# Calculate the required torque for a cam design

• Travis T
In summary: No, i don't know for both ways and method. Would be great if you could give some advice on these.I was thinking i can estimate the required motor torque by calculating resultant force from Condition2 (which is the highest torque required to reach the position moving from initial Condition1). Am i going the wrong direction?
Travis T
TL;DR Summary
Would like to check the design of snail cam require how much motor rated torque?
Hi all,

I'm currently designing a cam mechanism.

Would like to check how much motor rated torque required for the following design of snail cam ?
To ease calculation, i have include some assumed factor as below. Two extreme condition (rotation degree) to compare.

What is the motor rated torque required for the design? (is 0.30Nm enough?)

*please let know if any factor missing or not logic.
*would like to have estimation for motor selection only, thus to simplify, insignificant and complicated factor can be ignore

Is this homework?

Calculate the torque at the extreme positions, at least three positions in between, and in each of the flat parts. Then decide if you need to calculate at some more points.

Show clearly the center of rotation, and the direction of rotation. Is the cam follower slowly rising, then falling fast? If so, calculate the fall time to find if it stays in contact with the cam.

jrmichler said:
Is this homework?

Calculate the torque at the extreme positions, at least three positions in between, and in each of the flat parts. Then decide if you need to calculate at some more points.

Show clearly the center of rotation, and the direction of rotation. Is the cam follower slowly rising, then falling fast? If so, calculate the fall time to find if it stays in contact with the cam.

Hi Jr,

Thanks for reply, this is not a homework.

Which way does this turn? It will make a lot of difference.

Dr.D said:
Which way does this turn? It will make a lot of difference.

Hi Dr. D,

condition1 shall be initial position,
when trigger, motor will rotate direction (1); cam follower will move up following the profile,
rotate until condition2, motor will stop (rev can be set; 340degree),
then motor rotate in reverse direction (2); cam follower back to initial position.

Your problem statement is incomplete. What is there to resist motion? If these two elements were simply free in space (no gravity), they would be able to rotate without any applied torque at all. What resists the motion to require a torque?

Dr.D said:
Your problem statement is incomplete. What is there to resist motion? If these two elements were simply free in space (no gravity), they would be able to rotate without any applied torque at all. What resists the motion to require a torque?

Hi Dr.D,

Compress spring is to always attach the cam follower to the profile of cam.
Here i attach a figure (side view) with other element for better understanding on the design.
Hope this could help explain the mechanism and question. Thanks.

Ah, now you tell us! I presume you are aware that there are other ways to keep a follower in contact with a cam profile?

Do you know how to use the method of virtual work with a potential energy term included? That will get the system torque pretty easily (provided, of course that you specify the cam lift profile).

Dr.D said:
Ah, now you tell us! I presume you are aware that there are other ways to keep a follower in contact with a cam profile?

Do you know how to use the method of virtual work with a potential energy term included? That will get the system torque pretty easily (provided, of course that you specify the cam lift profile).

Hi Dr.D,

No, i don't know for both ways and method. Would be great if you could give some advice on these.

I was thinking i can estimate the required motor torque by calculating resultant force from Condition2 (which is the highest torque required to reach the position moving from initial Condition1). Am i going the wrong direction?

Until you specify the cam lift curve, all you have is a picture. It is very hard (actually impossible) to apply mathematics to a picture. I suggest you get a machine design book (Shigley comes to mind) and read up on cam design.

Travis T

## 1. What is torque and why is it important in cam design?

Torque is a measure of the rotational force required to move an object around an axis. In cam design, torque is important because it determines the amount of force needed to rotate the cam and perform its intended function.

## 2. How do you calculate the required torque for a cam design?

The required torque for a cam design can be calculated using the formula: T = F x r, where T is torque, F is the force applied, and r is the distance from the axis of rotation to the point where the force is applied. This formula takes into account the force required to overcome friction and the distance from the cam to the point of rotation.

## 3. What factors affect the required torque in cam design?

The required torque in cam design is affected by several factors, including the shape and size of the cam, the weight and size of the object being moved, the speed of rotation, and the amount of friction present in the system. These factors should be carefully considered when designing a cam to ensure the correct amount of torque is applied.

## 4. How does the type of cam affect the required torque?

The type of cam used in a design can greatly impact the required torque. For example, a flat-faced cam will require more torque than a roller cam due to the increased surface area in contact with the follower. Additionally, the shape and size of the cam profile can also affect the required torque.

## 5. Can software be used to calculate the required torque for a cam design?

Yes, there are various software programs available that can assist in calculating the required torque for a cam design. These programs take into account all the necessary factors and can provide accurate results to aid in the design process.

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