Kent company solves lamp wiring challenge for British luxury sports car

Motoring Posted 23/10/17
Kent-based Convert Ltd – manufacturers of cable looms and harnesses – has designed a stand-a-lone waterproof grommet which has helped solve a lamp wiring challenge for a British luxury car manufacturer.

Convert worked with Wipac – a design and manufacturing company specialising in high technology exterior LED lighting for the prestige automotive market – on its new lighting project for the luxury sports car manufacturer.

The project required a waterproof yet compact high performance LED lighting system, with an external profile of between 3-5mm for the sealed connector which would house the wiring. In order to provide a water-tight finished unit, traditional methods of mounting 35mm electrical connectors onto the lamp housings were not feasible due to their physical size.

To find a solution, Wipac turned to Convert - their long standing electrical engineering company and one of the UK’s leading manufacturer of cable looms and harnesses.

Vince Bailey, Wipac head of purchasing, said: “It’s standard industry practice that all lamp units for high performance LED lighting systems are waterproof. Internal space constraints are also becoming a critical issue as demand increases for us to produce more complex lamps, with a high number of different internal elements, but not to increase the overall size of the finished lamp.”

“We’ve worked with Convert for seven years,” said Vince. “They provide cable harnesses for all our head and rear lights. We knew we could trust them to come up with an innovative design solution.”

To overcome this challenge, Convert’s team of engineers conceived a design with a grommet that would be integral to the cable harness for the lamp enclosure. A second vehicle grommet was also required to protect the vehicle’s internal compartments from the potential water ingress.

However, a number of hurdles had to be overcome when sourcing the grommet.

Firstly, whilst it’s not unusual to use grommets for traditional filament bulb lamp enclosures, commercially available parts for these styles of lamps didn’t provide the required level of moisture projection.

Secondly, the high temperature cable required in LED lighting made this design even more demanding.

Dave Lord, managing director of Convert, which is based in Edenbridge, Kent, said: “We started trials to find an automotive grade material that would be malleable enough to make final lamp assembly feasible and that would bond to the cable insulation to provide the waterproof seal. However, we found the materials that bonded to the cable were too stiff to allow final assembly. Similarly, softer materials wouldn’t create the required bond due to the special properties of the high temperature cable outer insulation jacket.”

“It soon became obvious that a new solution was needed to overcome this problem,” said Dave. “It was then we had our Eureka moment and developed the concept of the stand-a-lone grommet.”

This new style of grommet required cable tunnel guides of exactly the correct size to allow the cable to pass through the grommet. This created a waterproof seal once fixed to the cable harness, which in turn would be stable and secure when fitted to the finished lamp.

To produce the initial parts, Convert invested in a low volume mould machine and tooling.

The prototype grommet passed the required tests to meet the waterproofing standard IP66K to which Wipac works, meaning it was able to withstand water spray at 145PSI (Pounds per Square Inch) from 3 metres for a test duration of 2-3 minutes.

Convert’s stand-a-lone waterproof grommet is now successfully used in Wipac’s lamps for both a British luxury car manufacturer and a British high performance sports car manufacturer.

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