As in almost all areas, Häfner relies on a wide range of sizes for the 3D spools. The diameters range from 100 to 355 m. Plastic monofilaments of 500 and 750 g up to 5 kg can be wound onto them. Large central holes help with secure clamping. Spools from a diameter of 135 mm have a 51 mm wide central bore. This allows users to use holders from their own production. Häfner bobbins in sizes 750 g and 1 kg are suitable for winders with fully automatic bobbin changing. Tie-off holes in the flange edges are also suitable for monofilaments with large diameters. The flange can be customized to the user's requirements. The spools are also available in transparent versions on request. This makes it easier for users to select the right monofilament colors. Label surfaces make it easier to identify the spool and winding material.

Individually customized

This flexibility is based on Häfner's many years of experience in the development of coils for industry and in the in-house manufacture of the tools for them. The company became involved in the standardization of plastic reels and their elements for a wide variety of applications at an early stage.

The company develops individual coils for specific requirements, as the example of a coil development for superconductors shows. Superconductors are used in magnetic resonance imaging systems, among other things. The production and processing of these special wires, some of which are rectangular in shape, involves extremely tight tolerances. The superconductors must therefore be placed on the coils with absolute dimensional accuracy, wound tightly layer by layer, carefully stored, transported and unwound. This turns the plastic coil into a precision part. This begins with the lowest possible tolerances for concentricity and does not end with the rigidity of the coil flanges. The surfaces of the cores and the inside of the flanges must not have any unevenness that could negatively affect the winding pattern and damage the winding material. The width of the core must be as dimensionally accurate as possible so that a precisely defined number of layers of the superconductor can lie next to each other with as little play as possible. This dimensional accuracy must be guaranteed over the entire height of the flange, even during the winding process. In addition, despite their low weight, the coils must remain usable even with robust handling, as barely visible warped flanges and other hidden damage can turn the entire winding content into scrap. These bobbins must also not change under changing weather, climate and humidity conditions. The bobbins of the Häfner VMV series are primarily used for this purpose.

Häfner developed the VMV series with the aim of making plastic reels fit for special loads. They offer greater precision and stability in use than the reinforced machine reels (VM). The VMV coils are reusable. In addition to the aforementioned superconductors, they can carry bare wires, stainless steel wires, braided wire, alloyed wires, stranded wire, steel cables, twisted conductors, metal strips, square wire, data cables, power cables and extruded cables up to a winding volume of almost 172 cm³. They can withstand high weights, are durable and easy to handle. The properties of VMV reels protect the bearings of the machines. They are therefore required and appreciated in many highly automated industrial sectors, including North America. To meet the demand there, Häfner has adapted a VMV size to the inch dimensions used in North America.

Bringing welding wires onto spools

Sometimes it's the little things that make the difference, for example the SD clip. Black, just the width of a thumb and elastic, it can be clamped onto the flanges of welding wire spools. Welding rods were and are often handled in a robust manner. The beginning of the wire is placed on the spool core by hand and inserted into a holder. After winding, the end of the wire is also bent by hand and inserted into a holder in the spool flange. In the user's production process, employees have to pull the bent end of the wire out of the flange and cut it off. This is often not the right treatment for high-quality welding wires. Surfaces and structure can be damaged. In addition, expensive material is constantly wasted. Häfner's customers want to avoid this. The SD clip holds the wire in position on the spool after winding and lies like a bar between the spool flanges. Spring elements between the bar and the support on the wire press the winding material firmly together. The rubber coating on the underside of the clip prevents damage and at the same time dampens any movement of the wire during transportation. During the production process, the employee simply removes the clip. The wire can then be fed into the production process without further delay or loss of material. This clip also fits on the 3D spools.

Thomas Dohna, tat / ag agency