How do I choose a ball screw?

How much weight can a ball screw hold?

A ball screw drive translates rotational motion to linear motion or vice versa and can apply or withstand high thrust loads – upward of 750,000 lbs static capacity using a Ø6.

How do you calculate ball screw force?

So you can calculate the rotational vector component of force based on torque and the radius of the ballscrew. T = F1 x D/2, where: F1 is the vector component (tangent to the ballscrew) of the force applied by the screw onto the ball bearing. Linear force is produced because of the angle of the ballscrew thread.

Which is the most important criteria for selection of an ball screw actuator?

The distance the actuator needs to move in one direction, known as the stroke length, is the first requirement to consider in choosing between ball screw or belt drive. Ball screw actuators are commonly found at lengths of 1000 mm or less, although larger diameter ball screws can be used at lengths up to 3000 mm.

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How do you determine the diameter of a ball screw?

Shaft diameter Lead 15mm —— 20mm 15mm —— 30mm 20mm —— 20mm 20mm —— 40mm 30mm —— 60mm Since the screw shaft length has to be 1,200 mm as indicated in Section [Selecting a Screw Shaft] on B15-70, the shaft diameter of 15 mm is insufficient. Therefore, the Ball Screw should have a screw shaft diameter of 20 mm or greater.

What is the difference between a lead screw and a ball screw?

The key difference between a ball screw and a lead screw is in the way the load is carried between the moving surfaces. A ball screw uses recirculating ball bearings to minimize friction and maximize efficiency while a lead screw depends on low coefficients of friction between sliding surfaces.

Do ball screws have backlash?

Backlash is caused by the clearance between the ball bearing elements and the screw and nut tracks resulting in lost motion in the screw. A ball nut with all the backlash removed is called preloaded.

What is the purpose of ball screw?

Ball screws are used in aircraft and missiles to move control surfaces, especially for electric fly by wire, and in automobile power steering to translate rotary motion from an electric motor to axial motion of the steering rack. They are also used in machine tools, robots and precision assembly equipment.

How many types of ball screws are there?

By ball circulation method, the Ball Screws are divided into return-pipe type, deflector type and end-cap type. And by preloading method, fixed-point preloading (double-nut method, offset preloading) and constant-pressure preloading are selectable.

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How do you calculate the breakaway torque of a ball screw?

That will be your breakaway torque. For the lead screw: F = c*N where F is the static friction force, c is the static friction constant and N is the normal force. In this case you have to convert the Force to Torque Torque = Force x Lead /2pi.

How do you calculate ball screw speed?

DN Value. The concept of DN is a simplified way of determining the maximum rotational speed of a ball screw. DN is simply the multiplication of nominal diameter of the ball screw (in mm) times the maximum allowable speed (in rpm).

What is the pitch of a ball screw?

Pitch is the distance between screw grooves and is commonly used with inch sized products and specified as threads per inch. Lead is the linear travel the nut makes per one screw revolution and is how ball screws are typically specified. The pitch and lead are equal with single start screws.

How do I choose a lead screw?

Here’s an overview of the most important factors to consider when selecting a lead screw for an application.

  1. Load capacity. Begin by looking at the required load capacity. …
  2. Pressure-velocity factor. …
  3. Efficiency. …
  4. Speed. …
  5. Duty cycle. …
  6. Backlash. …
  7. Life. …
  8. Lubrication.

What is ball screw stroke?

Stroke: The linear distance in either direction that a ball screw or ball nut travels in moving the load. Temperature: Ball screw assemblies operate with normal efficiency between temperatures of -65 degrees F to 300 degrees F with suitable lubrication.

What is lead in ball screw?

Lead is the linear travel the nut makes per one screw revolution and is how ball screws are typically specified. The pitch and lead are equal with single start screws. For multiple start screws the lead is the pitch multiplied by the number of starts.

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