Thermal Spray Coatings On Golf Club Heads

The game of golf is taken simply as a recreation by many but very seriously by others. While the game of golf itself may seem very simple indeed, there is actually a tremendous amount of physics involved in getting the golf ball into the hole. There are so many variables involved in the trajectory of the golf ball starting with the angle of attack of the golf club on to the ball, the existing wind force, the drag of the grass, the heaviness or lightness of the air depending upon humidity levels, the material of the golf ball itself, the surface of the golf ball as it creates drag against the wind, the material of the golf club itself and its inertia, the material of the golf club head and so on. While addressing every single variable is beyond the scope of this article, we will be addressing only the material of the club head here as it pertains to the use of thermal spray coatings technology. Even then, we will have to limit our discussions in the interests of remaining concise.

Thermal spray coatings have been used as facing materials on golf club heads in recent years. The general idea is that by facing the golf club head with a material that is very hard, the force of the swing gets little attenuation and all of the energy is transferred to the golf ball. Hence, in the early days of introducing thermal spray coatings technology to golf, engineers used the plasma thermal spray process to deposit aluminum oxide on the face of golf club heads. Since then, innovations in thermal spray processes have taken place and nowadays the coating of choice seems to be tungsten carbide cobalt material sprayed by the high velocity oxy-fuel process. In this process, the coating particles are given a tremendous amount of thermal energy as well significant kinetic energy and are subsequently propelled and deposited on to the substrate material. This is the current state of technology in the application of thermal spray coatings on to golf club heads. However, this is not the correct solution in my humble opinion. The reasoning behind the statement is addressed in the following paragraph.

When you apply a thermal spray coating of tungsten carbide on to a golf club head face, the extreme hardness of the surface will definitely impart a higher amount of energy on to the ball. This is what is needed when the golfer tries to hit the ball to cover as large a distance as possible. However, when the ball is to be hit with a high level of control gently as in putting, you do NOT want a tremendous energy transfer between the club and the ball. In such cases, you actually need some force attenuation taking place. Thus a straight tungsten carbide thermal spray coating will not work under these circumstances. Either you need different coatings for different clubs or a single coating system that will address all of the energy transfer needs of the golfer. Obviously, manufacturers of golf clubs will prefer the latter, since it is amenable to lowered manufacturing costs and better quality control since the same coating system gets put on for all club heads.

Additionally, application of a single coating system allows for automatic adjustment of energy transfer phenomena on medium range hits by being in between the long range and the short range energy transfer requirements. Such a coating system can be obtained by depositing first a softer coating relative to the tungsten carbide. A suggestion would be to deposit a cobalt nickel chromium aluminum yttrium coating first and then follow up with tungsten carbide cobalt high velocity thermal spray coating. This will allow the energy transfer between the club and the ball to be maximized on long range hits and cushioned on short range hits; obviously the energy transfer would be some what in between for medium range hits. This is akin to the use of multiple springs with varied spring constants for the purpose of shock absorption in motor vehicles. Hence with the use of a dual coating system, thermal spray coatings technology used on golf club heads can go farther than it is in the current state of technological affairs.