CNC VTLs maintain wheel maker's market lead

A trio of vertical turning and boring machines are proving critical in maintaining Titan Steel Wheels' world lead in the manufacture of off-highway vehicles' wheels and rims.

A trio of re-manufactured Toshulin SKQ12 vertical turning and boring machines are proving critical in maintaining Titan Steel Wheels' world lead in the manufacture of off-highway wheels and rims for mining, construction, military vehicles and mobile cranes.

The three machines - all supplied by the T W Ward Machinery CNC Retrofit division - are key machines in a flowline production environment where machining tolerances of +/-1mm are commonplace.

And apart from costing considerably less than their brand new counterparts, the Toshulins are no different in terms of functionality, performance and appearance, according to Neil Vivash, Chief Production Engineer at the site in Cookley, near Kidderminster.

"With their new drive systems, hydraulics, electronics and chucking systems as well as CNC controls, they really are superb in every respect," he declares.

"Only the castings are left from the original, and would I challenge anyone to spot the difference!" Titan Steel Wheels has occupied its expansive site in Worcestershire for many years, in the very early days under a number of guises including John Wright and Co (iron puddling/tin plating), Chaddersley Manufacturing Co (start of wheel manufacture in Cookley in 1911), Steel Stampings and presently Titan Steel Wheels.

While OEMs like JCB are included on the customer list, most production (the plant has a capacity for 600 wheel rims a day) is exported, a factor recognised by a Queen's Award for Export in 1996.

Neil Vivash says the business has changed dramatically over the years, moving from being a high-volume, small variety operation to today's scenario of wide variety, small batch work where the average batch is 25 and where 100-off is unusual.

To meet such demands, Titan Steel Wheels has adopted what he describes as some of the most advanced wheel rim production equipment, including laser-tracked submerged arc welding and high-tech CNC machining.

The result, he adds, is probably one of the world's most effective wheel rim manufacturing plants where minimal lead times and cost-effective production techniques are by-words.

The use of a novel variable-based programming routine also contributes to shopfloor efficiency, allowing operators to minimise machine changeover and resetting times.

After calling up a 'standard' program, the operator simply replaces a set of variables with actuals for bore size, plate height and thickness as well as stud hole dimensions, for example.

"It not only speeds things up, but it also simplifies programming enormously," adds Neil Vivash.

Basically, the manufacturing process involves rolling flat bands of steel into 'rings' that are flash-butt welded and either pressed or rolled to form.

The mounting faces are welded-in (to accommodate the axle) then the gutter groove is CNC machined (some wheel types have these rolled in) in the vertical plane along with the axle mounting bores and stud holes.

Finally, an electro-ferritic paint shop applies an undercoat (usually yellow), and a top coat in any specified colour, if required.

While preferring not to call them rebuilt machines "since re-manufactured is a better description", Neil Vivash describes how the first Toshulin was installed to satisfy a particularly demanding machining tolerance of +/-1mm that was needed to maintain product integrity on wheels destined for vehicles capable of 80 mph and more.

"A toolmaker, for instance, would probably smile at us having to achieve +/-1mm," he continues, "but it's a demanding requirement when you're rolling, stamping, pressing, welding and machining steel plate up to 60mm thick.

T W Ward's re-manufacturing practices involve the laser calibration of all machines to VDI/DGQ 3441 accuracy standards and, depending on outside influences such as tooling and workholding, the Toshulins easily satisfy machining tolerances of +/-0.02mm.

Neil Vivash again: "The process requirements to produce the axle mounting bore and stud holes to such a tolerance meant that our usual 30 wheel rims an hour output would have been reduced to just nine an hour, so we obviously had to do something.

The answer was to establish a dedicated line for the new wheel and, after looking at all the different VTLs available - including new - we chose the Toshulin from T W Ward, for a number of reasons.

"Of course, cost came into the equation but so did quality of build, functionality and performance.

The SKQ12's spindle speed of 250 revs/min from the 40kW spindle motor was more than adequate, and its 1250mm diameter table easily accommodated the 620 mm diameter wheel rims.

"The fact that we have experience of T W Ward's re-manufacturing skills, and complementary engineering and service back-up, also came into the equation," he continues.

"Sometime ago we took delivery of a Webster and Bennett 36 inch table VTL and as well as completely re-manufacturing the machine to 'as new', Ward had also re-designed its toolchanger - thus solving a perennial problem on such models.

With the new line installed, Titan Steel Wheels soon found that the Toshulin's performance compared favourably with and invariably exceeded the other VTLs on site.

Neil Vivash again: "Because we are machining material from 6mm to 60mm thick, we are limited to a certain extent over the maximum surface speeds that can be run with our carbide tooling.

However, the machine was on par with some of its counterparts and in many cases it out-performed them.

Eighteen months later, when Titan Steel Wheels wanted to expand production to accommodate the introduction of a new three-piece wheel design for heavyweight vehicles to compete with five-piece rims, Neil Vivash and his team again went to the market.

"We never close our eyes to what may be out there," he says, "but we came back to the Toshulin SKQ12 - and T W Ward - for the same reasons.

In terms of value for money, there was really no comparison!".

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