1. What is Ball Screw Back Drive?

Ball screw back drive refers to the torque required to move a load along the axis of a ball screw when external force is applied. It's important for determining whether a screw will back-drive under load or remain stationary.

2. How Does the Calculator Work?

The calculator uses the back torque equation:

Where:

• \( Force \) — Applied axial force (Newtons)
• \( Lead \) — Screw lead (meters per revolution)
• \( Efficiency \) — Mechanical efficiency of the ball screw (decimal, typically 0.7-0.95)
• \( 2\pi \) — Conversion factor from linear to rotational motion

Explanation: The equation calculates the torque needed to overcome the screw's mechanical advantage and efficiency when back-driving.

3. Importance of Back Torque Calculation

Details: Calculating back torque is essential for determining whether a ball screw assembly will maintain position under load or require a brake to prevent unwanted movement.

4. Using the Calculator

Tips: Enter force in Newtons, lead in meters, and efficiency as a decimal (e.g., 0.9 for 90%). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is typical ball screw efficiency?
A: Ball screws typically have efficiencies between 70-95%, with higher quality screws achieving better efficiency.

Q2: How does lead affect back drive torque?
A: Larger leads require more torque to back-drive, making them less likely to move under load.

Q3: When is back drive a concern?
A: Back drive is critical in vertical applications or systems where maintaining position is important for safety or functionality.

Q4: How can I prevent unwanted back driving?
A: Options include selecting screws with smaller leads, adding a brake, or using self-locking screw types.

Q5: Does lubrication affect back drive torque?
A: Yes, proper lubrication can improve efficiency, potentially reducing the torque needed to back-drive.