While there have been major improvements in material application time, energy consumption, and emissions generation, the assembly plant paint shop process remains as the largest cost/time constraint in vehicle manufacturing. However, even more change in materials, processes, and equipment will come with the vehicle lightweighting targets necessary to meet future emissions and fuel economy regulations.
How will new lightweighting and mixed material car body designs work with existing paint shop process? Without getting too philosophical, we can compare the current transitions to Aristotle’s credited statement: “The whole is greater than the sum of its parts.”
Automotive Paint Shop
The paint shop is the third of four main processes involved in manufacturing automobiles (press shop, body shop, paint shop, and trim shop). Typically, it occupies 1/3 of an assembly plant space, but historically has consumed more than 50% of the energy, 90% of the water, and half of the capital expense needed to assemble cars.
In addition to drying the primers and topcoats used to protect and color the vehicle body, there are several mini-processes occurring simultaneously within the operation of conventional paint shop ovens, such as:
- Drying/curing of bonding adhesives in various vehicle structure joints and seams.
- Final tempering (strengthening) of various substrates used in vehicle structures.
- Managing the heating/cooling expansion and contraction rates in the gaps between joint made of different substrates.
- Sealing the vehicle interior/exterior from passing dust, moisture, and wind noise through joints and seams.
The table below summarizes drivers including regulatory, substrate, and process/material demands, that OEMs face in the complex management of paint shop processes:
As a result, OEMs have worked with coating and equipment suppliers to design process and material improvements to create “thin-film” metal pretreatments and “wet-on-wet” coatings. Other new, integrated paint shops have eliminated an oven or a part of the spray process. There has been additional interest in innovative solutions that enable the combination of functional coating processes, and lowering baking oven time/temperature to save material and energy.
One such solution is Henkel’s award winning BONDERITE® M-NT 1800™ Series Process (formerly TECTALIS), an efficient alternative to traditional zinc phosphate treatments. It is an innovative zirconium-based multi-metal pretreatment which leads to superior corrosion resistance and paint adhesion, yet involves fewer process steps, time, energy and waste.
Keeping in mind that “the whole is greater than the sum of its parts;” materials, body design, and manufacturing engineers have to coordinate downstream operations occurring in the paint shops such as sealing, tempering, and NVH applications as they introduce new body architecture and joining systems (especially those with mixed materials, such as steel, aluminum, carbon fiber, and plastic bodies). Further steps can only be realized by developing a roadmap that is shared among those stakeholders involved in vehicle design, materials, manufacturing, and regulation.