From the Sector

In recent years, Italian circular knitting machine manufacturer Santoni (part of the Lonati Group) and Groz-Beckert have worked together to develop a new self-cleaning knitting system for the INNOTAS circular knitting machine. The knitting system is also called INNOTAS and consists of the circular knitting machine needle SAN™ DUO and the corresponding sinker SNK DUO-OL.

Following various preliminary investigations, the go-ahead was finally given in January 2015 for the joint development of a self-cleaning system in the needle area with side-by-side needles and a low shank.

The circular knitting machine needle SAN™ DUO with the sinker SNK DUO-OL was developed to meet the desired requirements. In the knitting system, there are two needles in the needle channel and two sinkers in one sinker channel. The benefits became apparent in initial field trials with experienced end customers in 2016. In the following years, the knitting system was continuously analyzed and further optimized.

The double filling in the needle channel significantly reduces soiling. In addition, the further developed shape of the knitting system ensures that any yarn lint is automatically removed from the machine during the knitting process. This extends the cleaning interval, making work more time-efficient and increasing productivity.

Both the needle SANTM DUO and the sinker SNK DUO-OL are characterized by a particularly low shaft with a predetermined breaking notch. The low shank minimizes soiling, while the predetermined breaking groove enables controlled needle breakage in the event of wear at the desired point. This reduces errors in the knitting process and machine downtimes.

Cavitec, part of Santex Rimar Group, presents the redesigned Caviscreen at Techtextil Frankfurt. Caviscreen features latest technology for breathable laminates.

Caviscreen was developed as a hotmelt coating and laminating unit for breathable sportswear, rainwear and protective clothing – with and without applying a membrane. The redesigned machine shows a brand-new method to supply adhesive more evenly and precisely. Using PUR adhesive (polyurethane reactive adhesive) goes with additional benefits like strong bonding capabilities and versatility.

Caviscreen’s hotmelt screen printing is a special system for high-end application garments. With this Caviscreen system, a PUR adhesive is transferred onto the substrate through a rotary screen, similar to the well-established textile printing method. The adhesives are fed from the drum melter through a heated hose to the traversing adhesive distribution system inside the rotary screen, just behind the doctor blade.

The adhesive is pressed by the doctor blade through the screen holes and transferred to the substrate. Different dot pattern (mesh or irregularly) and different screen thicknesses allow different coating weight and adhesive coverages.

The traversing adhesive dispenser is used to distribute the adhesive automatically over the set working width that – an additional technical benefit – can be set without any mechanical changes.

Cavitec’s screen coating system achieves high bonding strength while using less adhesive than other coating processes, because of applying the coating on the surface of the substrate and like this, the adhesive has less tendency to penetrate the substrate.

Bonding strength, softness of the fabric and the breathability are defined by the coating weight and the coverage. The rotary screen allows users to regulate and adapt the coverage respectively the coating weight. Cavitec offers a large selection of screens that are essential to fulfil the fabric requirements. A further advantage is the ease and efficiency of switching from one screen to another by simply unlocking the bayonet fitting. The IR-heater cover opens pneumatically and the lightweight screen can be easily removed by hand. Unlike with other methods, there's no need to deal with hot oil or any other heated liquid that requires cooling down.

The Caviscreen technology supports manufacturers by reducing costs with screens priced at a mere fraction, just 10%, of common gravure roller prices.

Groz-Beckert offers interested machine builders various cooperation opportunities to jointly develop new products or improve existing ones. In collaboration with Vanguard Pailung, a manufacturer of ultra-high-speed knitting machines for body-size products, Groz-Beckert has developed an innovative slider needle for a new generation of machines. Groz-Beckert's Technology and Development Center (TEZ) provides the appropriate framework for so-called co-development projects.

In June 2022, Vanguard Pailung approached Groz-Beckert with a cooperation request. Together with Groz-Beckert, the company wanted to develop a new needle solution for an innovative ultra-high-speed machine. Together with an innovative slide needle, the new machine was to exceed the speed and productivity of known knitting systems of large circular knitting machines.

Machine and needle development ran in parallel and were closely coordinated. The first field tests took place in the Vanguard Pailung laboratory in Monroe/NC, USA in February 2023. The successful development was presented to a wide audience for the first time at ITMA 2023 in June.

Unlike latch needles, slide needles do not form the stitch via a needle latch, but via a slide that is controlled by its own channel. The advantage of this is that the needle can withstand high speeds, as there is no latch impact, which in turn increases productivity.

The use of the new slide needle in ultra-high-speed machines ensures a particularly high level of process reliability. With the new needle variant, the closer is guided safely and precisely in the groove in the needle shank. At the same time, the base of the needle shank is closed, which ensures maximum stability. The slider needle reliably prevents the so-called latch impact and thus makes a decisive contribution to process reliability. Its use ensures a uniform and speed-independent loop structure, even at maximum speeds.