This Safety and Health Information Bulletin is not a standard or regulation, and it creates no new legal obligations. The Bulletin is advisory in nature, informational in content, and is intended to assist employers in providing a safe and healthful workplace. Pursuant to the Occupational Safety and Health Act, employers must comply with hazard-specific safety and health standards and regulations promulgated by OSHA or by a state with an OSHA-approved state plan. In addition, pursuant to Section 5(a)(1), the General Duty Clause of the Act, employers must provide their employees with a workplace free from recognized hazards likely to cause death or serious physical harm.
The most common type of injury associated with mechanical power presses is amputation. Such injuries are often the result of point of operation hazards. The point of operation is the area on a press where material is processed. Amputations may occur when the required point of operation guards and devices are not in place or are not properly installed and the operator is able to place a hand, finger or any other body part in the working area of the press while it is cycling. Press operators may also be injured if one of the safety components of the press fails and the clutch/brake control electrical circuit has not been constructed to provide for control reliability. Control reliability means the system's components are integrated and function together as a unit; if one system component fails, the press will not initiate a successive stroke until the failure is corrected.
This Safety and Health Information Bulletin (SHIB) describes an accident involving an amputation that occurred when the press double cycled. The operator was injured when he placed his hand in the point of operation area and the presence sensing device (PSD) failed. Had the system been control reliable, this failure should have stopped the machine from operating.
This SHIB also highlights safety measures in OSHA's Mechanical Power Presses standard, 29 CFR 1910.217, that address this situation.
The purpose of this SHIB is to:
A mechanical power press is a machine that shears, punches, forms or assembles metal or other materials by means of tools or dies mounted on slides or rams. It operates in a controlled, reciprocating motion toward and away from the stationary bed containing the lower die.
When the upper and lower dies press together, the desired workpiece is produced. Once the downstroke is completed, the formed workpiece is removed, a new workpiece is fed into the die and the process is repeated. These presses are characterized by the type of clutch they use: full revolution or part revolution. See OSHA's Machinery and Machine Guarding Definitions standard, 29 CFR 1910.211(d)(5) and (d)(6), for a definition of these two types of clutches. Point of operation safeguarding devices required on part revolution clutch presses may include, but are not limited to, two hand controls, presence sensing devices, type A and type B gates, pull outs, and movable barriers. See 29 CFR 1910.217(c)(3).
OSHA's Omaha, Nebraska Area Office investigated an amputation accident involving a guarded 60 ton, part revolution, mechanical power press. The press on which the amputation occurred incorporated a two hand control point of operation device and a PSD. The two hand controls were located 22 inches from the die area. The safety distance met the requirements in 29 CFR 1910.217(c)(3)(vii)(c).
The PSD on this press was installed by the employer who followed the manufacturer's wiring schematic. A PSD signals the machine to stop operating when any part of the operator's body is within the sensing field.
On the day of the accident, a worker, without using hand tools, reached into the die area to clear jammed material and the press double cycled. This resulted in the amputation of three fingers on his left hand. The press was immediately locked-out and removed from service.
This press had double cycled four days before the accident. At that time, the double cycling did not cause an injury. After that initial incident, the employer's maintenance personnel inspected the press and concluded that a faulty timer caused the press to double cycle. Maintenance personnel replaced the timer and the employer returned the press to service.
After the accident, the employer contacted the press manufacturer to determine what was causing the press to double cycle. The manufacturer's electrician evaluated the press and concluded that the PSD was not wired correctly. The schematic that came with the PSD was incorrect which led to improper installation of the device. The manufacturer's electrician rewired the PSD and corrected the schematic.
The employer's electrician conducted a follow-up test of the press's electrical circuit (the timer contacts, limit switches and control relays) and validated that these components were functioning properly. The press was then put back into service.
OSHA's Mechanical Power Presses standard, 29 CFR 1910.217, contains requirements to protect workers from point of operation hazards. Requirements that apply to the press involved in this specific accident, include:
Following the recommendations below will further reduce the risk of amputation hazards to part revolution clutch press operators.
The purpose of this SHIB is to minimize the potential for fatal or serious amputation injuries. The underlying cause of the highlighted accident was an improperly installed PSD that caused a failure of the safety control system's ability to detect a fault and prevent the unintended next stroke.
The accident might have been prevented if these requirements were followed: ensuring control reliability prior to putting the machine in service, conducting regular inspections, training operators and using point of operation guarding and other safety devices in conjunction with the use of hand tools.
Additionally, implementation of a safe work practice that does not allow operators to place their hands in the hazardous zone of the machinery would have resulted in a near miss rather than an amputation injury. Enforcing this policy will serve as a front line defense in preventing mechanical power press-related injuries.
The references listed below provide more detailed information on machine guarding, controlling amputation hazards and definitions of terms used in the standard.
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