Nowadays, such new terminology as perimeter weighted forged irons, cast-blade, and constant MOI (moment of inertia) are often seen and somehow catch our eyes. Nonetheless, they are nothing but confusing. This page will explain such terms especially with their relationship to the trends in the marketplace,  in addition to physics and mechanisms of irons.

There are two main and noticeable market segments in the market of irons: 1) forged irons represented by such products as Mizuno T-Zoid and Ben Hogan Apex; and 2) cast irons represented by products like Ping i Series and Callaway irons. One of the most notable recent trends in the irons market is perimeter weight forged irons, which are manufactured by the double or triple forging method. As opposed to the traditional chromium plating finish, perimeter weight forged irons are often nickel plated for a softer feel (see "Materials" for details). Previously, most recreational golfers assumed that the term "forged" was synonymous with "blade", and were not interested in using them. However, today there are many forged models that feature cavities and slightly larger sized club-heads. This gives a wider range of players the opportunity to experience the softer feel of forged irons, while having the added forgiveness of cast irons.Another noticeable trend in the market is the multi-metal design for cast irons with a lower center of gravity (CG). This approach is employed by many manufacturers, but most notably by Callaway with its HawkEye Tungsten Injected Titanium Irons and Taylor Made FireSole Irons. Callaway claims that its new proprietary weighting system allows its engineers to create a center of gravity lower than any of the company's previous iron models. The Hawk Eye 5-iron has a center of gravity that is approximately 24 percent lower than the other low CG models like the Great Big Bertha Tungsten-Titanium Irons or Big Bertha X-12 Irons. The weighting system makes its CG very low.

Production Method - Irons are manufactured either by investment casting or forging. The casting process, which is used for the majority of irons produced today, is the "lost wax method". This method involves the creation of male molds first made of wax to create the female molds which later are filled with molten metal. Typically, golf iron heads are casted in 17-4 or 431 stainless steel. In contrast, forged irons are forged from a solid piece of soft carbon steel (mild steel) and then finished by hand. On average, mainly due to hand finish forged irons tend to be less consistent and more expensive.

Materials - Although the use of titanium has proven to be valuable in the design of drivers and some fairway woods, it is not the case in irons. Because of the fact that the club-head of irons can be much heavier than that of drivers, titanium proved to be rather pointless, unless it is used in combination with heavier, more dense metals. Consequently, stainless steel still remains the material of choice for most iron manufacturers. Carbon steel is also still used by several companies (both for forgings and castings) because of its forming capability and superior feel characteristics. Nickel is also used for castings, and plating as well, because of its unique combination of strength and softness (see "Materials" for more information).

Flow Design - You may have heard of a terminology "flow design", which appears to be used for changing or adjusting the club-head or shaft design in accordance with the flow of clubs -- from a short iron to the middle and then to long irons. Obviously, as you see in the table below, any set of clubs employs the "flow design" concept -- the shaft length, loft, lie angle were all changed in accordance with the flow of clubs. But, often such specs as shaft weight, kick-point, and sometimes like swing-weight are not variables. The flow design incorporates factors normally considered as non-variables in order to optimize the performance. Constant MOI (Moment of Inertia), for example, is one of such concepts, but it appears to be rather meaningless unless it is coordinated with other factors, and particularly if you don't know what MOI value is most suitable for you (see "MOI" for more details).

Sole Design - Sole geometry is often cited by manufacturers. It is often claimed that an increased sole camber or a rounded sole reduces turf drag, and therefore helps improve playability in tough lies. In general, the shorter the irons, the more bounce. Traditionally, long irons are built with a slight scoop angle. From a deep rough, the bounced sole minimize the turf drag, and that is why we are taught to open the club face under such circumstances.

Shaft Length, Loft and Lie Angle - The iron sets sold by retailers and pro shops usually consist of eight irons (3-PW), while most of manufacturers offer from 1-iron through lob wedge. For a complete set, you may have to buy such clubs as a sand wedge and 2-iron as individual clubs. The typical shaft length, loft and lie angle of a forged iron models are as follows:

Typical Forged Iron Model Configuration

	7	8	9	PW	SW
Shaft Length	36.75"	36.25"	36.00"	35.75"	35.50"
Loft Angle	35°	39°	43°	48°	56°
Lie Angle	60.5°	61°	61.5°	62°	63°

The technological advancement in the investment casting technology as well as new material applications to golf equipment have resulted in clubs with lower center of gravity and less loft. The cavity-back and perimeter weighted clubs, therefore, tend to be less lofted than the specifications of forged irons shown in the above table. However, it appears that, as average golfers tend to prefer additional distance for all golf clubs, many manufacturers started to sell less lofted irons for additional distance. As a result, the loft of 10 years old 8-iron may be equivalent to that of today's 9-iron. This makes it necessary for many golfers to carry three or sometimes even four wedges in the bag.

Hosel - The design of a hosel influences the torsional movement of the club. Additional torsional moment, which becomes available from such designs as offset hosel, increases the potential distance with a commensurate loss of accuracy. The distance between the CG of club-head and the shaft axis as well as the gravity angle are basically determined by hosel. Offset clubs allow golfers to keep the club-head behind the hands, making it easier to keep the face closed at impact. For irons, however, since accuracy is normally more important than additional distance, club designs to lower the torsional moment (which is calculated as mass times distance) are rather considered to be beneficial to lower handicap golfers and professional golfers. (The inset hosel is example of a technique used to minimize the distance and the torsional moment.)

Mens Irons  Womens Irons