22 Jan 2020

The big picture – Plant documentation

In the EC machine directive they are referred to as “assemblies of machinery”, in the industry they are mostly known as plants. However we may call them, all of them need an instruction manual. It’s just the way it is.

The conflict

Writing a technical documentationWhen multiple machines have a control related link and work together as one, the machine directive refers to them as an “assembly of machinery”. If this situation occurs, the assembly must be seen as a new machine, meaning the manufacturer must conduct the whole conformity process for it. This process contains the attachment of a type sign, the conduction of a risk assessment – whereby interfaces are taken into consideration – and the compilation of an instruction manual. For many manufacturers this complex description is a thorn in the flesh. “Way too expensive”, “This is already described in the individual machine descriptions”, Nobody reads this”… Arguments that break my little writer’s heart in my role as technical editor.

Sympathy and understanding

Oh well, I understand the manufacturers’ concerns. When 38 DIN A4 folders full of instruction manuals are submitted, one may doubt the necessity. Because THAT really won’t be read. A moderate use of relevant information surely is already important when compiling the particular machine instructions. This is also explained in many seminars about “shortening texts”. Topping this with plant description? Absolutely! And please, make it good enough to save the operator a look into all the individual machine descriptions during normal operation.

Plant documentations: A collection of references?

experts at a clients factory

An assembly of four machines was described in a superior instruction manual. 32 pages describe all life stages and the corresponding safety related information… 32 pages? Suspicious. A look into the manual leads quickly leads to numerous references. The chapter “Operation” contains four notes of the following kind: “Further information about the operation of machine 1 can be found in manual xyz”. These references repeat themselves in almost every chapter. Not a single step of action is described. An unreasonable demand of the reader. This can be done better. But how?

Mastering technical documentation

First of all I would like to point out that an instruction manual for an assembly of machinery is above all one thing: A manual. So let us focus on Chapter “1.7.4 Instructions” of the machine directive. We find out what an instruction manual must contain and of course that the instruction manual is mandatory for a plant. A trained technical editor will additionally take the standard DIN EN 82097-1 into consideration. It may not be a harmonized standard, however it can be considered “state of the art”. The standard for the compilation of manuals and the requirements of the machine directive make a good guideline for the creation of the general instructions. But how can the manual be designed in an overseeable and scientific manner?

A technical report as guide

technical documentationHere the DIN technical report 146 comes in handy. The report is a good guide through the jungle of plant descriptions. Because the full and detailed input of all information regarding a huge plant would be way beyond the realistic scope. References to particular machine instructions are not prohibited, but rather desired. To reasonable context at least. Table 1 – text integration/references of the report shows chapter for chapter where a reference on the supplier documentation is desired and where the integration of texts makes sense. Sadly the technical report is just a technical report and not a standard. But it still makes a good guide for the compilation of the plant description and can also be referred to as “state of the art”.

Logical thinking required

Logical thinking already helps with the compilation. The individual machines are ideally described in the smallest details in their instruction manuals, which have been checked for completeness by the plant manufacturer. Excellent. A risk assessment has also been compiled of course. And now we begin:

 

  • Safety
    The intended use of the machine is mandatory and is, of course, not described in any of the machine instructions. The remaining risks of the plant have been determined in the risk assessment and must be listed for safe use in the plant instructions. The remaining hazards of the individual machines complete the chapter remaining hazards. This way the reader gets a direct overview of all hazards, as well as of all safety equipment and relevant safety and warning instructions from the individual machine instructions.

 

  • Overview
    A chapter about function and structure should help the reader understand how the plant works and where the particular components – in this case the particular machines – are located. This way the reader gets an oversight of the big picture. Simple structure schematics or drawings often help. The description of the structure can be referenced.
    The chapter Technical Data contains data of the whole plant, for the plant itself could have e.g a higher noise level than a single machine. This must be stated in the plant documentation.

 

  • Assembly, etc.
    Chapters like Assembly or Commissioning are to be handled with heart and mind. If commissioning is taken care of by the manufacturer, a description will not be necessary. A corresponding declaration will do in this case. However if it is taken care of by the operator, a complete description of relevant activity would be beneficial.

 

  • Operation
    Operation is an important component and should not consist of a chain of references. Target group oriented reviews of the single steps of action are required. A look at the essential is helpful here. If a plant e.g. is meant for the construction of car engines, this activity should be described in the instructions. This means the description of how the operator conveys the individual components to the plant, how the main process is started and stopped and how the regular processes can be started. There is usually a main operating desk on which the operator controls everything. If an operator can switch the tools of single machines, e.g. to fasten different types of screws, but does not have to this for the construction of car engines, this does not have to be described in the main plant instructions.

 

  • Maintenance
    The maintenance schedule is usually very comprehensive, however it gives the reader a direct overview of when he must conduct which kind of maintenance work. This also a matter of customer loyalty. Does the customer have to compile his own maintenance schedule out of the 12 machine instructions or does the plant manufacturer directly provide this information bundled in the plant description? A maintenance schedule for the whole plant should definitely be preferred, ideally specifying who should perform the individual maintenance operations. Usually there are trained professionals for the maintenance of plants, with the operator only being allowed to conduct selected maintenance operations himself. In this case it is recommended to describe the maintenance work of the operator. Specific descriptions of maintenance operations in the individual machine instructions can however also be referenced in general. The compilation of a maintenance schedule can be a real time killer, because the maintenance operations have to be painstakingly searched for in every single instruction manual and often have to be adjusted to the unified assorting (e.g. by month/operating hours, etc.) of the overall maintenance schedule.

 

  • Malfunction
    With malfunctions it’s just like with operations. New failure indications often result out of the overall controls. These can be included and described in the plant documentation. Including expected malfunctions definitely makes sense. In the case of the plant for car engine manufacture, a typical malfunction would be an empty storage compartment for screws. Corrective actions would be simple: Refill the screws and operations can continue. For further malfunctions like “Engine overheating in machine 2” a reference to the specific machine’s instructions would be enough.

 

Conclusion

Plant documentation will always be a tough challenge. However manufacturers should not see it as an unpleasant waste of money. Instead a well-conceived plant documentation can prevent operation errors and lead to more customer satisfaction. The manufacturers should see the document, which is legally required anyway, as an instrument of customer loyalty and should provide a well-conceived document.

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