Engineering Controls Database
Punch Press 2 – Noise Case Study
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Overview: The case history presented here is one of sixty-one case histories that were published by the National Institute for Occupational Safety and Health (NIOSH) in 1978 as part of an industrial noise control manual [NIOSH 1979]. The case histories are examples of engineering tasks that have been completed not only by professional noise control engineers but also by non-acoustical specialists who used common sense to solve their noise problems. The case histories were chosen primarily because the amount of noise reduction actually achieved was measured. Such engineering results, even if not directly applicable to a specific situation, illustrate general principles that may point the way to a successful result. They are intended to be useful to production and safety engineers, health personnel, and other factory personnel who are not specialists in noise control. Case study: This case study concerns high-speed (approximately 1200 strokes/ min) Bruderer punch presses which are centrally located in a 20-m by 30-m steel building. Operation of the 40- and 70- ton presses causes OSHA noise over-exposures of the three workers in the general area around the press, as well as two press operators. The presses were clearly identified as the cause of the noise problem because sound levels were low when the presses were not operating and between 95 dBA and 100 dBA, depending on proximity to the units, when they were in operation. |
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| Hearing loss is one of the most common occupational diseases in America today and the second most self-reported occupational illness or injury. Approximately 30 million workers are exposed to hazardous noise on the job and there are approximately 16 million Americans with noise-induced hearing loss. | |
Action was initiated because management became aware that the press room was extremely noisy in comparison to other plant operations. The press enclosure design called for formed steel angles to be used as structural members to support removable enclosure panels - the concept is shown in Figure 1. The ultimate panel system employed (see comments below) consisted of 1/2-in- plywood framed on one side with 1 x 3's tacked on. Expanded sheet metal formed a backing on the framed side of the 2-ft-wide panels. Foamed-in-Place foam was then applied to the backing. The panels were hung by clips to cross members on the framing. Each panel was thus easily removable for press screening. |
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| NIOSH [1979]. Industrial noise control manual – revised edition. Cincinnati, OH: U.S. Department of Health Education and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 79-117. | |
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noise noise noise control noise control punch press punch press |
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Sound levels at the closest worker position to either press (the operator who sits 2 ft away from the die), are now in the 88- to 90-dBA range. Treatment does not interfere with the operation, and productivity is unaffected. Comments: Initial panel designs were found unacceptable: Panels of 16-gauge galvanized steel backed with 1-in.-thick glass fiber duct insulation were found to rattle, and the glass fiber became pulverized by vibration and became unglued. The implemented treatment is clearly acceptable. It reduces noise exposure to OSHA compliance levels for minimum cost and impact on operation. However, better performance could have been obtained (at added expense) by using standard acoustical panels or larger plywood sections to minimize acoustical leaks at the many joints. The open top could also be sealed. The expanded foam adds little to treatment performance, since its acoustical properties are nil. Acoustical foam, held in place with expanded metal, would probably improve the enclosure performance. |