- Part Number:1910
- Part Number Title:Occupational Safety and Health Standards
- Subpart:1910 Subpart O
- Subpart Title:Machinery and Machine Guarding
- Standard Number:
- Title:Mechanical power presses.
- Appendix:
- GPO Source:
The operating levers on hand-tripped presses having more than one operating station shall be interlocked to prevent the tripping of the press except by the "concurrent" use of all levers.
A means of selecting Off, "Inch," Single Stroke, and Continuous (when the continuous function is furnished) shall be supplied with the clutch/brake control to select type of operation of the press. Fixing of selection shall be by means capable of supervision by the employer.
The "Inch" operating means shall be designed to prevent exposure of the workers hands within the point of operation by:
It shall be the responsibility of the employer to provide and insure the usage of "point of operation guards" or properly applied and adjusted point of operation devices on every operation performed on a mechanical power press. See Table O-10.
Ds = 63 inches/second × Ts
where:
Ds = minimum safety distance (inches); 63 inches/second = hand speed constant;
and
Ts = stopping time of the press measured at approximately 90° position of crankshaft rotation (seconds).
Guards shall be used to protect all areas of entry to the point of operation not protected by the presence sensing device.
Ds = 63 inches/second × Ts;
where:
Ds = minimum safety distance (inches); 63 inches/second = hand speed constant;
and
Ts = stopping time of the press measured at approximately 90° position of crankshaft rotation (seconds).
Dm = 63 inches/second × Tm;
where:
Dm = minimum safety distance (inches); 63 inches/second = hand speed constant;
and
Tm = the maximum time the press takes for the die closure after it has been tripped (seconds). For full revolution clutch presses with only one engaging point Tm is equal to the time necessary for one and one-half revolutions of the crankshaft. For full revolution clutch presses with more than one engaging point, Tm shall be calculated as follows:
Tm = [ 1/2 + (1 ÷ Number of engaging points per revolution)] × time necessary to complete one revolution of the crankshaft (seconds).
Hand feeding tools. Hand feeding tools are intended for placing and removing materials in and from the press. Hand feeding tools are not a point of operation guard or protection device and shall not be used in lieu of the "guards" or devices required in this section.
Note to paragraph (e)(1)(ii): Inspections of the clutch/brake mechanism, antirepeat feature, and single-stroke mechanism conducted under the directed component of the inspection program are exempt from the requirement to maintain certification records specified by paragraph (e)(1)(i)(C) of this section, but inspections of the clutch/brake mechanism, antirepeat feature, and single-stroke mechanism conducted under the general component of the inspection program are not exempt from this requirement.
Overloading. The employer shall operate his presses within the tonnage and attachment weight ratings specified by the manufacturer.
Explanation of above diagram:
This diagram shows the accepted safe openings between the bottom edge of a guard and feed table at various distances from the danger line (point of operation).
The clearance line marks the distance required to prevent contact between guard and moving parts.
The minimum guarding line is the distance between the infeed side of the guard and the danger line which is one-half inch from the danger line.
The various openings are such that for average size hands an operator's fingers won't reach the point of operation.
After installation of point of operation guards and before a job is released for operation a check should be made to verify that the guard will prevent the operator's hands from reaching the point of operation.
Table O-10
[In inches]
Distance of opening from point of operation hazard | Maximum width of opening |
---|---|
1/2 to 1 1/2 | 1/4 |
1 1/2 to 2 1/2 | 3/8 |
2 1/2 to 3 1/2 | 1/2 |
3 1/2 to 5 1/2 | 5/8 |
5 1/2 to 6 1/2 | 3/4 |
6 1/2 to 7 1/2 | 7/8 |
7 1/2 to 12 1/2 | 1 1/4 |
12 1/2 to 15 1/2 | 1 1/2 |
15 1/2 to 17 1/2 | 1 7/8 |
17 1/2 to 31 1/2 | 2 1/8 |
This table shows the distances that guards shall be positioned from the danger line in accordance with the required openings.
The employer shall report, within 30 days of the occurrence, all point-of-operation injuries to operators or other employees to either the Director of the Directorate of Standards and Guidance at OSHA, U.S. Department of Labor, Washington, DC 20210 or electronically at http://www.osha.gov/pls/oshaweb/mechanical.html; or to the State Agency administering a plan approved by the Assistant Secretary of Labor for Occupational Safety and Health.
The control system shall perform checks for proper operation of all cycle control logic element switches and contacts at least once each cycle. Control elements shall be checked for correct status after power "on" and before the initial PSDI stroke.
The control system shall have provisions for an "inch" operating means meeting the requirements of paragraph (b)(7)(iv) of this section. Die-setting shall not be done in the PSDI mode. Production shall not be done in the "inch" mode.
Ds = Hs × (Ts + Tp + Tr + 2Tm) + Dp
Where:
Ds = Minimum safety distance.
Hs = Hand speed constant of 63 inches per second (1.6 m/s).
Ts = Longest press stopping time, in seconds, computed by taking averages of multiple measurements at each of three positions (45 degrees, 60 degrees, and 90 degrees) of crankshaft angular position; the longest of the three averages is the stopping time to use. (Ts is defined as the sum of the kinetic energy dissipation time plus the pneumatic/magnetic/hydraulic reaction time of the clutch/brake operating mechanism(s).)
Tp = Longest presence sensing device response time, in seconds.
Tr = Longest response time, in seconds, of all interposing control elements between the presence sensing device and the clutch/brake operating mechanism(s).
Tm = Increase in the press stopping time at the top of the stroke, in seconds, allowed by the brake monitor for brake wear. The time increase allowed shall be limited to no more than 10 percent of the longest press stopping time measured at the top of the stroke, or 10 milliseconds, whichever is longer.
Dp = Penetration depth factor, required to provide for possible penetration through the presence sensing field by fingers or hand before detection occurs. The penetration depth factor shall be determined from Graph h-1 using the minimum object sensitivity size.
Penetration Depth Factor Calculation Graph

[39 FR 32502, June 27, 1974. as amended at 39 FR 41846, Dec. 23, 1974; 40 FR 3982, Jan. 27, 1975; 43 FR 49750, Oct. 24, 1978; 45 FR 8594, Feb. 8. 1980; 49 FR 18295, Apr. 30, 1984; 51 FR 34561, Sept. 29, 1986; 53 FR 8353, Mar. 14, 1988; 54 FR 24333, June 7, 1989; 61 FR 5507, Feb. 13, 1996; 61 FR 9227, March 7, 1996; 69 FR 31882, June 8, 2004; 76 FR 80739, Dec. 27, 2011; 77 FR 46949, Aug. 7, 2012; 78 FR 69550, Nov. 20, 2013]