The authoritative public forum
  for Metal Finishing since 1989
-----

Why are liquid coating still preferred in automotive applications (vs. powder coatings)?

Hi,

I am currently conducting a study to figure our what hinders further adoption of powder coatings in the automotive industry. The main questions are:
- In what automotive applications are liquid coatings preferred and why?
- What would need to be improved in powder coatings for powder to be considered for these applications?
Appearance is certainly one element. What else?
Thanks for your help!

Petr Salz
Consultant - Netherlands
May 12, 2009

---

First of two simultaneous responses --

Petr,

When you talk about the Automotive Industry, what specifically do you mean? Are you inquiring about body panels, components, stampings, brackets.... I think we need a little more specific information to be able to answer that question.

David J. Wolf
Medina, Ohio
May 18, 2009

---

Second of two simultaneous responses --

Hi Petr,
Reading between the lines you already understand that PC has been used to some degree for many years as a top coat in the automotive industry, even longer by the component manufacturer. Further adoption by other manufacturers must be limited by capital costs as the two systems have different processing requirements. Many years ago accident repair difficulties were quoted as one element in preventing PC as a replacement. I think powders and equipment are now up to the job (BMW with metallic & clear coat) and it is the world wide recession that is preventing any investment by the automotive industry.

Terry Hickling
Birmingham, United Kingdom
May 19, 2009

---

Paint thickness/tolerance ratio will probably be above appearance, powder coating has the cosmetics needed for auto application. There are very tight tolerances on automotive parts and the powder application is just to thick. So in answer to one of your questions, thinner film application powders need to be developed. You might see thin film powder referenced occasionally, but generally they are talking about flat black(you can have any color powder formulated in thin film as long as it's black) :-)
The space needed and cost of changing over a wet line to powder or adding a powder line can be prohibitive.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
May 20, 2009

As far as I understand colour control is a big factor. if automotive for class A finish's does go anywhere it would probably be coil, the appliance industry has already switched over.

Ronald Zeeman
Coil Coating - Brampton, Ontario, Canada
May 21, 2009

---

Thank you all for your ideas.
Do you have suggestions for what a powder coating manufacturer could do to overcome some of the current hurdles? For example, following up on Sheldon's remark on coating being too thick for some automotive parts, a thinner powder coating might solve some problems. What else could be improved?

Petr Salz
- Netherlands
May 25, 2009

Powders resulting in low film weights (<25 microns) are available from the major players in PC mf. It still boils down to... how would the workers at GM feel if the bosses spent millions of dollars n a new PC plant... maybe they did and thats why they may go into the hands of the liquidators. With a world wide recession, car factories closing down or on a three day week, why spend money... just keep it for the CEO's retirement plan.

Terry Hickling
Birmingham, United Kingdom
May 27, 2009

---

If you are referring to the full body of vehicles being powder coated, then there is already progress in this field. Indeed, it is generally widely accepted that the German manufacturer BMW is the only car manufacturer with a fully functional outputting powder coating plant. They use it to spray a clear coat only. There are obvious inhibitors to powder coating which would need to be overcome... Firstly, spraying to waste on a scale of car manufacturing would be very costly. The knock on effect of this means that colour change would be nigh on possible, as recovery in plants that spray different colours isn't feasible. Contamination is already endemic! The major factor is film thickness. As above, orange peel is a big worry. (Luckily, the Germans love orange peel!) You can tell which BMW's have come out of Germany, and are thus powder coated, by the orange peel effect on the surface. Future developments to reduce the overall DFT to sub-25 microns would perhaps help.

Mini are currently experimenting with powder coating, and it is expected that they will have a functioning plant in the near future. It must be said that car manufacturers are using the very latest in powder coating technology (i.e., Auger pumps and SRV 038 powder turbines) No one knows what the actual BMW plant looks like inside, indeed I have seen an artists impression from Sames, who claim that BMW uses their guns to spray. Interestingly though, other equipment makers have laid claim to the same!

Christian Booth
- Manchester, UK
June 5, 2009