osha 10 hour machine guarding #3

Scientific Technologies Inc.

Performance Criteria for Safeguarding


Purpose

The primary objective of this standard is to establish the requirements for the design, construction, installation, operation and maintenance of the safeguarding used to eliminate or control hazards to individuals associated with machine tools.


Clause 1 Scope …performance requirements for the

design, construction, operation, and maintenance of the safeguarding listed below when applied to machine tools. a) Guards b) Safeguarding devices c)Awareness devices d) Safeguarding methods e) Safe work procedures


General Safeguarding Requirements

Guards, safeguarding devices, awareness devices, safeguarding methods, safe work procedures and complementary equipment shall meet the requirements of this clause...


Clause 6.1 When a component, module, device or system failure occurs, such

that it or a subsequent failure of another component, module, device or system would lead to the inability of the safety-related function(s) to respond to the normal stop command or an immediate stop command, the safety-related function shall: prevent initiation of hazardous machine motion(or situation) until the

failure is corrected or until the control system is manually reset; or initiate an immediate stop command and prevent re-initiation of

hazardous machine motion(or situation) until the failure is corrected or until the control system is manually reset; or

prevent re-initiation of hazardous machine motion(or situation) at the next normal stop command until the failure is corrected or until the control system is manually reset


Guards

Clause 7.1.6 1) Interlock devices used in conjunction with barrier guards shall be specifically designed and constructed for use in safeguarding applications.

Clause 7.2.3 Components, subassemblies or modules of the interlock or machine control system shall meet the requirement of 6.1


Guards

7.2.6 c) operation such that the interlock is opened, re-closing the interlock shall not, in or of itself, cause any hazardous motion of the machine.

7.2.8 The user shall ensure that barrier guards that are frequently removed or that have moveable or hinged sections are interlocked


Safeguarding devices

8.3.19 Components, subassemblies or modules of electro-optical, RF, and area scanning presence sensing devices shall be designed and constructed to meet the requirements of 6.1

8.3.2.3 …When an individual can pass through the sensing field of the presence-sensing device…shall require that the device or machine control be manually reset before hazardous motion can occur


Safeguarding devices

8.3.2.4 Components, subassemblies or modules of the interface or machine control system shall meet the requirement of 6.1


Muting 8.3.2.5 Muting of the device shall be permitted during the non-hazardous

portion of the machine cycle. Muting of the device shall be accomplished such that a single failure of a component, a subassembly or a module of the system/device that affects the performance of the safety-related functions shall not prevent a normal stop command from being initiated or shall cause an immediate stop command. In the event of a failure, reinitiation of the machine shall be prevented until the failure is corrected or the system or device is manually reset.

In the presence of a failure, repetitive manual resets of the system shall not be used for production.

If the machine has reversing capability where a muting hazard is possible, the control system shall include automatic means so muting is only permitted in the forward direction


Muting

If an individual can pass through a sensing field when the device is muted, means shall be provided to ensure that the individual is outside of the hazard area, or that the machine ceases hazardous motion when the muting is removed


Safety Mats

8.5.1.1 Safety mat devices, including multiple mats combined to form one sensing surface, shall be designed and constructed to detect the presence of individuals on its sensing surface.

E8.5.1.1 A safety mat device should have a minimum object sensitivity…anywhere on the mat sensing surface, including the area where mats are joined to form a single surface (emphasis added)


Safety Mats 8.5.2.3 The safety mat device shall be fixed

at a location so that the effective sensing surface prevents individuals from reaching the hazard…The user shall ensure that only authorized individuals may relocate the safety mat.

8.5.2.5 Components, subassemblies or modules of the interface or machine control system shall meet the requirement of 6.1


Complementary Equipment

12.1.1 Safety blocks, slide locks, chain locks, locking pins, or other mechanisms that restrict hazardous motion shall be interlocked…and be designed and constructed to… hold the full working force of the machine …or hold the maximum anticipated load(normally the static weight) of the movable portion of the machine, its tooling, and attachments


Stop and emergency stop devices

Stop and emergency stop devices are not safeguarding devices…[and] …shall meet the requirements of ANSI/NFPA 79

E12.9 If an emergency stop device is to be interfaced into the control system, it should not reduce the level of performance of the safety related function


Stopping Distance

Ds = K(Ts) + Dpf


Safety

The words “safe” and “safety” are not absolutes. Safety begins with good design. While the goal of this standard is to eliminate injuries, this standard recognizes that risk factors cannot practically be reduced to zero in any human activity. This standard is not intended to replace good judgement and personal responsibility.


Questions?

osha 10 hour machine guarding #3

Business

machine control system

machine tools

machine cycle

safety mat devices

safeguarding devices8

mat sensing surface

presence sensing devices

safeguarding applications