Maximum Ball Speed Plus Largest Sweet Spot

A longer drive and larger sweet spot have long been the holy grails of golf technology. In earlier days, golf design­ers manipulated face thickness to enhance the coefficient of restitution (COR) to produce a longer driving distance. Since the adop­tion of COR standards by the USGA, meeting the legal COR limit has become a default stan­dard amongst reputable drivers in the market place.

The variable face thickness con­cept was not in­vented overnight. It was widely known amongst golf designers and top players that by grinding the club face, driving dis­tance could be notably improved.  The first invention that bore some resemblance to the current implementation was a patent filed in 1994 by Glenn Schmidt and Rich­ard Helmstetter of Callaway Golf.  It called for a gradual increase of vertical thickness from toe and heel toward the center of the club face. This early implementation was simply a way to prevent stress failure of the striking face.

Six years later in 2000, the first contemporary oval design that places a thicker face behind the sweet spot emerged. It was again pioneered by Callaway. Titleist soon followed with a similar concept.  In 2002, Ping filed the first pat­ent on the reversed cone face structure.  Not to be left behind, TaylorMade followed up with its own version of it soon after.

There are several design concepts within variable face thickness: dome, reversed cone, and x face. All intend to accomplish the objective of putting just enough thick­ness behind the sweet spot to prevent stress failure and less thickness around the rest of the club face. By manipu­lating the thickness contrast between the sweet spot and the area outside of it, the trampoline effect is maximized.

With COR standardized, golf designers are once again tasked to outdo themselves. The new challenge is to maximize ball speed under the COR limit of .830. As a long-time supplier to the long drive circle, we noted over a decade ago that the extent of the club face percussion can be identified by striking the driver face with the edge of a quarter. A sharp and high-pitched sound usually cor­responds with a high percussion, hence a higher COR.

In one of our previously patented inventions for titanium composite matrix golf shafts, we used a sandwiched titanium structure to improve structural strength. Our engineers concluded that a sandwiched titanium face would naturally be thinner and stronger than a one-piece structure as advocated by most golf companies. The best analogy is to compare plywood to solid wood.  A piece of properly constructed plywood is stronger than its equiva­lent in solid wood. This was the origin of the dual face invention, and this concept was granted a patent by the U.S. Patent Office in 1999.

By using a dual face structure, we created a much larger sweet spot with an exceedingly higher ball speed upon impact as compared to the single-layer club face struc­ture. This dual face tech­nology will be built into the maximum COR Hathaway V4 and V6 adjust­able drivers.