Machine Safety: Actuator controls versus machine actuators

Why is knowing the difference between a machine actuator versus an actuator control important? The hazard on a machine is what’s really important to reducing risk! Understanding two standards-based definitions can help.

06/12/2013


Why is knowing the difference between a machine actuator versus an actuator control important? The hazard on a machine is what’s really important to reducing risk! 

What is the hazard? Motion caused by a machine actuator can be a hazard to an operator, maintenance technician, set-up engineer, or clean-up personnel, to mention a few. However, the power (electrical, hydraulic, pneumatic, etc.) applied to the actuator control also can be a hazard to the same personnel. So, is looking at the hazard the best way to understand these terms? 

Perhaps some definitions of these two terms may help clear up the confusion. Several international and domestic standards define:

  1. An actuator control as an operator control device used to initiate or maintain machine motion or other machine function(s). Some examples given include; two-hand control, treadle bar, foot control, inching button, e-stop device, etc.
  2. A machine actuator as a power mechanism used to cause motion of a machine. Some examples given include; air cylinder, motor starter, hydraulic valve, etc.

That said (and not to add more confusion) the machine safety standards also explain that a PSD (presence sensing device) device is an example of an actuator control. An example is when the robot arm retracts from a light curtain field initiating a signal to the machine control system to automatically cycle the machine. Or, when a “safe drive” automatically detects a fault and causes a Cat 1 machine stop. Where’s the operator in these examples? 

Regarding machine actuators, I’ve also seen the metal rod inside an operator control device described as an actuator because it causes the contact(s) to open and remove power. Therefore, can a machine actuator also cause the stopping of a machine motion as well as causing machine motion? What about the friction clutch in a mechanical power press? Is this device a machine actuator since it either causes or stops motion and is powered via electric, hydraulic, pneumatic or spring type energy? 

I believe by now the answer might be as clear as mud. So, what’s the point? It’s my opinion that this discussion is a good example where industry experts can help interpret the intent and requirements of machine safety industry standards. After all, has anyone ever seen a prescriptive Standard for compliance?

Has this presented you with any new perspectives? Add your comments or thoughts to the discussion by submitting your ideas, experiences, and challenges in the comments section below. 

J.B. Titus, CFSE

Related articles:

Inside Machines: Does adopting ISO 13849-1:2006 change the U.S. model for compliance and enforcement?

Machine Safety – does OSHA reference consensus standards for compliance?

Machine Safety: Is OSHA okay with my 'acceptable' risk mitigation?

Contact: http://www.jbtitus.com for “Solutions for Machine Safety”.



Jummah , Non-US/Not Applicable, Saudi Arabia, 06/14/13 10:07 AM:

As far as safety concerns, those who works on resturants, where they are only or not recieving any taining on HMI, they always pay the price. One day I was taking a meal in some resturant, I saw a guy used to serve me, was holding his arm to his neck by medical band, when I asked, he told me, that 2 of his fingers were minced at the meat machine. That is a painful accedent, could it be any way for the control system to avoid this or at least minimized it.

thankyou.
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
2017 Lubrication Guide; Software tools; Microgrids and energy strategies; Use robots effectively
Prescriptive maintenance; Hannover Messe 2017 recap; Reduce welding errors
Safety standards and electrical test instruments; Product of the Year winners; Easy and safe electrical design
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Mobility as the means to offshore innovation; Preventing another Deepwater Horizon; ROVs as subsea robots; SCADA and the radio spectrum
Future of oil and gas projects; Reservoir models; The importance of SCADA to oil and gas
Diagnostic functions for system safety; Specifying industrial enclosures; Effective decision support for a crisis
Transformers; Electrical system design; Selecting and sizing transformers; Grounded and ungrounded system design, Paralleling generator systems
Natural gas for tomorrow's fleets; Colleges and universities moving to CHP; Power and steam and frozen foods

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
Featured articles highlight technologies that enable the Industrial Internet of Things, IIoT-related products and strategies to get data more easily to the user.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Maintenance Manager; California Oils Corp.
Associate, Electrical Engineering; Wood Harbinger
Control Systems Engineer; Robert Bosch Corp.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me