Meets High Torque & Temperature Requirements, Saves Assembly Costs

Pragati Automation, India manufactures Machine Tool accessories. They assembled torque motors for Bio-Directional Tool Turret, where very high torques are induced. During the assembly, the Rotor was heat shrink fit on to the shaft and Stator was heat shrink to housing with high interference. These motors develop temperatures of 120 deg C continuous. Shrink fit of assemblies involves – heating costs and time, additional labor and still lower reliability and customer wanted to improve on these.

Eliminates Need for Expensive Machining

A leading manufacturer of industrial cleaning equipment in India developed a new model of portable cleaning machines. The drive bearing needed to be mounted in the cast iron gear housing. As the Gear housing is cast, it is very difficult to maintain the tolerances. Machining the bearing seat area involved high machining cost and time. The unmachined seat area had gaps to 0.2mm.

Eliminates Need for Expensive Machining or Brazing

A leading tool manufacturer in Australia was launching new model of pliers for electronic components. Customer considered press fits or brazing the pliers hands to the jaw. They found that all these methods were undesirable. Press fit involved expensive machining to maintain very tight tolerances. Brazing needed expensive brazing machines, was very much dependant of operator skills and was expensive too.

Replaces Expensive Shrink Fit, Reduces Assembly Time and Costs

Interference fit methods of press fit or shrink fit are commonly used for joining cylindrical parts. The bonding is provided by the friction between mating surfaces. In shrink fit mating parts have a high degree of interference and fit together either by heating or cooling the components. Shrink fit needs requires heating equipment and creates bottleneck in mass production. Further there are risks that during the assembly elastic limits of parts might be exceeded or parts may be deformed.

Augments Strength and Adds Reliability

Mehala Machines is a manufacturer of garment sewing machines in India. Mehala’s High-speed Integral Clutch Motors used in Sewing Machines had their rotors (silicone steel) fixed to shaft (En8) with interference press fits. The interference press fits hold the assembled parts together with friction and are expected to have high load bearing capability, however Mehala was receiving field complaints of rotor spin offs. When parts are assembled with the contact area is still limited to the high ‘peaks’ and ‘valleys’ on the mating surfaces and is typically less than 30 – 40% - due the load on mated parts and micro-movements these peaks and valleys are grinded off and the gaps increases resulting the spin-offs.