Posted to News on 10th Jun 2009, 15:56
Ball screws offer advantages of rolled and ground types
Abssac is thought to be the first supplier in the UK to offer single-piece, rolled ball screws that have a thread form right up to the end journal and a diameter that is equal or greater than that of the screw thread diameter. In the past, this format of screw and larger journal has only been possible by using a machined or ground screw thread form, or by bonding a section of screw to a separate journal - which would inevitably increase the unit cost.
At first glance this innovation seems simple but, when you start to consider the limitations in thread rolling processes and take into account that previously it has been impossible to roll a thread on anything other than a single diameter bar stock for the entire length of the screw, you start to see the technological advance.
A rolled ball screw will always be more competitively priced than a ground screw equivalent, and this has always caused a dilemma for design engineers: use a machined or ground screw to get the larger journal for greater axial thrust attachment security and available bearing choice, or sacrifice the larger journal advantage for the lower-cost rolled screw.
Products in Abssac's new SRT ball screw series are manufactured entirely from one piece of material and for the first time offer the benefits normally associated with both rolled screw and ground screw formats.
By providing a high linear accuracy, the new ball screw series enables customers to replace expensive ground ball screws with rolled screw alternatives at less cost and with operational confidence. As standard, two precision tolerances are available: C7-20 (0.05mm/300mm, 20 microns axial play) or C10-50 (0.2mm/300mm, 50 microns axial play).
As standard the new series is available in SCM415H hardened tool steel (HRC58/62) or 440C hardened Stainless Steel (HRC55+). With all the ball screw sizes, a range of flanged, cylindrical and end-threaded ball nut designs mean that connection to any linear device is made simple.
Table of leads (mm) available for different screw diameters:
tstart{c,60%}
thead{diameter (mm)|1.0|2.0|2.5|4.0|5.0|6.0|8.0|10|12|15|20}
tdata{4|#|#|||||||||}
tdata{5||||#|||||||}
tdata{6|+|#||||#||#|||}
tdata{8|+|+|#||#||#||#||}
tdata{10||+|||#|||#|||#}
tdata{12||#||||||#|||}
tend{}
# = Available in SCM415H hardened tool steel (HRC58/62)
+ = Available in 440C hardened stainless steel (HRC55+)
Follow the link for more information about the SRT rolled ball screw series.
