The latest product safety standards for machine tools, such as ISO 16089 (2015) for the safety of grinding machines, follow the three-step method of risk reduction as explained in ISO 12100 (2010). Step 1 is always the design of the intrinsic safety of the machine. Step 2 follows with the design of additional safety measures, and step 3 focuses on the operating instructions (including warning signs on the machine) and operator training. A very effective risk reduction can be achieved when the working area of the machine is completely enclosed (this is part of step 2). The automatic machining processes can take place (almost) without putting the operator at risk. However, operator access to the work area is sometimes required for manual intervention, such as adjustment within the work area or workpiece change or troubleshooting or maintenance. Careful instructions are then required to enable the operator to fully control the situation and to protect himself from the respective hazards by paying the necessary attention.
The current safety standard for stationary grinding machines ISO 16089 (2015) focusses primarily on the safe design of the abrasive product guard. However, it does not sufficiently clear give guidance to the machine designer, how thick the enclosure doors and windows need to be in case of an abrasive product guard is missing such that they are safe for the intended use. Answering this question, seems to be somewhat difficult in particular for gear grinding machines with very heavy grinding tools. The randomness of consequences, when a grinding wheel is breaking and generating ejected wheel fragments with largely unpredictable shapes, is a complicated obstacle.
In order to gain significant results by impact tests, it turns out to be indispensable to repeat many tests until deducing a design convention becomes feasible. Therefore, BGHM and DGUV conducted 434 grinding wheel bursting tests, which generated a total of 812 single impact test results. Together with similar Japanese tests, a practical safe design convention could be deduced.