Reducing robot risk: how to design a safe industrial environment
The increase in industrial automation (IA), and particularly the use of industrial robots, is increasing the chance of an unexpected interaction between a human operator and a piece of other mobile equipment or moving machine. The onus is on designers to implement appropriate and often overlapping safety precautions to avoid consequences ranging from interruptions in production to injury or even death. While safety is paramount, designers must still design and keep an eye on both initial costs and total cost of ownership. This article will discuss best practices in plant safety and review some of the techniques and products used to establish and maintain a safe industrial environment and their applications. Factory safety affects everyone in the organization Safety in an industrial plant is a multi-faceted topic that requires involvement from all levels of the organization, from the shop floor to the executive suite. Ideally, a safe factory is designed from the ground up, but many plant buildings predate the widespread adoption of automation, the use of industrial robots, and the rise of the Industrial Internet of Things (IIoT) technologies.
Numerous national and international safety standards apply to different types of industrial machinery, safety equipment, and production processes. Among these are: n ANSI/RIA 15.06 (Robot and Robot System Safety) n ISO 13856-1:2013 (Safety of machinery: Pressure sensitive protective devices) n ISO 13849-1 (Safety of machinery: Safety related parts of control systems) n ANSI B11.19-2003 (Safeguarding Equipment and Protecting Employees from Amputations) n CSA Z432-16 (Safeguarding of Machinery) Designers must take time to familiarize themselves with the applicable specifications before they begin. The preferred approach in developing a safe factory environment has several layers. The process begins with a comprehensive identification, evaluation, and analysis of the hazards, and an assessment of their relative importance. There are several ways to reduce the risk posed by the hazards thus identified. Examples include: n Decreasing the potential severity of harm n Improving the possibility that the harm can be avoided n Reducing the number of personnel with access to the hazardous area, or their duration of exposure
After the initial analysis, the next stage is to develop a Hazard Control Hierarchy that ranks these measures in order of effectiveness and preference for each risk. ISO 12100:2010 (Safety of machinery – General principles for design) is the primary standard addressing the concept and methodology of tiered risk reduction. The preferred solution is to eliminate the risk completely or substitute a safer alternative that minimizes the opportunity for unexpected human-machine interactions (Figure 1). An example is installing an automated material
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handling system to replace a manual loading operation.
If that is not feasible, the next most desirable course of action is to add safeguarding devices that prevent a hazardous event from occurring. If such a device is activated, it typically initiates an automatic operation without human input; a machine is shut down, or a robot is disabled until an operator performs a manual reset. Examples of such devices include light curtains, interlocks, and pressure mats. Other options are less desirable because they require human action as part of hazard avoidance: these options include visual or audio alarms, enhanced safety training, and protective equipment such as face shields, ear plugs, or gloves.
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