We reveal how GM maintains a high level of quality control during painting procedures at the manufacturer’s Michigan plant

A little over a year ago, quality control procedures at the General Motors Orion Assembly Plant in Michigan picked up on the fact that ‘cratering’ caused by AAa lterations to the surface tension of the wet paint was appearing on some of the vehicles coming off the production line. This occurrence was immediately investigated by one of the facility's specialist defect teams, which, in the words of Anton Busuttil, Orion Assembly paint area manager, “drilled down” through numerous factors to pinpoint the source of the fault.

But the team already had a possible clue: the fault is one which occurs when traces of silicon come into contact with the paint. It turned out that an Orion paintshop operative had been wearing rubberised bracelets to work; such items now have to be left in employees' lockers before a shift.

Busuttil tells the bracelet story to illustrate one of the core maxims by which GM seeks to ensure the highest possible quality standards for the paint finish of its vehicles; quite simply, that the attention to detail of the personnel who work in its paintshop areas is every bit as important as the technologies which are deployed there, even more stringent than elsewhere in the plant.

A constant reminder of that distinction is provided by the special overalls which give GM paintshop personnel their nickname: the Blue Suit Crew.

On a more practical level, these personnel undergo extra ‘paintshop defect orientation’ training. “It is about getting them to understand why we have a no-touch approach and why they have to wear white gloves all the time,” states Busuttil. “They need to appreciate that everything they do can directly impact the customer.” A simple but effective part of the training involves the use of a powerful lamp to highlight the particles of otherwise invisible dust which can be found on an item of everyday clothing.

Busuttil says that paintshop personnel need to recognise that they are effectively working in a laboratory ‘cleanroom’. Indeed, the paintshop has its own air filtration system and the internal air pressure is maintained at a slightly higher level than the rest of the plant. The booths have additional systems so that they are even more rigorously conditioned. Furthermore, staff entering the area go through an ‘air shower’ to remove any particles which may have adhered to their Blue Suits.

Paintshop personnel also need to accept that there may be times when their working conditions are less than ideal. If the weather outside is especially hot and humid – at Orion this could mean 95°F and 90% humidity – then it is not practical to cool the air brought into the paintshop to a level that is entirely comfortable for staff because it would cause excessive condensation, with adverse effects on finish quality.

Indeed, says Busuttil, acceptance of these conditions is a formal part of the training. “People understand that when they are coming into the paintshop there might be some days of the year when it is a little bit uncomfortable, but it is all about the car and the customer and they understand that,” he explains.

Technology & painting phases

While specific defects such as instances of ‘cratering’ can be identified and counted, Busuttil says that there is “new technology out there that helps you measure the quantifiable nature of paint appearance and colour harmony, so there are measurements that we can use for process control.” Indeed, he confirms that GM works with an undisclosed vendor to ensure that it has such tools. Within the Orion plant, Busuttil reveals that there are in fact three teams focused on defect reduction in specific phases of the painting process. One has responsibility from the bodyshop up to pre-treatment; the next covers the process up to the basecoat or ‘pre-topcoat'; and the third is a topcoat team.

He says that the composition of the teams is very broad, with their members drawn from all areas of the plant. “They are not just managers and engineers,” he states, explaining that people who work on the shopfloor on a regular basis “see the product day-in, day-out” and hence possess an in-depth familiarity with the required quality levels. As such, he notes, they can provide “a very good litmus test”. The actual painting process at the plant is a ‘three wet’ sequence with water-based pre-treatment and basecoats followed by a solvent-based topcoat. Busuttil adds that the heat treatment which follows each of the first two stages is not a ‘full bake’ but a ‘flash’ that gets “ninety plus per cent of the water out of the solids”.

A global perspective

On a worldwide basis, GM spends about $1 billion on energy every year, against a turnover which is more than a hundred times greater. Significant disparities in the regional cost of energy can affect the business case for investment in certain locations, particularly where energy-intensive paintshops are concerned.

Al Hildreth, GM’s company energy manager, bears the responsibility for ensuring that relevant GM expenditure is as cost-effective as possible. Although his immediate concern for day-to-day operations is confined to North America, he also collates information on best practices on a worldwide basis and feeds that back to the company’s central management.

Hildreth observes that an important factor is the percentage of “outside air’ involved in paintshop processes. If it is as high as 90% or more, painting can account for as much as 70% of the total energy consumption involved in building a car. However, if the use of recirculation means it is as low as 10%, then painting may account for only 50-60%.

"New technology out there helps you measure the quantifi able nature of paint appearance and colour harmony…" – Anton Busuttil – GM

GM is working towards a 20% reduction in its total energy consumption over the period 2010-20. Hildreth states that there is no specific budget for paintshop projects, though their energy-intensive nature means they are bound to feature heavily in continuing energy-saving efforts.

Modernising ageing installations

The age of an installation will also govern the technologies it employs. Hildreth points out that many of GM’s facilities worldwide are quite old – “25 years or more” – and that, as they are replaced, the company naturally tends to look to invest in the most modern technologies it can justify in the circumstances.

Hildreth cites as an example the $600 million modernisation of the Orion plant roughly three years ago in which innovations in the paintshop included: the introduction of the three-wet process; the use of chromium oxide thin film instead of conventional phosphating; the implementation of radiant tube heating; and the use of 90% recirculated air instead of the 10% previously employed.

The whole plant, he states, became 50% more energyefficient than before, with the paintshop making a disproportionate contribution to that figure. Indeed, Hildreth confirms that the Orion paintshop is currently regarded by GM as one of its most energy-efficient worldwide.

A fresh perspective

This summer, one special initiative took place under the US Government’s Environmental Defense Fund Climate Corps project. Three young graduate engineering students were invited to take a look at some of GM’s paintshop operations and come up with suggestions for improving their energy efficiency. Hildreth says the exercise proved fruitful; the youngsters spotted several opportunities which have now been formally recognised by GM as worth pursuing in practice.

At the Orion facility, the pumping operations in the pre-treatment area were confirmed as an area for further optimisation. “I’m not surprised,” he states Hildreth. “You can always find opportunities even in a brand new plant.” More fundamentally, though, Hildreth says that one of the central maxims of all industrial product and process enhancement is just as true for paintshops as for any other area of activity: that the greatest opportunities for ensuring efficiencies are to be found in the design phase. That, he says, is where “80%” of all potential energy savings are determined.

A new paintshop in Fairfax

Fairfax, Kansas – the production site for Chevrolet Mailbu and Buick LaCrosse vehicles. Though many of the paintshop technologies there will be identical to those at Orion, Hildreth says the company aims to implement all the lessons it has learned so far and to achieve a level of performance which will push the new facility to the forefront of its paintshops worldwide in terms of energy-efficiency.

According to Hildreth, the improvements will involve the greater use of variable speed drives for pumping operations and the more efficient use of water. “A process water expert was part of the project team,” he reports. As for the future of GM’s paintshop development, Hildreth believes it will be marked by “incremental change in existing facilities and step change in new ones”.