Hickory? Steel? As with anything, technologies progress and the next “big thing” comes along. Hickory was the material choice for shafts in the beginning of golf and consistency of the product was difficult to achieve. Steel shafts were developed and touted the benefits of more consistent product, but there were design limitations with steel, such as lighter weight shafts. Graphite shafts were introduced in the 1970’s, but the material was in its infancy at the time and not quite understood as to how to design and produce quality shafts. That was 30 years ago, and a lot significant technological and manufacturing improvements have been made since then. Now many choices confront consumers when it comes to graphite shaft options. What sets shafts apart from one another are the technologies applied in graphite shaft designs which benefit the consumer by producing a more consistent product that the consumer can relate back to better scores.
Graphite fiber has been around since the late 1800’s, when Thomas Edison used a graphite fiber filament in the first incandescent light bulb. Nearly 100 years later, graphite fiber found its first use in golf shafts and since that time shafts have continued to develop and improve. As the quality, availability and selection of graphite fiber has improved, so have the shafts produced from this material. Why graphite fiber? It is one of the lightest, strongest materials ever developed. Graphite fiber is 1/4th the density of steel and up to 10 times stronger than most steels. Graphite fiber comes in a multitude of modulus (stiffness) values, which allow designers to combine different types of fiber into one shaft design. Combining these materials gives shaft designers the ability to control torque (from <2.0 degrees up to 6.0 degrees or greater), flex (flexible Ladies to X-stiff), and weight (40 grams to 120 grams). The flexibility of designing different shafts to fit different needs is almost limitless.
One main advantage of graphite versus steel is the wide range of stiffnesses of which graphite fiber is made. Steel materials have one stiffness, so designs are reliant on changing wall thickness or step patterns in order to achieve different flex /torque profiles. Also, steel is an isotropic material, which means it has the same mechanical properties in all directions; therefore, steel shaft designs have limitations. Graphite fiber shafts are anisotropic, which means that the mechanical properties are specific to the direction which the fibers are aligned. Why is this important? With graphite fiber, we can orient the fiber in the specific direction in which the mechanical properties of the shaft need to be optimized. For example, in order to control torque, the graphite fibers run at ±45° down the length of the shaft. By using a graphite fiber with a low modulus (stiffness), a higher torque shaft will be produced. If a high modulus graphite fiber is used to control torque, this results in a much lower torque shaft, which can lead to improvements in control of off-center clubhead hits and improved accuracy. With graphite shafts, our designers are able to use very high modulus graphite fibers that allow them to produce shafts that can have the combination of low torque, light weight and specific flex profiles, such as those found in our Proforce products (Proforce V2, Proforce AXIVCore).
AXIV Technology is a proprietary 4-axis material that UST is using in the design of its latest and most technologically advanced shafts. What is AXIV Technology and how does it work? Through our partnership with Japan’s Mamiya OP, we have developed this unique woven graphite fabric that combines graphite fiber in four distinct directions that maximizes torque, flex and hoop stiffness in one single layer of material compared to standard two- or three-directional woven materials. By strategically placing AXIV material within the shaft, our designers can influence torque, flex, trajectory, and feel. For example, the new Proforce AXIVCore shaft has AXIV material in the butt section to help reduce ovalization of the shaft throughout the swing, which improves consistency and control and improves the overall feel of the shaft. Why four directions? There are three main variables that need to be controlled in a shaft design that give the most optimum performance: torque (±45°), flex (0°), and hoop deflection (90°). Typical graphite shafts use individual layers for each direction. There are separate layers for torque (±45°), flex (0°), and hoop (90°). With AXIV material, fibers are precisely woven into these four directions (0°, 90°, +45°, -45°) all within one layer of material. This allows our designers to strategically place AXIV material where it is needed the most. For the Proforce AXIVCore, we designed these shafts with AXIV material on the inside of the butt end of the shaft. In order to create more stability under the hands and to improve hoop stiffness, we determined the exact amount of AXIV material needed in this section of the Proforce AXIVCore shaft that is required to optimize both stability and hoop stiffness.