Optimal web forming and lower fibre penetration
The demands on modern nonwovens for the hygiene industry and their manufacturing process are ever increasing. In addition to carefully selected raw materials and gentle fibre processing, a uniform basis weight, surface quality and skin-friendliness are major demands that consumers place on hygiene products. CMC Consumer Medical Care GmbH, a wholly owned subsidiary of PAUL HARTMANN AG, specialises in the production of cotton-wool and cosmetic products for end users at its facility in Düren. In 2005, the company spun off from the renowned Hartmann Group, known for its medical devices. With nonwovens and cotton wool products in the fields of medical, baby and home care, as well as cosmetics, CMC is one of Europe’s leading providers.
The very clean and absorbent products consist of short cotton fibres that are mixed in part with synthetic fibres. For web forming CMC relies on non-woven cards from Hergeth and ERKO Trützschler with a width of 2.6 metres and production speeds of 20 to 30 metres/minute . After forming, the web is thermobonded or spunlaced, pre-finished and finished. The three lines operate around the clock in three shifts. Thus, in addition to throughput, a high level of operational reliability and plant availability are essential requirements for positive production figures.
Forming as pillar for success in nonwovens
Nonwoven forming is the core process on the way to the finished nonwovens product. Here the pre-blended fibres are separated by so-called roller cards via rotating needle rollers and placed on a woven process belt at high speed, using the airlaid process. Next the card web is thermobonded or spunlaced in further downstream processing steps. The fibre-to-fibre friction as well as the friction between the fibre and the plastic belt creates electrostatic charges during the forming process.
CONDUCTO® 2203 for higher process stability
Up to now, the fabrics used by CMC for web forming have either been single or double layer, smooth and open-mesh. However, Thomas Konrad, Head of Engineering at CMC, was not happy with the result. In retrospect he states „In addition to electrostatic charges, the process stability was affected by fibre penetration, jamming in the fabric as well as fibre build-up on the belt.” Contamination on the belt or in the line has repeatedly resulted in outages or production downtime. To combat these process-specific weak spots constructively, CMC decided to test the innovative CONDUCTO® 2203 forming belt from GKD – GEBR. KUFFERATH AG. This single-layer forming mesh of the brand WEAVE IN MOTION features bronze wires woven into the mesh along the running direction. They ensure complete and permanent electrostatic discharge, and thus optimal web take-off. Due to the balanced interaction of fineness and structure, CONDUCTO® 2203 increases the efficiency of production flow and simultaneously minimises the cleaning process with process-optimised air permeability. GKD produces this mesh on special, exclusively developed weaving machines that make CONDUCTO® particularly solid and efficient by applying high force. The solid twill weave is tightly meshed and – compared to the various belts used in the past – has surprisingly low air permeability with otherwise unchanged process parameters. The air permeability of 370 cfm instead of previously 1100 cfm is a reliable measure against fibre penetration and jamming. Markings can definitely be ruled out thanks to an interwoven pin seam that is easy to close.
Card web sets new standards
The results and customer satisfaction speak for themselves: “This belt helped us to reduce our process interruptions significantly.“ says Thomas Konrad. The quality of the card web sets new standards by its web evenness and good fibre position. Tested according to ATEX standard class 3, the belt ensures visible security in web forming thanks to interwoven bronze wires in warp direction. Production is significantly more stable and efficient. Meanwhile CMC has converted all other lines – including the ones with two cards – to CONDUCTO® 2203 and defined the process belt as internal standard for this procedure. However, CMC is not the only company impressed by the performance of the CONDUCTO® belt. As double-layer variant this belt type with antistatic properties is also suited for sophisticated web forming in spunbond processes.