Technology Roadmap for Energy Reduction in Automotive

5.0 Automotive Paint
In the automotive paint shop, the body structure from BIW undergoes a series of operations to
paint both the interior and exterior of the structure. Prior to 1985, the majority of domestic cars had
single-stage paint when they arrived from the factory. Today, the traditional automotive paint
process is multi-stage. It usually begins with the application of pretreatment and electrocoat,
followed by a primer layer. Typically, after the primer
is cured, a topcoat of basecoat and clearcoat is applied
and cured. The topcoat chemistry is based on water,
solvent, or powder. The end result of this process is a
five-layer, shiny and durable finish.
While it produces a lustrous finish, this process is
both costly and time-consuming. The normal paint
process can take 3 hours per vehicle to complete and
uses considerable amounts of materials, electricity,
Ford Compact Painting System
natural gas, and labor or robotics. Some new
technologies are available that may reduce the total cost and time of vehicle painting. Compact
paint systems, for example, eliminate either the need for a separate primer layer altogether or
reduce process complexity while retaining the benefits provided by the primer layer. Either method
reduces the total cost and time of vehicle painting.
In general, there are three basic ingredients in automotive paint: resin, pigment, and solvent. The
resin is the component that holds together the pigment in suspension, provides adhesion to the
surface applied, and determines the quality and durability of the paint job. The average aftermarket
automotive paint-mixing system includes about 100 colors or toners with the capability to mix
formulas that include metallic and pearl paint colors. The solvent provides transferability; without
it, the paint would be too viscous to transfer.
Automakers have the capability to paint vehicles in a wide variety of colors and types of paint.
Most vehicle manufacturers decide on a standard color for production and submit a painted sample
to their suppliers. The paint manufacturer then produces a formula for the “standard sample” and is
allowed a plus or minus tolerance which can result in slightly different shades of the same color.
For this reason paint manufacturers usually have the standard formula followed by two alternates.
Metallic paints add another level of complexity to the paint process, as they are classified in
multiple categories (e.g. extra fine, fine, medium, medium coarse, coarse, etc.). The metallic colors
control the value (lightness and darkness) of the color, similar to the way white affects pastels.
Temperature, paint film thickness, flash-off time between coats, fluid tip sizes, speed of the spray
gun, surface type (plastic or metal), and humidity can cause lighter or darker variations in metallic
colors.
Paint processes include paint booths, ovens, compressed air, abatement of volatile components,
application of coatings, storage, and handling of materials, and waste treatment. Drying processes
rely heavily on steam and natural gas. Most are automated to some degree and utilize numerous
robots and computer-controlled systems. The supply chain elements that are most closely
integrated with paint include producers and suppliers of paint, paint booth and oven/curing
systems, robotics, and abatement systems.
TECHNOLOGY ROADMAP FOR AUTOMOTIVE MANUFACTURING ENERGY REDUCTION 17