Driver Insert

David BirsenBrooke Gladstone

Huan Kiat Koh

Background

• Hardwoods used until 1990’s; Ti alloys popular in modern drivers

• Range from alpha (~90% Ti) to beta (~75% Ti) alloys

• USGA regulations as a result of new materials– Set maximum COR of 0.830 in 1998– Measure ball velocity and pre-impact club head

velocity using Characteristic Time Test

Objective

• Minimize the mass by minimizing depth– Equation:

• Rationale:– Lighter clubs can be swung faster so ball travels

farther– Minimizes cost– Maximizes COR

Constraints

• Oval cross-section• Length of 90mm and height of 55mm• COR ≤ 0.83• Cost ≤ $5.00 per part • Recyclable• Yield stress >> Stress at Impact• High Young’s Modulus • Processability: needs to be made in bulk

Material IndicesEquation for Coefficient of Restitution (Johnson)

1st Constraint:

2nd Constraint:

CES Plot: Level 2

Material Options: Level 2

• Options include:– Boron Carbide– Nickel– Nickel-based superalloys– Nickel-chromium alloys– Tin– Titanium alloys

Material Selection: Level 2• Material properties for shortlisted materials were tabulated

and compared.• The material with the best combination, Titanium Alloys, was

chosen.

CES Plot: Level 3

Highlighted materials have a cost close to $50/kg (0.1 kg and $5 at most per part)and are recyclable

Material Options: Level 3• Titanium alloys that meet the restrictions on price and

recyclability:– Titanium, alpha alloy, Ti-5Al-2.5Sn-0.5Fe, annealed– Titanium, alpha alloy, Ti-8Al-1Mo-1V, duplex annealed– Titanium, alpha alloy, Ti-8Al-1Mo-1V, single annealed– Titanium, alpha alloy, Ti-8Al-1Mo-1V, solution treated & stabilized– Titanium, alpha-beta alloy, Ti-6Al-2Sn-2Zr-2Mo, annealed– Titanium, alpha-beta alloy, Ti-6Al-2Sn-2Zr-2Mo, solution treated & aged– Titanium, alpha-beta alloy, Ti-6Al-2Sn-2Zr-2Mo, triplex aged– Titanium, alpha-beta alloy, Ti-6Al-4V, aged– Titanium, alpha-beta alloy, Ti-6Al-4V, solution treated & aged– Titanium, beta alloy, Ti-5Al-2Sn-4Mo-2Zn-4Cr (Ti-17)– Titanium, commercial purity, Grade 2

Differences between Ti Alloys

Final Material Selection

• Titanium, beta alloy Ti-5Al-2Sn-4Mo-2Zn-4Cr (Ti-17)– Only beta alloy available with the set constraints

• Depth: 1.556 mm• Mass: 28.1 g

Processing Method

Final Recommendation

• Ti-17 Beta Alloy• Processed by sheet forming– Good tolerance

• Stamped from one large sheet• Polished• Natural protective layer so no special finishing

References• Ashby, Michael F. Materials Selection in Mechanical Design. 4th ed. Oxford:

Butterworth-Heinemann, 2011. Print.• Elerf, Glenn. Force of a Golf Club on a Golf Ball. The Physics Factbook. 2001. Web.

April 12 2012.• GOLF CHANNEL Newsroom. USGA, R&A Rule on 'Spring-Like' Effect. The Golf

Channel. August 6, 2002. Web. March 12, 2012• Johnson, K. L. Contact Mechanics, Chapter 11. Cambridge [Cambridgeshire]:

Cambridge University Press, 1985. Print. (Page 363, 364)• Tirosh, O. "Mechanics - Golf Swing." Golf Swing Analysis. Web. February 20 2012.• Titanium and It’s Alloys as Used in Golf Club Heads. In Golf, Inc. Web. April 2, 2012.• Titanium and Titanium Alloys. Everything Material, ASM International. 2012. Web.

April 7 2012.• Titanium Alloys – Characteristics of Alpha, Alpha Beta and Beta Titanium Alloys. A

to Z of Materials. 2004. Web. April 9 2012.• What is C.O.R.? What is CT? Wish on Golf. Web. March 12, 2012.