Ball Screw Selection Verification | Critical Speed | Buckling Load

[@sagarbhapkar9155]

what about selected bearing life calculation...

[@mastermechanicaldesign]

Hi Sagar, I missed the bearing service life calculation. But definitely we should calculate bearing life. I'll cover in upcoming "dedicate series on bearings" Just for note to calculate service life : I have checked BK 25 bearing (Fixed type) [C] Dynamic load rating is 19.3 kN and we have axial load : 680 N Radial load: There is not radial load theoretically. but where will be some due to component fitment error. (Let say 50 N) and [P] Equivalent load lets consider 1000 N Service life in million revolution L10 = (C/P) power 3 3 for ball bearings, 10/3 for roller bearings

[@sagarbhapkar9155]

@@mastermechanicaldesign thank u sir for replay Plz continues upload such nice video with practical example

[@cpangautomation]

Hello, I'm from Vietnam, where we have limited access to standard design documents, and our educational programs are based on materials from the Soviet Union since the 1980s. I really want to access standard knowledge through international standards. Let's develop our technical foundation! Thank you for sharing valuable knowledge!

[@mastermechanicaldesign]

You are most welcome 😊. I'm glad to help

[@xuantruongcan3418]

The series video is really useful. Can you make an example of a HORIZONTAL Ball screw selection calculation?

[@mastermechanicaldesign]

Yes, I'll 👍

[@Sasikumar14261]

This is the video i have been searching for past 3 years. Very very clear explanation and you had done a great job bro. Thanks for your video

[@mastermechanicaldesign]

I'm so glad 😊

[@deepakpanneer8609]

Crystal clear explanation and really great video to understand the calculation for ball screw. Very much useful. looking forward for many more such videos.

[@mastermechanicaldesign]

Thank you deepak, Sure I'll bring lots of selection calculation videos

[@harshpatel817]

You done really great job man !

[@mastermechanicaldesign]

Thanks a lot!

[@sivasugandan5381]

Thank you for such an good video... can you please say me how to choose ball screw for radial load

[@mastermechanicaldesign]

Hii Sivasugandan, there is already radial load (twisting load) on ball screw, because of applied motor torque. and axial load due to lifting weight. But on Bearing support units the is not much radial load because of vertical condition, if there would be significate radial load, then we have to consider radial load too in calculation of "Equivalent dynamic load on bearing." in bearing selection, bearing life calculations. Please let me know, if have any confusion

[@harshpatel817]

I'm also experience SPM and robotics design engineer.. i learnt all this myself... It's great to see someone is making this video.. Want more videos on such a topics.. Would love to be in contact with you.

[@mastermechanicaldesign]

Hi Harsh, So good to hear from you, we are working in same field, and yes whatever I have learned by either hard work or self mistakes, I'm trying to explain everything in form of videos here, So that it may help the learning curve of the new generations engineer. and Yes, This is just starting.. there is so much to come on this channel. Yes I would like to connected on LinkedIn, ID is in channel about section Thank you so much.

[@elanchezhiyan.e2057]

hello bro, you use a vertical moment so you choose the total load as a axil load but i need the axial load calculation for horizontal moment. you can tell about the calculation for it.

[@mastermechanicaldesign]

In this example, the total axial force is the weight of the drilling system plus drilling axial force. Fot horizontal orientation- total axial force will be drilling axial force (as it is) plus frictional force of ball screw + LM guide for given weight of drilling system

[@gangwars377]

Plz make video on gearmotor selection

[@mastermechanicaldesign]

Hi Gangwar, Are you asking for in general selection or for linear actuator ?

[@harivinayak2698]

Can you make please a video on how we will drive a system with belt and pulley mechanism instead of a ball screw. Thankyou for all the lessons.

[@mastermechanicaldesign]

Definitely I will start a timing belt based linear actuator design series

[@harivinayak2698]

@@mastermechanicaldesign Thankyou

[@jaypeepal8593]

Thanks a lot ❣️

[@mastermechanicaldesign]

You're welcome 😊

[@niranjanrawle3488]

Sir i think here we have thin about an aspect of self locking condition. Like friction angle , and helix angle

[@mastermechanicaldesign]

Hi Niranjan, Please elaborate, I didn't get

[@Tezza120]

I have a question about the buckling load. If the ballscrew is fixed at the top like in your example, why do you use 680N for the load as this load is in tension only. The load that would cause buckling would be compression and would be if it were accellerating in gravity's direction - ie moving up and decellerating or accellerating downwards. Although as specified here 2m/sec2 accelleration is less than gravity at 9.8 m/sec2 so it will always be in tension. Please dicuss as I would like to learn together.

[@mastermechanicaldesign]

Yes, very good question, Let suppose the motor is ON and the ball screw nut plus load attached to nut (which is a drilling system in this project) is going downward. Means there is tension in the ball screw. But when drilling starts, a reaction force will start applying on the ball screw nut in upward direction. Which will put the ball screw in compression (portion of ball screw with is above nut and below top fixed bearing support. This same case will happen in any pressing application. So we should definitely check buckling load capacity which can take our system max axial force

[@mastermechanicaldesign]

I have also explained, buckling load also depends on bearing support unit type. Is it fixed or slide. In case of fixed type bearing support at both ends. Buckling load will be max. Nf value 1. And you know the reason, the ball screw one side (either above nut or below the nut) will always be in compression.

[@AnandKumar-hz3jb]

Plz do one video about Bearing life calculation

[@mastermechanicaldesign]

Sure Anand, already planned, a separate series on bearing selection calculation every thing, as soon as possible ☺️

[@AnandKumar-hz3jb]

Thank you sir

[@niranjanrawle3488]

From where u get that bearing support factor value. Catoluge pg. No.??

[@mastermechanicaldesign]

Hiwin - Page no 3 THK- Page no 1-61

[@mj-ti4gv]

Can you calculate sliding frictional force @master mechanical design

[@mastermechanicaldesign]

For LM guide sliding coefficient of friction - 0.02 to 0.1

[@DHINAGANESHKR]

sir, where did you find the bearing block size ?

[@mastermechanicaldesign]

Hi, You can find bearing block size in any bearing manufacture catalogue, Here I have selected form HIWIN.

[@shanmugapriyana2419]

Hi sir..I wanted to select a Lead and screw dia for the velocity of 1000mm/sec with carrying around 2 to 4 kgs weight.. which screw I can go for...the accuracy is +/-1mm

[@mastermechanicaldesign]

Hi Shan, as your required linear speed is 1000 mm/s, Means Ball screw lead size should be 20 mm, or more than 20 mm, and rotation speed will be 3000 RPM or above, which is critical, Ball screw rotational speed should not go beyond 3000 RPM. (Critical speed limitation), My advice is you should consult with ball screw OEM.

[@rahulbansal5867]

how these calculation will change for horizontal allignment

[@mastermechanicaldesign]

Almost same. Only load will be change, from gravity to frictional load

[@praveenchoudhary5137]

Sir horizontal load application k case me hum static and dynamic force kese calculate krenge....🙏

[@mastermechanicaldesign]

Ad video banaunga ispe

[@praveenchoudhary5137]

@@mastermechanicaldesign ji sir thanku

[@awateajay4170]

let suppose if this application is horizontal then all calculation are same or they changes @ g= 9.81

[@mastermechanicaldesign]

Hi ajay, Yes definitely calculation will be changed. In Horizontal condition, Like first of all resultant force (axial load ) will change, due to change in direction of g. Then critical speed limit will also change due to different mode shapes in horizontal Also there will be slight differences in buckling load. But yes steps will be the same. But i have seen that the manufacturers catalogue hasn't defined. Critical speed and buckling load formula for different conditions. We can use the same formula, no need to be too accurate. Consider sufficient SOF. However as nerds, we can go for Dynamic FEA cross check.

[@VinayakaprasadM]

From where did u get that Root diameter value for ball screw. Please share the catalog and page number ?

[@mastermechanicaldesign]

Catalog- Hiwin Ball screw, Link is in description, Page no 67, For Root diameter- Refer selected ball screw RD value. 👍

[@raghavkansal9701]

The drive link for the CAD models is not working. COULD you please look into the issue. Thanks

[@mastermechanicaldesign]

Updated!! check this again.

[@mahmoudjaraa2889]

hello my friend, i have searched a lot about the table you used to get the root dia and did not find it in the catalog, how can i get it ?

[@mastermechanicaldesign]

Please do check in THK or Hiwin catalogue (Search by term "root")

[@HatemFERCHICHI-yy3xk]

how to calculate sliding frictional force

[@caramellom]

Hii, I have a question, for a 10 m long horizontal loading device the Nc critical speed is very low, its almost something like 73 RPM. How can I fix this. This device also needs to be very precise. Also the load is very heavy 5 ton. what should I do? I have limited time so I'm really stressed. Even though I somehow solve this problem The Fk and Fp values become a problem. What diameter should I choose? Since in the HIWIN manufacturers catalog the recommended ones can be only 80 and 100 for 10000 meter long ballscrew. But I afraid if it is too much (I mean the diameter value). I would be deeply grateful for your response in advance.

[@mastermechanicaldesign]

Hi Caramellom, I would like to know more detail, what exactly it is. load is too much, and you also need precision. Second, I would suggest is to avoid using ball screw as travel distance is too much, instead use rack and pinion but as your device need to be precise too, so you I don't think you will as much precision in rack and pinion mechanism, but you should at least work out on it. you can email me which pictures.

[@caramellom]

​@@mastermechanicaldesign thank you so much for your help I mailed you the details, you are right I should use a rack and pinion system.

[@vinayakmodagekar9801]

helo sir , how that mass in inertia 55 occurred.what is the unit for it

[@mastermechanicaldesign]

Please leave time stamp

[@DHINAGANESHKR]

hello sir, If the load acting along the z axis is around 10kN, and the screw length is 500mm, lead is same as 10mm and speed is 750 rpm, I followed your previous video and I found the possible ball screw diameters as 20mm, 25mm, 32mm, 40mm (based on bearing block size ). but I could not find valid reason for the elimination of the diameters 20mm and 25mm . what will be your ball screw diameter selection based on your experience sir? can you provide it with a valid reason, thank you sir?

[@mastermechanicaldesign]

Hi, there is no such valid reason, we can start verification process from lowest size 20 mm, and if failed, we can go for 25 and 32 so on. I have start with 32 mm directly, as per past experience. more about this in linked video, watch after 19:00 kzbin.info/www/bejne/bJTUY4NthK17Y9Usi=x4KhhS3BWCR69FYw

[@sumitpatil9317]

how to define the load is moderate or heavy ?

[@mastermechanicaldesign]

Could you leave time stamp, I'm not getting where you exactly want to know?

[@sumitpatil9317]

How to decide thrust load or axial load is heavy or moderate while selecting ball screw supporting conditions. Is there should be any range of load as per application? The time stamp is 7.08.

[@satheeshkumarkumar3824]

How to calculate the frictional force value

[@mastermechanicaldesign]

As ball screw is like a ball bearing. ball point contact in their path, so we don't have to calculate frictional force in case of ball screw. just consider efficiency 90-95 %

[@seethapathyaiyah3739]

Hello I watched your this video. I liked the same.I am an Electronic person and for my one project I need a rack and pinion arrangement for movement. Can you help in this?

[@mastermechanicaldesign]

Yeah please email me

[@seethapathyaiyah3739]

​@@mastermechanicaldesign Thanks for your reply and will you please let me how I get i touch with you.

[@seethapathyaiyah3739]

Please let me know your contact detail so that I can get in touch with you. Thanks

[@bglo6225]

Process is correct but few numbers have come wrong in some places.

[@madevanv5675]

Hi there, It's seems you have made mistake while calculating the Critical Speed .. Kindly look at the values that you entered and check for final value please

[@mastermechanicaldesign]

Hi Madevanv, yes there are some typos mistakes. Please ignore, just follow the steps and formulas for calculations.

[@shivammachhi771]

I did not understand accelerate value which is 0.2 s

[@mastermechanicaldesign]

Hi Shivam, this is acceleration time value, like how quickly you want to achieve ball screw at final speed from rest, which also related to motor acceleration and ball screw pitch, and you can calculate it as per application requirement, as per cycle time of application. in this ball screw selection procedure, I have considered 0.2 sec acceleration time as application requirement, as an example. and as per my own experience, 0.2 to 0.5 sec acceleration time is normal for ball screw with servo motor, in most of application.

[@satishmds81]

680 not correct. Its 550+(55X2)=660

[@mastermechanicaldesign]

Yes, there is typo mistake

[@murugar8572]

your mail ID bro?

[@mastermechanicaldesign]

Hi Murugar, My email id is [e-mail]