Manufacturer of cutting and shredding equipment used to subcontract machining until the summer of 2005, but two CNC lathes and a machining centre in a package now do the work.
Brian Purser and son David run a very successful development and manufacturing operation - Mobile Frag Sales - producing and assembling cutting and shredding equipment created from the company's highly successful worldwide patents. For instance, the two versions of the 510 tonne and 240 tonne Rail Cropper that are used in-situ to chop railway track into manageable lengths has been very successful in the UK market and has potential users queuing up from all over Europe. As a result of the increasing production capability at the Cheadle (Stoke on Trent, UK) facility, a new assembly operation is now being established in North America to penetrate the US market.

The success of the Rail Cropper is best described by director David Purser, who maintains that one man with an excavator fitted with the hydraulic powered shear unit can complete a trackside task in under 20 minutes that a team of men with blow torches would spend upwards of 30h to achieve.

And users agree! Said David Purser: 'One of our main problems was to control the Rail Cropper's build and quality.

We used to subcontract machining under licence until the summer of 2005, but due to a few problems, we decided to approach several machine tool suppliers about installing our own equipment to bring this manufacture in-house.

We quickly found it was Colchester Lathe at Heckmondwike, West Yorkshire that was able to 'tick all the boxes' and supply two CNC lathes and a machining centre as a package that covered all our requirements.' Mobile Frag Sales wanted a single source of supply that could ensure a good aftersales support for these machines.

The equipment had to be able to provide a combination of power and capacity, have very simple to use programming software and maintain the ability to machine to high accuracy.

Said Purser: 'We were not particularly interested in cycle times.

Quality and functionality was the order of the day, so we ordered two Colchester MultiTurn combination CNC lathes, with bed lengths of 2000 and 4000mm, and a Richmond VMC 1000 vertical machining centre with Anilam 6000 control.' The company's six man production team, which is currently being expanded to nine, were trained by Colchester Lathe.

As well as 'hot desking' and moving from machine to machine as required to produce batches of between eight and 16 parts, they are also required to produce prototype and development parts for Brian Purser's continual stream of new ideas, as well as fixturing and tooling.

Typical components include ram tubes, hydraulic cylinder piston rods, ram eyes, cylinder glands and hydraulic unions, the largest part weighing in at 270kg.

Said Purser: 'The MultiTurn lathes have proven to be a boon to use because of the high levels of inherent flexibility we can take advantage of.

We do not grind - we turn to size, and the machines are fully capable of holding 0.07mm tolerances on a 272mm diameter cylinder bore that is 1000mm deep, as well as on 600mm long piston rods with a 0.02mm tolerance on a 79mm outside diameter.' Both MultiTurns are flat bed machines which have a common Fanuc 0i-TC control with the simple use Manual Guide 0i conversational programming assistance and electronic handwheels.

The on-screen programming involves direct input of drawing dimensions that is ideal for the large variety of component types produced at Mobile Frag Sales.

There is also the facility to call up the on-board library of macros that are easily customisable to what is specifically required.

This simplifies programming further and presents a very clear representation of toolpath graphics on the screen.

The MultiTurn 2000 has a 250mm chuck size with a 400mm swing and 585mm by 165mm in the gap bed.

The nominal turning length is 1156mm, the eight-station all-electric turret is 30 VDI and the 7.5kW main motor has a speed range of 15 to 2,700 rev/min.

On the MultiTurn 4000 swing is greater at 554mm, with 830mm by 216mm in the gap bed and a chuck size of 315mm.

The nominal turning length is 3000mm and a larger 11kW motor has a speed range of 15 to 2,000 rev/min.

The Richmond VMC 1000 with its Anilam 6000 control and highly rated Machinist Language programming routines has been able to be really exploited.

On a 180mm thick ram eye, for instance, it is U-drilled from solid to 45mm diameter and interpolated to 125mm diameter taking 5mm depths of cut.

It is then finish bored to a 0.075mm tolerance.

The Richmond has a table 1120mm by 510mm, ample for Mobile Frag Sales' machining requirements, plus an 11kW BT40 heavy duty spindle and 20-tool carousel.

The Rail Cropper is a totally self-contained unit that is carried and powered from the hydraulic system of the excavator, making the device mobile and very flexible.

In use, it simply chops the rail line into 6m lengths ready to be lifted by a crane onto suitable transport.

Purser explained how the 'inventiveness' of the unit, which took 18 months to perfect, involves avoiding shock during the cut.

The design enables the unit to be easily positioned so the moving jaw pressurises the rail against a fixed anvil and causes a stress fracture across the 'ball' top of the rail and the steel simply cracks into two.

Indeed, the jaws are the critical area of the cropping device and they have a life expectancy of some 400 tonnes of rail.

They are produced from a special cast ingot specified by Brian Purser that is rolled into a special section ready for machining on the Richmond.

Such has been the success when machining these toughened jaws that Purser is currently ordering another Richmond, this time the latest version to be launched at MACH 2006 that will have multiple pallet loading capability.

It will be turnkey engineered by the Colchester Lathe application team.

An increase in production is planned at Mobile Frag Sales as new business is being won through agents appointed in Holland, France, Germany, Denmark, Sweden, Finland, Norway and the USA as well as from two sales offices in Russia.

Further agencies are also being appointed in other parts of the world helping to increase the projected build target to 6,000 units a year over the next 15 years.

However, with Brian Purser's roving eye for new ideas, it is no surprise that several other versions are already under development: for fixed installation in scrap yards; a special request has been made on the continent for cropping rails into one metre lengths which can then be dropped direct into re-melting furnaces; mobile application in shipyards; a special unit for building demolition; and currently in prototype machining is a unit that is able to split rocks.