Iron Designs

<strong>First injection molded polymer body and metal ironhead</strong><br /> 1989 – Dynacraft IMI-703 (prototype model only)

Described in US patent #5,333,871, this was the golf industry’s first ironhead designed by injection molding a light and strong polymer material over a heavy steel sole and inner core piece. The intent was to create an ironhead with a very low center of gravity and weight distribution that could be varied a lot more significantly than in any full homogenous metal or multi-metal construction. The model remained an innovative prototype only when the company for which Wishon designed at the time decided not to incur the high cost of injection mold tooling dies to manufacture the full set.

<strong>First vertical flow weighted iron set</strong><br /> 1990 - Dynacraft Genesis Irons

Numerous sets of irons from the mid-1990s to present times which have been made by a several of the largest golf companies borrowed the weighting concept of progressing the placement of weight low on the long irons to higher on the short irons from Wishon’s 1990 Genesis iron design. This progressive weighting concept was called Vertical Flow Weighting. The Genesis iron was the first in the golf industry to introduce vertical flow weighting to keep the center of gravity (CG) low on the low lofted heads to help increase launch angle, and then gradually moving the mass higher in the back cavity through the middle and short irons to prevent hitting the ball too high with the high lofted irons in the set.

<strong>First set of irons to use different steel alloys for different heads within the same set</strong><br /> 1991 - Dynacraft Vari-Steel Irons

The Vari-Steel, short for variable steel alloys, was designed using 17-4 stainless steel for the body material of the long irons, 431 stainless for the middle irons and 1030 carbon steel for the short irons in the matched set. While most certainly a “pain” for the foundry to manufacture because of the requirement to change steel alloys in the investment casting process and monitor different heat treatment procedures for each segment of the set, the Vari-Steel irons employed the use of three different steel alloys in the same set to offer golfers a difference in ‘feel’ and material hardness through the set.

<strong>First set of irons to combine hollow and solid body construction within the same set</strong><br /> 1991 - Dynacraft Innerdyn Irons

Full sets of two-piece, investment cast hollow body irons brought about greater perimeter weighting and movement of the CG further back from the shaft –both proven game improvement features for middle to higher handicap players. However, moving the CG further back from the shaft is not necessary in the higher loft irons, where the loft is enough to enable all levels of golfers to easily get the ball up.

The Innerdyn irons incorporated a combination of hollow body, rear-CG long irons with one-piece, solid body middle and short irons. The Innerdyn recognized that a low and rear-located CG was worthwhile in the longer, less lofted irons, but such a design feature is wasted on the irons where the normal loft increase and length decrease combine to make the iron easy-to-hit. Thus the game improvement features of the Innerdyn were offered were they were needed, not where they were not, and kept the total price of the set more affordable than all hollow iron set designs.

Notably, the Innerdyn irons stand as the forerunner to sets of irons made with hybrid type irons and conventional type irons in the same matched set which were first introduced in the early 2000s by several of the large golf companies.

<strong>First one-piece investment cast ironhead with undercut cavity</strong><br /> 1994 – Golfsmith RMC270 Irons

Ironheads with an undercut back cavity became a popular offering of many companies in the late 1990s and early 2000s. The first such ironhead design which attempted to “scoop out” metal from the lower back area of the iron to position weight farther behind the face to move the CG farther back from the shaft for a higher shot trajectory was the RMC270, which was designed by Tom approximately 5-6 years before undercut irons became a popular style of design with other companies in the golf equipment industry.

<strong>First set of ironheads with all CNC machined faces</strong><br /> 1995 - Golfsmith CNC5000 Irons

In the middle-1990s virtually all ironheads were manufactured by investment casting. While a very accurate process for repeating specifications and shapes in volume production, the faces of investment cast irons at this time were never consistently flat. In addition, in the middle 1990s the dispute over V- or U-shaped scorelines and which was better for generating more backspin was raging in the golf equipment industry.

The CNC5000 ironheads were investment cast with the scorelines in the faces from the casting process after which each face was precision computer machined to a condition of flatness within a tolerance of 0.001”. A milling pattern was chosen which created a ridged texture on the entire face that increased the friction between the face and the ball in an effort to enhance backspin on the ball. However, perhaps the most significant part of the manufacture of the CNC5000 was that after face milling the irons still had consistent USGA conforming score lines –given the nature of face flatness variations from the investment casting process, machining the face after casting could have created wide variations in the width and depth of the lines on the face. Thus to even manufacture the CNC5000 irons, the casting process had to be improved to make a very flat face right out of casting so that when the faces were machined, the scorelines were still consistent and USGA legal.

Notably, the CNC5000 irons represented the first time a full set of irons had been made with milled faces, a technique even today that is relegated oonly to some companies’ wedges.

<strong>First iron set with progressive topline thickness for vertical center of gravity change</strong><br /> 1996 - Golfsmith XTR II Plus Irons

In a design shape and style that Tom later admitted was a bit too visually different for most golfers to accept, the XTR-II ironhead set represented a design in which the topline width was designed to be thin on the long irons (3.5mm wide on the #1-iron) and then allowed to widen progressively on each ironhead through the set (12mm on the wedges). Through this design feature, it was possible to keep more of the head mass lower for a lower CG in the long irons, while progressively moving the CG higher to offset hitting the ball too high as loft increased through to the short irons and wedges. Later modern designs such as the Cleveland Micro-Cavity irons, in which weight is removed from the topline to enhance the CG location, stand as a concept pioneered initially in a Tom Wishon design.

<strong>First titanium iron with bi-metal construction introduced in the USA</strong><br /> 1997 - Golfsmith MWD1000 Irons

Titanium alloy irons had a short life in the golf industry, chiefly because a full set sold for nearly $2000, second because the first sets introduced by Tommy Armour Golf were hugely larger in blade size than what golfers were comfortable with playing. When formed into a hollow body, thin face woodhead, a titanium design performs better than any other metal wood because its high strength to modulus ratio allows for a faster ball velocity off the face.

However, when a Titanium alloy was formed into a solid body construction for an iron, the spring face capability is eliminated and the low density of the titanium requires the head to be extremely large to achieve normal iron head weights. The MWD-1000 irons recognized that the potential for Titanium in an iron design could only be realized by designing the head as close as possible to a normal ironhead size, and then employing the use of heavy density weights attached to the head to reach normal headweight and to improve the perimeter weighting and CG requirements of a game improvement ironhead design. Thus the MWD-1000 irons became the first solid titanium alloy ironhead to utilize a second high density metal (brass) in the design to allow the creation of a more normal size head with greater perimeter weighting (MOI).

<strong>First iron with multiple face thickness variations for CG and weight distribution control</strong><br /> 1998 - Golfsmith Jetstream 2 Irons

In 1998, Tom had discovered that moving the center of gravity (CG) 2mm to 3mm toward the heel side of the center of the face would allow the golfer to more effectively rotate the club back to square on the downswing and thus reduce the chance of pushing or fading the ball. For some time, it had been agreed by all club designers that a lower CG was preferred for average to less skilled players. Prior to this time, investment cast stainless steel irons were always made with a uniform face thickness of 3mm to facilitate consistency in flow of the molten metal the investment casting process so the center of gravity (CG) position had to be controlled by the height of the blade or the width of the sole.

The Jetstream 2 irons were designed with different thicknesses over different areas of the face –the upper toe area was reduced to 2mm and the lower toe area to 2.5mm to keep weight from being high on the head and too far from the shaft. The bottom areas of the face were increased to 4mm thickness to help move the CG lower in the head. Thus the original height of the blade and sole width could be retained while still being able to manipulate the position of the CG in the head. This design required very precise production dies to be made to ensure the accuracy of the face thickness design in the casting process to be able to move the CG to the desired position lower on the head and a little closer to the shaft to offer golfers more control and accuracy.

<strong>First iron manufactured with aluminum alloy body</strong><br /> 1998 - Golfsmith TG System Irons

Tom knew from his previous experience with designing the titanium + brass MWD1000 irons that a key element in iron performance was to be able to re-position as much of the head’s total mass in specific areas of the head to improve off-center hit forgiveness (MOI) and/or to lower the center of gravity (CG) to increase the launch angle of the shot and make the iron easier for less skilled golfers to hit well up in the air to fly. To gain the most mass possible to move to desired areas of the iron requires that the body of the iron be made from the lightest material possible that is still able to withstand the force of impact.

The predominant metal used in the manufacture of ironheads since irons were first invented in the 1700s has been steel. However, steel is a high density material. For their basic shape and size, steel ironheads allow very little additional mass to be left over to be re-positioned on the head to enhance the MOI or change the CG location. While titanium irons were developed in the late 1990s did allow mass to be positioned on the head for MOI improvement, their much higher cost soon proved that golfers simply would not pay that much for a set of irons.

Because irons are subjected to far less impact stress than woods, Tom decided to turn to a high grade aluminum alloy to construct the body of the ironhead. Because aluminum has a density less than half that of titanium and 70% lower than steel, an aluminum body iron would allow a tremendous amount of the total weight of an ironhead to be able to be moved to areas on the head which would greatly increase the MOI and lower the CG.

The TG System irons were truly an innovative advance in clubhead production engineering. They were designed and manufactured with a stainless steel sole and twin heel and toe located tungsten weights on the back to lower the CG and increase the MOI. In addition, the face of each TG System iron was plasma coated to give the face the required durability. Thus the TG System irons became the first aluminum body iron ever designed and offered a greater amount of weight distribution enhancement than any iron yet made.

<strong>First Thin Face Forged Steel Set of Irons</strong><br /> 2000 - Snake Eyes Fire Forged Irons

Because of his experience between 1994 and 2000 designing numerous thin face drivers with a high strength steel face with a higher Coefficient of Restitution (COR), in 2000 Tom went to work to determine if it could be possible to design an iron with a higher COR to offer golfers more distance. This was a difficult task because of two primary reasons: 1) as loft increases, the ball cannot flex the face inward as much to generate a higher ball velocity, and 2) irons are typically designed with an asymmetrically shaped face. Clubheads with a more symmetrical shape face such as drivers are far easier to design to enable the face to flex inward more from impact with the ball.

By working with a technically astute clubhead production foundry which also had the ability to formulate experimental steel alloys to achieve different mechanical properties, Tom spearheaded the task to create a new high strength steel alloy with a yield strength in excess of 250KSI but also with slightly more elasticity (lower modulus) than other steel alloys used in clubhead design. This custom steel alloy was then true forged at a thickness of only 2.1mm to create the faces which were welded to each of the head bodies in the Snake Eyes Fire Forged iron set.

Testing with the Fire Forged thin, high strength steel face irons showed an increase in Smash Factor (Ball Velocity divided by Clubhead Velocity) over previously designed thick face irons. Air cannon COR testing showed the Fire Forged irons had a COR of 0.805, compared to the typical 0.775 COR of a conventionally made investment cast stainless steel or forged carbon steel iron.

<strong>First forged iron to incorporate a 5-step forging process</strong><br /> 2003 – Wishon Golf 550C and 550M forged carbon steel irons

In 2002, Tom was asked by one of the leading clubhead production foundries to help solve a problem for one of the foundry’s other golf company customers. This company was trying to promote a new forged carbon steel iron on the PGA Tour but had been receiving criticism from a number of the tour players that the face profile shape at the leading edge position of the heads in the set was too inconsistent.

After researching the problem, Tom determined the inconsistency in the shape of the leading edge came because the final grinding of the heads required the foundry’s workers to grind too much off the bottom of the sole directly under the leading edge to remove the wide flat section left from the shearing off of the excess steel after the typical 4th and final step in the forging process.By making another forging die mold, and forging the heads one more time, the area under the leading edge of the face which had to be ground to blend with the sole radius was greatly reduced to a very small and narrow section of steel. The workers could then more accurately grind off this small section of excess steel without changing the profile of the leading edge. The result was the foundry could now deliver heads which demonstrated a very high level of consistency for overall face profile shape.

However, an additional benefit of adding a 5th step to the forging process was not realized until the Wishon Golf 550C and 550M forged cavity and muscle-back irons were being designed and tested in the fall of 2002. While the 550’s displayed the same high level of face profile consistency known to come from the additional forging step, golfers involved in the testing of the 550’s reported a much softer feel of impact than they had ever felt with previous forged carbon steel irons.

Investigation of these claims eventually showed that by forging the heads one more time than had been done before, the carbon steel alloy used to make each head was being pressed much tighter in the 5th die mold. Photomicrograph analysis showed the additional 5th forging step had compressed the steel in each head much tighter than was possible from the previous 4 step forging process. This 5th forging step thus had the effect of greatly reducing the natural ‘voids’ (microscopic holes) inside the grain structure of the steel that are present in all forged ironheads. By eliminating a huge number of these voids, the internal vibrations from impact were also reduced, which had the effect of transmitting a softer and more solid feel to the golfer.

Word of this change in the forging process soon circulated around the golf industry and by 2004, other golf companies were marketing the claim that “their new 5-step forging process made their forged irons better and softer feeling.” In reality it was Tom Wishon who brought this production improvement to the forging process first.

<strong>First Variable Thickness Face Set of Irons</strong><br /> 2004 – Wishon Golf 770CFE Irons

Shortly after he started his own company, Tom wanted to go back to work on designing am iron model with a higher COR iron than his first attempt at this area of clubhead technology in 2000, the Snake Eyes Fire Forged Irons. While the Fire Forged thin face irons did prove it was possible to push the COR of an iron higher than had been previously seen, their COR of 0.805 was only marginally higher than the typical 0.780 COR of the majority of the investment cast stainless steel irons on the market.

In addition, the Fire Forged irons were made with a high strength steel face that was produced with the same uniform thickness over the entire face area. Wishon’s experience with having designed variable thickness faces for various driver head models in the late 90’s also prompted him to speculate if the same type of “thicker center/thinner perimeter” face construction could be utilized on an iron design to improve off-center hit performance. However, the challenge was how could the COR and off-center hit performance be improved for each iron in the set. From the 3-iron to the PW, loft increases incrementally by a total of more than 25 degrees. As loft increases, the impact force necessary to flex the face inward to achieve the higher COR decreases proportionally.

To allow each 770CFE (CFE =computer face engineered) iron to perform as close to the same as possible with respect to their face deflection, Wishon employed the use of three different steel alloys of different strength to progressively increase the faces’ ability to flex inward as the loft increased. In addition, as the loft increased for each iron through the set, each iron’s face was made progressively thinner to allow each higher loft face to flex inward close to the same as each other iron.

For the variable thickness face, Wishon also knew as loft increased through the set, the actual point of typical impact on the face changed slightly. Thus for each iron, the thicker center section had to be positioned in a slightly different area of the face plates. This type of design required very tight tolerances for the face thickness of each iron. To meet that challenge each face was CNC machined to its specific thickness dimensions to a tolerance of 0.05mm (0.002”).

While all this work pushed the measured COR of the 770CFE irons to 0.815, the other significant benefit was the performance of the variable thickness face for improving off-center hits. Shots hit 1” off center resulted in a loss of only 2.5% of the on center hit ball speed. The 770CFE irons were recognized as the “most innovative new iron” of 2004 by Golf Illustrated magazine and also achieved a Golf Digest Hot List recognition as well. The first variable thickness irons offered by a major golf company were introduced two years after Wishon Golf introduced the 770CFE.

<strong>First CNC Milled Cavity Iron Set</strong><br /> 2007 – Wishon Golf 560MC forged carbon steel irons

For decades, forged carbon steel irons were relegated to a muscleback shape with no cavity on the back to improve the heads’ off-center hit performance. In response to traditional golfers’ request for better off-center hit performance, the industry introduced the first cavity back forged carbon steel irons in the 1980s. While their off-center hit performance was better than a pure muscleback forging, that game improvement aspect of the forged cavity back iron fell well short of what was possible in the very deep cavity back style of investment cast stainless steel irons. The reason is because in the forging process, the depth of the back cavity is very limited. In forging, metal is “pushed around” the head and never actually removed or poured into a shell as it is with a cast stainless iron.

Motivated by a desire to figure out a way to offer the best of both worlds to golfers who wished to play a forged carbon steel iron, Wishon began to think what might solve the problem and allow a back cavity on a forged iron to be as deep and thus as forgiving as a cast iron. The answer came from the simple question of, “how can we actually carve more metal out of the back of this forged iron to increase its MOI and off-center hit performance while retaining the same soft feel of a forging?”

The 560MC forged irons started life as a raw carbon steel forging with a flat back with no shape pattern on the back of the raw forging. After forging, each head was placed into a CNC machining center which actually carved the entire deep back cavity from the back surface of the raw forged head. The result was the 560MC irons not only had the deepest back cavity of any forged iron previously made, but their MOI and off center hit performance was much higher than any other forged cavity back iron. MOI measurements of 5-irons showed the MOI of a forged muscleback was 1050g/cm2, the MOI of a forged cavity back was 2025g/cm2, while the MOI of the forged 560MC #5-iron was 3075 g/cm2.

<strong>First Set of All Hybrid Body Construction Irons</strong><br /> 2008 – Wishon Golf 785HF Hybrid Irons

During the development of the high COR 785HF hybrids, Tom began to think that while it was nice to offer a #2, 3, 4 and 5 hybrid in the 785HF design to allow golfers to replace their hard to hit lower loft irons, it might also be good if the 785HF set could be expanded to allow less skilled golfers and slower swing speed golfers a chance to replace their entire set of conventional irons with a full set of high COR hybrids, all the way through the Pitching Wedge.

Golfers with slower swing speeds and golfers who cannot hit down and through the ball with their conventional irons do struggle to get the full distance possible from their swing speed when hitting a conventional iron. This is chiefly because the center of gravity (CG) of a conventional iron is always very close to the face. It is also known that the farther back the CG from the face, the higher the launch angle of the shot can be, and from that, slower swingers can generate more distance by getting the ball to fly higher.

As a result, Wishon decided to expand the high COR 785HF hybrid design to include a full set option from the #2 all the way through the #9 and PW. In doing so, in 2008 when the 785HF’s were introduced, they not only represented the industry’s first high COR hybrid, but the industry’s first full set of hybrids all the way through the Pitching Wedge.

<strong>First Set of Irons with Variable Thickness Titanium Face</strong><br /> 2009 – Wishon Golf 870 Ti Irons

If there is one thing that is true about Wishon and his work, he is rarely 100% satisfied with any of his original clubhead designs. A few years after designing the 770CFE high COR, variable thickness face irons, Tom began to think about the 0.815 COR of the 770 irons and wonder if something could be done to push that COR right up to the USGA limit of 0.830. Knowing that titanium alloys possessed a higher strength to elasticity ratio than any high strength steel alloy, and realizing titanium has a 40% lower density than steel Tom began to work on designing a set of irons with a thin but variable thickness construction face made from titanium.

There is no question sets of irons with a titanium face had been introduced in the golf industry in the late 1990s. Tom himself had designed a Ti face iron set for the Harvey Penick line of custom designed clubheads during that time. But all previous Ti face irons were designed with the same 3mm thick face as was being used in investment cast stainless steel irons. The only technical focus of the early Ti face irons was to use the lighter weight titanium face to gain additional weight to place in other areas of the head to improve the MOI and off-center hit performance. By replacing the steel face with a titanium face, 40% of the weight previously used in the steel face was now available to be re-positioned elsewhere on the head to improve the MOI or change the center of gravity (CG) location.

Tom’s concept was to basically duplicate the thin, variable thickness steel face design of the 770CFE irons but with a beta grade titanium alloy for the face. Through this, Tom felt the higher strength to elasticity property of the titanium could increase the COR of the face, and the reduction in the weight of the face through changing from steel to low density titanium would additionally allow the MOI of the 870Ti irons to be higher than the MOI of the 770CFE irons for even better off center hit performance.

During a trip to speak at various European PGA educational programs in the summer of 2008, Wishon brought a final 870Ti iron prototype to a meeting he had with the technical department of the Royal & Ancient of St Andrews. After the meeting, Wishon asked the R&A to conduct a COR test on the 870Ti prototype iron. The test showed the 870Ti had an actual COR of 0.829, which proved Tom had been able to achieve his goal of improving the COR of an iron from the 0.815 level of the 770CFE to reach the limit in the rules.

 

One Comment

  1. Brian:

    While it is true that loft has an effect on the smash factor (ball speed divided by clubhead speed) it is also true that with a good, thin face design, the max smash factor of 1.49 can be achieved up to a loft of 28*. We’ve seen that in our hit testing and robot hit testing of our thin face high COR fwy woods, hybrids and 8670Ti irons.

    TOM

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