Sustainability is a key issue for every business and is a particular concern for those in the manufacturing sector. But when thinking about sustainability solutions, sensors may not be particularly high on most people’s list of things to consider. However, that could be a mistake, as Tim Dodd at ifm electronic, explains.
It would be hard to overestimate the benefits to a business operating sustainably. Sustainability means reduced costs, lower environmental impact and enhanced reputation with existing and potential customers. But when it comes down to hard facts, what does sustainability actually mean? A simple but useful working definition is the efficient and optimally frugal use of materials, labour and resources, bearing in mind that the most important of the resources is likely to be energy.
What does all this have to do with sensors? Most of us would likely agree that using materials and resources efficiently depends on accurate and reliable control. And there’s a very old cliché which says what you can’t measure, you can’t control. This statement may be old, but it’s undoubtedly true, and, of course, to make measurements, you need sensors. Ultimately, therefore, it would not be unreasonable to claim that sensors – or at least the data they provide – are the foundation stones of sustainability.
Level
Surely, though, modern manufacturing plants will already be equipped with all the necessary sensors, so what scope is there for using sensors to enhance sustainability? Well, let’s take a look, starting with something very simple: level sensors in liquid storage vessels.
It may well be that such vessels are equipped with very simple high- and low-level sensors to indicate when the tank is almost empty and when it is full. That could be good enough to keep the plant working, but might it not be useful to know more about the level in the vessel? Is there, for example, an optimum level at which the machine fed by the vessel works best? Or is the level in the tank dropping more quickly than usual, suggesting the possibility of a leak?
To obtain information like this, a sensor that provides an output proportional to the actual level in the vessel is needed. Often, this can be arranged very simply by using a pressure sensor installed at the base of the vessel, which, in effect, provides a continuous readout of the vessel’s weight plus its contents.
Sometimes, however, a more sophisticated solution, such as a radar level sensor, may be needed. Radar sensors can measure liquid levels with millimetre accuracy at a range of up to 10m from the surface of the liquid. This makes them ideal for hygienic applications as they never come into contact with the liquid they are monitoring. Another benefit is that they are typically installed above the vessel rather than at its base, and so are usually very easy to retrofit.
Temperature
Moving on to temperature, it’s not hard to see that accurate temperature control, especially when temperatures significantly above or below ambient are involved, is important for maximising energy efficiency. Accurate temperature control can also lead to improved product quality and reduced wastage. Fortunately, modern temperature sensors are capable of very high accuracy and are available in a wide range of types and sizes. This means it’s often worth reviewing existing temperature control systems to see whether energy-saving improvements can be made at no more cost than fitting a replacement sensor.
Pressure
Pressure is another process variable that’s worthy of attention. Pressurising vessels and plant – or generating vacuum – uses energy so, as with temperature, accurate control is crucial for energy efficiency. However, with pressure, there is another aspect: a slow loss of pressure may indicate a leak that would otherwise be hard to spot. The substance leaking may be valuable, dangerous to people and the environment or even valuable and dangerous. Therefore, a new or additional pressure sensor could quickly repay its small cost by revealing such a problem.
So much for directly monitoring process variables, but what about monitoring machines? Here, one type of sensor that isn’t as widely used as it deserves is the vibration monitor. This can be a valuable addition to almost any type of motor-driven plant or machine and is usually easy to retrofit. The sensor will allow any anomalous increase in vibration to be swiftly detected, and this will almost always suggest that problems are developing. If increased vibration is, for example, a sign that a bearing is starting to fail, the machine will be using – and wasting – more energy than usual. It will probably also be heading for a complete breakdown with loss of production and, in many cases, scrapped products and wasted raw materials.
Quality
With scrapped products in mind, let’s move on to quality control. Most production lines incorporate some form of quality control, but the degree of sophistication varies greatly. The ‘gold standard’ for automated quality control is often a sophisticated vision system and associated computing power, but these systems can undeniably be costly. Fortunately, there are now simpler, more affordable systems that, in appropriate applications, are very effective. The reduction in cost also means that checks can be carried out more frequently across the whole manufacturing process.
An example is a laser line-scan system, which uses a laser beam to measure and store the profile of a known good component. Profiles of subsequent components are compared with this, and even small deviations can be detected. This means that problems due to, for example, worn tooling can be detected before they reach the stage where components have to be scrapped or expensively reworked.
Another alternative to a full vision system is a 2D vision sensor. In addition to being less costly, the best of these are very easy to set up, taking no more than a few minutes in straightforward applications. Despite their ease of use, these versatile devices can check patterns, shapes, areas, dimensions, contours and even target contrast, either as individual parameters or in combination. Once again, this allows developing problems to be spotted early before they lead to scrapped products and wasted materials.
Adding or upgrading sensors in manufacturing plant clearly has the potential for gaining sustainability benefits, but there’s an elephant in the room! How should all of the additional data produced by these new and/or enhanced sensors be collected and handled? The answer to the first part of the question is relatively simple: networked sensors using the well-established IO-Link technology will minimise the need for additional field wiring. They will also ensure that all the data collected by the sensors is transmitted reliably and without interference or distortion to the plant control system.
Beyond the sensor
That in itself may be enough for considerable sustainability benefits to be achieved, but thanks to new technological advances, even more can be done. Until very recently, converting the huge amount of data collected by sensors in modern plants into a usable and useful form required specially developed plant-specific software; the expense of developing this software was rarely justified. However, easy-to-use yet versatile software solutions, such as ifm’s moneo system, are available now. These incorporate powerful ‘wizards’, allowing users to configure them easily to suit their requirements.
These novel systems typically provide flow modelling, automatic alarm generation, and fully customisable user interfaces that allow plant and machine information to be presented in numeric, graphical or dashboard formats, according to the user’s requirements. Also provided are powerful features for analysing and summarising the data collected by the system, which makes it easy to spot trends over time that may reveal slow declines in plant performance and efficiency, leading to energy and material wastage.
Modern sensors provide the information needed to achieve efficient, sustainable operation in machines, plants and processes of all kinds. IO-Link provides an effective and convenient way of collecting the information from the sensors and feeding it to the control system, and the new generation of configurable plant monitoring software allows even more value to be squeezed from the data by converting it into useful, readily accessible information.
So, when you’re next thinking about upgrading the sustainability of your operations, keep sensors in mind. And if you’d like additional guidance on choosing the right sensing technology for your specific applications, don’t hesitate to contact ifm electronic.
