Needled nonwovens are materials made of artificial or natural fibres, used e. g. as: insulating coatings, soundproofing, filters, paper felts, upholstery, sewing accessories and in fillings under newly built roads. Technology of their creation, known for around a hundred years, has not changed significantly over time despite the fact that it is rather efficient and requires relatively low investment, it has not been improved ever since.
The needling process comprises of high frequency piercing of fibres bound together using plates equipped with – depending on material width – from few to several thousands of special needles. They are especially serrated, and by passing through the fibre layer they cause the fibres to entangle, thus increasing material consistency. Because of accidental events or wear, the needles break, resulting in difficult to detect, but also important, lowering of quality of the manufactured material. Until now, material quality has been monitored using laboratory measurements of strength performed on samples cut out during manufacturing. This technique is highly ineffective from the point of view of costs and speed of damage detection.
The main goal of the project was creation of a system monitoring the state of the needle loom (the plate with needles) and checking if breaking the needles results in drop of quality of the manufactured material below the required level.
The system designed by SKA Polska gathers data from thousands of sensors, performs the analysis in real time by comparing the data to learned breakage patterns, and makes decisions on the basis of an extensive knowledge base, containing relationships between process parameters, state of the tool and quality parameters of the material. Creation of such knowledge base required both long-term studies of the nonwovens themselves for influence of different parameters of the manufacturing process on their properties as well as mathematical modelling of the material and its manufacturing cycle in order to expand results of the studies to all classes of nonwovens.
A nontrivial task for us was also to design the sensors themselves and to create the data acquisition system which synchronizes and digitizes data streaming from thousands of sensors. It has been implemented using the so called concept of matrix sensors. Individual sensors are grouped logically in matrices comprising independent modules. Despite the fact that there are thousands of sensors (one per each needle), the cost of the whole system is low in comparison with the value of the needling machine. It may be also installed in already existing production lines. The system is equipped with an operator interface which enables control of needle state „in real time” as well as conducting analyses of its influence on the quality of manufactured material.
Thanks to the monitoring system, the manufacturer of nonwovens will save on the costly quality control and at the same time the quality of the offered products will remain the same. Machine downtimes will be shorter – their servicing and spare parts replacement shall be easier to predict and to plan. Thanks to analysis of the manufacturing process, the entrepreneur shall be able to manufacture his product more efficiently.
A video clip presenting a nonwoven needling
Several economic entities from Europe have been engaged in the project, e.g.: manufacturers of nonwovens and machines for their production, research and development companies and a renown, German scientific textile institute.