Injection of measurement

Vehicle manufacturing, like many other key industries, is faced with massive change due to external influences such as the environmental lobby and the evolution of alternative fuel sources.

As many new developments are being adopted daily, it is almost impossible to keep pace with the change.

Some components are now so complex that the individual vehicle makers would actually struggle to make them.

Such specialised development has ensured the success of companies like Delphi Diesel Systems, formerly Lucas Varity, whose expertise in the design and manufacture of diesel fuel injection technology - particularly the latest modular, common rail system, is world-renowned.

Its current customers include Ford, Isuzu, Peugeot, Citroen, EUI, and Renault among other household names.

Much of this development has been in response to the demand for cleaner, greener, more fuel-efficient engines, equally accelerated by the hefty burden of tax imposed on fuel by some governments.

The Delphi Diesel Systems factory in Sudbury, Suffolk, employs 850 people to develop and manufacture high-pressure diesel injection systems in response to increased demand from vehicle manufacturers world-wide.

Such technology relies on complex electronic control units and highly accurate injectors, capable of metering the exact amount of fuel, in a pre-set spray pattern, at an appropriate angle, into the engine without sacrificing power or economy.

Manufacturing these components is complex, precise, and highly skilled, with many of the actual processes and designs remaining on the company's top-secret list.

The tolerances demanded by the design engineers are a significant factor in the success of the injectors.

Mike Gardiner, quality engineering manager at Delphi, revealed: "Manufacturing tolerances in the 60s and 70s were very tough, but for today's exacting standards we now talk in terms of tenths of a micron." He added: "our design engineers requested tolerances that can no longer be measured by human beings." Our job was to comply with requests and find a solution to ensure that standards of quality and efficiency were maintained.

Critical to the whole process is the metrology centre sited at the heart of the manufacturing plant.

Mike Lait, Delphi's measurement systems manager, offered a piece of practical advice for all precision manufacturers: "Until you can measure it, you can't make it".

This has proven to be very true for the latest injector technology from Delphi, which required accuracy of one tenth of a micron and the ability to locate points of intersection and measure angles and tolerances that were completely invisible to the human eye, even using high magnification systems.

Mike Gardener and Mike Lait focused on everything available on the metrology market to seek out a system that actually could do the job.

The experience was an eye opener. A previous encounter with video measuring systems had proven to be disastrous, as the system could not produce the levels of accuracy and repeatability demanded by the engineers.

However, it did open their eyes to the possibilities of video-based measurement and the search for a suitably accurate VMS began. Mike Gardiner stated: "One factor that had to be removed from the equation was human input and judgement - it was simply not good enough!" Their search identified a number of potential systems, which claimed to meet their stringent specifications, and the hard work of product testing and evaluation began.

After an exhaustive testing and research programme, carried out throughout the UK and Europe, a system which met and exceeded their specification was finally chosen. The Nikon Nexiv, promoted as the world's most accurate VMS, had lived up to its claims by outperforming every other machine from an extensive list of possible suppliers.

All potential units had to pass a very tough repeatability and reproducibility test before being considered.

The Nexiv was the only system to meet and exceed this critical R&R test.

Mike Lait stated: "We were being asked to measure things we couldn't see, and demands were made for us to be able to repeat and reproduce the results time and time again.

Nikon's support team gave us the confidence that they could understand our problems and challenges, and were firmly on the same wavelength.

The software proved to be adaptable to meet our needs.

The Nexiv has certainly proved capable of meeting all of its claims and has revealed a capacity for a far greater number of tasks through its inherent flexibility and adaptability." Today the Nexiv is an integral part of the manufacturing process and is used to measure and evaluate samples and prototypes as well as assessing variance in manufactured samples and even for creating certified master parts.

The unit is employed in problem solving and proving process capability and can be relied upon as a constant where any critical tolerances are concerned.

Anything that is difficult to measure is now referred to the Nexiv.

The key issue for Delphi Diesel Systems was accuracy, but a secondary factor was always speed.

Mike Gardiner continued: "There is simply no point in having superb accuracy unless you can prove or disprove something in a matter of minutes.

Nexiv is superb when it comes to the latter.

Its ability to run a complex measuring task on a component and provide guaranteed, accurate results within minutes is unmatched.

Stopping a manufacturing run of 500,000 units per month to wait for a week while results were sorted out could be very costly indeed! The result of investment in technology like the Nexiv has been higher quality, fewer failures and, of course, more success for the company through increased sales of more efficient, more reliable systems.

In summary, Mike Lait revealed: "it's only when you actually own something like the Nikon Nexiv that you begin to realise the potential for so many other tasks.

It's truly a multitask tool with significant advantages, and our future metrology equipment investment plans will definitely include Nexiv."