Eaton single-sources 486 different types of spring

By commissioning William Hughes to manufacture and supply, direct to its production line, all springs for about two dozen of its most popular hydraulic valve products, Eaton Hydraulics has removed a m

By commissioning William Hughes to manufacture and supply, direct to its production line, all springs for about two dozen of its most popular hydraulic valve products, Eaton Hydraulics has removed a major administrative chore from the ordering system.

The 28 components involved, those bought in greatest volume and representing the bulk of spending, have sidelined the traditional buying process altogether.

The nature of the direct line feed (DLF) deal has removed the need to raise orders, to monitor stock levels, to inspect and book in parts on delivery, or to query weekly invoices.

Six months experience confirms that purchasing and production systems flow more smoothly with DLF.

In fact Eaton is sourcing the whole of its spring requirements, all 486 different types at last count, from William Hughes alone.

What swayed Buyer Sharon Davies to embark on such a policy, with an annual spend upwards of £100,000 on springs, was the attitude demonstrated by the manufacturer.

This offered the advantage of instituting the best of modern delivery systems while preserving the priceless value of dealing with a specialist technical supplier.

This would have been lost by going down the alternative route of contracting out to a jack-of-all-trades logistics company.

First fact to be recognised is that every one of Eaton's products - hydraulic motors, pumps and valves serving users in agriculture, construction, motor, marine, mining and general industry - incorporates springs.

The products are of superior quality, so the components necessarily have to be likewise.

Second important impression made was the extraordinary detail of the would-be supplier's preliminary audit.

William Hughes analysed every type of spring in Eaton's extensive stock, checking first each component's function, with a critical examination of design to see if it could be improved by a change of shape or material, and an appraisal of potential for cost savings which could be passed on to the customer.

As an example, two types of spring might have been made of almost identical material but different wire diameters to exert unequal forces within quite dissimilar envelopes.

The spring maker could (and did) suggest refinements of design and recommended making them of the same material and wire diameter without altering desired performance characteristics.

This is an ongoing process, with an aim of achieving cost savings by using thinner diameter wires where feasible, and dependent on whether the inside or outside coil diameter is critical.

An objective is to narrow down from a current range of four wire diameters (1, 1.25, 1.5 and 1.75 mm to just two: 1 and 1.5 mm).

Part of the audit revealed that, of 486 spring varieties, only 28 satisfied the normal criterion for direct feed from the manufacturer to bins on the customer's production line.

To make direct line feed feasible the parts generally have to be called off in quantities of 500 or more.

This allows the manufacturer to dedicate some machinery to virtually continuous production.

So much for the 28 spring types on regular bulk delivery, but what of the other 458? No problem.

For springs in slightly lower demand, say more than 150 but less than 500 at a time, the answer is batch production, with William Hughes making in one run enough for a whole year's supply, and holding them on the shelf to be called off as required.

The remainder, those springs in occasional demand, are produced to order as necessary.

In a direct line feed situation it is vital for the supplier to continuously monitor the user's rate of consumption.

Nowadays a William Hughes engineer makes routine weekly visits to the hydraulic systems manufacturer, checks the contents of every appropriate tote bin, and tops up as necessary, always with the correct spring type.

Often he will also look at stock levels of other springs, not part of the DLF scheme, which experience tells him may be falling; and when appropriate he will alert local staff to question if a fresh batch should be called off the warehouse shelf.

Monetary savings achieved for Eaton by Sharon Davies are easily identifiable.

There is the elimination of much paperwork and inspection procedures associated with springs accepted on direct line feed.

Plus the concomitant reduction of stock levels, and some improvements in spring design to trim costs without sacrificing efficiency.

Nevertheless, a shrewd buyer does not place herself in what might be thought of as a position of some risk by both changing supplier and abandoning checks on components being delivered direct to the production line.

Consequently Sharon Davies carefully examined William Hughes' credentials.

She visited one of its major direct line feed clients, MEM Electronic Switchgear in Birmingham, to witness at first hand a spring DLF operation, and was invited to consult a selection of other DLF users such as subcontract suppliers to motor manufacturers like Ford, Rover and Toyota.

Sharon Davies also toured the spring maker's factory to assess its equipment capability and staff expertise, acutely aware that a feature of the proposed DLF scheme potentially exposed Eaton to a risk of flawed components, with consequences of losing production, sending out faulty systems and injuring its own reputation for quality.

William Hughes QS 9000 accreditation was a major assurance.

Extra assurance and supporting evidence was provided by Eaton Project Engineer Paul Donnelly, who also paid visits to the spring maker in order to conduct a quality audit on the company.

He discovered that William Hughes' own assessment was pretty well spot on, and readily agreed that the supplier was at least 98% on target.

A comforting aspect is that direct delivery to the production line has been a feature of William Hughes business for the past 16 years.

The spring maker knows that he is expected to allow no interruption to his capacity because he has to keep pace with the customer's rate of production, and there can be no question of faulty product.

Small wonder that almost one-eighth of William Hughes engineers are dedicated to quality control.

When it came to assessing installed equipment and technical capability, nobody can ignore the level of continuing investment in the most modern and technically advanced spring making machinery.

Around 5% of company turnover is dedicated to upgrades and expansion each year.

Much of the plant is unique in this country and features the most sophisticated spring technology in the world.

During the past year the company has installed three CNC automated multi-head coiling and bending centres costing almost ?200,000 apiece.

And there is the prospect of more to come.

The current list of 486 different spring types is not the end of the story.

Eaton Hydraulics continues active development of new, more advanced systems to meet the emerging needs of its markets.

Invariably a new design of hydraulic system is accompanied by a requirement for yet another spring type.

William Hughes is well equipped to answer this demand too, and regularly responds to a call to produce springs for prototype products at a rate of nearly once a week.

Eventually perhaps eight or ten of the proposed hydraulic system designs will go into full production.

Among such fruitful enterprises for Eaton may be counted its recent announcements of additions to the Vickers System-Pak and Value-Pak ranges of hydraulic power units, and the new Vickers M Series open circuit piston pump.

Among key features of the power units is SAE straight thread porting throughout to minimise leakage, and line-mounted spin-on return filters for ease of maintenance.

The M Series will be available in four frame sizes with a pressure capability up to 320 bar intermittent at very low noise levels, 60% quieter than earlier generation industrial design pumps.

As these advanced Eaton Hydraulic systems come on to the European market in volume, it is reasonable to expect that William Hughes will again be charged with the responsibility of supplying top quality springs to match top quality products, with direct line feed playing a significant role if volumes are high enough.

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