In today's world of intense competition, packaging manufacturers are emphasising on product innovations and optimising their production efficiency to reduce operational costs. This has led to several packaging manufacturers to focus on minimising down time and resultant production loss by implementing 'remote diagnostic' technologies such as 'sensors'.
A sensor is a device that measures or detects real world conditions, such as motion, heat or light and responds to these conditions through signals. For instance, an optical sensor detects the intensity or brightness of light.
In recent years, the use of sensor technology by the packaging industry has experienced substantial growth, largely due to the increasing complexity of production sequences and demand for process safety and reliability. Presently, sensors are used in food, beverages and pharmaceutical packaging industries.
Sensors monitor and control a range of packaging operations, including depalletizing, filling and closing, checkweighing, labelling, shrink wrapping and palletizing of final products. Moreover, the sensor industry is constantly evolving to cater to a number of new application areas that are being identified from time to time. The most common sensor solutions used in the packaging industry are inductive sensors, capacitive sensors, photoelectric sensors, colour/contrast sensors and ultrasonic sensors.
Photoelectric sensors: Over the years, photoelectric sensors have emerged as the most widely used sensor for packaging applications. Photoelectric sensor, which consists of a light source (LED), a receiver (phototransistor), a signal converter and an amplifier, detects a change in light intensity. It provides three primary methods of target defection - diffused, retro- reflective and thru-beam.
In recent years, the demand for photoelectric sensors by the packaging industry has witnessed a substantial surge as they are now used for a range of applications such as confirming the arrival and position of a container/bottle to be filled, palletizing/depalletizing and ensuring proper infeed of bottles (especially opaque bottles). Further, the sensor also verifies that an adequate supply of filling material is available in the vessel.
Colour/contrast sensors: Contrast sensors, which is also referred to as colour mark or registration mark sensors, usually detect the difference between two colours, often corresponding to a target colour and a background colour. On the other hand, colour sensors detect a specific colour. However, colour sensors can now be programmed to detect up to ten or more unique colours, thanks to the advancements in the technology.
Some of the typical applications for colour/contrast sensors in the packaging industry are colour matching, measuring the area of a learned colour, detecting the presence/absence of colour, identification of products based on colour and detection of a registration mark.
Vision sensors: Vision sensors enable manufacturers to detect defective pieces by conducting scanning and analysis of visual data collected through the camera. As a result, vision sensors are mainly used in industrial inspection, quality control and design and manufacturing of diagnostic applications. In packaging industry, vision sensors are used to perform various tasks such as ensuring the presence and proper alignment of labels, presence of caps on bottles, exact number of units in cartons etc.
Capacitive sensors: Capacitive sensor is a non-contact device, capable of high-resolution measurement or monitoring of position of any conductive target. Capacitive sensors are mainly preferred due to their ability to measure high resolutions, including subnanometer resolutions, non-sensitivity to material changes, cost effectiveness and compactness. In the packaging industry, capacitive sensors are mainly used for applications like label positioning, label counting, glue detection, ensuring glue thickness etc.
Inductive sensors: An inductive sensor is an electronic proximity sensor, which detects metallic objects without touching them. The sensor enables packaging manufacturers to confirm the presence of internal seal (made of aluminium foils) or external over-wraps.
Ultrasonic sensors: An ultrasonic sensor typically utilises an ultrasonic transducer that produces an electrical output in response to received ultrasonic energy. Ultrasonic sensors are devices, which are designed to detect or quantitatively determine physical parameters such as pressure, temperature, position or velocity over a measuring range. They are, therefore, used for detecting container presence/absence, container size, product level, container orientation, tamper/safety seals and surface coatings.
In view of rapidly growing demand for sensors by various manufacturing industries, including automation, pharmaceutical, packaging and consumer goods, the global market for sensors is expected to reach US $ 61.4 billion by 2010. The US sensor market, which would touch US $13.5 billion by 2010, would continue to remain the largest market worldwide. Besides, rapid technological advances in the field of biosensors and nanosensors are enabling widespread use of these novel technologies. As a result, the global sale of nanosensors is expected to rise at an average annual growth rate of 25.5 per cent to US $592 million by 2009. Also, nano-biosensors are projected to grow at an average annual rate of 32.9 per cent till 2009.
(Courtesy: Onboard ITC Limited)