Momentary stops in production equipment are a headache for people involved in production. Many people are troubled because the cause is unclear. Here, we will consider as much as possible the definition of a momentary stop, the causes of its occurrence, how to deal with it, and what edge computing can do for momentary stops.
These stops often occur suddenly and without warning, and do not necessarily occur with all manufacturing equipment. Sometimes the equipment will recover without any problems if it is turned off and restarted, and sometimes it will recover naturally even if left alone. In other words, the cause of the occurrence is often not immediately known and difficult to predict. This is a headache for production engineers.
Don't overlook root cause
There is always a cause for troubles with production equipment, not just minor stops, but in many cases, the trouble occurs due to certain specific conditions. It is the job of production engineers to find and deal with these conditions, but in the case of minor stops, it is often difficult or time-consuming to find these specific conditions. This is because minor stops do not necessarily occur when certain conditions are met, and they are often not reproducible.
Also, if production engineers are busy, they may decide that it is more cost-effective and time-saving to leave minor stops alone when they only occur occasionally for a few seconds, considering the effort required to investigate the cause. In other words, there are cases where production lines are operated with the understanding that minor stops will occur to a certain extent.
However, if minor stops become frequent, there is an increase in cases where they lead to major stops and breakdowns, so caution is required.
For this reason, some production lines have sensors installed in the equipment's mechanisms to monitor minor stops. In such cases, measures are taken when minor stops become frequent, but if they are not so frequent, it is common to continue monitoring without taking any measures.
The need to reduce short stops
Minor stops are often ignored because it takes time to determine the cause, but they must be reduced because they reduce the operating rate of manufacturing equipment. For example, if there is a 5-minute stop per hour, the equipment operating rate will decrease by about 8-9% on an hourly basis. This number is a fairly high frequency, but it is easy to understand that minor stops can lead to a decrease in equipment operating rate. Also, as mentioned above, frequent stops can be a sign of serious trouble.
In other words, it can be said that not overlooking even small stops, and at least understanding the frequency of stops, is important for maintaining equipment operating rate and avoiding serious trouble.
Causes of minor stops that can be verified on-site
There are many possible causes for short stops, but the following two are relatively easy to verify. If short stops occur frequently, these are the first two things to suspect.
Sensor installation is incorrect
In many cases, sensors are installed at key points in equipment to detect product handling errors and control mechanical parts. These sensors are often secured with screws, and vibrations during operation or transportation can loosen the screws and cause the sensor to shift out of position. If the sensor shifts out of position, it will not detect correctly when it should exceed the set threshold. In short, vibrations cause the position to shift slightly, causing a momentary stop to occur or not even if the conditions are met.
From this, if a momentary stop occurs, and you find that the screws are loose and retighten them, and the momentary stop disappears, it is likely that the cause is a loose screw in the sensor mounting part.
Thermal effects
Most modern production equipment is controlled by computers. For this reason, if heat causes the CPU to become unstable, it will affect the equipment's control system. Because heat flows through the air, minor stops may or may not occur depending on changes in the air flow inside the equipment.
If a minor stop occurs, opening the control device cover and cooling it with a fan will eliminate the minor stop, and this is likely due to the effects of heat.
What can be done on-site to avoid minor stops?
Check the screw fastening parts
As mentioned above, if the screws on the sensor become loose, it becomes more likely that momentary stops will occur. It is a good idea to check the screws periodically for looseness. Also, loose screws in the mechanism can lead to unnecessary vibrations, so be sure to check these regularly as well.
Check the cooling fan and increase air conditioning
Regularly check that the cooling fan is working properly. In some cases, you may need to consider replacing or adding a cooling fan. It may also be effective to strengthen the air conditioning in the factory. This is something you should be especially careful about in the summer.
Relaxed operation
Also, in order to avoid minor stoppages, it is important not to operate the equipment at the very limit of the operating conditions guaranteed by the equipment manufacturer, such as temperature and time.
What edge computing can do to identify the cause of minor stoppages
If the above methods cannot identify the cause of the momentary stop, or if you want to efficiently and systematically identify the cause of the momentary stop that has low reproducibility, you can introduce continuous monitoring using edge computing.
Sensors that detect movement in the moving parts of the equipment, as well as sensors that correspond to all other possible causes, are attached to the places where abnormalities are expected to occur. Then, when the sensors installed in the moving parts react, it is considered that the momentary stop occurred. In addition, the reactions of sensors other than the moving parts are also detected and analyzed at that time. This makes it possible to consider responses based on more specific and objective data, and to display the data in graphs for more visual analysis. This is called "visualization of momentary stops."
The advantage of using edge computing for continuous monitoring is that the data collected from the sensors is automatically accumulated in the edge server. Then, once a certain amount of data has been accumulated, it is enough to suck up the data in the cloud or offline. This makes it possible to monitor momentary stops, which have low reproducibility and are unknown when they occur, more efficiently than if a person were to attach themselves to the equipment and monitor it constantly.
Edge computing can be introduced after the fact, but if the budget allows, it is a good idea to introduce equipment such as an edge server in advance. In addition to detecting momentary stops, various applications are expected in the future, such as product inspection and predictive maintenance.
Alternatively, you could install an application that collects data on an edge server that you have purchased, and when momentary stops can no longer be ignored, use edge computing to identify the cause. This would be effective when you have a limited budget to spend at one time and it is difficult to introduce full-scale edge computing all at once.
There is a solution to the troublesome delays
Above, we have mainly introduced the causes of momentary stops and countermeasures that can be verified on-site. Momentary stops are a nuisance that troubles production engineers because it is difficult to determine the cause, but that does not mean there are no countermeasures. As introduced in this article, it is possible to use edge computing, which has been attracting attention in recent years for its use in the manufacturing industry, and it can be said that the number of countermeasure options is increasing. Since it is not a major stoppage, it tends to be ignored when it occurs, but there is no doubt that it is a factor in reducing operating rates. Let's aim to improve production efficiency by taking effective measures.
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