The increasing role of functional safety in complex machine design

01/30/2014


Declaration of Conformity, affixing a CE Mark

When all the procedures listed above have been followed, it’s time to put all the relevant documentation into a “Technical File.”

According to Annex VII of the Machinery Directive, this technical documentation must:

  • Contain all diagrams, calculations, test reports, and documents that are relevant to conformity with the essential health and safety requirements of the Machinery Directive
  • Be archived for at least 10 years from the last day of manufacture of the machine (or the machine type)
  • Be submitted to the authorities on legitimate request.

Critical items for the Technical File can be documented integrated safety engineering software, for CE Marking in machine construction and engineering. Such workflow-oriented software supports the designer with an engineered solution for the demanding process of CE Marking, including the risk assessment, management of harmonized standards, and inclusion of SISTEMA and other documents derived from all design and testing.

Figure 3: Here are the paths to conformity for CE Marking. Courtesy: SickWith the technical documentation developed and placed into a Technical File, the manufacturer can now complete and issue the EC Declaration of Conformity.

As mentioned before, there are several paths to CE Marking (Figure 3).

Most machines are not listed explicitly in annex IV of the Machinery Directive, and are thus subject to the standard process. In these cases, it is the responsibility of the manufacturer to apply the CE Marking, without involving a body or the authorities (“self-certification”). However, the manufacturer must compile a Technical File so that the documentation can be submitted to national authorities on request.

Machines that are particularly hazardous are subject to special procedures. Annex IV of the Machinery Directive contains a list of categories of machinery that may be subject to one of the two conformity assessment procedures involving a Notified Body: EC type examination or full quality assurance in accordance with Annex X.

If harmonized standards exist for the machine or safety components, and these standards cover the entire range of requirements, the declaration of conformity can be obtained in one of three ways:

  • Self-certification (most common method)
  • EC type-examination by a Notified Body
  • Usage of a full quality management system that has been assessed.

If no harmonized standards exist for the machine or if the machine or parts of the machine cannot be built to harmonized standards, the declaration of conformity can only be achieved as follows:

  • EC type-examination by a Notified Body where the manufacturer shall make available his machine and the related technical documentation so that it can be determined by means of a type-examination whether or not the machine meets the essential health and safety requirements. The Notified Body tests for compliance with the directive and prepares an EC type-examination certificate that contains the results of the tests.
  • Usage of a full quality management system (QMS) that has been assessed: The full QMS shall ensure conformity with the requirements of the Machinery Directive and be assessed by a Notified Body. The manufacturer is always responsible for the effective and appropriate usage of the QMS as outlined in Annex X of the Machinery Directive.

Once all the requirements have been met, the CE Mark can be applied to the machine and the manufacturer is permitted to place the machine on the market in the European Union.

Applying standards, getting the CE Mark

Figure 4: When a robot is added to an existing injection molding machine to unload parts, although each has a CE Mark, the combined system needs a new risk assessment. In this case, the U.S. manufacturer called upon Sick to assist in the risk assessment,Consider the following complex machine consisting of several pieces of existing equipment combined into a single machine. Here, a robot (Figure 4) is unloading finished parts from an injection molding machine. 

The U.S. manufacturer designed and built the molding machine but chose to purchase the robot as an off-the-shelf component and integrated it accordingly. Each machine is complex in its own right, and each machine has a completed Technical File and CE Mark, in accordance with the applicable type C standard: EN ISO 10218-1:2011 for the robot, and EN 201:2009 for the injection molding machine.

Combined, they make a complete machine that requires a new risk assessment to consider all the new hazards and tasks associated with its operation and integration. This may include the application of EN ISO 10218-2:2011 for robot systems and integration.

While injection or compression plastics-molding machinery with manual unloading is listed in Annex IV, the resulting manufacturing system with robot unloading is not listed in Annex IV. In this case, the manufacturer can proceed with the conformity assessment by self-certification, in accordance with Annex VIII. However, a machine of this complexity may influence the manufacturer to contract with a third party to help with the resulting risk assessment and Technical File preparation. Due to liability concerns or lack of expertise, the manufacturer may have the equipment assessed by a Notified Body for Type Examination to ensure compliance to the directives.

Conforming to the directives and preparing the Technical File to support CE Marking can be a very difficult process, especially for U.S. machine builders going through the process for the first time. While this article touched on the main procedures, it is by no means a comprehensive, detailed analysis. A machine builder needs a deep, thorough knowledge of the directives, procedures, and standards involved to demonstrate conformance, or it needs to ask for outside help from an experienced consultant or a safety systems vendor.

- Mark Nehrkorn is manager of safety services and solutions, Sick Inc. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering, mhoske(at)cfemedia.com.

ONLINE

Control Engineering Machine Safety blog 

Harmonized standards list 

German Social Accident Insurance 

Annex IV of the Machinery Directive 

Key concepts

  • Machine Directive integrates functional safety into machine design.
  • Evaluate safety standards properly to get CE Marking for machines placed in Europe.
  • Some U.S. machine builders remain challenged by the transition from the old safety standard EN954-1 to the new ISO 13849-1 or IEC 61061 safety standards.

Consider this

Even if you’re not designing a machine for the European market, considering and documenting safety during machine design can be a best practice.


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