Miura-san believed the manufacturing process of forging irons was fundamentally flawed. So, he changed it. This resulted in a revolutionary new technique that elevated Miura irons to the highest industry standards with the tightest tolerances.
Miura uses raw material called S20C, which is also referred to as premium soft carbon steel. This premium steel is delivered to the Miura factory in various girths and lengths from which billets of steel are measured and cut to correspond with the desired weight of the individual models. Achieving the highest tolerances in the industry starts here.
Once prepared to the desired length and thickness, the billets are heated to 1200°C. The first strike compresses the billet into a flat shape which allows the raw material to be placed easily into a die. The proprietary Miura process forges the club head without a hosel attached. This technique allows the Miura craftsmen to manipulate the grain structure and create the renowned Miura look and feel.
Within seconds of the first strike, the heated steel is placed into a second die where the subsequent strike forges the steel into the golf head.
The innovation of the deburring technique is what separates Miura from its competition. Following the second strike, the club head is placed in a tray where it cools before beginning its journey to the next stage. Heating the club head once while delivering the first two strikes significantly improves the precision of the forging process.
During this stage, the club head is reheated to a temperature of 800-900°C. By allowing it to cool and then be reheated, the shape of the head is maintained while still allowing the grain structure to be manipulated. This is an additional and time-consuming step but is responsible for what Miura refers to as W.D.D. Accurate Forged. During this step the weight, distribution, and density of the club head are defined. In order to reach this stage, the Miura factory has produced three individual sets of dies for each model and loft. Dies alone will not deliver a quality iron—each model needs a precise amount of heat and force. Forging also requires the skill, patience, and experience of a Miura craftsman.
Stamping an iron includes marking the Miura logo, numbers, and scoring lines. A variety of proprietary machines and techniques are used to perform the steps without compromising the club head’s integrity. The most critical part of this process is the stamping of grooves and scoring lines. Due to the golf industry’s dimensional standards, the Miura craftsmen must be precise. Additionally, the scoring lines become the foundations for the lie, loft, and offset of each iron. If the scoring lines are imperfect, they affect the club head’s integrity.
This is often referred to as the most unique aspect of the Miura forging process. It is here that the hosel is attached to the club head by a “spin forged” technique. No additional agents are used to attach the hosel. Instead, friction creates between the hosel and head melds the two components. This allows for the ultimate delivery of precise lofts, lies and offset. It is at this stage that the actual club head has taken shape and throughout the remainder of the process the weight tolerance of +/- .5 grams will be maintained.
