Meeting the EU Machinery Directive for CE Compliance
What is the Machinery Directive (And why is it important even outside of the EU)
All machinery with mechanical hazards that is to be sold to the European Union must meet the requirements of the CE Machinery Directive (Directive 98/37/EC). The CE Machinery Directive is similar to (and in most cases a superset of) the American National Standards Institute (ANSI) machine specific standards for safety, (e.g. ANSI B11.19-1990 "Machine Tools, Safeguarding"). In the U.S., the Occupational Safety & Health Administration (OSHA) states: "OSHA encourages employers to abide by the more current industry consensus standards [such as the CE Machinery Directive] since those standards are more likely to be abreast of the state of the art than an applicable OSHA standard may be."
Further, several industry groups reference the CE Machinery Directive and specifically the safety control system standard: EN 954-1 "Safety of machinery—Safety-related parts of control systems…" in their machine safety standards. (For example, the Semiconductor industries consortium (SEMI) calls out EN 954-1 as a normative reference in their S2 safety standard "Facility Standards & Safety Guidelines for Semiconductor Manufacturing Equipment"). Most Asian countries either recognize the CE mark as sufficient, or have drafted safety standards that strongly reflect (and in some instances mimic) the CE Machinery Directive and the supporting EN standards.
In short, the CE Machinery Directive and the EN standards that support it have become the de-facto world standard suite for machinery safety because, as standards go, these are well thought out, comprehensive and conservative.
Even if you don't intend to sell equipment in Europe, meeting the CE Machinery Directive requirements is a well understood way to keep the machine operators safe (and should put your company in a more legally defensible position against lawsuits resulting from machine misuse).
Because of its comprehensive, conservative nature, meeting the CE Machinery Directive is surprisingly complicated. First, the mechanical hazards must be evaluated to understand what level of safety control system is necessary using EN 1050 "Safety of machinery. Principles for risk assessment". The result of the EN 1050 risk assessment then dictates the level of fault tolerance and monitoring required in the safety control system as outlined in EN 954 1. To simplify the discussions on this page, we have assumed that we are working with a typical servo motor or high power stepper motor driven machine. In nearly all of these machines there is a likelihood of significant irreversible bodily injury or death caused by moving mechanics (basically, this is defined as anything more severe than a bruise or sprain). This then requires that the safety control system meet EN 945-1 Level 2 or 3 combined with requirements on guarding the hazards. (Under certain instances, if the risk is high enough and the frequency of exposure is also high, Level 4 may be required, but this is not very common.) Once you have determined what level of safety control system you require, then EN 954-1 dictates what you need to do to provide the required level of protection. Typical safety control systems for level 2, 3 or 4 are constructed using safety control "relays," positively-driven E-Stop switches, interlock switches, guard-lock switches, and contactors with positively-driven feedback contacts, all wired together by the machine builder to interrupt power to the mechanical hazards. (The requirements for all of these devices are each called out by various other EN standards.) There is then a procedure described in ISO 13849-2 which details how to do an FMEA (Failure Mode Effects Analysis) to prove that your system is fault tolerant. Then the system must be tested to make sure that the monitoring of the safety system will report errors when they occur to fully meet the requirements. The requirements become more difficult and expensive to comply with if you want to allow for a controlled stop before removing hazardous power and/or if you want to construct a two area (Main + load/unload) machine.
All of the above sounds like a lot of work, hassle and expense -and it is. To make it even more frustrating, meeting these important requirements rarely, if ever makes your machine more attractive to your customers at the time of sale. It slows time-to-market and increases development cost without providing any differentiating market value. Basically, all machinery vendors are forced to mark their machines as compliant, so customers don't perceive any difference.
One way to reduce the effort is to take shortcuts when designing a safety control system without reading, or partially ignoring, any or all of the EN standards referenced by the CE Machinery Directive hoping that your test lab does not catch any errors or omissions. Unfortunately, this can often result in significant rework and delay of product launch when the test lab discovers insufficient compliance. If you're "lucky" enough to pass a machinery safety compliance inspection with errors and/or omissions then, of course, there is a real liability issue. Clearly, taking "shortcuts" is not advisable.
Light at the end of a short tunnel...
Fortunately, the eF-785 is pre-engineered to remove nearly all of this work from your project plan. All you have to do is to assess whether you need a level 2 or 3 safety control system based upon your risk assessment. If you need a level 3 system, install the eF-785 with guard-locks on any movable guards (i.e. protective doors or covers). If you require a level 2 system, install the eF-785 with interlock switches on any Main area moveable guards, and guard locking switches on any moveable guards in the Load area. That's it.
The safety review and certification of the eF-785 to EN 954-1 explicitly included an FMEA of a safety control system constructed as detailed on this page to make sure the installation instructions, when followed, would result in a safety control system compliant with the standards. So, if you install the eF-785 according to these instructions, using the recommended 3rd party components, your machine will be compliant.