This research investigated the efficacy of machine enclosures in reducing employee exposures to metalworking fluid mist. Four hundred fifty-five personal samples from automotive machining and grinding operations collected over six years were divided into three groups based on the type and extent of enclosure and local exhaust ventilation. The sample groups were (1) machining equipment with original equipment manufacturer (OEM) total enclosures and local exhaust ventilation, (2) machining equipment with partial or retrofit enclosures and local exhaust ventilation, and (3) machining equipment with little or no enclosure. The results of the Mann Whitney U test of the three data sets indicated that the employees operating equipment with OEM enclosures had significantly lower exposures than employees operating equipment that had either of the other two control methods. There was no difference between the exposures of operators of equipment with retrofit enclosures compared to operators of equipment without enclosures. The median exposure for operators of equipment with OEM enclosures was 0.21 mg/m3, about half that found with the other two control methods. Each of the data sets was compared to exposure criteria; 100% of the exposures associated with OEM enclosures were below 1.0 mg/m3, and 90% of the exposures were below 0.5 mg/m3. The other two methods were not as effective as OEM in reducing exposure to below these criteria. These results indicate that OEM enclosures provide the most effective control of metalworking fluid mist exposure.
Previous work on vibratory finishing has led to a better understanding and establishment of the mass finishing processes. Despite the sustained efforts made to date, vibratory finishing remains a field where the findings made have been based largely on empirical evidence. Through force sensor analyses and scanning electron microscopy imaging, in this work a successful attempt has been made in uncovering the underlying science—through first principles of Newtonian physics—behind vibratory finishing, providing explanations for the observations made. Trials were carried out in a high-frequency vibratory bowl, the first of its kind in the vibratory finishing industry. Through these trials, mathematical formulations have been derived, essentially providing a reliable way for the industry to estimate the process cycle time.
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