Casting advancements 'drive' golf industry: Casting technology has propelled the science of golf light-years ahead of the days when hickory shafts were common and woods were actually made of wood.

When the likes of Tiger Woods, Phil Mickelson, David Duval and Sergio Garcia chase the storied green jacket at the Masters amidst Augusta's dogwoods and azaleas next month, few spectators or TV analysts will likely give too much thought to the advanced manufacturing technology in each pro's golf bag. On the other hand, the golfers are certainly familiar with the science of their weaponry, and the impact that the precise metallurgy and engineering have on the feel of each club.

The game of golf is serious business. Just ask the 27 million golfers in the U.S. who open their wallets each year to purchase $2.5 billion in golf clubs. Whatever the skill level, try to separate a golfer from his precision "hardware"--which usually is thought of as an extension of the golfer's body itself--and you'll have a fight on your hands.

With that "top of the world" exhilaration you experience after dissecting the fairway with a beautiful tee shot, one might think that the years at the range have finally honed the perfect swing (at least until the next hole). More than likely, however, the credit should go to an investment casting foundry.

The Move Toward Casting

Investment-cast irons and woods first arrived on the scene in the late 1960s and early 1970s at a time when irons were mostly forged and woods were wood--made from persimmon and maple trees. These woods began to be replaced in the 1980s because an engineered metal casting could offer so much more. "From a design standpoint, you couldn't move the weight around in traditional wood--you were at the mercy of the density of the wood," said Gordy Schupmann, golf product engineering manager, Hitchiner Manufacturing Co., Milford, New Hampshire.

Cast woods and irons were somewhat slow to catch on, primarily because casting technology was lagging at the time. "The ability to cast thin-wall clubs accurately and repeatably while improving tolerance performance by a magnitude of two helped drive the trend toward casting," said Schupmann.

While some pros play with forged products today, it's the higher handicap, or more average golfer, that should really appreciate the cast club design. According to Schupmann, forged steel clubs are more difficult to hit because the weight cannot be distributed around the perimeter of the club. "The cast club is more forgiving. You don't have to hit off the center of the club as consistently to hit a straight shot. Forgings are really for the premium golfer, as there's much less room for error."

A recent PGA Magazinearticle noted that: "The late Gary Adams revolutionized the industry 20 years ago with the 421 stainless steel Taylor Made metal wood. It was cast. It had to be. Casting allowed more design options by pouring molten steel into [molds] instead of trying to press heated metal into a die."

A cast design also offers several production advantages, including tooling costs (modifications are quick and relatively easy, as is repair), leadtimes (prototypes can be made in as few as 3-5 days), and consistency (fewer pieces and welds result in tighter tolerances with less variance).

PGA Magazine also noted that forged clubs come with a 25% higher cost than a comparable cast item. Added Schupmann, "Also, there are more secondary operations on a forging. Score lines, artwork and product name all must be machined. All these things can be done during the casting process." Today, Louis Pardini, director of purchasing for Tommy Armour Golf Co., Morton Grove, Illinois, estimates that about 85% of all golf clubs are cast.

Design Criterion

Pardini, a golf industry veteran, remembers the trend toward cast hardware and the early calls from foundries jockeying to produce the golf products. "They'd sell us on how they had produced space shuttle castings. I'd say, 'Yes, but have you ever made a golf club?'"

The golf club is a highly engineered component and one that must carefully account for human physics and 100 mph swings in product performance. Clubhead design requires a balance of performance, durability and ability to manufacture, said David Rose, Metalwoods' engineer. "Weight distribution of clubhead mass is crucial for ball trajectory."

Designers and their casting suppliers must pay close attention to the club's center of gravity, tolerance performance (extremely thin walls of 0.030 in. and 0.040 in. for steel and titanium, respectively) and weight (+2, -1 grams). Other vital concerns are the angles of the lie (angle of the club head and hosel) and loft (angle the clubface makes with the ground), both of which are typically within [+ or -] 1 [degrees]. "Casting a wall at 0.030 of an inch and still withstanding an impact at 85-100 mph is a challenging undertaking," Schupmann said.

For the foundry, there are a number of things that often push the casting envelope. These include castability (are there isolated heavy sections that must be fed, where will weight be placed?), weight vs. size (can weight be met at the specified volume?), type of plating, engraving issues (is it near welding, what is its impact on castability and finishing?), available room for gating, and club construction (such as add-on weights, stickers or medallions).

Despite the advanced technology and tools, there's still a great deal of gray area that challenges designers, and is something that can't be put into the print. "The club must not only perform in the hands of the professional, but also provide that 'feel' they are looking for," said Paul Mikkola, Hitchiner's executive vice president/ operations. "As a result, the science and techniques available through CAD are sometimes not used as well as they should be. But as the physics are better understood, the design possibilities of casting give designers more degrees of freedom than they would enjoy with other processes."

Cosmetics

While appearance is often an afterthought in many casting markets, aesthetics is very much a critical issue in the golf industry. "Once the design is finalized, it's all about cosmetics, cosmetics, cosmetics," said Schupmann.

Added Cast Alloys President Jim Collins: "Golf clubs are like jewelry for men. The golf industry places the same very high value on cosmetics as it does on dimensional characteristics."

Said Mikkola, "It's one of the quirks of this business. Even if you have a club that hits the ball fantastically, if the golfer looks down at an ugly piece of metal, it isn't going to sell. looks have a lot to do with what the pros will put in their bag."

Schupmann said it must not only be highly attractive, but differentiable from other products--no small feat with the high number of golf equipment suppliers today. "The pluses and minuses that can be tolerated, on say an automotive part, just can't be allowed on a golf club. We're light-years ahead of what we used to produce from a cosmetic standpoint. With the exception of maybe medical implants, golf clubs are as difficult a cosmetic casting job as I've seen."

Materials

Most cast irons and woods are produced of 17-4 and 4-31 stainless steel; common investment cast alloys that have been used in aerospace applications for years. "These alloys' principal benefit is high strength in a stainless composition," said Raymond Monroe, executive director, Steel Founders' Society of America, Barrington, Illinois. "In golf equipment, high strength gives high hardness, which transmits the maximum energy from the club to the ball, making the ball go further."

A newer trend increasingly hitting the links is cast titanium clubs. Considered a "space-age" metal, titanium has grown in importance and value over the years, according to the Investment Casting Institute, Dallas. Process improvements in vacuum melting (because titanium is so reactive and oxidizes very quickly, it must be melted under a vacuum) and molding has spurred tremendous growth in the production of aerospace, medical and sports equipment applications. The growth in the production of titanium golf heads has been described by many as "phenomenal."

Titanium is gaining attention due to its high-strength, low-density benefits (titanium's strength is on par with steel but at half the weight). It allows golf designers to increase the size of the club while maintaining the weight and strength. "The trend is toward a larger head to give golfers more confidence in striking the middle," said Schupmann.

An article from the Journal of The Minerals, Metals & Materials Society described the benefits of a hollowed cast titanium head: "The net result is a club that is claimed to give greater distance (greater clubhead speed because of the longer arc), but also a straighter shot because of the greater resistance to twisting of the shaft, and a higher moment of inertia in the head. In golf terms, the golfer can now drive the ball farther and further without swinging harder because of a bigger sweet spot."

"Titanium gives designers a whole new pallet to design with in which they can locate the weight in the head to impart and improve certain playability characteristics," said Collins. "They can increase the overall size of the head--larger face, bigger sweet spot--to improve play."

Mikkola believes steel will remain the material of choice for golf equipment, although the likes of titanium and amorphous metals will continue to capture intrigue. "Moving forward, the golf industry will continue to gain various properties that it has never seen before."

Initial Club Design

Typically, the process of designing a cast golf club follows a certain methodology. Engineers first run CAD/CAM (computer-aided design/manufacturing) to experiment with the vast number of design variables while precisely calculating the playing characteristics of the club before it ever strikes a ball.

Next is the creation of a prototype to help validate the new design and determine whether further modifications are needed--before significant expense is incurred. Wax replicas of the proposed design can be made in a day, and the prototype clubhead can be back from the foundry within a few days, ready for grinding, assembly and preliminary testing.

Next, the club undergoes prototype testing, which can include a "mechanical/robotic golfer" that tests facets of performance not easily reproduced by human golfers. Typical attributes examined are things like spin rates, launch angles and distance between each club in the set. This testing is followed up by an evaluation by human golfers on the test range. If changes to the design are necessary to improve playability, the prototype is modified or recast and the testing cycle is repeated.

Upon approval of the fully tested design, the next step is to build the production-quantity molds required for the investment casting process.

Casting

Upon the completion of the mold tooling, liquid wax is injected into the mold and cooled to create wax replicas of the clubheads. According to Ping, the wax is more expensive on a pound-per-pound basis than the actual stainless steel used to cast the clubheads. These individual replicas are attached by their gates (where the molten metal will flow into the desired clubhead design) to the tree.

After a dip in a cleaning solution, the wax tree is alternately dipped into wet ceramic slurry and then dry ceramic sand. This process builds up the layers of a shell capable of withstanding the heat of molten metal. After the shell build, the wax must be removed before metal can be poured in. The molds are turned upside-down in a steam autoclave. After several minutes, the wax melts and drains and is collected for recycling.

The empty ceramic shells are preheated to almost 2000F (1093C) in preparation for the stainless steel pour, which has a melting point of 2500F (1371C). After pouring, the brittle ceramic shell is separated from the solidified metal casting through the use of a vibrating hammer or other method. Any remaining ceramic material clinging to the iron head is removed by sandblasting. The result is a perfect stainless steel copy of the wax tree. The clubheads are then separated from the tree via bandsaw, and most of the gate will be grinded off the clubhead. After visual inspection, the loose clubheads undergo a heat treatment.

Other steps involved in the final product include grinding off the parting lines, as well as some welding, finishing and painting before shipping the heads to the manufacturer for final assembly.

Collaborative Efforts

With today's golf designs lasting 18 months to 2 years, the time to market has become extremely critical. For instance a putter manufacturer might want samples in its hands 2-3 weeks after final approval and be in full production maybe 4 weeks after that, said Schupmann.

"Most golf customers do R&D through prototyping on CAD/CAM equipment, which means when we get a new design from customers, they expect a very rapid turnaround from wax to metal," said Collins. "We have key processes and equipment to do this: shell room dry tunnels, quick-shell systems and onsite heat treatment capabilities. This allows us to turn prototype waxes around in 3-4 days."

Collins also cited how a customer once called on a Tuesday and needed putter heads cast, finished and assembled by Friday for a PGA show. "A few years ago, this customer would have been laughed out of the building," he said. The foundry cast, finished and shipped in 4 days, and 65 consecutive putts were sunk at a contest at the exhibitor's booth.

Casting suppliers to the golf industry not only demonstrate dime-turning agility, but are also called upon to deliver far more value-added than a raw casting. Golf companies routinely require completely finished and painted heads and, in some cases, want the head assembled with the shaft, grip and glue.

About half of the work is done after casting, Schupmann said, noting the grinding, polishing, straightening and painting attention that each club receives. Added Collins: "The most difficult part is finishing--things like face angle, score lines, etc. That's where you separate yourself."

The role that the golf club foundry has played has changed over the years. According to Schupmann, it was not uncommon years ago for a model to simply show up at the foundry's door. "It was frustrating because we could see that we could have put a radius here or a suggested a different wall transition and saved the customer money.

"Nowadays, they bring our casting and finishing people to the table early so they don't come up with something difficult to cast or needlessly expensive to produce. We talk about how we're going to produce it and oftentimes can give designers tangible ways to minimize cost." According to Mikkola, this has become an imperative part of the process as manufacturers stretch to reduce costs in what has become a very price-sensitive market for golf equipment.

Unlimited Possibilities

The future of cast golf club designs has more to do with governing body politics than it does with current technology. "There was a time when clubhead designs were limited by the ability to produce," said Mikkola. "Now you can cast almost anything--in just about any configuration.

"The pushing of the envelope is not a matter of foundries' ability to manufacture, but instead the extent of what will gain approval from the U.S. Golf Assn." MC

This article was adapted from one that originally appeared in Engineered Casting Solutions.

For More Information

For a free copy of this article circle No. 343 on the Reader Action Card.

"Advanced Materials in Golf Clubs: The Titanium Phenomenon," CS. Shira and F.H. Froes, p. 35-37, JOM, Warrendale, PA (May 1997).

Investment Casting Handbook, H. T. Bidwell, Investment Casting institute, Dallas (1997).

Final Report from Titanium Industry Workshop, sponsored by American Society of Mechanical Engineers, the International Titanium Assn., The U.S. Dept. of Energy Battelle Pacific Northwest National Laboratory and the Northwest Alliance for Transportation Technology (1997).

International Titanium Assn., Broom field, CO www.titanium.org.

RELATED ARTICLE: Production Moving Offshore

More than 50% of the high-end investment cast clubheads sold in the U.S. today are reportedly produced in Taiwan and China. Nearly all of the major club makers in the U.S. are buying some cast clubheads from Chinese foundries. This trend has caused a dramatic shift in product strategies for U.S. investment casters and has resulted in the mothballing and changing of plants that had been supplying heads to U.S. consumers.

--Ken Kirgin, Stratecasts, Inc.