Ramping Up PVD

Physical vapor deposition (PVD) is a coating technology widely used in some types of applications, such as applying hard coatings to cutting and forming tools. The term is applied to a variety of vacuum deposition methods used to develop thin films by condensation of a vaporized form of the coating material onto various surfaces. Because PVD involves purely physical deposition and adhesion of the coating material to the substrate, it takes place at temperatures far lower than its cousin chemical vapor deposition, which can require temperatures of hundreds of degrees Celsius. As a result, PVD is applicable to a wide variety of substrates, including plastics and other relatively low-melting materials.

Holding PVD technology back in some applications, however, have been the need to pull a vacuum in the chamber and the fact that it is basically a line-of-sight process—that is, it will coat only part surfaces directly exposed to the vapor source. Now American Trim LLC (Lima, OH) says it and a couple of partners are addressing at least some of these perceived drawbacks and enabling wider use of PVD coatings on a variety of high-volume automotive and other parts.

Said to be the largest of its kind in the world—it features a 6-ft diameter opening and is 12 ft long—the PVD chamber at the Advanced Materials Commercialization Center (AMCC; Lima) was primarily designed for decorative finishing of automotive parts such as bumpers, motorcycle parts including frames, appliances and automotive parts. However, there’s also potential for PVD technology to provide functional coating capability for solar panels, fuel cells, advanced energy systems and advanced medical instruments, American Trim says.

According to the company, the PVD chamber allows it to supply customers and potential customers with sample parts showing a variety of coatings on their product. American Trim will initially use the technology to deposit “chrome-like” finishes on plastic and other substrates at a low cost while potentially eliminating process steps typical in plating operations.

The chamber is the centerpiece of the AMCC, a partnership between American Trim and Lima’s James A. Rhodes State College. The project got off the ground with the help of $1.38 million in funding from the Third Frontier Wright Project, an Ohio state grant that supports research and development for new product innovation. The partners say the AMCC is designed to attract development programs for PVD technology.

Potential customers will find a fully functioning prototype production line which serves as an incubator leading to full production. Typical speed of the prototype PVD process is 1–10% of actual production; American Trim says the relatively low throughput rate is the result of the need to build flexibility into the line to allow simulation of a variety of processes, both newly developed and existing.

But equipment is also scalable to production volumes, facilitating completion of the Production Part Approval Process (PPAP) process used in the automotive supply chain. PPAP requires component suppliers to demonstrate that they understand their customers’ requirements, that products supplied meets those requirements, that the supplier’s process is capable of producing conforming product, and that a production control plan and quality management system are in place.

Lending a further boost to the project is DuPont CoatingSolutions (Houston), which is working with American Trim to develop automotive applications for a combination powder coat/PVD process that uses a powder base coat supplied by DuPont to provide a protective, functional layer and smooth out the part surface before decorative PVD coating. According to the companies, the powder base coat eliminates the need for sanding or buffing even on rough parts such as metal castings. Parts are cleaned using an aqueous process, pretreated and dried before application and curing of the powder base coat. After PVD deposition of a very thin layer of metal, they receive a clear acrylic topcoat for added durability.

Although the combination process was primarily designed for decorative finishing in the heavy duty truck and automotive industries, DuPont and American Trim say it may also be applicable for appliance parts, recreational vehicle, furniture and building components.