Steinmeyer, Inc. announced another option to its standard line of precision ball screw products – hybrid ball screws using ceramic rolling elements. By using balls manufactured from silicon nitride instead of tool or stainless steel, Steinmeyer is able to eliminate micro-welding in the ball nut. The major benefits include longer lifetime, lower friction and less lubricant required. In a preloaded nut, micro-welding typically occurs whenever the lubricant film breaks down between the balls and thread, resulting in direct metal-to-metal contact. When the nut moves with respect to the screw shaft, tiny bits of the steel balls break off and mix with the lubricant in the nut, thus contaminating it. Over time, the solid metal chips in the oil or grease adversely affect the lubricant’s ability to function effectively and cause adhesive wear. Premature failure follows.
With dissimilar materials in contact, namely high grade tool or stainless steel for the shaft and nut body and silicon nitride for the recirculating balls, micro-welding is prevented. There is an extra cost for these ceramic balls and they are available in limited diameters. Steinmeyer offers hybrid ball screws in diameters ranging from 6 mm to 40 mm with pitches of 1 mm, 3 mm, 5 mm and 10 mm (not all permutations).