How to Choose a 4th Axis Rotary Table for a VMC

Introduction

Adding a 4th axis to a Vertical Machining Center (VMC) significantly reduces setups and improves efficiency. However, selecting the wrong rotary table can lead to machine interference or insufficient rigidity. Here are the four key factors to consider before purchasing.

1. Workpiece Size and Table Diameter

The table diameter should be large enough to support your workpiece but small enough to avoid colliding with the machine spindle or enclosure. A common rule is to choose a table diameter that covers at least 1/3 of your workpiece's footprint.

2. Load Capacity and Weight

Calculate the total weight of your workpiece plus the fixture. Ensure this combined weight does not exceed the rotary table's allowable load-bearing capacity. If machining long shafts, consider using a tailstock to distribute the weight and maintain rigidity.

3. Machine Table Space

Measure the available T-slot space on your VMC. A larger rotary table (e.g., 250mm) may offer higher rigidity but require more space. Ensure there is enough clearance for the table to rotate 360° without hitting the machine doors.

4. Drive Type: Roller Cam vs. Worm Gear

Roller Cam: Offers high rigidity, zero backlash, and high indexing speed. Ideal for complex multi-side machining.

Worm Gear: More cost-effective but generally has lower speed and requires more maintenance.

Note: Contact our engineering team to confirm the exact drive type for your specific machining requirements.

Conclusion

Choosing the right 4th axis depends on your specific workpiece and machine setup. If you are unsure, send your machine model, controller, and workpiece dimensions to our team for a configuration check.