Musings on Automation: Form-Fill-Seal Machine
Published on : Friday 05-08-2022
PV Sivaram explains the concept of an automatic form-fill-seal machine to an aspiring engineer.
On a wet Sunday morning, as a regular habit, I set off for a walk with my nephew Anand, who had secured admission to study engineering. As we reached the playground, we ran into my friend Vinod, who is a maintenance manager at a plant which fills edible oil into pouches. Mr Vinod appeared rather disgruntled, so I asked him the reason. He explained that even on a Sunday he had to go to his factory because there was a production halt due to a problem in a machine. Anand, being the curious student, immediately piped up, and asked which machine was it. Mr Vinod was not in any mood to explain, and curtly replied that it was a fully automatic filling machine, and went his way. A short reply was not sufficient for the inquisitive budding engineer, and he turned to me.
I explained – edible oil as it reaches us, goes through several processes. The end step is filling the oil into bottles or pouches or tetrapaks. The machine which fills the fluid, in this case cooking oil into pouch is called a form-fill-seal machine. Form fill seal systems do exactly what the name suggests. We send packaging material through our mechanism so that it forms a pouch, then fills it with the product, and immediately seals your product inside the pouch to complete packaging at a rapid pace. The quantity to be filled in a package has to be quite accurate. It can be per volume, in which case it is called volumetric filling, or it can be by weight, in which case it is called gravimetric filling. Usually for liquids we prefer volumetric filling, as being more convenient. You might have noticed that edible oil packets are labelled as for example 920 gm. This is the weight of one litre of oil, and the machine is calibrated for volumetric filling. The matter is critical, because providing an accurate measure is a legal requirement. Under-weight attracts penalties, whereas filling excess is a loss to the company.
Source: Wikipedia
If we think of dry solids, it is more convenient to fill by weight. There are challenges here as well. If we try to weigh, and then fill, the process becomes a start-stop process. Start-stop machines are jerky and noisy and therefore have more maintenance issues. An alternative is to do continuous weighing and filling. This means that the product is weighed while getting filled, and when a desired weight is reached, the flow of material is interrupted. This process is faster, but calibration can be trickier, particularly if the product to be filled tends to form clumps like for example salt.
I explained further, even though by now his forehead was wrinkled, that filling is only one part of the control challenge. The pouch into which the filling is done has to have the product name, brand, and important information. This comes already printed on the paper or plastic film. This paper or film comes as a big roll long enough for several hundreds of packets. Now it is obviously important to have the packet labels properly aligned so that each packet has all the same information. This is achieved by a process called print mark recognition.
At this point rain increased in intensity, and we rushed home.
PV Sivaram, Evangelist for Digital Transformation and Industrial Automation, is mentor and member of steering committee at C4i4. He retired as the Non-Executive Chairman of B&R Industrial Automation and earlier the Managing Director. He is a past President of the Automation Industries Association (AIA). After his graduation in Electronics Engineering from IIT-Madras in 1976, Sivaram began his career at BARC. He shifted to Siemens Ltd and has considerable experience in Distributed Systems, SCADA, DCS, and microcontroller applications.
Sivaram believes strongly that digitalisation and adoption of the technology and practices of Industry4.0 is essential for MSME of India. He works to bring these concepts clearer to the people for whom it is important. He believes SAMARTH UDYOG is nearer to the needs of India, and we must strike our own path to Digital Transformation. Foremost task ahead is to prepare people for living in a digital world. He is convinced that the new technologies need to be explored and driven into shop floor applications by young people. We need a set of people to work as Digital Champions in every organisation.
