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1910.217:
Mechanical power presses
(a) General requirements.
(1) [Reserved]
(2) [Reserved]
(3) [Reserved]
(4) Reconstruction and modification.
It shall be the responsibility of any person reconstructing, or
modifying a mechanical power press to do so in accordance with
paragraph (b) of this section.
(5) Excluded machines.
Press brakes, hydraulic and pneumatic power presses, bulldozers,
hot bending and hot metal presses, forging presses and hammers,
riveting machines and similar types of fastener applicators are
excluded from the requirements of this section.
(b) Mechanical power press guarding and construction, general
-
(1) Hazards to personnel associated with broken or
falling machine components.
Machine components shall be designed, secured, or covered to minimize
hazards caused by breakage, or loosening and falling or release
of mechanical energy (i.e. broken springs).
(2) Brakes.
Friction brakes provided for stopping or holding a slide movement
shall be inherently self-engaging by requiring power or force
from an external source to cause disengagement. Brake capacity
shall be sufficient to stop the motion of the slide quickly and
capable of holding the slide and its attachments at any point
in its travel.
(3) Machines using full revolution positive clutches.
(i) Machines using full revolution clutches shall incorporate
a single-stroke mechanism.
(ii) If the single-stroke mechanism is dependent upon spring
action, the spring(s) shall be of the compression type, operating
on a rod or guided within a hole or tube, and designed to prevent
interleaving of the spring coils in event of breakage.
(4) Foot pedals (treadle).
(i) The pedal mechanism shall be protected to prevent unintended
operation from falling or moving objects or by accidental stepping
onto the pedal.
(ii) A pad with a nonslip contact area shall be firmly attached
to the pedal.
(iii) The pedal return spring(s) shall be of the compression
type, operating on a rod or guided within a hole or tube, or
designed to prevent interleaving of spring coils in event of
breakage.
(iv) If pedal counterweights are provided, the path of the travel
of the weight shall be enclosed.
(5) Hand operated levers.
(i) Hand-lever-operated power presses shall be equipped with
a spring latch on the operating lever to prevent premature or
accidental tripping.
(ii) 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.
(6) Two-hand trip.
(i) A two-hand trip shall have the individual operator’s
hand controls protected against unintentional operation and
have the individual operator’s hand controls arranged
by design and construction and/or separation to require the
use of both hands to trip the press and use a control arrangement
requiring concurrent operation of the individual operator’s
hand controls.
(ii) Two-hand trip systems on full revolution clutch machines
shall incorporate an antirepeat feature.
(iii) If two-hand trip systems are used on multiple operator
presses, each operator shall have a separate set of controls.
(7) Machines using part revolution clutches.
(i) The clutch shall release and the brake shall be applied
when the external clutch engaging means is removed, deactivated,
or deenergized.
(ii) A red color stop control shall be provided with the clutch/brake
control system. Momentary operation of the stop control shall
immediately deactivate the clutch and apply the brake. The stop
control shall override any other control, and reactuation of
the clutch shall require use of the operating (tripping) means
which has been selected.
(iii) 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.
(iv) The “Inch” operating means shall be designed
to prevent exposure of the workers hands within the point of
operation by:
(a) Requiring the concurrent use of both hands to actuate the
clutch, or
(b) Being a single control protected against accidental actuation
and so located that the worker cannot reach into the point of
operation while operating the single control.
(v) Two-hand controls for single stroke shall conform to the
following requirements:
(a) Each hand control shall be protected against unintended
operation and arranged by design, construction, and/or separation
so that the concurrent use of both hands is required to trip
the press.
(b) The control system shall be designed to permit an adjustment
which will require concurrent pressure from both hands during
the die closing portion of the stroke.
(c) The control system shall incorporate an antirepeat feature.
(d) The control systems shall be designed to require release
of all operators’ hand controls before an interrupted
stroke can be resumed. This requirement pertains only to those
single-stroke, two-hand controls manufactured and installed
on or after August 31, 1971.
(vi) [Reserved]
(vii) Controls for more than one operating station shall be
designed to be activated and deactivated in complete sets of
two operator’s hand controls per operating station by
means capable of being supervised by the employer. The clutch/brake
control system shall be designed and constructed to prevent
actuation of the clutch if all operating stations are bypassed.
(viii) Those clutch/brake control systems which contain both
single and continuous functions shall be designed so that completion
of continuous circuits may be supervised by the employer. The
initiation of continuous run shall require a prior action or
decision by the operator in addition to the selection of Continuous
on the stroking selector, before actuation of the operating
means will result in continuous stroking.
(ix) If foot control is provided, the selection method between
hand and foot control shall be separate from the stroking selector
and shall be designed so that the selection may be supervised
by the employer.
(x) Foot operated tripping controls, if used, shall be protected
so as to prevent operation from falling or moving objects, or
from unintended operation by accidental stepping onto the foot
control.
(xi) The control of air-clutch machines shall be designed to
prevent a significant increase in the normal stopping time due
to a failure within the operating value mechanism, and to inhibit
further operation if such failure does occur. This requirement
shall apply only to those clutch/brake air-valve controls manufactured
and installed on or after August 31, 1971, but shall not apply
to machines intended only for continuous, automatic feeding
applications.
(xii) The clutch/brake control shall incorporate an automatic
means to prevent initiation or continued activation of the Single
Stroke or Continuous functions unless the press drive motor
is energized and in the forward direction.
(xiii) The clutch/brake control shall automatically deactivate
in event of failure of the power or pressure supply for the
clutch engaging means. Reactivation of the clutch shall require
restoration of normal supply and the use of the tripping mechanism(s).
(xiv) The clutch/brake control shall automatically deactivate
in event of failure of the counterbalance(s) air supply. Reactivation
of the clutch shall require restoration of normal air supply
and use of the tripping mechanism(s).
(xv) Selection of bar operation shall be by means capable of
being supervised by the employer. A separate pushbutton shall
be employed to activate the clutch, and the clutch shall be
activated only if the driver motor is deenergized.
(8) Electrical.
(i) A main power disconnect switch capable of being locked only
in the Off position shall be provided with every power press
control system.
(ii) The motor start button shall be protected against accidental
operation.
(iii) All mechanical power press controls shall incorporate
a type of drive motor starter that will disconnect the drive
motor from the power source in event of control voltage or power
source failure, and require operation of the motor start button
to restart the motor when voltage conditions are restored to
normal.
(iv) All a.c. control circuits and solenoid value coils shall
be powered by not more than a nominal 120-volt a.c. supply obtained
from a transformer with an isolated secondary. Higher voltages
that may be necessary for
operation of machine or control mechanisms shall be isolated
from any control mechanism handled by the operator, but motor
starters with integral Start-Stop buttons may utilize line voltage
control. All d.c. control circuits shall be powered by not more
than a nominal 240-volt d.c. supply isolated from any higher
voltages.
(v) All clutch/brake control electrical circuits shall be protected
against the possibility of an accidental ground in the control
circuit causing false operation of the press.
(vi) Electrical clutch/brake control circuits shall incorporate
features to minimize the possibility of an unintended stroke
in the event of the failure of a control component to function
properly, including relays, limit switches, and static output
circuits.
(9) Slide counterbalance systems.
(i) Spring counterbalance systems when used shall incorporate
means to retain system parts in event of breakage.
(ii) Spring counterbalances when used shall have the capability
to hold the slide and its attachments at midstroke, without
brake applied.
(iii) Air counterbalance cylinders shall incorporate means to
retain the piston and rod in case of breakage or loosening.
(iv) Air counterbalance cylinders shall have adequate capability
to hold the slide and its attachments at any point in stroke,
without brake applied.
(v) Air counterbalance cylinders shall incorporate means to
prevent failure of capability (sudden loss of pressure) in event
of air supply failure.
(10) Air controlling equipment.
Air controlling equipment shall be protected against foreign material
and water entering the pneumatic system of the press. A means
of air lubrication shall be provided when needed.
(11) Hydraulic equipment.
The maximum anticipated working pressures in any hydraulic system
on a mechanical power press shall not exceed the safe working
pressure rating of any component used in that system.
(12) Pressure vessels.
All pressure vessels used in conjunction with power presses shall
conform to the American Society of Mechanical Engineers Code for
Pressure Vessels, 1968 Edition, which is incorporated by reference
as specified in Sec. 1910.6.
(13) Control reliability.
When required by paragraph (c)(5) of this section, the control
system shall be constructed so that a failure within the system
does not prevent the normal stopping action from being applied
to the press when required, but does prevent initiation of a successive
stroke until the failure is corrected. The failure shall be detectable
by a simple test, or indicated by the control system. This requirement
does not apply to those elements of the control system which have
no effect on the protection against point of operation injuries.
(14) Brake system monitoring.
When required by paragraph (c)(5) of this section, the brake monitor
shall meet the following requirements:
(i) Be so constructed as to automatically prevent the activation
of a successive stroke if the stopping time or braking distance
deteriorates to a point where the safety distance being utilized
does not meet the requirements set forth in paragraph (c)(3)(iii)(e)
or (c)(3)(vii)(c) of this section. The brake monitor used with
the Type B gate or movable barrier device shall be installed
in a manner to detect slide top-stop overrun beyond the normal
limit reasonably established by the employer.
(ii) Be installed on a press such that it indicates when the
performance of the braking system has deteriorated to the extent
described in paragraph (b)(14)(i) of this section; and
(iii)
Be constructed and installed in a manner to monitor brake system
performance on each stroke.
(c) Safeguarding the point of operation -
(1) General requirements.
(i) 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.
(ii) The requirement of paragraph (c)(1)(i) of this section
shall not apply when the point of operation opening is one-fourth
inch or less. See Table O-10.
(2) Point of operation guards.
(i) Every point of operation guard shall meet the following
design, construction, application, and adjustment requirements:
(a) It shall prevent entry of hands or fingers into the point
of operation by reaching through, over, under or around the
guard;
(b) It shall conform to the maximum permissible openings of
Table O-10;
(c) It shall, in itself, create no pinch point between the
guard and moving machine parts;
(d) It shall utilize fasteners not readily removable by operator,
so as to minimize the possibility of misuse or removal of
essential parts;
(e) It shall facilitate its inspection, and
(f) It shall offer maximum visibility of the point of operation
consistent with the other requirements.
(ii) A die enclosure guard shall be attached to the die shoe
or stripper in a fixed position.
(iii) A fixed barrier guard shall be attached securely to the
frame of the press or to the bolster plate.
(iv) An interlocked press barrier guard shall be attached to
the press frame or bolster and shall be interlocked with the
press clutch control so that the clutch cannot be activated
unless the guard itself, or the hinged or movable sections of
the guard are in position to conform to the requirements of
Table O-10.
(v) The hinged or movable sections of an interlocked press barrier
guard shall not be used for manual feeding. The guard shall
prevent opening of the interlocked section and reaching into
the point of operation prior to die closure or prior to the
cessation of slide motion. See paragraph (c)(3)(ii) of this
section regarding manual feeding through interlocked press barrier
devices.
(vi) The adjustable barrier guard shall be securely attached
to the press bed, bolster plate, or die shoe, and shall be adjusted
and operated in conformity with Table O-10 and the requirements
of this subparagraph. Adjustments shall be made only by authorized
personnel whose qualifications include a knowledge of the provisions
of Table O-10 and this subparagraph.
(vii) A point of operation enclosure which does not meet the
requirements of this subparagraph and Table O-10 shall be used
only in conjunction with point of operation devices.
(3) Point of operation devices.
(i) Point of operation devices shall protect the operator by:
(a) Preventing and/or stopping normal stroking of the press
if the operator’s hands are inadvertently placed in
the point of operation; or
(b) Preventing the operator from inadvertently reaching into
the point of operation, or withdrawing his hands if they are
inadvertently located in the point of operation, as the dies
close; or
(c) Preventing the operator from inadvertently reaching into
the point of operation at all times; or
(d) [Reserved]
(e) Requiring application of both of the operator’s
hands to machine operating controls and locating such controls
at such a safety distance from the point of operation that
the slide completes the downward travel or stops before the
operator can reach into the point of operation with his hands;
or
(f) Enclosing the point of operation before a press stroke
can be initiated, and maintaining this closed condition until
the motion of the slide had ceased; or
(g) Enclosing the point of operation before a press stroke
can be initiated, so as to prevent an operator from reaching
into the point of operation prior to die closure or prior
to cessation of slide motion during the downward stroke.
(ii) A gate or movable barrier device shall protect the operator
as follows:
(a) A Type A gate or movable barrier device shall protect
the operator in the manner specified in paragraph (c)(3)(i)(f)
of this section, and
(b) A Type B gate or movable barrier device shall protect
the operator in the manner specified in paragraph (c)(3)(i)(g)
of this section.
(iii) A presence sensing point of operation device shall protect
the operator as provided in paragraph (c)(3)(i)(a) of this section,
and shall be interlocked into the control circuit to prevent
or stop slide motion if the operator’s hand or other part
of his body is within the sensing field of the device during
the downstroke of the press slide.
(a) The device may not be used on machines using full revolution
clutches.
(b) The device may not be used as a tripping means to initiate
slide motion.
(c) The device shall be constructed so that a failure within
the system does not prevent the normal stopping action from
being applied to the press when required, but does prevent
the initiation of a successive stroke until the failure is
corrected. The failure shall be indicated by the system.
(d) Muting (bypassing of the protective function) of such
device, during the upstroke of the press slide, is permitted
for the purpose of parts ejection, circuit checking, and feeding.
(e) The safety distance (D(s)) from the sensing field to the
point of operation shall be greater than the distance determined
by the following formula:
D(s) = 63 inches/second X T(s)
where:
D(s) = minimum safety distance (inches); 63 inches/second
= hand speed constant;
and
T(s) = stopping time of the press measured at approximately
90 degree position of crankshaft rotation (seconds).
(f) Guards shall be used to protect all areas of entry to
the point of operation not protected by the presence sensing
device.
(iv) The pull-out device shall protect the operator as specified
in paragraph (c)(3)(i)(b) of this section, and shall include
attachments for each of the operator’s hands.
(a) Attachments shall be connected to and operated only by
the press slide or upper die.
(b) Attachments shall be adjusted to prevent the operator
from reaching into the point of operation or to withdraw the
operator’s hands from the point of operation before
the dies close.
(c) A separate pull-out device shall be provided for each
operator if more than one operator is used on a press.
(d) Each pull-out device in use shall be visually inspected
and checked for proper adjustment at the start of each operator
shift, following a new die set-up, and when operators are
changed. Necessary maintenance or repair or both shall be
performed and completed before the press is operated. Records
of inspections and maintenance shall be kept in accordance
with paragraph (e) of this section.
(v) The sweep device may not be used for point of operation
safeguarding.
(vi) A holdout or a restraint device shall protect the operator
as specified in paragraph (c)(3)(i)(c) of this section and shall
include attachments for each of the operator’s hands.
Such attachments shall be securely anchored and adjusted in
such a way that the operator is restrained from reaching into
the point of operation. A separate set of restraints shall be
provided for each operator if more than one operator is required
on a press.
(vii) The two hand control device shall protect the operator
as specified in paragraph (c)(3)(i)(e) of this section.
(a) When used in press operations requiring more than one
operator, separate two hand controls shall be provided for
each operator, and shall be designed to require concurrent
application of all operators’ controls to activate the
slide. The removal of a hand from any control button shall
cause the slide to stop.
(b) Each two hand control shall meet the construction requirements
of paragraph (b)(7)(v) of this section.
(c) The safety distance (D(s)) between each two hand control
device and the point of operation shall be greater than the
distance determined by the following formula:
D(s) = 63 inches/second X T(s);
where:
D(s) = minimum safety distance (inches); 63 inches/second=hand
speed constant;
and
T(s) = stopping time of the press measured at approximately
90 degree position of crankshaft rotation (seconds).
(d) Two hand controls shall be fixed in position so that only
a supervisor or safety engineer is capable of relocating the
controls.
(viii) The two hand trip device shall protect the operator as
specified in paragraph (c)(3)(i)(e) of this section.
(a) When used in press operations requiring more than one
operator, separate two hand trips shall be provided for each
operator, and shall be designed to require concurrent application
of all operators’ to activate the slide.
(b) Each two hand trip shall meet the construction requirements
of paragraph (b)(6) of this section.
(c) The safety distance (D(m)) between the two hand trip and
the point of operation shall be greater than the distance
determined by the following formula:
D(m) = 63 inches/second X T(m);
where:
D(m) = minimum safety distance (inches); 63 inches/second=hand
speed constant; and
T(m) = 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 T(m) 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, T(m) shall be calculated as follows:
T(m) = [1/2 + (1 divided by Number of engaging points per
revolution)]
X time necessary to complete one revolution of the crankshaft
(seconds).
(d) Two hand trips shall be fixed in position so that only
a supervisor or safety engineer is capable of relocating the
controls.
(4) 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.
(5) Additional requirements for safe-guarding.
Where the operator feeds or removes parts by placing one or both
hands in the point of operation, and a two hand control, presence
sensing device of Type B gate or movable barrier (on a part revolution
clutch) is used for safeguarding:
(i) The employer shall use a control system and a brake monitor
which comply with paragraphs (b)(13) and (14) of this section;
(ii) The exception in paragraph (b) (7)(v)(d) of this section
for two hand controls manufactured and installed before August
31, 1971 is not applicable under this paragraph (c)(5);
(iii) The control of air clutch machines shall be designed to
prevent a significant increase in the normal stopping time due
to a failure within the operating valve mechanism, and to inhibit
further operation if such failure does occur, where a part revolution
clutch is employed. The exception in paragraph (b)(7)(xi) of
this section for controls manufactured and installed before
August 31, 1971, is not applicable under this paragraph (c)(5).
(d) Design, construction, setting and feeding of dies .
(1) General requirements. The employer shall:
(i) Use dies and operating methods designed to control or eliminate
hazards to operating personnel; and
(ii) Furnish and enforce the use of hand tools for freeing and
removing stuck work or scrap pieces from the die, so that no
employee need reach into the point of operation for such purposes.
(2) [Reserved]
(3) Scrap handling.
The employer shall provide means for handling scrap from roll
feed or random length stock operations. Scrap cutters used in
conjunction with scrap handling systems shall be safeguarded in
accordance with paragraph (c) of this section and with 1910.219.
(4) Guide post hazard.
The hazard created by a guide post (when it is located in the
immediate vicinity of the operator) when separated from its bushing
by more than one-fourth inch shall be considered as a point of
operation hazard and be protected in accordance with paragraph
(c) of this section.
(5) Unitized tooling.
If unitized tooling is used, the opening between the top of the
punch holder and the face of the slide, or striking pad, shall
be safeguarded in accordance with the requirements of paragraph
(c) of this section.
(6) Tonnage, stroke, and weight designation.
All dies shall be:
(i) Stamped with the tonnage and stroke requirements, or have
these characteristics recorded if these records are readily
available to the die setter;
(ii) Stamped to indicate upper die weight when necessary for
air counterbalance pressure adjustment; and
(iii) Stamped to indicate complete die weight when handling
equipment may become overloaded.
(7) Die fastening.
Provision shall be made in both the upper and lower shoes for
securely mounting the die to the bolster and slide. Where clamp
caps or setscrews are used in conjunction with punch stems, additional
means of securing the upper shoe to the slide shall be used.
(8) Die handling.
Handling equipment attach points shall be provided on all dies
requiring mechanical handling.
(9) Diesetting.
(i) The employer shall establish a diesetting procedure that
will insure compliance with paragraph (c) of this section.
(ii) The employer shall provide spring loaded turnover bars,
for presses designed to accept such turnover bars.
(iii) The employer shall provide die stops or other means to
prevent losing control of the die while setting or removing
dies in presses which are inclined.
(iv) The employer shall provide and enforce the use of safety
blocks for use whenever dies are being adjusted or repaired
in the press.
(v) The employer shall provide brushes, swabs, lubricating rolls,
and automatic or manual pressure guns so that operators and
diesetters shall not be required to reach into the point of
operation or other hazard areas to lubricate material, punches
or dies.
(e) Inspection, maintenance, and modification of presses
-
(1) Inspection and maintenance records.
(i) It shall be the responsibility of the employer to establish
and follow a program of periodic and regular inspections of
his power presses to ensure that all their parts, auxiliary
equipment, and safeguards are in a safe operating condition
and adjustment. The employer shall maintain a certification
record of inspections which includes the date of inspection,
the signature of the person who performed the inspection and
the serial number, or other identifier, of the power press that
was inspected.
(ii) Each press shall be inspected and tested no less than weekly
to determine the condition of the clutch/brake mechanism, antirepeat
feature and single stroke mechanism. Necessary maintenance or
repair or both shall be performed and completed before the press
is operated. These requirements do not apply to those presses
which comply with paragraphs (b) (13) and (14) of this section.
The employer shall maintain a certification record of inspections,
tests and maintenance work which includes the date of the inspection,
test or maintenance; the signature of the person who performed
the inspection, test, or maintenance; and the serial number
or other identifier of the press that was inspected, tested
or maintained.
(2) Modification.
It shall be the responsibility of any person modifying a power
press to furnish instructions with the modification to establish
new or changed guidelines for use and care of the power press
so modified.
(3) Training of maintenance personnel.
It shall be the responsibility of the employer to insure the original
and continuing competence of personnel caring for, inspecting,
and maintaining power presses.
(f) Operation of power presses.
(1) [Reserved]
(2) Instruction to operators.
The employer shall train and instruct the operator in the safe
method of work before starting work on any operation covered by
this section. The employer shall insure by adequate supervision
that correct operating procedures are being followed.
(3) Work area.
The employer shall provide clearance between machines so that
movement of one operator will not interfere with the work of another.
Ample room for cleaning machines, handling material, work pieces,
and scrap shall also be provided. All surrounding floors shall
be kept in good condition and free from obstructions, grease,
oil, and water.
(4) 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.
| This
table shows the distances that guards shall be positioned
from the danger line in accordance wtih the required openings. |
Table
O-10
[In inches]
|
| Distance
of opening from point of operation hazard |
Maximum
width of opening |
1/2
to 1 1/2
1 1/2 to 2 1/2
2 1/2 to 3 1/2
3 1/2 to 5 1/2
5 1/2 to 6 1/2
6 1/2 to 7 1/2
7 1/2 to 12 1/2
12 1/2 to 15 1/2
15 1/2 to 17 1/2
17 1/2 to 31 1/2 |
1/4
3/8
1/2
5/8
3/4
7/8
1 1/4
1 1/2
1 7/8
2 1/8 |
(g) Reports
of injuries to employees operating mechanical power presses.
(1) The employer
shall, within 30 days of the occurrence, report to either the
Director of the Directorate of Safety Standards Programs, OSHA,
U.S. Department of Labor, Washington, D.C. 20210, or the State
agency administering a plan approved by the Assistant Secretary
of Labor for Occupational Safety and Health, all point of operation
injuries to operators or other employees. The following information
shall be included in the report:
(i) Employer’s
name, address and location of the workplace (establishment).
(ii) Employee’s name, injury sustained, and the task being
performed (operation, set-up, maintenance, or other).
(iii) Type of clutch used on the press (full revolution, part
revolution, or direct drive).
(iv) Type of safeguard(s) being used (two hand control, two
hand trip, pull-outs, sweeps, or other). If the safeguard is
not described in this section, give a complete description.
(v)
Cause of the accident (repeat of press, safeguard failure, removing
stuck part or scrap, no safeguard provided, no safeguard in
use, or other).
(vi) Type of feeding (manual with hands in dies or with hands
out of dies, semiautomatic, automatic, or other).
(vii) Means used to actuate press stroke (foot trip, foot control,
hand trip, hand control, or other).
(viii) Number of operators required for the operation and the
number of operators provided with controls and safeguards.
(h)
Presence sensing device initiation (PSDI).
(1) General
(i) The
requirements of paragraph (h) shall apply to all part revolution
mechanical power presses used in the PSDI mode of operation.
(ii) The relevant requirements of paragraphs (a) through (g)
of this section also shall apply to all presses used in the
PSDI mode of operation whether or not cross referenced in this
paragraph (h). Such cross-referencing of specific requirements
from paragraphs (a) through (g) of this section is intended
only to enhance convenience and understanding in relating to
the new provisions to the existing standard, and is not to be
construed as limiting the applicability of other provisions
in paragraphs (a) through (g) of this section.
(iii) Full revolution mechanical power presses shall not be
used in the PSDI mode of operation.
(iv) Mechanical power presses with a configuration which would
allow a person to enter, pass through, and become clear of the
sensing field into the hazardous portion of the press shall
not be used in the PSDI mode of operation.
(v) The PSDI mode of operation shall be used only for normal
production operations. Die-setting and maintenance procedures
shall comply with paragraphs (a) through (g) of this section,
and shall not be done in the PSDI mode.
(2) Brake
and clutch requirements.
(i) Presses
with flexible steel band brakes or with mechanical linkage actuated
brakes or clutches shall not be used in the PSDI mode.
(ii) Brake systems on presses used in the PSDI mode shall have
sufficient torque so that each average value of stopping times
(Ts) for stops initiated at approximately 45 degrees, 60 degrees,
and 90 degrees, respectively, of crankshaft angular position,
shall not be more than 125 percent of the average value of the
stopping time at the top crankshaft position. Compliance with
this requirement shall be determined by using the heaviest upper
die to be used on the press, and operating at the fastest press
speed if there is speed selection.
(iii) Where brake engagement and clutch release is effected
by spring action, such springs(s) shall operate in compression
on a rod or within a hole or tube, and shall be of non-interleaving
design.
(3) Pneumatic
systems.
(i) Air
valve and air pressure supply/control.
(A) The
requirements of paragraphs (b)(7)(xiii), (b)(7)(xiv), (b)(10),
(b)(12) and (c)(5)(iii) of this section apply to the pneumatic
systems of machines used in the PSDI mode.
(B) The air supply for pneumatic clutch/brake control valves
shall incorporate a filter, an air regulator, and, when necessary
for proper operation, a lubricator.
(C) The air pressure supply for clutch/brake valves on machines
used in the PSDI mode shall be regulated to pressures less
than or equal to the air pressure used when making the stop
time measurements required by paragraph (h)(2)(ii) of this
section.
(ii) Air
counterbalance systems.
(A) Where
presses that have slide counterbalance systems are used in
the PSDI mode, the counterbalance system shall also meet the
requirements of paragraph (b)(9) of this section.
(B) Counterbalances shall be adjusted in accordance with the
press manufacturer’s recommendations to assure correct
counterbalancing of the slide attachment (upper die) weight
for all operations performed on presses used in the PSDI mode.
The adjustments shall be made before performing the stopping
time measurements required by paragraphs (h)(2)(ii), (h)(5)(iii),
and (h)(9)(v) of this section.
(4) Flywheels
and bearings.
Presses whose designs incorporate flywheels running on journals
on the crankshaft or back shaft, or bull gears running on journals
mounted on the crankshaft, shall be inspected, lubricated, and
maintained as provided in paragraph (h)(10) of this section to
reduce the possibility of unintended and uncontrolled press strokes
caused by bearing seizure.
(5) Brake
monitoring.
(i) Presses
operated in the PSDI mode shall be equipped with a brake monitor
that meets the requirements of paragraphs (b)(13) and (b)(14)
of this section. In addition, the brake monitor shall be adjusted
during installation certification to prevent successive stroking
of the press if increases in stopping time cause an increase
in the safety distance above that required by paragraph (h)(9)(v)
of this section.
(ii) Once the PSDI safety system has been certified/validated,
adjustment of the brake monitor shall not be done without prior
approval of the validation organization for both the brake monitor
adjustment and the corresponding adjustment of the safety distance.
The validation organization shall in its installation validation,
state that in what circumstances, if any, the employer has advance
approval for adjustment, when prior oral approval is appropriate
and when prior approval must be in writing. The adjustment shall
be done under the supervision of an authorized person whose
qualifications include knowledge of safety distance requirements
and experience with the brake system and its adjustment. When
brake wear or other factors extend press stopping time beyond
the limit permitted by the brake monitor, adjustment, repair,
or maintenance shall be performed on the brake or other press
system element that extends the stopping time.
(iii) The brake monitor setting shall allow an increase of no
more than 10 percent of the longest stopping time for the press,
or 10 milliseconds, whichever is longer, measured at the top
of the stroke.
(6) Cycle
control and control systems.
(i) The
control system on presses used in the PSDI mode shall meet the
applicable requirements of paragraphs (b)(7), (b)(8), (b)(13),
and (c)(5) of this section.
(ii) The control system shall incorporate a means of dynamically
monitoring for decoupling of the rotary position indicating
mechanism drive from the crankshaft. This monitor shall stop
slide motion and prevent successive press strokes if decoupling
occurs, or if the monitor itself fails.
(iii) The mode selection means of paragraph (b)(1)(iii) of this
section shall have at least one position for selection of the
PSDI mode. Where more than one interruption of the light sensing
field is used in the initiation of a stroke, either the mode
selection means must have one position for each function, or
a separate selection means shall be provided which becomes operable
when the PSDI mode is selected. Selection of PSDI mode and the
number of interruptions/withdrawals of the light sensing field
required to initiate a press cycle shall be by means capable
of supervision by the employer.
(iv) A PSDI set-up/reset means shall be provided which requires
an overt action by the operator, in addition to PSDI mode selection,
before operation of the press by means of PSDI can be started.
(v) An indicator visible to the operator and readily seen by
the employer shall be provided which shall clearly indicate
that the system is set-up for cycling in the PSDI mode.
(vi) The control system shall incorporate a timer to deactivate
PSDI when the press does not stroke within the period of time
set by the timer. The timer shall be manually adjustable, to
a maximum time of 30 seconds. For any timer setting greater
than 15 seconds, the adjustment shall be made by the use of
a special tool available only to authorized persons. Following
a deactivation of PSDI by the timer, the system shall make it
necessary to reset the set-up/reset means in order to reactivate
the PSDI mode.
(vii) Reactivation of PSDI operation following deactivation
of the PSDI mode from any other cause, such as activation of
the red color stop control required by paragraph (b)(7)(ii)
of this section, interruption of the presence sensing field,
opening of an interlock, or reselection of the number of sensing
field interruptions/withdrawals required to cycle the press,
shall require resetting of the set-up/reset means.
(viii) The control system shall incorporate an automatic means
to prevent initiation or continued operation in the PSDI mode
unless the press drive motor is energized in the forward direction
of crankshaft rotation.
(ix) The control design shall preclude any movement of the slide
caused by operation of power on, power off, or selector switches,
or from checks for proper operations as required by paragraph
(h)(6)(xiv) of this section.
(x) All components and subsystems of the control system shall
be designed to operate together to provide total control system
compliance with the requirements of this section.
(xi) Where there is more than one operator of a press used for
PSDI, each operator shall be protected by a separate, independently
functioning, presence sensing device. The control system shall
require that each sensing field be interrupted the selected
number of times prior to initiating a stroke. Further, each
operator shall be provided with a set-up/reset means that meets
the requirements of paragraph (h)(6) of this section, and which
must be actuated to initiate operation of the press in the PSDI
mode.
(xii) [Reserved]
(xiii) The Control system shall incorporate interlocks for supplemental
guards, if used, which will prevent stroke initiation or will
stop a stroke in progress if any supplemental guard fails or
is deactivated.
(xiv) 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.
(xv) 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.
(xvi) The control system shall permit only a single stroke per
initiation command.
(xvii) Controls with internally stored programs (e.g., mechanical,
electro-mechanical, or electronic) shall meet the requirements
of paragraph (b)(13) of this section, and shall default to a
predetermined safe condition in the event of any single failure
within the system. Programmable controllers which meet the requirements
for controls with internally stored programs stated above shall
be permitted only if all logic elements affecting the safety
system and point of operation safety are internally stored and
protected in such a manner that they cannot be altered or manipulated
by the user to an unsafe condition.
(7) Environmental
requirements.
Control components shall be selected, constructed, and connected
together in such a way as to withstand expected operational and
environmental stresses, at least including those outlined in Appendix
A. Such stresses shall not so affect the control system as
to cause unsafe operation.
(8) Safety
system.
(i) Mechanical
power presses used in the PSDI mode shall be operated under
the control of a safety system which, in addition to meeting
the applicable requirements of paragraphs (b)(13) and (c)(5)
and other applicable provisions of this section, shall function
such that a single failure or single operating error shall not
cause injury to personnel from point of operation hazards.
(ii) The safety system shall be designed, constructed, and arranged
as an integral total system, including all elements of the press,
the controls, the safeguarding and any required supplemental
safeguarding, and their interfaces with the operator and that
part of the environment which has effect on the protection against
point of operation hazards.
(9) Safeguarding
the point of operation.
(i) The
point of operation of presses operated in the PSDI mode shall
be safeguarded in accordance with the requirements of paragraph
(c) of this section, except that the safety distance requirements
of paragraph (h)(9)(v) of this section shall be used for PSDI
operation.
(ii)
(A) PSDI
shall be implemented only by use of light curtain (photo-
electric) presence sensing devices which meet the requirements
of paragraph (c)(3)(iii)(c) of this section unless the requirements
of the following paragraph have been met.
(B) Alternatives to photo-electric light curtains may be used
for PSDI when the employer can demonstrate, through tests
and analysis by the employer or the manufacturer, that the
alternative is as safe as the photo-electric light curtain,
that the alternative meets the conditions of this section,
has the same long term reliability as light curtains and can
be integrated into the entire safety system as provided for
in this section. Prior to use, both the employer and manufacturer
must certify that these requirements and all the other applicable
requirements of this section are met and these certifications
must be validated by an OSHA-recognized third-party validation
organization to meet these additional requirements and all
the other applicable requirements of paragraphs (a) through
(h) and Appendix A of this
section. Three months prior to the operation of any alternative
system, the employer must notify the OSHA Directorate of Safety
Standards programs of the name of the system to be installed,
the manufacturer and the OSHA-recognized third-party validation
organization immediately. Upon request, the employer must
make available to that office all tests and analyses for OSHA
review.
(iii) Individual
sensing fields of presence sensing devices used to initiate
strokes in the PSDI mode shall cover only one side of the press.
(iv) Light curtains used for PSDI operation shall have minimum
object sensitivity not to exceed one and one-fourth inches (31.75
mm). Where light curtain object sensitivity is user-adjustable,
either discretely or continuously, design features shall limit
the minimum object sensitivity adjustment not to exceed one
and one-fourth inches (31.75 mm). Blanking of the sensing field
is not permitted.
(v) The safety distance (Ds) from the sensing field of the presence
sensing device to the point of operation shall be greater than
or equal to the distance determined by the formula:
Ds = Hs X (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
Dp = 3.4 (S-0.276)
(vi) The presence sensing device location shall either be set
at each tool change and set-up to provide at least the minimum
safety distance, or fixed in location to provide a safety distance
greater than or equal to the minimum safety distance for all
tooling set-ups which are to be used on that press.
(vii) Where presence sensing device location is adjustable,
adjustment shall require the use of a special tool available
only to authorized persons.
(viii) Supplemental safeguarding shall be used to protect all
areas of access to the point of operation which are unprotected
by the PSDI presence sensing device. Such supplemental safeguarding
shall consist of either additional light curtain (photo-electric)
presence sensing devices or other types of guards which meet
the requirements of paragraphs (c) and (h) of this section.
(A) Presence
sensing devices used as supplemental safeguarding shall not
initiate a press stroke, and shall conform to the requirements
of paragraph (c)(3)(iii) and other applicable provisions of
this section, except that the safety distance shall comply
with paragraph (h)(9)(v) of this section.
(B) Guards used as supplemental safeguarding shall conform
to the design, construction and application requirements of
paragraph (c)(2) of this section, and shall be interlocked
with the press control to prevent press PSDI operation if
the guard fails, is removed, or is out of position.
(ix) Barriers
shall be fixed to the press frame or bolster to prevent personnel
from passing completely through the sensing field, where safety
distance or press configuration is such that personnel could
pass through the PSDI presence sensing field and assume a position
where the point of operation could be accessed without detection
by the PSDI presence sensing device. As an alternative, supplemental
presence sensing devices used only in the safeguard mode may
be provided. If used, these devices shall be located so as to
detect all operator locations and positions not detected by
the PSDI sensing field, and shall prevent stroking or stop a
stroke in process when any supplemental sensing field(s) are
interrupted.
(x) Hand tools. Where tools are used for feeding, removal of
scrap, lubrication of parts, or removal of parts that stick
on the die in PSDI operations:
(A) The
minimum diameter of the tool handle extension shall be greater
than the minimum object sensitivity of the presence sensing
device(s) used to initiate press strokes; or
(B) The length of the hand tool shall be such as to ensure
that the operator’s hand will be detected for any safety
distance required by the press set-ups.
(10)
Inspection and maintenance.
(i) Any
press equipped with presence sensing devices for use in PSDI,
or for supplemental safeguarding on presses used in the PSDI
mode, shall be equipped with a test rod of diameter specified
by the presence sensing device manufacturer to represent the
minimum object sensitivity of the sensing field. Instructions
for use of the test rod shall be noted on a label affixed to
the presence sensing device.
(ii) The following checks shall be made at the beginning of
each shift and whenever a die change is made.
(A) A
check shall be performed using the test rod according to the
presence sensing device manufacturer’s instructions
to determine that the presence sensing device used for PSDI
is operational.
(B) The safety distance shall be checked for compliance with
(h)(9)(v) of this section.
(C) A check shall be made to determine that all supplemental
safeguarding is in place. Where presence sensing devices are
used for supplemental safeguarding, a check for proper operation
shall be performed using the test rod according to the presence
sensing device manufacturer’s instructions.
(D) A check shall be made to assure that the barriers and/or
supplemental presence sensing devices required by paragraph
(h)(9)(ix) of this section are operating properly.
(E) A system or visual check shall be made to verify correct
counterbalance adjustment for die weight according to the
press manufacturer’s instructions, when a press is equipped
with a slide counterbalance system.
(iii) When
presses used in the PSDI mode have flywheel or bullgear running
on crankshaft mounted journals and bearings, or a flywheel mounted
on back shaft journals and bearings, periodic inspections following
the press manufacturer’s recommendations shall be made
to ascertain that bearings are in good working order, and that
automatic lubrication systems for these bearings (if automatic
lubrication is provided) are supplying proper lubrication. On
presses with provision for manual lubrication of flywheel or
bullgear bearings, lubrication shall be provided according to
the press manufacturer’s recommendations.
(iv) Periodic inspections of clutch and brake mechanisms shall
be performed to assure they are in proper operating condition.
The press manufacturer’s recommendations shall be followed.
(v) When any check of the press, including those performed in
accordance with the requirements of paragraphs (h)(10)(ii),
(iii) or (iv) of this section, reveals a condition of noncompliance,
improper adjustment, or failure, the press shall not be operated
until the condition has been corrected by adjustment, replacement,
or repair.
(vi) It shall be the responsibility of the employer to ensure
the competence of personnel caring for, inspecting, and maintaining
power presses equipped for PSDI operation, through initial and
periodic training.
(11) Safety system certification/validation.
(i) Prior to the initial use of any mechanical press in the
PSDI mode, two sets of certification and validation are required:
(A) The
design of the safety system required for the use of a press
in the PSDI mode shall be certified and validated prior to
installation. The manufacturer’s certification shall
be validated by an OSHA-recognized third-party validation
organization to meet all applicable requirements of paragraphs
(a) through (h) and Appendix A
of this section.
(B) Alter a press has been equipped with a safety system whose
design has been certified and validated in accordance with
paragraph (h)(11)(i) of this section, the safety system installation
shall be certified by the employer, and then shall be validated
by an OSHA-recognized third-party validation organization
to meet all applicable requirements of paragraphs (a) through
(h) and Appendix A of this
section.
(ii) At
least annually thereafter, the safety system on a mechanical
power press used in the PSDI mode shall be recertified by the
employer and revalidated by an OSHA-recognized third-party validation
organization to meet all applicable requirements of paragraphs
(a) through (h) and Appendix A
of this section. Any press whose safety system has not been
recertified and revalidated within the preceding 12 months shall
be removed from service in the PSDI mode until the safety system
is recertified and revalidated.
(iii) A label shall be affixed to the press as part of each
installation certification/validation and the most recent recertification/revalidation.
The label shall indicate the press serial number, the minimum
safety distance (Ds) required by paragraph (h)(9)(v) of this
section, the fulfillment of design certification/validation,
the employer’s signed certification, the identification
of the OSHA-recognized third-party validation organization,
its signed validation, and the date the certification/validation
and recertification/revalidation are issued.
(iv) Records of the installation certification and validation
and the most recent recertification and revalidation shall be
maintained for each safety system equipped press by the employer
as long as the press is in use. The records shall include the
manufacture and model number of each component and subsystem,
the calculations of the safety distance as required by paragraph
(h)(9)(v) of this section, and the stopping time measurements
required by paragraph (h)(2)(ii) of this section. The most recent
records shall be made available to OSHA upon request.
(v) The employer shall notify the OSHA-recognized third-party
validation organization within five days whenever a component
or a subsystem of the safety system fails or modifications are
made which may affect the safety of the system. The failure
of a critical component shall necessitate the removal of the
safety system from service until it is recertified and revalidated,
except recertification by the employer without revalidation
is permitted when a non-critical component or subsystem is replaced
by one of the same manufacture and design as the original, or
determined by the third-party validation organization to be
equivalent by similarity analysis, as set forth in Appendix
A.
(vi) The employer shall notify the OSHA-recognized third-party
validation organization within five days of the occurrence of
any point of operation injury while a press is used in the PSDI
mode. This is in addition to the report of injury required by
paragraph (g) of this section; however, a copy of that report
may be used for this purpose.
(12) Die
setting and work set-up.
(i) Die
setting on presses used in the PSDI mode shall be performed
in accordance with paragraphs (d) and (h) of this section.
(ii) The PSDI mode shall not be used for die setting or set-up.
An alternative manual cycle initiation and control means shall
be supplied for use in die setting which meets the requirements
of paragraph (b)(7) of this section.
(iii) Following a die change, the safety distance, the proper
application of supplemental safeguarding, and the slide counterbalance
adjustment (if the press is equipped with a counterbalance)
shall be checked and maintained by authorized persons whose
qualifications include knowledge of the safety distance, supplemental
safe-guarding requirements, and the manufacturer’s specifications
for counterbalance adjustment. Adjustment of the location of
the PSDI presence sensing device shall require use of a special
tool available only to the authorized persons.
(13) Operator
training.
(i) The
operator training required by paragraph (f)(2) of this section
shall be provided to the employee before the employee initially
operates the press and as needed to maintain competence, but
not less than annually thereafter. It shall include instruction
relative to the following items for presses used in the PSDI
mode.
(A) The
manufacturer’s recommended test procedures for checking
operation of the presence sensing device. This shall include
the use of the test rod required by paragraph (h)(10)(i) of
this section.
(B) The safety distance required.
(C) The operation, function and performance of the PSDI mode.
(D) The requirements for hand tools that may be used in the
PSDI mode.
(E) The severe consequences that can result if he or she attempts
to circumvent or by-pass any of the safe-guard or operating
functions of the PSDI system.
(ii) The
employer shall certify that employees have been trained by preparing
a certification record which includes the identity of the person
trained, the signature of the employer or the person who conducted
the training, and the date the training was completed. The certification
record shall be prepared at the completion of training and shall
be maintained on file for the duration of the employee’s
employment. The certification record shall be made available
upon request to the Assistant Secretary for Occupational Safety
and Health.
[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]
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