PSDI supplementary information

Only part-revolution mechanical power presses where an operator's body cannot completely enter the bed area are approved for PSDI. This is the basic limitation OSHA sets to ensure PSDI is used only where current technology can provide safe operation; see Appendix D to 1910.217 (Nonmandatory Supplementary Information) and the PSDI rule language in 1910.217(h).

• Practical point: if the press is a full-revolution press or its bed area could permit a person's body to fully enter, PSDI is not allowed.

No. Flexible steel band brakes are not acceptable on presses used in the PSDI mode of operation because they lack long-term structural reliability compared with other brake types. See the brake guidance in Appendix D to 1910.217 and the PSDI brake requirements in 1910.217(h)(2)(ii).

• Practical point: choose brakes with proven structural integrity and avoid flexible band designs for PSDI-equipped presses.

The standard requires a brake capable of fast, consistent stopping by providing high stopping torque so stopping times remain short and repeatable. The PSDI appendix explains that the requirement in 1910.217(h)(2)(ii) is intended to define a high torque capability that ensures fast and consistent stopping times; see Appendix D to 1910.217.

• Practical characteristics that meet this intent include high brake torque, low brake moment of inertia, and design features that minimize variability in stop time.

Design features that reduce the possibility of significantly increased stopping time include high torque, low moment of inertia, low pneumatic air volume (if pneumatic), non-interleaving engagement springs, secure spring retention, and structural over-design. OSHA discusses these design priorities in Appendix D to 1910.217 and the related regulatory requirement is in 1910.217(h)(2)(iii).

• Practical tips: lock brake adjustments, use locknuts where springs are externally accessible, and prefer brake designs that avoid single-point spring failure modes.

Yes — higher clutch/brake air pressure may be permitted temporarily to increase clutch torque to free a jammed die, but positive measures must prevent that higher pressure from being present at other times. OSHA explains this in Appendix D to 1910.217 and the pneumatic pressure control requirement appears in 1910.217(h)(3)(i)(C).

• Practical controls: implement fixed procedures, interlocks, or temporary controlled settings to ensure normal operation uses the manufacturer-recommended regulated pressure for stopping-time calculations.

Proper lubrication following the press manufacturer's recommended maintenance and inspection procedures is key, and lubrication is considered the single greatest deterrent to bearing failure. See the Flywheels and Bearings section in Appendix D to 1910.217 together with the PSDI requirements in 1910.217(h).

• Practical point: follow the manufacturer's lubrication schedules, inspect bearings regularly, and document maintenance to reduce catastrophic failure risk.

No. Approval of brake monitor adjustments required by 1910.217(h)(5)(ii) is not considered a recertification and does not necessarily require an on-site inspection by the validation organization. OSHA explains this in Appendix D to 1910.217.

• Practical point: validation organizations normally can evaluate brake monitor adjustments from the documented effect on the safety system's certification/validation records, but periodic brake inspection and maintenance are still required.

The PSDI set-up/reset means may be initiated by a special momentary pushbutton alone, or by a special momentary pushbutton combined with the initiation of a first stroke using two-hand controls. This guidance appears in 1910.217(h)(6)(iv) and is discussed in Appendix D to 1910.217.

• Practical point: document the required set-up/reset sequence in your control procedures and train operators on the exact method used for each press.

It is normally preferable to limit the PSDI setup/reset time interval to a maximum of 15 seconds, though OSHA allows up to 30 seconds where an operator must perform many tasks outside the press (lubricating, trimming, deburring). See 1910.217(h)(6)(vi) and the discussion in Appendix D to 1910.217.

• Practical point: choose the shortest reasonable time that allows safe performance of outside tasks while preserving PSDI safety integrity.

Yes; one acceptable method is to make the supplemental guard and the presence sensing device part of a hinged arrangement where the alignment of the presence sensing device itself acts as the interlock, so moving the guard misaligns the device and deactivates the press. OSHA describes this method in Appendix D to 1910.217 in relation to the interlocking requirement of 1910.217(h)(6)(xiii).

• Practical point: document the interlock design and validate that moving the guard reliably deactivates PSDI control as required.

OSHA requires the control system to provide an "inch" operating means, but die-setting must not be done in the PSDI mode and production is not permitted in the "inch" mode because inching bypasses the sensing device and reduces safety. This prohibition and requirement are explained in 1910.217(h)(6)(xv) and discussed in Appendix D to 1910.217.

• Practical point: ensure procedures strictly separate modes — use PSDI for allowed production, use inch only for controlled set-up/maintenance per written procedures, and never use PSDI for die-setting.

No. The use of mirrors to bend a single light curtain sensing field around corners to cover more than one side of a press is prohibited because it reduces the reliability of the presence sensing device. See 1910.217(h)(9)(iii) and OSHA's explanation in Appendix D to 1910.217.

• Practical point: use multiple properly positioned sensing devices or other approved guarding methods to cover multiple sides rather than mirror-bending a single device.

Minimum object sensitivity means the largest acceptable interruption size that the presence sensing device must reliably detect; OSHA uses a minimum object sensitivity of 1.25 inches (31.75 mm) as an example. Safety distance must be derived from measured stopping times made with clutch/brake air pressure set to the manufacturer's recommended value for full clutch torque, using the heaviest upper die planned for use and including the longest stopping time at specified downstroke positions; the formula also accounts for the brake monitor allowance (Tm). See 1910.217(h)(9)(v) and Appendix D to 1910.217 for the detailed explanation.

• Practical checklist for measurement: regulate air pressure to manufacturer's recommended value, test with the heaviest upper die, adjust counterbalance per manufacturer's instructions, measure stopping times at the specified three downstroke positions, and include twice the brake-monitor-allowed stopping-time increase (2 x Tm) in safety-distance calculations.

Yes; OSHA recommends that when a press is equipped for PSDI operation, the presence sensing device be active as a guarding device in other production modes to enhance reliability and ensure it remains operable. See this recommendation in Appendix D to 1910.217 and the relevant control-system provisions in 1910.217(h)(6).

• Practical point: using the PSDI sensor across modes keeps the device exercised and more likely to function correctly when needed.

No. The PSDI safety system focuses on an integrated system approach and does not require redundancy of structural press components where adequate reliability can be achieved by proper design, maintenance, and inspection. OSHA explains this concept in Appendix D to 1910.217 and ties it to the safety philosophy in 1910.217(b)(13).

• Practical point: focus on good design margins, preventive maintenance, inspections, and safety-system integration rather than mandatory duplication of major structural press elements unless the hazard analysis shows redundancy is necessary.