Picture this: a heavy, moveable, interlocked guard is affecting an operator's ability to load parts into a machine as often as required. Frustrated, the operator circumvents the interlock and props open the guard. A severe injury results. Could this happen in your workplace?
"Scenarios like this may occur when human interaction with a machine (or ergonomics) is not considered when designing or modifying equipment and selecting safeguards," says WSPS Machine and Robotics Safety Consultant Robert Vomiero.
"While musculoskeletal disorders (MSDs) and associated lost time and productivity are big concerns when ergonomic principles are overlooked, there's also greater potential for acute injuries as this example shows."
"When you design machines and choose safeguarding that meets the capabilities of people, you can greatly reduce the obstacles that may lead to machine-related injuries and downtime," notes Robert.
These four obstacles can occur when human factors are overlooked.
- Failing to consider the need for frequent access to a machine and maintenance activities. "If high-frequency access is required, you need to select safeguarding that protects humans but still allows the process to be executed in an efficient manner," says Robert. Likewise, safeguards must enable inspections, cleaning and repair to take place without causing MSDs or other injuries to the maintenance crew.
- Poor visibility of the process. "A clear line of sight from the start control to the hazard zone, along with well-positioned indicator lights, will enable operators to determine the status of the machine - is it in automatic or semi-automatic mode? - before entering, and to do a visual check to ensure no-one is in the hazard zone before start-up."
- Inability to reach controls. A machine operator in distress can't reach the emergency stop button. The operator's reaching distance and arm length must be considered before the stop button is installed.
- Unrecognized hazards at load/unload stations. “While stations may be compliant from a safeguarding standpoint, we need to ensure we’re not creating ergonomically unsound situations.” For example, how heavy are the parts being loaded and how far must they be carried? Is the height of the fixture they are loading appropriate?
Risk assessment to the rescue
"The best tool workplaces have for identifying machine-related and MSD hazards and finding solutions is a risk assessment," says Robert.
A risk assessment is the cornerstone of both CSA Z432-16 Safeguarding of Machinery, and CSA Z434-14 Industrial Robot and Robot Systems standards. “While both standards include ergonomic considerations, workplaces should also reference CSA Z1004, Workplace ergonomics, and Ontario's MSD Prevention Guidelines when carrying out a risk assessment for machine hazards,” he advises.
Here are Robert's tips for carrying out the risk assessment:
- Consider all the tasks involved in the life cycle of the equipment: design, set up, operation, production, changeover, maintenance, etc.
- Apply the AUTO principle. Can workers access the machine by going Around, Under, Through, or Over?
- Analyze each machine-related task from an ergonomics perspective. "Look for excessive weight, overextension, bent or awkward postures, height and distance travelled, etc.
- Brainstorm safeguarding methods and consider the obstacles listed earlier. Are controls clearly laid out and easy to access? Is there an unobstructed line of sight to the process? If frequent access is required, consider a light, moveable, interlocked guard or a light curtain. Can maintenance activities be done from a distance using new technologies?
- Examine the ergonomic implications of the guarding you choose. For example, two-handed controls keep hands safely away from the hazard zone, but if they are too high for the operator or too far away, MSDs may result.
"The risk assessment process pays dividends when it comes to minimizing risks in the workplace," concludes Robert.
How WSPS can help
Connect with a consultant to find out more about these services from WSPS' machine guarding and ergonomics specialists:
Risk Assessments for Machinery and Robotics (with ergonomic considerations)
Risk Assessment Training and Facilitation (with ergonomic considerations)
Lockout Placard Development Program
Risk Assessments for Machinery and Robotics
Ergonomics Design Review
Ergonomics Risk Assessment - Industrial
Managing Machine Safety (3.5 hour, classroom)
Safeguarding of Machinery: Understanding and Applying CSA Z432 (1 day, classroom)
Lockout (1 hour, eCourse)
Lockout/Tagout Safety Essentials (3.5 hour, classroom)
Resources and videos
Hear Robert present the session Machine Safety and Ergonomics: When Two Hazards Collide at Forum North: Partners in Prevention event - November 1-2 in Thunder Bay. Learn more and register.
The information in this article is accurate as of its publication date.