Heavy becomes light

A lead screw module from the igus drylin® product range in the bottling plants from Fricke Abfülltechnik GmbH & Co. KG ensures simple positioning of the 80 kg bottling head above the container. The unit is supplied ready to install, and fully meets the requirements of the machinery builder with respect to lack of lubricants. In addition, the linear unit as a complete solution is more cost-effective than alternative systems.

Fricke Abfülltechnik GmbH & Co. KG in Minden is well known to manufacturers of viscous and pasty substances. Fricke plants are in use world-wide whenever containers such as buckets, canisters, or hobbocks must be filled accurately – for instance with paint and varnish, dispersions, or glue and other construction materials.

For these tasks, Fricke has developed a plant product range characterised by a high degree of flexibility. The plants can be adapted to a wide range of container types. The user can also define the level of automation and the type of filling (upper or lower level filling).

All plants have in common the filling arm, which is driven pneumatically and inserted into the container, as well as the integrated weighing cell, which supports calibrated filling. The plants are easy to commission: the user only needs to connect the plant with compressed air and electric power using connectors, and connect the product supply line. Additional modules that can also be installed retroactively on demand perform downstream tasks, such as sealing and labeling the containers

The concept of the greatest available flexibility also includes variable positioning of the filling head. This creates the prerequisite that various containers can be filled on one and same line.

Fricke originally used a pipe-in-pipe system to reposition the filling arm, which proved to be relatively stiff. In their search for a better solution, the company's design engineers reviewed various systems after they had accurately specified the requirements. The system needed to absorb large loads, for the filling arm with the valve alone weighs 80 kg. This is exacerbated by high lever loads and the weight of the product in the feed hose.

In addition, the linear system needed to operate without lubricants, since it is used above the product containers, and to exclude any possibility of contamination. For the same reason, abrasion and wear-free operation was called for, and last but not least, costs also played an important role.

Under these conditions, the responsible parties at Fricke decided in favour of lead screw modules from the igus® drylin® product range. Lead screw module systems of type series drylin® SLW-2080 are used. Their centrepiece are the proven, hard anodised drylin® W profile rails and a carriage guided by four drylin® W housing bearings. Using a hand crank that actuates a drylin® trapezoidal lead screw nut, the operator accurately positions the filling head, which was mounted on the carriage.

Since all moving components are guided by tribologically optimised iglidur® plastic bearings with incorporated lubricants, the entire system operates without lubricants and with minimal abrasion. Important requirements by Fricke have therefore been met. Even the requirement for easy operation has been put into practice: in spite of the significant loads, the lead screw module is easily and accurately moved with the hand wheel and the trapezoidal thread. At an installed width of 150 mm for the carriage, and a very low profile design, the system is easily integrated into the surrounding structure.

Fricke additionally installed a clamping mechanism because the head moves in cycles during the filling process and creates vibrations. Internal movements can therefore not be fully excluded.

The lead screw module of installation size SLW 2080 can absorb a static load of 1,600 N (axially) and 6,400 N (radially). When Fricke decided in favour of the solution, this was the largest linear axis of the SLW type series in the igus® product range; an additional installation size SLW-25120 has been added in the meantime. Motor powered units are also available, which Fricke does not require since the linear system is only moved when the plant is reconfigured for a different container size. In addition, the design engineers deliberately avoid electrical drives. Michael Krietemeyer: "Many bottling plants work under explosion protection conditions. Since we work with a standardised construction kit system, we generally use a pneumatic drive for stroke motions of the filling head, which can also be used in EX plants."

The ready to install system supplied by igus® also compels in terms of cost considerations: alternatives such as recirculating ball bearings would be significantly more expensive. Fricke is also satisfied with the installed materials – and remains flexible in this regard: when particularly corrosive or aggressive media are filled, the option exists to replace individual elements of the lead screw module with stainless steel components. Appropriately durable iglidur® materials would be available for the glide elements and trapezoidal lead screw nuts.

While the drylin® SLW lead screw modules are certainly the largest and most prominent igus® products in Fricke bottling plants, they are not the only ones. The material handling technology that feeds containers to the filling operation employs concealed guide rails from the drylin® W-product range for smooth motions and to accurately position the containers. Even the energy supply system business segment is represented in the plants: igus® energy chains ensure that energy and signals are reliably transmitted to the moving parts of the bottling plants.