When getting started with robotics, often a question arises as to which standard(s) apply to a machine. Or stated differently, “Is this a robotic system that does packaging, or a packaging machine that includes a robot?”
The answer is important because different standards may have differing requirements. Standards that may apply to a robotic packaging machine include:
· ANSI R15.06 for robots
· ANSI/PMMI B155.1 for packaging and processing machinery
· ANSI B20.1 for conveyors,
· ANSI B11.19 for safeguarding
Other standards may apply as well. Depending on which standard(s) is applied, the requirements for machinery safety may differ. To recognize the right approach for your organization, it’s helpful to understand how standards are structured, which responsibilities and requirements are associated with the standards, and ISO restrictions.
Standards structure. A hierarchical structure to industry standards can assist in addressing the issue of guarding. This structure is explained in the Foreword to ANSI B155.1 Safety requirements for packaging and processing machinery (2016).
This structure is derived from the identical ISO structure (see ISO Guide 51).
The robot and conveyor standards are all type C standards. ANSI B155.1 is a hybrid type A and type B standard. The type C standards would generally take precedence over B155.1 due to the following common premise:
However, one of the challenges of type C standards is that they tend to lag behind the state of the art. The fields of robotics and automation are dynamic, and changes occur rapidly. For example, mobile robots have been in use for several years, but the industry standard for mobile robots R15.08 is only being published in mid-2020. If your application does not fit the traditional robot scenario, what can you do?
Which standards to use. B155.1 can be used for packaging and processing machinery that include robots. B155.1 specifically refers to R15.06 as shown:
The responsibilities for suppliers and users of packaging and processing machinery are contained in clause 4 of B155.1:
The requirements of ANSI B155.1 are contained in clause 5 as shown below:
The fundamental requirement under ANSI B155.1 is to achieve acceptable risk, which is defined in the standard as:To meet the requirements of achieving acceptable risk requires looking at the specific applications and the risk assessment for them. These requirements, although general, provide some flexibility in the dynamic landscape of packaging and processing machinery automation.
ISO restrictions. R15.06 is a U.S. national adoption of the international standard ISO 10218-1 and -2. ISO standards are only allowed to contain requirements for machinery builders, not end users. The rules of standards development under ISO differ then in ANSI in the U.S. in two key ways.
· Products liability: Although international, ISO standards are primarily written around the legal structure of the European Union. This means that the language used is not necessarily written with a consideration of how it might be used, or misused, in the U.S. legal system. More information is available at Product Liability Prevention Guide.
· Legacy machinery: R15.06 does not include responsibilities or requirements other than for new robotic systems. Under the ISO rules, the standards are not allowed to apply to legacy/existing machinery. As such, R15.06 does not contain such requirements.
There are no such restrictions under the ANSI rules, and B155.1 includes guidance and requirements for both legacy machinery, and suppliers, component suppliers, and end users of packaging and processing machinery.
PMMI recommends that machinery users apply the ANSI B155.1 standard to the packaging system as a whole, and make use of the type C standards as useful guidance to meet the requirements of B155.1.
There is often an inclination to choose the safest alternative out of an abundance of caution. This often occurs with decisions about control system reliability—selecting PLd or Categery 3 when a lesser specification may be sufficient. There are cost implications to such conservative decisions, and not just the initial purchase. More complex or higher-reliability control systems are usually more difficult to troubleshoot, diagnose, and maintain. The standard(s) used will often determine these kinds of requirements, thus the proper application of the standards is important.
In closing, ANSI B155.1 can be used for packaging and processing machinery that includes robots and robotic systems. By applying the B155.1 as the base standard and drawing on the specific applicable requirements of R15.06, machinery users will be able to obtain the best of both worlds—packaging and processing machinery with automation.
Knowing how to apply the industry standards can assist in developing productive, safe and effective solutions. PMMI can assist, contact Tom Egan, Vice President of Industry Services for PMMI, the Association for Packaging and Processing Technologies, at email@example.com.
Bruce Main, PE, CSP is the owner of design safety engineering, inc.