Terminology
Defeat in a simple manner
Render inoperative manually or with readily available objects (e. g. pencils, pieces of wire, bottle openers, cable ties, adhesive tape, metallized film, coins, nails, screwdrivers, penknives, door keys, pliers; but also with tools required for the intended use of the machine), without any great intellectual effort or manual dexterity.
Manipulation
In terms of safety technology: an intentional, unauthorized, targeted and concealed invervention into a machine's safety concept, using tools.
Sabotage
Secret, intentional and malicious intervention into a technical system, in order to harm employees or colleagues. Word's origin:
The wooden shoe (Fr.: sabot) of an an agricultural worker or Luddite in the 19th century, which was thrown into a lathe.
When designing and constructing machinery, manufacturers specify what the machines can and should be able to achieve. At the same time they also specify how the user should handle the machine. A successful design involves much more than simply the machine fulfilling its technological function in terms of the output quantity documented in the implementation manual, and the quality and tolerances of the manufactured products. It must also have a coherent safety and operating concept to enable users to implement the machine functions in the first place. The two areas are interlinked, so they ought to be developed and realized in a joint, synchronous operation.
Numerous product safety standards (e. g. EN 1010 or EN 12 717) are now available, offering practical solutions. Nonetheless, planning and design deficiencies are still to be found, even on new machinery. For example:
- Recurring disruptions in the workflow, brought about for example by deficiencies in the technological design or in the part accuracy (direct quote from a plant engineer: “The greatest contribution design engineers can make to active health and safety is to design the machines to work exactly in the way which was promised at the sale.”)
- Opportunities for intervention or access, e. g. to remove the necessary random samples, are either difficult or non-existent
- Lack of segmented shutdowns with material buffers, so that subsections can be accessed safely in the event of a fault, without having to shut down the entire plant and lose valuable time starting it up again
Ill-conceived safety concepts are still found in practice on a regular basis. Many errors are made with interlocked safeguards, for example, when:
- Non-hazardous or frequently operated function elements, e. g. actuators, storage containers, filler holes are installed behind (interlocked) safeguards
- The interlock interrupts the hazardous situation quickly and positively when a safeguard is opened, but afterwards the machine or process is unable to continue or must be restarted
Nobody has any doubt that designers act to the best of their knowledge and belief when they design and implement technological functions as well as those functions relating to persons or operators. One can't really blame them for assuming that subsequent users will behave reasonably and correctly when using the machinery. But it's precisely here that caution is advised: Human behavior is mainly benefit-oriented, both in everyday and in working life. People strive to perform the tasks they are given or have set themselves as quickly and as well as necessary, with the least exertion possible.
People will also try to intervene actively in support of a process, if it isn't running quite as it should. They will make every effort to rectify troublesome faults as quickly and simply as possible. If they can't because of the design (and the fault rectification procedure set down in the operating manual), they will find a way out by defeating the interlock, for example. They will often regard the additional work as a personal misfortune for the smooth performance of their work function. By defeating the safety measures that have been provided the procedure is much less complex, and is therefore seen as a success. Successful behavior tends to be repeated until it is reinforced as a habit, which in this case is unfortunately contrary to safety and indeed dangerous.
The more such rule breaches are tolerated at management level and go unsanctioned, the greater the probability that the rules will continue to be breached without punishment. Incorrect conduct becomes the new, informal rule. For over the course of time, the awareness of the risks that are being taken will lessen and those involved become convinced that they have mastered the potential hazards through vigilance. But the risk is still there; it's just waiting for its chance to strike.
There's no question that the factors that trigger an accident seem initially to rest with the conduct of those affected. However, design errors on the machine encourage the misconduct that's so dangerous (even life threatening) to those involved. Such machines do not comply with the EC Machinery Directive. In other words: It is the manufacturer's responsibility to design protective measures in such a way that they provide a sufficient level of safety, in accordance with the determined risk, while still guaranteeing the functionality and user friendliness of the machine. Ultimately it is always better to accept a calculable, acceptable residual risk with a carefully thought out safety concept, tailored to the practical requirements, than to expose the machine operator to the full risk of insecure processes following successful manipulation.