ball screw calculator

8/17/2019 Ball Screw Calculator

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Ball Screw Best Practices:

Screw OD Screw Lead

(in) (in/rot)

0.625 0.250

*Smaller screw leads will reduce maximum linear*Increasing a ball screw diameter will increase the*Support the screw properly or it!s length and app*"eavy grease is a good general use lubricant or*%ever overload the screw or you risk permanet d*%ever ever exceed the critical rotation speed.*I avoiding backlash is critical# use preloaded nut

*& 'exible coupling element must be used bewteeimpossible to control and(or the system will be un

%or&s'eet otes:*This worksheet assumes ballscrews are hardenedrigid.*se the drawing to the right as a reerence. +ou csure to select the proper end support conditions.*+our ball screw system is the most vulnerable toside.


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O"tp"t +or

(,) (in-l$)

.0 0.0

(in-l$) (l$)

0.-10 2.34

(l$)

40

SO7839S:

ear 8atio5input turns(output turns6

8ated 3ontin"o"sMotor ;or


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http8((www.learneasy.ino(7=7


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;otal Slidin1 Mass

(in) Pic& (l$)

=.0 +i>ed-S"pported 20.0

Motor Drive Specications

Press Tab to Cycle Through !np"t #a

peed and efciency while increasing mechanical advantage. critical speed and buckling load.

lication.all screws# unless the environment is particularly dusty in which case use a dry $lm l

ormation on the bearings or a bent screw.

.

n the motor and the screw or else the motor speed will betable.

steel# are properly lubricated# and the setup is ade)uitely

n anlyse your system over distance ,- or ,# /ust make

amage when the ball nut is ully extended to one extreme

Screw Diensions(t'ese diensions appl* to all calc"lations)

Distance Between S"pports5,

-or ,

6

9nd S"pport3onditions

5o either ,- or ,6


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ce O

Motor 8ated Speed

(l$) (8PM) (in/in)

-#@?- ?4=00 0@3

Screw pplication Details

>ial Stress ;orsional Stress

(psi) (psi) (psi)

[email protected] -4?.0 >>.

Screw B"c&lin1 Load 3ritical Speed

(rp) (

4=

Ma> Linear +orce O"tp"t5compare this to the buckling load below and the

rated load o your ball nut.6

Ma>i" Pos5compare this to

;otal 9


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ro/ects(backstop(controller(Topic2;:allscrewCalculations.pd

d

https://tech.thk.com/en/products/pdf/en_b15_006.pdfhttps://tech.thk.com/en/products/pdf/en_b15_006.pdf


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Lead n1le

(in/secA2) () (de1)

0.0 5 >.@4

ria$les

bricant.

Ma>i" cceleration5o sliding mass6

Screw 9Ccienc*5:all screw A >3;?@B6

5,ead Screw A 3;23B6


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tp"t Speed

O"tp"t Power

(in/sec) (%)

-2. .0

+actor o@ Sa@et* ("t Stress)

(/)

2

n/sec)

.2

si$le Linear Speedthe critical speed below6

Si1ns o@ Screw %ear


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ixed;Supported

ixed;Supported

ixed;Supported

ixed;Supported


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ixed;ree

Suported;Supported

ixed;Supported


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Ball Screws

Pros:

*,ow backlash.

*"igh thrust loads.

*,ow wear over time allowing or long working lie.

*,ow riction.

*"igher duty cycle.

3ons:*%oisy.

*"igh cost.

*Disk o losing balls rom the nut i overtravel occurs.

*Eravity can cause back driving in vertical applications.

;ips:

*3;?@B 5Fhen properly lubricated6.

*Eround is more precise G more expensive than rolled.

*"aving two nuts on a single ball screw will not double the orcecapability o the system.

*Smaller screw leads will reduce maximum linear speed andefciency while increasing mechanical advantage.


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*Increasing a ball screw diameter will increase the critical speedand buckling load.

ote: Typical coefcients o riction8 33- or ball bearings# .33@ orproper lubrication.


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Lead Screws

Pros:

*,ow Cost.

*Huiet.

*Desistant to back driving.

*,ow vibration.

*Fide range o leads.

3ons:*"igher riction and hotter operating temperature.

*perating lie can be hard to predict.

*Susceptible to backlash issues# especially when worn over time.

;ips:

*


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*The increased riction on the lead screw might actually be desirableor some applications# such as a manual milling machine where theriction will reduce the propensity o the bed to walk as a result ovibrations.

pro$le rail# .3- or a cam ollower# and .-@ or plain bearings based on


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cc"rac*8 The ability o a system to hit a targeted linear position.

Bac&-drivin1 @orce8 The orce needed to rotate the screw or nut in a reverse ashion.

Bac&las'8 7easurable ree motion between a screw and nut.

3ritical speed8 Consider this the maximum rotational speed o the screw. &t this spee

D"t* c*cle8 & percentage rating that compares the amount o running time to rest tim

D*naic load ratin18 The maximum thrust load a screw and nut assembly can trans

Lead8 ,inear distance o travel in one revolution o the screw. 5i.e. Inches(revolution6

Lead acc"rac*8 The variation in travel distance within a standard length o screw. 5i.e.

Pitc'8 ,inear distance between individual threads. Pitch is a actor o lead or single th

Preload8 &mount o tension or pre;applied orce set into a bearing to remove loosenes

8epeata$ilit*8 The ability o a system to go to the same location in repeated attempt

8ollin18 & manuacturing process that orms threads on screw shats by using pressuro manuacturing than grinding.

Static-load ratin18 The max load that can be applied to a screw and nut assembly in


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I.


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ay be able to back;drive a screw drive and create tor)ue and(or linear motion.

ith the screw diameter and supported length.

sting or ?3 sec beore running again would have a @B duty cycle.

inches.

s# this reduces axial and radial play and increases stiJness and repeatability.

splace material and create thread orms. This is a cheaper 5and less precise6 method

ball screw calculator

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