In the daily work of the technical department, most of the enquiries received are not technical difficulties but the question of why this machine behaves in this way. The description from the customer's site is often only a sentence or two: the vacuum level does not come up, the water content does not come down, the filter element is blocked shortly after it was fitted. To answer such a question properly, the site conditions, the condition of the machine and the state of the oil first have to be established in full, and only then does the analysis begin.
The three kinds of question asked most often
Classifying the enquiries received over a year by their symptom puts them into three groups. None of the three points at the machine itself; they point at the gaps between the instructions, the operation and the site conditions. This is also the main basis on which we decide where an improvement is needed: the places that come up often and are described in vague terms are mostly the places the documentation does not cover, rather than places where the customer is unwilling to cooperate.
| How the customer asks | The usual actual cause | The gap it exposes |
|---|---|---|
| The vacuum level does not come up | The condition of the vacuum pump, a leak in the system, or oil that is high in gas and water | No investigation order that distinguishes between the cases |
| The water content does not come down | The water is in the emulsified or the free state, while degassing only deals with the dissolved state | The limits of the degassing capability are not stated |
| Short filter element life | A bypass valve that has not been reset, an element fitted the wrong way round, or a failed coarse filter in the feed stage | The installation and changeover steps are not specified firmly enough |
Working back from the questions to the gaps in the product
A symptom that is asked about repeatedly indicates a gap in the documentation or in the design, not that the customer does not know how to use the machine. Take the vacuum level that will not come up: the usual practice on site is to strip down and check the pipework, and the direction is often wrong. When the oil itself is high in water and gas, the system can hold the vacuum; it is only the ultimate value that is not reached. If the documentation sets out the working vacuum and the ultimate vacuum separately, a great deal of investigation is saved.
The question of the water content is of the same kind. If the upper limit, the test basis and the range of application of the degassing are stated, the customer knows under which conditions this result can be expected and under which conditions a different approach is needed. The question of the element life points instead to the operating procedure: the direction of installation, the resetting of the bypass valve and the depressurising order during the changeover. If these steps are not written down as check items, passing them on by experience will eventually go wrong.
How the answers are turned into product changes
Our practice has three parts. First, the frequent questions are compiled into a structured investigation order and written into the documentation in the form of symptom, what to look at first, possible cause, action to take, so that the site staff can follow it step by step without contacting the manufacturer from the beginning each time. Second, the points the documentation cannot express clearly are built into the product: the working vacuum and the ultimate vacuum are presented separately in the panel indications, and the parts that are easily fitted the wrong way round are made so that they cannot be fitted the wrong way round.
Third, every change is tied to something that can be verified. Once a change has been made, it cannot be left to subjective judgement; it needs a matching way of verifying it. The question of the direction of installation can be solved by making the part foolproof in itself. The question of the operation of the protective functions has to be confirmed item by item by triggering them in the factory test. The capability of the vacuum system has to be demonstrated with the measured hold-up and vacuum test data.
The more often it is asked, the more the documentation has to change
There is a value here that tends to be underestimated: the process of the customer asking the questions is itself a stress test of the documentation. If a step confuses the site, sooner or later somebody will ask about it. Rather than wait for them to ask, write the confusing points clearly in advance and change them so that they no longer confuse. The value of the documentation does not lie in how much of it there is, but in that the site can do it right by following it; working through it once yourself after writing it often reveals the points that are still not clear.
Internally we have an agreement for handling questions of this kind: every recurring question is recorded, including the site conditions, the course of the investigation and the final conclusion. As those records accumulate they become the input for the next product iteration. That is also the most concrete output of the technical department: not a particular drawing, but one fewer occurrence of the same kind of question the next time, and that saves more effort than any other improvement.
When customers ask the same question again and again, it means we have not yet written the answer where it can be seen on the machine.