-date CNC technology also enabled the company to use the Interact to bring back in-house several production jobs, and one in particular.

"Although a network of subcontractors satisfy a certain amount of our metalcutting needs, it was the steady demand for ramp catches that was part of our justification for investing in the Heidenhain system".

Produced in batches of 300, the ramp catches - which require fairly straightforward two-dimensional milling - are used in all its vehicle conversions.

In each case, Brotherwood always uses a counterbalanced, deadlock-hinged ramp - a feature that has effectively become its trademark.

Brotherwood Automobility can even list Royalty in its customer files of vehicles it has converted for the disabled throughout the world, which also includes the Volkswagen Sharan, Ford Galaxy, Seat Alhambra, Fiat Multipla, Renault Kangoo and Citroen Berlingo.

"We bought the Interact secondhand, recognising that it was a solid machine with a rigid head, and immediately decided to have it retrofitted with the TNC 370 to replace the existing Heidenhain control", continues Clive Brotherwood.

"Having wide experience of Heidenhain CNC technology, I knew the control would combine powerful functionality with a surprisingly high level of user-friendliness and so I had no hesitation in specifying it.

In addition, the choice of CNC was also influenced by the fact that Olly, who would be operating the machine, would be using similar control technology at his technical college".

The retrofit was carried out by Heidenhain's Southern England agent, Engineering Equipment Centre of Bournemouth, and managing director Gary Blanch explains how the job was very straightforward.

"We simply dewired the old control and removed the pendant", he says, "then replaced and rewired the control, and the machine was ready for action".

The TNC 370 uses plain language programming with soft key function selection.

Its QWERTY typewriter keyboard accommodates G-code and ISO input, as well as program comments and alphanumeric program names.

Important for on machine programming is the flat panel screen display which provides graphic simulation in three planes, plan view or -D presentation.

A further user aid, especially when interpolating, is that speed control in each of the machine axes accommodate higher degrees of geometric accuracy and any servo lag is overcome.

The control features advanced program generation capability with numerous canned cycles, three-dimensional simulation graphics and helical interpolation, expanded 64 program memory and background programming.

"Although it is still early days, I've found the control to be easy to use - it's very user-friendly", says Hole.

"So far, I've programmed and machined parts with no problems, including the ram catches".

Rod Brotherwood, Managing Director, points out that one reason for the company's global success and continual expansion - last year the 46 employees produced 300 vehicles - is the fact that every new conversion/model of vehicle is approached with a clean sheet of paper.

"When I'm developing a car, I never copy anything that has been done before - either by us or by our competitors", he says.

"Apart from being appealing to the eye, it is critical the conversion has to be fit for purpose - and this is where the Interact plays a key role".

A typical conversion involves a complete strip-down of the vehicle, lowering the floor, adding a new roof for increased ceiling height, reorganising the chassis and suspension, and fitting new fuel tank, hydraulics system, axle carriers, brakes, seats and seat belts, for example.

All conversions comply with Department of Transport Type Approval, and in most cases, the only features not altered are the engine, lights and wheels.

"With anything up to 300 parts for each conversion, when we are developing a new vehicle each part is prototyped in our light machining area.

The Interact is critical here, because we are often 'tweaking' components to arrive at the optimum design.

Therefore, having a user-friendly, powerful milling capability is essential to that process.

Of course, the machine is also used in a production sense, since we produce these parts in batches of 20 to 40 for production and stores/spares purposes".

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