maxon

Spindle Drive Basicsmaxon spindle driveDesign Technical Data Spindle Drive Data Spindle, directly implemented in the gearhead Radial bearing Axial bearing Planetary gearhead 0–4 stages Motor Encoder The particular type of spindle required mustfirst be established before a spindle drive canbe designed. Every type of spindle has differentcharacteristics and a number of specific limits.These limits are taken into account in the technicaldata.Ball screw:− highly efficient− not self-locking− high load capacityMetric spindle:− self-locking− low costsTrapezoidal spindle:− same as metric spindle− higher load capacity than metric spindleThe “Technical Data” block contains generallyapplicable data on spindle, nut and gearhead.These are independent of the gearhead reductionratio.LengthThe data sheets show the spindle drives withthe standard lengths. Other lengths are availableas an option in 5 mm steps up to a givenmaximum length. Please give detailed requirementsfor special lengths.Max. efficiency/mass inertiaThe values stated refer to the spindle alone(without gearhead). The values with gearheadare given in the „Gearhead data“ main datafield.NutStandard spindle drives are supplied with athread nut. Flange or cylinder nuts are alsoavailable as an option. See details with correspondingreference number on page 258.BearingThe output stage and the spindle are supportedby preloaded axial bearings. This meansthat the high axial forces can be absorbeddirectly by the gearhead without additionalsupport.Line 7 Max. efficiencyThe given efficiency is a maximum value thatapplies when loaded with maximum feed force.Efficiency falls sharply with very small loads.The stated value refers to the complete spindledrive (gearhead and spindle).Line 20 Max. feed velocitySpecifies the maximum permissible feedvelocity.Line 21 Max. feed force (continuous)Is the maximum permissible feed force whichmay be continuously applied. Exceeding thisvalue results in a reduced service life.Line 22 Max. feed force (intermittent)Is the maximum permissible feed force whichmay be intermittently applied. „Intermittently“ isdefined as follows:− during max. 1 second− during max. 10% of operationExceeding these values results in a reducedservice life.Line 23 Mechanical positioning accuracyIn this value, following factors are taken intoconsideration:− backlash of the gearhead− accuracy of the spindle− axial play of the nutFeed forceFor the calculation of the feed force accelerationand friction forces as well as gravity have to betaken into consideration. Exceeding the maximumpermissible load must be avoided, as thisdamages the spindle. The maximum permissiblefeed force is displayed for standard spindles. Forlonger spindles, the permissible feed force canbe limited by the critical compressive force ofthe spindle. In this case, supporting the end ofthe spindle may be necessary.Max. axial force [N]4000350030002500200015001000250500Limitation for ball screwsGP 22 S not supportedGP 22 S supported0150 250 350maxon spindle driveGP 32 S not supportedGP 32 S supported450 550 650Spindle length [mm]TorqueThe required torque of the spindle M a [mNm]is calculated with the feed force F a [N] (load),the thread lead p [mm] and the efficiency of thespindle 1 .F a· pM a=2 · ϖ · η 1In combination with the gearhead, the requiredmotor torque M mot [mNm] is:F a· pM mot=2 · ϖ · i · ηWhere i is the gearhead reduction ratio and the efficiency of the complete spindle drive.Speed and feed velocityFeed velocity v [mm/s] is linked to output speedn [rpm] by the lead p [mm].p · nv =60In combination with the gearhead, the motorspeed n mot [rpm] is:v · 60 · in mot=pWhere i is the gearhead reduction ratio and pthe spindle lead.The spindle speed is limited by the resonancefrequency of the spindle and for ball screws additionallyby the ball return system.In addition, the maximum permissible speed ofthe gearhead has to be considered.Max. spindle speed [rpm]500045004000350030002500200015001000500Max. spindle speed at ball screws0150 250 350GP 22 S not supportedGP 22 S supportedGP 32 S not supportedGP 32 S supported450 550 650Spindle length [mm]Maximum strokeThe maximum possible stroke depends on thelength of the spindle L [mm]. The length of thenut L N [mm] and the thickness of its mountingplate X [mm] must be taken into consideration.Stroke = L − (L N + X + stroke reserve +opt. SPIN02)Mounting and safety instructionsUsing a ball screw with a flange nut, the mountingthrough a hole is only possible with theoptional rectangular mounting flange.The ball screw nut may never be removed. Asthe balls are preloaded remounting would beimpossible.The spindle may never block during operation,as this could damage the spindle nut orgearhead.Service life crucially depends on the precisionwith which the gear is fixed to the spindle nut.Eccentricities and angle errors sometimes resultin massive radial loading which must neverexceed the given maximum value.Additional information can be found in themaxon online catalog at the item under downloads.May 2012 edition / subject to change