Rack & Pinion Systems

Advantages of Using Long Racks

Through continuous improvements in production techniques, ATLANTA has been able to reduce the total pitch error for the 1,000 mm long hardened & ground racks, while achieving significant reductions of the total pitch error of 1,500 mm and 2,000 mm long hardened & ground racks. Therefore, for long travel lengths, it is possible to minimize the total pitch error seen.

Using long racks reduces the number of rack sections, which reduces the amount of time needed to mount the racks. It is also advantageous to use longer racks to reduce the number of rack joints, which can induce further error into the axis.

The new rack pitch error (GTf) values are as follows:

Rack Quality 1,000 mm Rack 1,500 mm Rack (GTf/1,500) 2,000 mm Rack (GTf/2,000)
5 0.026 mm 0.031 mm (0.021 mm/1,000 mm) 0.034 mm (0.017 mm/1,000 mm)
6 0.036 mm 0.043 mm (0.029 mm/1,000 mm) 0.047 mm (0.024 mm/1,000 mm)
7 0.052 mm 0.062 mm (0.041 mm/1,000 mm) 0.068 mm (0.034 mm/1,000 mm)


Mounting Example:

The best way to see the advantages of using long racks is the below mounting example comparing using 0.5, 1.0 and 2.0 meter long racks.

  • Travel Length: 6 meters, racks mounted end-to-end with companion rack
  • Error at Rack Joints from Companion Rack: < 0.025 mm

Using 3 pieces of 29.40.205 DIN 6 helical module 4.0 hardened & ground two-meter long rack:

2M
  • Pitch Error per rack GTf/2,000 = 0.047 mm
  • Total Pitch Error: 3 x 0.047 (racks) + 2 x 0.025 (rack joints) = 0.191 mm
  • Mounting Required: # of Screws Required = 3 x 16 = 48, Rack Joints = 2, Dowel Pins Required = Zero

Using 6 pieces of 29.40.105 DIN 6 helical module 4.0 hardened & ground one-meter long rack:

2M
  • Pitch Error per rack GTf/1,000 = 0.036 mm
  • Total Pitch Error: 6 x 0.036 (racks) + 5 x 0.025 (rack joints) = 0.341 mm
  • Mounting Required: # of Screws Required = 6 x 8 = 48, Rack Joints = 5, Dowel Pins Required = Zero

Using 12 pieces of 29.40.055 DIN 6 helical module 4.0 hardened & ground half-meter long rack:

2M
  • Pitch Error per rack GTf/500 = 0.032 mm
  • Total Pitch Error: 12 x 0.032 (racks) + 11 x 0.025 (rack joints) = 0.659 mm
  • Mounting Required: # of Screws Required = 12 x 4 = 48, Rack Joints = 11, Dowel Pins Required = 24

Rack Assembly Kit

If the ATLANTA Rack Assembly Kit is used instead of a companion rack, the total pitch error is reduced even further:

  • Error at Rack Joints from Rack Assembly Kit: < 0.005 mm
  • With 2.0 Meter Racks: Total Pitch Error reduced to 0.151 mm (-21%)
  • With 1.0 Meter Racks: Total Pitch Error reduced to 0.241 mm (-29%)
  • With 0.5 Meter Racks: Total Pitch Error reduced to 0.439 mm (-33%)



Advantages of Using Long Racks

  • Reduced Pitch Error values
  • Reduced number of rack sections required
  • Reduced amount of time needed to mount the racks
  • Reduced the number of rack joints