Vibration characteristics of golf club heads in their handheld grinding process and potential approaches for reducing the vibration exposure

Abstract

To control vibration-induced white finger among workers performing the fine grinding of golf club heads, the aims of this study are to clarify the major vibration sources in the grinding process, to identify and understand the basic characteristics of the club head vibration, and to propose potential approaches for reducing the vibration exposure. The vibrations on two typical club heads and two belt grinding machines were measured at a workplace. A simulated test station was also constructed and used to help examine some influencing factors of the club head vibration. This study found that the club head vibration was the combination of the vibration transmitted from the grinding machines and that generated in the grinding process. As a result, any factor that affects the machine vibration, the grinding vibration, and/or the dynamic response of the club head can influence the vibration exposure of the fingers or hands holding the club head in the grinding process. The significant influencing factors identified in the study include testing subject, grinding machine, machine operation speed, drive wheel condition, club head model, mechanical constraints imposed on the club head during the grinding, and machine foot pad. These findings suggest that the vibration exposure can be controlled by reducing the grinding machine vibration, changing the workpiece dynamic properties, and mitigating the vibration transmission in its pathway. Many potential methods for the control are proposed and discussed. Relevance to industry: Vibrations on handheld workpieces can be effectively transmitted to the hands, especially the fingers. As a result, a major component of the hand-arm vibration syndrome - vibration-induced white finger - has been observed among some workers performing the grinding and/or polishing tasks of the handheld workpieces such as golf club heads. The results of this study can be used to develop more effective methods and technologies to control the vibration exposure of these workers. This may help effectively control this occupational disease.

Characterizing vibration responses of a handheld workpiece and the hand–arm system

“…5 As a result, the major machine vibration components are correlated with the operation speed of the machine, which is usually at or above 1200 r/min or 20 Hz. 5 Therefore, besides controlling the unbalance of the rotating parts, the vibration exposure can be partially controlled by choosing appropriate operation speeds. Because the hand-arm system exhibits a major resonance in the range of 16-25 Hz, as shown in Figures 8 and 11, it may be useful to avoid the machine operation speeds near 20 Hz.…”

“…Figure 4. Simulated grinding interfaces: (a) R1, R2, and R3 were cut from laboratory rubber materials and (b) R4, R5, and R6 were cut from factory grinding wheel treads obtained from a workplace 5. …”

A Review of Hand–Arm Vibration Studies Conducted by US NIOSH since 2000

“…We, together with our collaborators, have also conducted a series of investigations on handheld workpiece vibrations. First, we measured and characterized the vibration exposure of workers grinding typical handheld workpieces (golf club heads) at a workplace and preliminary strategies/methods for controlling the grinding vibration exposure were proposed [ 169 ]. Second, we measured vibration responses of the workpiece–hand–arm system in laboratory experiments [ 170 ], and developed a model of the system based on the measured response functions [ 78 ], as illustrated in Figure 6c .…”

Identification of effective engineering methods for controlling handheld workpiece vibration in grinding processes

“…We have launched a systematic investigation to help control such vibration exposures. As the first step of the investigation, a series of experimental studies at a workplace were conducted to identify the basic vibration characteristics of the workpiece held in the worker's hands and pressed against a grinding wheel in order to shape the workpiece (Chen et al, 2017). In these studies, the vibrations from 6.3 to 1600 Hz in the one-third octave bands on workpieces and grinding machines were simultaneously measured.…”