Machinery Safety 101

Can Emergency Stop be used as an “on/off” control?

Emergency Stop Button
This entry is part 16 of 16 in the series Emer­gency Stop

Every couple of months I get an email ask­ing me if there is any reas­on why e‑stop func­tions can­’t be used as the primary power con­trol (on/off but­ton) for machinery. Fol­low­ing…

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Introduction to Functional Safety Seminars

Man training a group of people, pointing to Functional Safety topics on the whiteboard

If you are inter­ested in func­tion­al safety, and I know many read­ers are based on the stat­ist­ics I see for my oth­er func­tion­al safety-related posts, I think you will be inter­ested in this.…

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Emergency Stop Pull-Cords

This entry is part 15 of 16 in the series Emer­gency Stop

This art­icle was updated 2020-06-13, adding links to the Rock­well Auto­ma­tion and Schmersal pull-cord data, and on 2019-04-26, adding spe­cif­ic details related to IEC 60947 – 5‑5 [7]. When it comes to…

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Trapped Key Interlocking

This is a trapped key interlock on the door of an electrical switchgear cabinet. To open the door the key must be inserted and turned to withdraw a bolt that holds the door closed. With the bolt withdrawn, the key is held in the lock. The upstream switching device is held open by another interlock using the same key; since the key can only be in one of the two locks, it prevents accidentally closing the upstream switch while the cabinet is open for maintenance. The interlock is attached to the door with one-way screws to discourage casual removal of the lock, which would defeat the system.
This entry is part 3 of 7 in the series Guards and Guard­ing

Many machine design­ers think of inter­locks as exclus­ively elec­tric­al devices; a switch is attached to a mov­able mech­an­ic­al guard, and the switch is con­nec­ted to the con­trol sys­tem. Trapped Key Inter­lock­ing is…

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How to Apply a Safety Edge to a Machine Guard – Part 3: Stopping Performance

CNC machine with sliding doors and safety edges
This entry is part 7 of 7 in the series Guards and Guard­ing

In Part 2 of this art­icle, I looked at the pres­sure-sens­it­ive devices (safety edges) them­selves. This part explores the stop­ping per­form­ance require­ments that engin­eers and tech­no­lo­gists need to con­sider when apply­ing these…

How to Apply a Safety Edge to a Machine Guard – Part 2: Design Considerations

CNC machine with sliding doors and safety edges
This entry is part 6 of 7 in the series Guards and Guard­ing

In Part 1 of this art­icle, I looked at the pres­sure-sens­it­ive devices (safety edges) them­selves. This part explores the design require­ments that engin­eers and tech­no­lo­gists need to con­sider when apply­ing these devices.…

How to Apply a Safety Edge to a Machine Guard – Part 1: Pressure-sensitive devices

CNC machine with sliding doors and safety edges
This entry is part 5 of 7 in the series Guards and Guard­ing

Safety Edges are often for­got­ten as safe­guard­ing devices. Most machinery engin­eers and design­ers are famil­i­ar with inter­lock­ing devices and light cur­tains, but once we step away from the famil­i­ar, our…

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Q & A: Category 2 and Testing Intervals

Logical block diagram for ISO 13849-1 Category 2 architecture.
This entry is part 1 of 2 in the series Q&A

Dur­ing the Free Safety Talks that we did with Schmersal Canada and Frank­lin Empire, we had a “hot ques­tion” come up regard­ing Cat­egory 2 archi­tec­ture and the test­ing inter­val require­ment. The…

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Five reasons you should attend our Free Safety Talks

Banner for the Free Safety Talks

Reas­on #1 – Free Safety Talks You can­’t argue with Free Stuff! Last week we partnered with Schmersal Canada and Frank­lin Empire to put on three days of Free Safety…

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Safe Drive Control including Safe Torque Off (STO)

Graph illustrating STO Function
This entry is part 12 of 16 in the series Emer­gency Stop

Ed. Note: This art­icle was revised 25-Jul-17 to include inform­a­tion on safe stand­still. Safe Drive Con­trol includ­ing STO Motor drives are every­where. From DC vari­able speed drives and index­ing drives,…

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