Specialising in the sub-contract machining of precision components, Valco UK in Essex has invested heavily in a subtle blend of CNC machine tools over the last three years.
Specialising in the sub-contract machining of precision components, Valco UK in Essex has invested heavily in a subtle blend of CNC machine tools over the last three years. This has seen the 50-strong company progressively install 20 vertical machining centres and 10 CNC turret mills at its factory in South Woodham Ferrers. All the CNC mills are ProtoTrak models, supplied by XYZ Machine Tools of Devon, and these versatile machines form a vital link in Valco's manufacturing chain.

For as well as carrying out various preparatory operations for the VMCs, the mills also perform numerous small batch, 2D machining tasks in their own right.

Around 60% of the company's work load involves machining plastics components from sheet material to general tolerances of around 0.1mm.

Parts such as insulator panels, boards,channels, connectors and carriers are produced for customers in the telecommunications, marine, fibre optic, transport and defence sectors in average batch sizes from 10 to 500 off.

With a separate electronics division,many of Valco's projects involve machining components for sub-assemblies.

While the more complex plastics parts, and most metal ones, are produced on the VMCs, a wide range of standard components are now being effectively produced on nine ProtoTrak PRO 2000 CNC mills (with the AGE 2 control) and an EDGE 1500 CNC mill (with the new EDGE control) - which have been brought in over the last three years.

As production manager Gareth Irwin explained, the XYZ mills form a key element of the whole manufacturing operation.

'These CNC machines carry out a wide range of tasks and about 25% of their time is spent on blocking-up and other datuming type operations on plastics billets destined for the VMCs -- so as to optimise production efficiency.

However, they are also used to produce prototype components, before they go into full production, and simpler 2D type parts such as covers, plates, spacers which are usually required in fairly small batches.

Moreover, the machines also perform secondary operations on components produced on the VMCs.

The speed with which they can be set-up and programmed, combined with their ease of use and all-round versatility make the ProtoTrak mills virtually indispensable.' Prior to the arrival of the first XYZ CNC turret mill in 1997, Valco relied on manual milling machines to carry out such production functions.

But as workloads increased and the company bought more VMCs, the use of manual machines and rotary tables was proving less effective in terms of productivity and repeatable accuracy.

Back to Mr Irwin again.

'The introduction of the CNC mills showed us the way forward as we cut cycle times by at least a factor of three, significantly improved repeatability and quality levels and could respond more quickly to customer demands.' All programming is done at the machine on these easy-to-use, two-axis CNC systems.

Most of the components produced on the CNC mills are fairly simple 2D items, yet they still have to be produced as efficiently as possible.

A typical part is a 38 by 32 by 2.5mm thick magnetic support plate machined from SRBP sheet and required in batches of 25 off.

These parts entail profiling, machining a central 12.7mm wide slot and drilling four 3.6mm diameter holes.

Produced on a PRO 2000 mill the complete batch of plates can be processed in just 1 hour (some 40% faster than before).

While a 50 by 26 by 13mm thick PTFE spacer, which requires tenon type sections and four, 4mm diameter holes, is now being produced in a cycle time of just 6 min per part.

Although required in batches of 250 off, it's still more economical to machine the spacers on a CNC mill as even a VMC cannot produce the complete form in a single operation.

The XYZ machines are also used to produce flat plate plastics developments which are subsequently heated and bent to the desired form.

As well as producing sized blanks for the VMCs and carrying out secondary operations, the CNC mills are also used to finish part-machined components.

One example of this concerns a small aluminium box lid where the top face is profiled and drilled on a VMC and then transferred to a PRO 2000 to face the reverse side and machine recesses around the drilled holes.

Required in batches of 22 off, reverse side machining could have been performed on the VMC, but it would have taken almost 1 hour to set-up and program the machine.

With a programming time of only 5 min and a cycle time of just 1 min, it is far more effective to carry out such operations on one of the turret mills.

All-in-all, the mills have proved to be a profitable and versatile investment and the company is well pleased with the level of service and back-up it has received from XYZ MachineTools.

Valco always tries to have one of its CNC mills spare so that it can accommodate rush jobs without disrupting planned production schedules.

While on the versatility front, the PRO 2000 mills really proved their worth on a recent project which involved machining high quality ebonite fishing rod reels.

For as well as producing the prototypes (before production was switched to VMCs) several of the machines have also been used to polish the100mm reels after machining.