In theory, iron design is pretty simple: to achieve distance, you need a face with a fair amount of spring-like effect that precisely matches the correct centre-of-gravity position, all while maintaining the feel of a one-piece club.
So says Scott Manwaring, Callaway’s director of iron design. But then Manwaring explains how complicated this actually is – a science project that seems equal parts erector set and computer-generated imagery.
Modern iron design increasingly requires the use of multiple materials that mix heavy and light elements, high-energy polymers and previously unimaginable internal structures to get the weighting low and the face thin – yet maintain the classic feel that Bobby Jones would recognise. Companies are sourcing new metals made for airline brakes and roll cages to allow the face to flex at rates once reserved for drivers. Often there’s a heavy metal thrown in, too, like tungsten, a dense material the military uses on the tips of its bullets and missiles.
So as you look at these six new iron sets that deftly combine traditional shaping with high-tech engineering, you might wonder, What else can be done? Manwaring just shakes his head. “The theoretical limit of a playable iron design? I don’t know if we know the answer,” he says. “We’re going to keep trying to find out.”
JPX919 Forged (Top)
Does a hotter face come from a better material or a better method? Maybe both. These forged cavity-backs have extra strong boron-infused carbon steel. A hidden slot is cut through the sole to create a large flexible area on the face.
Tour B JGR HF2 (Middle)
The benefits of a thin face often come with a challenge: feel. That’s why a rubber polymer fills the internal back cavity to smooth vibration on this hot, L-shape face insert (seven irons).
Exotics EXS (Bottom)
This distance recipe combines a wraparound cupface with a hollow lower cavity. This yields flexing where more iron shots are hit. A tungsten toe weight stabilises the head, and a gel-coated cavity badge controls feel (seven irons).
Big Bertha (2019) (Top)
Callaway calls these irons its hottest and easiest-launching. A thin cupface injected with urethane provides maximum face flex and feel, and dense tungsten is suspended in another kind of urethane to increase launch angle.
Z 785/Z U85 (Middle)
Maybe the right mix of feel and distance requires two types of irons within your set. The single-piece forged carbon steel in the 785 provides tour feel in your scoring irons. The hollow, fast-face U85 offers speed where you need it (up to your 6-iron).
0311XF GEN2 (Bottom)
A high-strength, maraging-steel face is supported by a polymer that fills this hollow design, softens the feel and transfers more energy to the face. A larger shape and slightly wider sole add forgiveness.