US 6,602,149 · Granted 2003-08-05
How Callaway Bonded Two Materials Together to Make Stronger Golf Clubs
Golf clubs traditionally had one solid head, but Callaway invented a way to glue a metal striking face to a lighter composite back section, positioning them with a tiny gap to reduce stress at the bond. This hybrid approach makes the club head larger and hit harder without breaking at the joint.
The plain-English version
What it protects
The claim covers a golf club head where a metal face component is bonded to an aft body made of composite or thermoplastic material, with the specific positioning of the bond's leading edge between 0.100 and 0.500 inches from the face's interior surface. What's protected here is that exact undercut geometry and the controlled spacing that prevents stress concentration at the glue line.
Why it matters
In the early 2000s, oversized club heads became a competitive advantage in golf, and manufacturers needed to make heads larger while keeping them light enough to swing. By bonding a dense metal face to a lightweight composite back, Callaway could deliver both the appearance and performance of a premium club without excess weight. The patent's bonding geometry was engineered to prevent the joint from failing under impact stress, making the hybrid design commercially viable.
Real-world use
Every time a golfer strikes the ball with an oversized driver or fairway wood built after 2003, they're likely using a club head whose face and back were bonded together using this spacing principle to withstand the shock.
Original USPTO abstract
A golf club (40) having a club head (42) with a face component (60) and an aft body (61) is disclosed herein. The face component (60) has a striking plate port ion (72) and a return portion (74). The aft-body (61) is composed of a crown portion (62), a sole portion (64) and optionally a ribbon section (90). The face component (60) is composed of a metal material, and the aft-body (61) is preferably composed of a non-metal material such as a composite material or a thermoplastic material. The face component (60) is bonded to the aft-body (61) with a leading edge (180) of an undercut portion (62a and 64a) of the aft-body positioned a distance of 0.100 inch to 0.500 inch from the interior surface (60a) of the face component (60) in order to reduce the stress on the bonded joint of between the face component (60) and the aft-body (61). The club head (42) has a volume in the range of 290 cubic centimeters to 600 cubic centimeters, a weight in the range of 165 grams to 300 grams, and a striking plate portion (72) surface area in the range of 4.00 square inches to 7.50 square inches.
Patent details
- Publication number
- US 6,602,149
- Filing date
- 2002-03-25
- Grant date
- 2003-08-05
- Assignee
- Callaway Golf Company
- Inventor(s)
- JACOBSON DANIEL R.
- CPC class
- A63B53/04
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