SportsGolf Club Shafts
Carbon fiber shafts are longer but light, so they can produce high head speeds and longer carries.
Golf clubs must be able to "carry the ball further precisely in the desired direction." To increase the "carry," it is important to make the club as light as possible to increase the head speed and raise the initial speed of the ball, and to do this, the shaft must be made lighter. In doing so, one key challenge is to maintain enough strength to prevent breaking. Under the brand name of TORAYCA®, standard-elasticity high-strength yarns with a modulus of elasticity of 24 tf/mm2 and moderate-elasticity high-strength yarns with a modulus of elasticity of 30 tf/mm2 have been developed, to achieve straight materials offering good bending strength. In addition, there has been a need in recent years for lightweight shafts that not only have bending strength, but are also resistant to breaking due to "insufficient torsional strength," which led us to improve the elongation and strength of the high-elasticity material in the bias layer to achieve higher performance.
As for the other required performance of "directionality," it is important to make the shaft to have "resistant to twisting (improved torsional rigidity)" to prevent the directionality of the ball from dropping due to twisting of the shaft that occurs when the center axis of the shaft does not match the ball hitting point of the head. Torsional rigidity becomes the lowest when the layering angle is 0° or 90°and becomes the highest when this angle is ±45°; accordingly, a ±45° angle is incorporated into layering as a "twisting reduction measure," and the high-elasticity yarn with a modulus of elasticity of 40 tf/mm2 has taken roots as a standard anti-twisting bias material. Currently, torsional characteristics equivalent to those of a steel shaft are realized with the use of carbon fiber with a high modulus of elasticity of 46 tf/mm2 or more.
Historically, golf shafts initially used hickory wood (known for high strength and impact absorption) and other natural materials; thereafter, steel shafts appeared in the 1920s, and carbon shafts became the mainstream in the 1970s and have remained so until today.
After Shakespeare developed the first carbon shaft in 1972, other manufacturers followed suit. Carbon shafts became the darling of the media in Japan because G.Brewer from the U.S. who won the Pacific Club Masters Tournament was using CFRP clubs made by Aldila. In 1973, Olympic released a Japan-made carbon shaft using TORAYCA®/glass fiber textile. The initial product had a spec of 85 g/12° torque, but in the following year, a100% TORAYCA® product with a spec of 77 g/6.9° torque appeared and created the big boom dubbed the "black shaft" revolution.
A sheet-wound shaft using prepreg is basically constituted by an internal layer angled at ±45° (called "angle layer" or "bias layer"), lengthwise layer angled at 0° (called "straight material"), and reinforcement/thickness adding material at the head hosel. The shaft characteristics such as "flexibility, torque, weight and kick point" are determined by how these layers are combined. Carbon fiber allows these performance characteristics to be optimally designed with minimum weight, which was not possible with conventional metal materials, by combining desired layering angle, thickness, etc.
To adjust the flexibility, torque, weight, kick point and other elements of the golf shaft this way according to the physical strength of each golfer to give the club a good carry with excellent directionality, the characteristics of carbon fiber were utilized for design optimization, and various types of shafts designed for top golf pros and hard hitters to seniors and female golfers have adopted carbon fiber. Today, virtually 100% of wood clubs and 65% of iron clubs are made of carbon fiber. Undoubtedly this will be continue to be an important material to support the evolution of golf.