GD&T Tutorial 12B : RFS Vs MMC Vs LMC
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- Опубліковано 28 сер 2024
- GD&T Tutorial : RFS Vs MMC Vs LMC
In this video you will learn when to you Regardless of Feature Size RFS, Maximum Material Condition MMC and Least material Condition LMC
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Your explanation is simple and easy to understand. Thank you Palani sir
You are most welcome
It's an excellent video series on GD&T. I have ready ASME 14.5 but still, its was hard to understand. Thank you for the details expaination
You gave basic dimensions 20 mm but how it's comes upto 18.5
Good Explanation! its really help full for Non Mech also, Thank you sir
Most welcome!
Why vertical dimension is not changing??
Hello,
I have one question..
That why diameter of tolerance increases while it is given 1mm at MMC
The two Basic Dimensions 20 and 20 locate the hole's true center:
Based on the Actual Size of the Hole drilled we can apply an appropriate Bonus location tolerance due to the MMC condition modifier. All that is very clear.
But on your diagram - you only show the x-axis 20 mm dimension changing not the y-axis one. Also, you only show it changing to less than 20.
In reality - the tolerance zone is a cylinder so wouldn't both x and y-axis dimensions be affected in both directions?
Means - at the LMC (with the MMC modifier) the actual hole size is the largest (so 13 mm dia.):
This means that the X-axis location of the actual hole drilled would be allowed to be within 18.5 and 21.5 from Datum C and the Y-axis location of the hole would be allowed to be within 18.5 and 21.5 from Datum B. Isn't that the case?
Please let me know if I'm missing something.
Thanks!
he said it in the video :
For ease of understanding
Thank you for the explanation Sir. Just a quick question. That 19.5 shift could also be 20.5, right? on either side of the true center? and another thing, what do you mean by the worst condition of 10 Inner boundary in general terms?
Hi, Your videos are very nice & helpful. Thank you very much for sharing the knowledge
I just need one clarification from capability study, stand point. How Spec limit (USL & LSL) should be considered for the positional tolerance when it has MMC/LMC modifier.? Because, there are bonus tolerance based on the feature dimension change.
Can we straight away take position tolerance as 18.5 to 21.5 [Considering MMC in the above example].?
Please share your comment.
And if you already made any video for my query, please share it here. That would be great.
will be uploaded later
Thank you sir for your great service
Thank you for the lecture
For MMC scenario, it's easy to understand
For LMC scenario, I understood it is used to avoid thin hole-to-edge distance. But the concept shows that the smaller the hole, the more positional tolerance allowed
Question: wouldn't it be very hard for the mating pin to fit ??? Lets say 11mm hole is mate.. it is allowed to shift +/-1.5mm?? LMC seems a little confuse to me.
Hello Francis Chan, I've a doubt with MMC scenario as well, thought you could elucidate it more vividly. Why is the dia of positional tolerance keep increasing when the hole dia is increasing? I thought it so like that to satisfy the MMC. But I'm not satisfied with my conclusion. Can you please help me understand this?
@@shanmukhasrinivas4758
For MMC slide at 3:04, using 13mm green hole example
The hole dimension is 12+/-1 with positional GT dia. 1mm at MMC, that means your VC is 10mm (12 - 1mm lower limit - 1mm positional tolerance)
However, IF the hole was bored at 13mm, the machinist has 3mm positional diameter allowance for the mating pin location (opening more room for the mating pin).
@@francischan8263 thanks alot🤗
@@francischan8263 ua-cam.com/video/th8kZWAobog/v-deo.html
I'm not aware whether you've seen video or not. Is 0.2mm added to the positional tolerance as bonus tolerance which rounds to 0.5mm for LMC?
Can you please help me with this?
@Francis Chan I have the same doubt.. As the LMC condition moves towards MMC makes the hole smaller, in addition to this if we again add bonus tolerance to it the hole will shift completely making it impossible to assemble with pin of mating part. If you get it please explain to me.
Hello Sir,
In MMC, as the hole size increases (moving towards LMC) the position tolerance value also increases significantly. Why the position tolerance value increases with increase in hole size, even though the tolerance value in feature control frame is specified as dia 1mm. Please clarify this query both theoretically and with practical examples.
For assembly of parts can be ensured with parts having more geometric error when produced at LMC conditions, to get this flexibility, we used MMC, so that the tolerance values changes for each value of the hole. this is being explained in many videos.
check my videos on virtual condition and bonus tolerance
Thank u Sir, for your excellent explanation.
You are most welcome
Sir, is it right to design a positional tolerance with RFS?
Hi sir,
In MMC for internal feature, dia 11 should have maximum shift of dia 3, because at dia 11 we have maximum material left. Because then only we can get VC as dia 10. I am sorry, but do correct me if I am wrong.
Which material condition (MMC/LMC) is preferred and why? Please sir reply me
Could you please explain Virtual Condition?
Sir ... presentation is not available in the given link .. would you please look into it
Hello Sir
Sir can you explain the last part of the bonus tolerances of the video where MMC and LMC are not or are used on lay man's terms or with an example?
Sorry for the trouble
Sir, How do you apply LMC for holes.. The concept was little confused
Hole is an internal feature.
LMC - Least material condition.
So, for holes we will have larger values so that there is least material on the part.
So LMC = Nominal dia + tolerance.
For external features like stand-off, ribs, boss.
LMC = Nominal dia - tolernace.
This gives least material on the part.
MMC concept is reverse of LMC.
For holes, the Least material condition is the largest possible hole. Thus, giving a positional tolerance at largest possible hole dia, the subsequent smaller dia will have bonus tolerances(more space for mfg to work with) from reduction in diameter at each step.
By doing this, we're ensuring that even at the largest possible diameter, there is a minimum wall thickness ie., Distance from circumference of largest hole to edge of the solid block.
In sheet metal or plate applications, this concept is of paramount importance because, when your turret is piercing a hole on metal sheet, edge near to the hole might break if this tolerance is not taken into account.
sir how do you calculate position shift?
1.Sir MMC only use for increasing cylindrical tolerance or any other purpose to be have?
2.why rfs used?
MMC is used for getting bonus tolerance and RFS is used when we require tighter tolerance
Sir, what is the tolerance applicable to basic dimension which is 20
My doubt is as the dimension is shifting according to various sizes of hole in MMC and LMC cases, so what is the tolerance applicable to that basic dimension.
the tolerance applied in the FCF is applicable tolerance for Basic Dimension
@@PalaniKailash thanks sir
Sir could you please explain what is virtual condition and its significance
why position tolerance value increases with hole size increases in MMC condition?
Don't understand
Could you please elaborate in detail??
check videos on Virtual condition and bonus tolerance
Sir why does position tolerance zone increases with hole diameter in MMC?
We get a bonus with MMC
Sir, I have one small doubt. Here the center of the virtual condition boundary is the true center sir?.
Yes
@@PalaniKailash tq sir... I've sent an email sir ... Regarding a question
I don't understand why the center is19.5 from 20. I don't know what I am missing.
take the help of your seniors
@@PalaniKailash With due respect, that is not the answer to my question.
My reply was to your previous question. Now you have edited the question
How we will give geometrical tolerance value in the frame
check the video on Limits and Fits
Can you please tell me why one side shift in evry case, why it is different values with scenarios
Hi, watch my video "Viewers Doubts Clarified"
for answer to your question
@@PalaniKailash hi sir i did not find the viewer doubt vedio.
Could you please help me.
ua-cam.com/video/zUlGr5YFw_o/v-deo.html
Hi sir,
Still I'm not clear in maximum material boundary and least material boundary.pls can you explain sir
watch the videos on datum shift and virtual condition to understand better
Sir, Could u guide me how to get GDTP - senior level certification? Is it compulsory i should appear "GDTP-technology Level first...BTW, i have 15 years of AERO-manufacturing experience..Could u guide me?
Contact me in person 9886371971
Sir I have one dobut profile surface applicable MMC?
Profile tolerance is a feature (surface) control, so we can not apply MMC & LMC Modifiers
Why didn’t reduce the y axis value 20 remains constant??
Please explain anyone..
if you listen carefully, in the video, i have mentioned the reason.
For ease of understanding
Thanks 4 ur reply sir..I can try to understand what you said..
@@Saravanan. did you got the answer?
No..
@@PalaniKailash sir, i also not understand why the x axis only changing and why not the y axis?
can you help us please by clarifying this doubt?
I am not understand.
Sir, where we cannot apply MMC & LMC?
All geometric controls applied to feature can not use MMC and LMC
@@PalaniKailash I couldn't understand the meaning of it that you have replied means what is geometric control
Your voice is not clearly audible. Please try to improve from next video. Thank You!!!
Wow pretty confusing thanks. can't understand
good to know that you could not understand. catch up with another teacher
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