Golf club heads and methods to manufacture golf club heads

1. A method comprising:

providing at least two golf club heads, each of which includes a body portion having a toe portion, a heel portion, a top portion, a sole portion, a front portion, a back portion, a face portion coupled to the front portion and having a loft angle, and an interior cavity partially or entirely filled with a polymer material;

striking a golf ball at a golf club head speed with each of the golf club heads; and

determining a loudness for each strike of the golf ball based on a sound pressure measurement taken for a fixed duration of time with a microphone placed directly above the golf ball at a fixed vertical distance,

wherein the loft angles of the golf club heads are different from each other and are in a range of 21.5° or approximately 21.5° to 45° or approximately 45°,

wherein for a golf club head speed of 80 mph, the loudness tends to decrease with increasing loft angle at a rate ranging from 0.1420-0.3427 (sones/degree loft angle),

wherein for a golf club head speed of 85 mph, the loudness tends to decrease with increasing loft angle at a rate ranging from 0.1288-0.3914 (sones/degree loft angle), and

wherein for a golf club head speed of 90 mph, the loudness tends to decrease with increasing loft angle at a rate ranging from 0.0551-0.3208 (sones/degree loft angle).

2. A method as defined in claim 1 , wherein the fixed duration of time is approximately 300 milliseconds and the fixed vertical distance is approximately 24 inches.

3. A method as defined in claim 1 , wherein the polymer material comprises a thermoset material.

4. A method as defined in claim 1 , wherein for the golf club head speeds of 80 mph, 85 mph, and 90 mph, corresponding rates at which loudness tends to decrease with increasing loft angle are each based on a relationship between an average maximum loudness for each golf club head and the loft angles of the golf club heads.

5. A method as defined in claim 1 , further comprising performing the sound pressure measurement at a predetermined sampling rate.

6. A method as defined in claim 1 , wherein striking the golf ball with each golf club head is performed using a swing robot.

7. A method as defined in claim 1 , wherein a relative rate of change between loudness and loft angle is greatest for the golf club head speed of 85 mph, followed in turn by the rate at which loudness decreases with increasing loft angle for the golf club head speed of 80 mph and the golf club head speed of 90 mph.

8. A method comprising:

providing a first golf club head having an interior cavity partially or entirely filled with a polymer material, and a loft angle of 21.5° or approximately 21.5°;

providing a second golf club head having an interior cavity partially or entirely filled with a polymer material, and a loft angle of 24° or approximately 24°;

providing a third golf club head having an interior cavity partially or entirely filled with a polymer material, and a loft angle of 27° or approximately 27°;

providing a fourth golf club head having an interior cavity partially or entirely filled with a polymer material, and a loft angle of 31° or approximately 31°;

providing a fifth golf club head having an interior cavity partially or entirely filled with a polymer material, and a loft angle of 35° or approximately 35°;

providing a sixth golf club head having an interior cavity partially or entirely filled with a polymer material, and a loft angle of 40° or approximately 40°;

providing a seventh golf club head having an interior cavity partially or entirely filled with a polymer material, and a loft angle of 45° or approximately 45°;

striking a golf ball at a golf club head speed ranging from 80 mph to 90 mph with each of the first, second, third, fourth, fifth, sixth, and seventh golf club heads; and

determining a loudness for each strike of the golf ball based on a sound pressure measurement taken for a fixed duration of time with a microphone placed directly above the golf ball at a fixed vertical distance,

wherein loudness produced by the first, second, third, fourth, fifth, sixth, and seventh golf club heads tends to decrease with increasing loft angle for golf club head speeds of 80 mph, 85 mph, and 90 mph,

wherein for the golf club head speed of 80 mph, loudness tends to decrease at a rate of 0.3427 (sones/degree loft angle) or approximately 0.3427 (sones/degree loft angle),

wherein for the golf club head speed of 85 mph, loudness tends to decrease at a rate of 0.3914 (sones/degree loft angle) or approximately 0.3914 (sones/degree loft angle), and

wherein for the golf club head speed of 90 mph, loudness tends to decrease at a rate of 0.3208 (sones/degree loft angle) or approximately 0.3208 (sones/degree loft angle).

9. A method as defined in claim 8 , wherein the fixed duration of time is approximately 300 milliseconds and the fixed vertical distance is approximately 24 inches.

10. A method as defined in claim 8 , wherein the polymer material comprises a thermoset material.

11. A method as defined in claim 8 , wherein for the golf club head speeds of 80 mph, 85 mph, and 90 mph, corresponding rates at which loudness tends to decrease with increasing loft angle are each based on a relationship between an average maximum loudness for each of the first, second, third, fourth, fifth, sixth, and seventh golf club heads and their corresponding loft angles.

12. A method as defined in claim 8 , wherein a relative rate of change between loudness and loft angle is greatest for the golf club head speed of 90 mph, followed in turn by the rate at which loudness decreases with increasing loft angle for the golf club head speed of 80 mph and the golf club head speed of 85 mph.

13. A method as defined in claim 8 , wherein striking the golf ball with each of the first, second, third, fourth, fifth, sixth, and seventh golf club heads is performed using a swing robot and at least one of the first, second, third, fourth, fifth, sixth, and seventh golf club heads is an iron-type golf club head.

14. A method comprising:

providing a plurality of golf club heads, each of which includes a body portion having a toe portion, a heel portion, a top portion, a sole portion, a front portion, a back portion, a face portion coupled to the front portion and having a loft angle, and an interior cavity partially or entirely filled with a polymer material;

striking a golf ball at a number of golf club head speeds ranging from 80 mph to 90 mph with each of the golf club heads; and

determining a loudness for each strike of the golf ball based on a sound pressure measurement taken for a fixed duration of time with a microphone placed directly above the golf ball at a fixed vertical distance,

wherein the loft angles of the golf club heads are different from each other and are in a range of 21.5° or approximately 21.5° to 45° or approximately 45°,

wherein for golf club head speeds of 80 mph, 85 mph, and 90 mph, changes in loudness of the golf club heads are inversely related to changes in loft angle,

wherein for the golf club head speed of 80 mph, loudness tends to decrease with increasing loft angle at a rate ranging from 0.1420-0.3427 (sones/degree loft angle),

wherein for the golf club head speed of 85 mph, loudness tends to decrease with increasing loft angle at a rate ranging from 0.1288-0.3914 (sones/degree loft angle), and

wherein for the golf club head speed of 90 mph, loudness tends to decrease with increasing loft angle at a rate ranging from 0.0551-0.3208 (sones/degree loft angle).

15. A method as defined in claim 14 , wherein the fixed duration of time is approximately 300 milliseconds and the fixed vertical distance is approximately 24 inches.

16. A method as defined in claim 14 , wherein the polymer material comprises a thermoset material.

17. A method as defined in claim 14 , wherein for the golf club head speeds of 80 mph, 85 mph, and 90 mph, corresponding rates at which loudness tends to decrease with increasing loft angle are each based on a relationship between an average maximum loudness for each golf club head and the loft angles of the golf club heads.

18. A method as defined in claim 14 , wherein a relative rate of change between loudness and loft angle is greatest for the golf club head speed of 80 mph, followed in turn by the golf club head speed of 85 mph and the golf club head speed of 90 mph.

19. A method as defined in claim 14 , further comprising performing the sound pressure measurement at a predetermined sampling rate.

20. A method as defined in claim 14 , wherein striking the golf ball with each golf club head is performed using a swing robot.