Evolution of a technology

Even tried-and-tested products have potential for improvement. One example is classic trapezoidal threads, which Igus has further developed. Thanks to a special geometric interaction of metal spindle and lubrication- and maintenance-free threaded nut, Dryspin technology promises a long service life, improved efficiency, low wear and less movement noise. Now it is available in eight new sizes.

Trapezoidal threads have been classics of mechanical engineering for decades. The machine elements convert a rotary motion into a translational one - for example in window or door drives, in format adjustments in production plants or in laboratory technology. But almost every classic has potential for improvement. "We have ventured to set a market standard and say: there is room for improvement," emphasizes Thorben Hendricks, Head of the Dryspin Screw Drive Business Unit at Igus . The motion plastics specialist relies on optimized interaction between the geometries of the metal spindle and plastic threaded nut.

30 percent longer service life and 82 percent efficiency

Compared to classic trapezoidal threads, the thread flanks of the nut are enlarged at Igus, as is the width of the thread of the spindle. A small intervention with consequences: Because the enlargement of the thread flanks means that more high-performance plastic is used in power transmission. More material that is tribologically optimized, i.e. in terms of friction and wear. "Through the asymmetry, we have managed to extend the service life by around 30 percent compared to symmetrical trapezoidal threads," says Hendricks. Optimizing the flank angle also increases the usable portion of the energy supplied. We have flattened the flank angles of the threaded nut and spindle. As a result, we achieve above-average efficiency of up to 82 percent at high thread pitches."

Threads operate with low vibration and almost no noise

However, the new dryspin thread technology is not only durable and efficient, but also quieter than many conventional trapezoidal threads. This is because the tooth flanks are rounded rather than angular. The contact surface between the threaded nut and the spindle is thus reduced. And that leads to fewer vibrations, which can make themselves felt as rattling or squeaking. Hendricks: "Thanks to the rounded tooth flanks, the threads run vibration-free and almost noiselessly. The tighter manufacturing tolerance of the threaded spindles compared to DIN 103 7e also ensures more precise running behavior and enables significantly higher speeds in the application."

Portfolio of dryspin thread technology expanded by eight sizes

Igus began establishing its own thread technology on the market in 2013, initially as an alternative to steep threads. Now eight new sizes follow - matched spindles and threaded nuts, including dimensions with low pitches that enable quick one-to-one replacement of installed trapezoidal threads. The new threads are available with pitches of 6.35x6.35 RH, 8x40 RH, 10x3 LH, 12x25 LH, 14x4 RH, 16x5 RH, 18x4 RH and 20x10 RH. The threaded spindles are made of stainless steel or aluminum; the threaded nuts are optionally made of seven high-performance plastics and several geometries - from a cylindrical design with collar or wrench flats to the variant with spring preload.