Bespoke spring is a silent, invisible, automotive saviour
A major automotive plant in Germany discovered a possible issue with front seats that were deemed too heavy to manoeuvre back and forth, particularly for children seated in the rear of the vehicle. With the new model already in production, the oversight demanded a speedy bespoke retrofit.
The automotive giant's tier one seat supplier approached William Hughes to design, manufacture and supply a customised spring within a four-week timeframe. Adding to the challenge, there were a number of constraints imposed by the customer, as Peter Korzilius, business product and development manager at William Hughes explains: "The special spring had to be unseen, unheard and operate smoothly avoiding catch points, and we could only use the existing holes and edges available within the seat structure mechanism," he says. "Furthermore, the solution had to comply with strict health and safety regulations regarding spring assembly procedures."
Engineers from William Hughes invested a lot of time in the design office at the seat maker, where parameters such as extension force, track length, fitting space and mounting points could be assessed. Using high tensile wire less than 1mm in diameter, a special extension spring has been designed to fit with minimum effort on to the car seat structure without any modification to existing parts, thus ensuring continuity of production. The spring features a black plastic coating to help suppress noise and pass the required BSR (buzz, squeak, rattle) test. The paint is applied at William Hughes' plant in Stalbridge, where it is subject to dip-spin and oven cure.
Finally the entire length of the extension spring is covered in a thin plastic sleeve, partly to act as a damping facility to prevent it resonating like a guitar string, and partly to help prevent potential wear induced by rubbing against nearby parts of the metal structure. The sleeves are also assembled by William Hughes so that the entire solution is ready-to-fit.
Meanwhile, concurrent engineering ensured that the special tooling required to manufacture the prototype springs was developed over a period of three days. The first springs were supplied by William Hughes within two weeks ready for endurance testing. "The combination of design effort and rapid response is a factor that helps differentiate William Hughes in the bespoke spring marketplace," says Korzilius.
In production, a total of 1,400 bespoke springs will be required every day to meet demand from the automotive plant. The springs will be manufactured in Dorset. "The project is a good example of what William Hughes is all about," adds Korzilius. "We only make proprietary springs, we have no catalogue and we do not make for stock. We have built a reputation as a problem solving expert that works to customer requirements."
Another recent automotive project saw the company design a customised spring solution that is part of a spare seat latch mechanism for MPV-type vehicles. "When these seats are secured into the body of the vehicle there are strict regulations stating that they are not allowed to come loose under shock impact," explains Mr Korzilius. "There is a lot of spring technology involved in creating solutions of this ilk."
Such has been the success of the bespoke spring designed and manufactured by William Hughes that it has now become a generic solution that will be fitted to a growing number of new European-built MPVs due to be introduced over the course of the next two years. Volume levels are expected to reach millions per annum. Production will start in the UK but will eventually transfer to William Hughes' recently established production facility in Bulgaria. Having invested around £1 million in the past couple of years alone, all of the automated CNC spring-making machinery owned by William Hughes features the same control platform to ensure products and processes are fully transferable between sites.
Demand for bespoke solutions is also growing from the aerospace sector. A case in point was witnessed recently when a tier one aerospace supplier wanted special springs for use in ventilation equipment that supplies air to the cockpit of a European-built jet fighter aircraft. Springs manufactured by William Hughes are used in a growing number of vital systems used by the aerospace sector, including oxygen units, access hatches and the solenoid valves used to control hydraulic and cabin pressure systems. To meet the requirement for high temperature performance, many springs for the aerospace industry are manufactured from exotic materials such as Nimonic, Inconel and Ni-span. The bespoke springs for the fighter aircraft had to be supplied within a four-day turnaround, and engineers at William Hughes worked over a weekend to design and manufacture a bespoke solution, an effort that was rewarded with a glowing 'thank you' letter from the customer.
Switching sector again, the company has recently supplied bespoke springs to a leading manufacturer of seats for both indoor and outdoor events. The customer approached William Hughes with a problem that a number of other spring manufacturers had been unable to solve. It wanted to extend its folding seat product range into a new market that required the performance of the seat to be upgraded. To meet the standards for the new application, the pair of springs used to return the seat to the upright position needed to complete twice as many cycles, an increase from 50,000 to 100,000 operations.
In this case the solution proposed by William Hughes was neat, simple and effective. To address the issue of the extended operational life, the springs were treated with a shot-peening process that enhances fatigue life. The result is a spring that is no bigger than the original round wire spring, but has double the operational life.
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