Machinery Safety 101

Force and injury — How hard is too hard? ISO 21260 will help

ISO/TS 15066 body model
This entry is part 5 of 5 in the series Hier­archy of Con­trols

Force rep­res­ents the mech­an­ic­al energy that causes injury to the human body. ISO/TC 199 has been work­ing on answer­ing that ques­tion since 2012.

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Instructions for Use – the New ISO 20607

Instruc­tions are one of the basic items that users expect to get when they pur­chase a product, and yet these import­ant doc­u­ments are often poorly writ­ten, badly trans­lated, and incom­plete. Key product fea­tures are badly described, and inform­a­tion on fea­tures, set­tings and haz­ards may be absent. All of this des­pite the fact that the min­im­um require­ments…

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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 a recent exchange, I thought I would share the reas­ons for why this is such a bad idea. The short answer The short answer is an unequi­voc­al NO. Don’t…

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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. I am col­lab­or­at­ing with the IEEE Product Safety Engin­eer­ing Soci­ety’s Vir­tu­al Chapter to provide a series of three 35 minute sem­inars dis­cuss­ing the fun­da­ment­als of func­tion­al safety. The…

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Do-It-Yourself Safety Labels, Signs and Tags

Safety label on a roller conveyor
This entry is part 1 of 5 in the series Hier­archy of Con­trols

One of the great chal­lenges that all product design­ers face is the sourcing of appro­pri­ate product safety labels. There are many sources for off-the-shelf labels includ­ing some of the biggest names in mark­ing and labelling, but until now, none have offered a way for product man­u­fac­tur­ers to devel­op stand­ards-com­pli­ant haz­ard warn­ing signs and labels them­selves. If…

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Emergency Stop Pull-Cords

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

This art­icle was updated 2019-04-26, adding spe­cif­ic details related to IEC 60947 – 5‑5. When it comes to emer­gency stop devices there is no doubt that the red mush­­room-head push but­ton is the most com­mon – they seem to be every­where. The second most com­mon emer­gency stop device is the pull-cord, and like the light-cur­­tain in safe­guard­ing…

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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 a way to inter­lock guards that is equally effect­ive, and often more appro­pri­ate in severe envir­on­ment­al con­di­tions. Copy­right secured by Digi­prove © 2018Acknow­ledge­ments: As cited.Some Rights ReservedOri­gin­al con­tent here is pub­lished under…

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 devices. Copy­right secured by Digi­prove © 2018Acknow­ledge­ments: As cited in the text.Some Rights ReservedOri­gin­al con­tent here is pub­lished under these license terms: X License Type:Non-com­mer­cial, Attri­bu­tion, Share AlikeLi­cense Sum­mary:You may copy this con­tent,…

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. Copy­right secured by Digi­prove © 2018Acknow­ledge­ments: As cited in the text.Some Rights ReservedOri­gin­al con­tent here is pub­lished under these license terms: X License Type:Non-com­mer­cial, Attri­bu­tion, Share AlikeLi­cense Sum­mary:You may copy this con­tent, cre­ate…

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 under­stand­ing of how to apply safe­guard­ing devices like a safety edge becomes a bit foggy.  Copy­right secured by Digi­prove © 2018Acknow­ledge­ments: SafeInd, IEC, ISO, Rock­well Auto­ma­tio more…Some Rights ReservedOri­gin­al con­tent here is pub­lished…

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