- Standard Number:
OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.
|OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.|
April 20, 1986
|MEMORANDUM FOR:||GILBERT J. SAULTER
|FROM:||JOHN B. MILES, JR. DIRECTOR
Directorate of Field Operations
|SUBJECT:||Power Press Brakes|
This is in response to your memorandum of March 25, 1986, and relates to the memorandum of J. T. Knorpp of March 4, 1986, to Herbert M. Kurtz.
The OSHA standard related to mechanical power press brakes is 29 CFR 1910.212. Point of operation safeguarding is regulated under 29 CFR 1910.212(a)(3)(ii) and shall be in conformity with any appropriate standards. For enforcement purposes, OSHA field staff have consistently been directed to refer to the applicable industry consensus standards, published by the American National Standards Institute, Inc., (ANSI). ANSI B11.3-1982, Safety Requirements for Power Press Brakes, is the applicable standard under 29 CFR 1910.212(a)(3)(ii), since it expressed the accepted industry practices. (Also see the May 26, 1981 letter to C. A. Carlsson from Bruce Hillenbrand, which is a part of the incoming correspondence.)
ANSI B11.3-1982 describes specifications with alternatives for the proper safeguarding of power press breaks. The standard describes three (3) distinctly different types of press breaks. They are known as: 1) General-Purpose Power Press Brakes; 2) Special-Purpose Power Press Brakes; and 3) Combination Power Press Brake-Shear-Type Machines. These machines are described by Section 2.2, 2.3 and 2.4, respectively, in B11.3-1982.
Further discussion of press brakes for this memorandum is limited to general-purpose and special-purpose machines. The principle difference between these machines is the manner of control system for their operation. General-purpose machines are provided with only a single operator control station, while special-purpose machines may be equipped with multiple operator/helper control stations.
Usually, general-purpose brakes may be recognized by the control system which is mechanically linked to the clutch/brake mechanisms or the hydraulic control valving. Electric or pneumatic components are rarely a part of the control system and the controls can be disengaged only by mechanical means such as control locks, or removal of the control pedal. (See ANSI B11.3-1982, section 126.96.36.199.4.)
General-purpose mechanical power press brakes are activated by a significant amount of foot pressure upon a pedal which mechanically disengages the brake while simultaneously engaging the clutch and thereby initiating slide motion. Return springs disengage the clutch and re-engage the brake whenever foot pressure is released. Single stroke mechanisms are not required, and antirepeat devices are inapplicable.
General-purpose hydraulic power press brakes must be equipped with a single stroke capability, which will stop the ram at the top of the stroke even if the operator fails to release the operating control. (See ANSI B11.3-1982, section 188.8.131.52.3 (3) and 184.108.40.206.)
Special-purpose power press brakes are activated through a servo-system which is in turn controlled by one or more operator stations and controls. The servo-system may be electric, pneumatic, hydraulic or a combination of these methods, and controls the clutch/brake mechanism to permit ram motion. All special-purpose power press brakes are required to be equipped with antirepeat capability which limits the press to a single stroke even if the tripping control is held engaged. (See ANSI B11.3-1982, section 220.127.116.11.3(3) and 3.1.)
General-purpose power press brakes may be operated by a single operator, and any helper(s) must be safeguarded by location, by a barrier guard, by pull backs, or by restraints. Other forms of helper safeguarding are ineffective and not applicable to general-purpose power press brakes.
Special-purpose power press brakes are equipped with sophisticated control systems which are adaptable to all form of safeguarding concepts and devices. The devices include two-hand controls, and multiple operator/helper actuating controls.
General-purpose power press brakes may be modified to convert them to a special-purpose power press brake. Converted press brakes may then accommodate a broader variety of safeguarding concepts and are reclassified as special-purpose power press brakes.
Due to the great variety in types of power press brakes available and used in industry, it is imperative to clearly define the machine type being addressed before the hazards associated with the particular machine can be assessed. Under 29 CFR 1910.212(a)(3)(ii), the safeguarding of the point of operation of a power press brake is not simply a matter of whether or not it is barrier guarded. An evaluator must comprehend that point of operation safeguarding on a power press brake results from the synergism of the various provisions required by the ANSI B11.3-1982 standard. The ANSI B11.3 committee accomplished an extraordinary effort with the publication of ANSI B11.3-1932 and have very comprehensively expressed the various considerations necessary to achieve employee safety at the point of operation on power press brakes.
In response to the specific questions of the J. T. Knorpp memorandum of March 14, 1983, they are as follows:
- ANSI B11.3-1982 is the applicable standard describing point-of-operation safeguarding equipment and procedures necessary to safeguard employees who operate power press brakes. Applicable portions of ANSI B11.3 should be referenced when citing violations of 29 CFR 1910.212(a)(3)(ii).
- Antirepeat devices are required to protect operators at the point of operation on special-purpose power press brakes, per ANSI B11.3-1982, section 18.104.22.168.3(3) and 3.1. Single stroke capability is required on all power press brakes except a general-purpose mechanical power press brake. (Power press brakes utilizing electric controls are most likely special-purpose machines.)