HVAF: A New Way to Thermal Spray

HVAF Gun

The “HTS” in HTS Coatings stands for Hunsaker Thermal Spray, named after our President and our Owner, Jason and Ashley Hunsaker. Thermal spray is our name and thermal spray is our game. Thermal Spray has been around, in some form, since the late 1800’s. Initially used to coat battery plates with lead, thermal spray is the process of heating up metal and spraying it onto a surface. It is kind of like spray painting with metal except without all the graffiti. Sometimes known as metallizing, thermal spray comes in many forms and has even more applications.

Thermal Spray 101

ARC Spray

ARC Spray

While there are many different types of thermal spray, the big four at HTS are Flame Spray, ARC Spray, Plasma Spray and High Velocity Oxy-Fuel, or HVOF. Flame spray is one of the oldest forms of thermal spray in use. It uses metal wire, oxygen and acetylene to restore old parts with metal-based materials such as stainless steel and bronze. ARC spray uses metal wire and electricity and is great for building up parts with high wear areas. Plasma spray is the original method used for harder, carbide coatings and due to its high temperature and powdered material injection, it can be used for ceramic coatings as well. Our most popular thermal spray method is HVOF. It uses hydrogen, oxygen and argon gas to spray carbide coatings, like plasma spray. However, it can also use many other materials such as stainless steel, Inconel and Stellite®. For a full list of our thermal spray capabilities, check out our Thermal Spray services page. For years, HVOF has been the industry standard in thermal spray technology, but there’s a new kid in town.

High Velocity Air Fuel

Advances in spray gun technology have led to the development of High Velocity Air Fuel or HVAF thermal spray. HVAF uses compressed air and propane as opposed to the oxy-fuel mixture of HVOF. It seems like a small change, but it has a huge impact on coatings. The two biggest improvements over HVOF are lower spray temperatures and higher spray rates.

Lower Temperatures

HVAF can be sprayed at upwards of 1,000° C less than HVOF. Lower spray temperatures allow for a slow cooker effect on the metal powders. The powder particles are gently heated producing a purer spray. HVAF coatings have more resistance to material erosion, corrosion and cavitation. HVAF also creates a coating that adheres better to the surface of the part. While the gentle heating is like that of slow cooking, the time it takes to do it is not.

Higher Spray Rates

The spray rate of HVAF can be four to five times faster than that of HVOF. This means we can lay down more coating in less time. Not only is there a possibility of more coating, but that coating is more uniform. HVAF produces coatings that are more precise in thickness and parts that are smoother than ever before. The combination of smoother coatings and better bond strength have allowed for HVAF to make an extremely wear resistant and cost-effective coating. This is optimal in many applications but especially for hydraulic rods; an application previously inefficient for thermal spray. HVAF is truly ground-breaking thermal spray technology.

The Cutting-edge of Thermal Spray Technology

Overall these factors extend the life of parts even longer than any other thermal spray method we have seen to date. HVAF widens the application of thermal spray to new production and repair markets. In applications where hard electroplated chrome, or hard chrome plating, was the only solution, thermal spray now competes. HVAF offers the same erosion, corrosion and cavitation resistance of HVOF but at a whole new level. The smooth and uniform coatings of HVAF will take thermal spray to markets not possible before. HVAF is the new way to thermal spray. Will your part be a part of the future?

Call us today to see what HVAF can do for you!