Machine & Operator Safety
New machine directive offers flexibility
By Mike Miller and Wayne Solberg
By Mike Miller and Wayne Solberg
Keeping up with changing safety standards is nothing new for machine builders. But the new European Commission’s Machinery Directive, which became effective Dec. 29, 2009, will significantly reshape how designers approach machine safety projects.
This directive will be mandatory for Canadian machine builders who design machines destined for Europe. They will also continue to be required to meet a variety of Canadian standards, including Z432, Z460, Z462, Z22.1-09, as well as other local and national standards.
To comply with the new machinery directive, machine builders and integrators must choose to adhere to either EN/ISO 13849-1 or EN/IEC 62061. The old method, EN954, used to demonstrate compliance, is in a transition period until Dec. 31, 2011, after which point it will be withdrawn.
EN/ISO 13849-1 pertains to safety of machinery and safety-related parts of control systems. It specifies system reliability in one of five performance levels (PLs). These levels are primarily used for low complexity devices and circuits.
EN/IEC 62061 pertains to safety of machinery and functional safety of safety-related electrical, electronic and programmable electronic control systems. It defines the integrity of the safety function in terms of Safety Integrity Levels (SIL). These levels are primarily used on more complex devices.
Both methodologies use quantitative calculations to define the performance and integrity of the safety functions, based on safety data typically supplied from the component manufacturers.
Both standards are based on the determination of the risk levels involved with the identified hazards of the machine and its functions. A documented risk assessment of the machine must be the basis of any safety circuit or safety function to clearly define the level of performance or integrity of that safety function.
This performance-based approach makes it easier for designers to quantify and justify the value of safety. The ability to tailor the specific safety functions to the application by using a more methodical approach helps reduce cost and complexity, improves machine sustainability, and helps achieve a more optimum level of safety for each defined safety circuit to improve the return on investment.
Automation suppliers are continuing to get their safety product certified, and may offer education and training programs, as well as other tools to help machine builders meet these new requirements.
For example, Rockwell Automation released a product library file designed for use with the SISTEMA calculation tool. The SISTEMA tool, developed by Germany’s BGIA organization, automatically calculates the attained PL of the safety-related parts of a machine’s control system in the context of EN ISO 13849-1.
The machine safety world continues to change and these new functional safety standards represent a giant leap forward. Machine builders should take steps now to evaluate the directive’s impact on their equipment.
Mike Miller is the Business Development Manager, and Wayne Solberg is the Global Technical Consultant, for Rockwell Automation.