Driver Insert

1. Driver Insert David Birsen Brooke Gladstone HuanKiatKoh

2. 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

3. Objective • Minimize the mass by minimizing depth • Equation: • Rationale: • Lighter clubs can be swung faster so ball travels farther • Minimizes cost • Maximizes COR

4. 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

5. Material Indices Equation for Coefficient of Restitution (Johnson) 1st Constraint: 2nd Constraint:

6. CES Plot: Level 2

7. Material Options: Level 2 • Options include: • Boron Carbide • Nickel • Nickel-based superalloys • Nickel-chromium alloys • Tin • Titanium alloys

8. Material Selection: Level 2 • Material properties for shortlisted materials were tabulated and compared. • The material with the best combination, Titanium Alloys, was chosen.

9. 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

10. 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

11. Differences between Ti Alloys

12. 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

13. Processing Method

14. 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

15. 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.