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................................1/4
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 |
(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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