Face driver

Constant face drivers for turning

Constant face drivers are used to machine workpieces on lathes or milling machines, such as shafts that need to be milled or turned. These tools help rotate the workpiece precisely during machining.

Components of the Constant Face Driver:
- Base Body: The main part that contains everything.
- Guide Discs or Drive Jaws: These attach to the workpiece and make it rotate.
- Centering Point: Used to position the workpiece accurately.

How it works:
- Preparation of the Workpiece: A partially machined metal piece with small central holes called 'centers' is used. These centers guide the workpiece during machining.
- Mounting on the Lathe: The constant face driver is mounted on the lathe spindle. The jaws grip the workpiece and make it rotate. The centering point enters the workpiece's center hole, ensuring perfect alignment.
- Action of the Jaws: When the lathe rotates, the jaws hold the workpiece in place and make it turn, preventing it from slipping.
- Pressure and Centering: The centering point moves to adapt to the workpiece, keeping it stable. The force with which the point presses on the workpiece is adjusted by springs, which vary depending on the weight and rotational speed of the workpiece.

To choose the right constant face driver, you need to consider:
- Direction of Rotation: Whether the workpiece rotates to the right or left.
- Workpiece Dimensions: The maximum diameter the jaws can grip and the diameter of the workpiece to be machined.
- Centers: The diameter of the centers must be appropriate for the constant face driver.

Interpretation of the Diagram for Constant Face Drives for Turning and Milling Cylindrical Parts or Shafts

The Constant Face Drive is a tool that ensures precise turning without shape errors or tolerance deviations around the rotation axis of the workpiece. Given the importance of correct adjustment, it is strongly recommended to follow these guidelines to avoid injuries, including very serious ones, during turning operations. In case of doubts, it is advisable to contact technical experts, such as the staff at Tadaah, who can provide support for the purchase and optimal use of Constant Face Drives.

The following information refers to and is valid only for perfectly intact and new Rohm products; however, it is always advisable to contact Tadaah or Rohm for further verification in any case.

Below is the necessary material for the machining processes:

1. Preparation of the Raw Workpiece: The workpiece is initially machined with a facing and centering phase (creating center holes) on both sides.
2. Mounting the Constant Face Drive: The Constant Face Drive can be mounted directly in the self-centering chuck or, if it has a Morse taper, it can be secured in the self-centering chuck with a suitable reduction.
3. Use of the Tailstock with Dynamometer: On the opposite side of the Constant Face Drive, a tailstock equipped with a dynamometer is mounted. This tool allows you to know exactly the preload of the Constant Face Drive during the turning operation.

Preload Adjustment:
To work safely, efficiently, and precisely, while also avoiding serious injuries to personnel, it is essential to correctly adjust the preload of the Constant Face Drive's jaws. Use the data provided below to accurately calculate the preload of the Constant Face Drive with the tailstock. We attach a scale with an example, whose solution and result are highlighted by the red line.

Data needed for the calculation:
- Weight of the workpiece
- Material of the Workpiece: It is important to know the material's resistance to machining, expressed in daN per mm².
- Outer Diameter of the Constant Face Drive Disk
- Outer Diameter of the Turning
- Depth of cut and feed rate per revolution of the tool
- Tool Feed Direction: This can be from the self-centering chuck towards the outside (C) or from the tailstock towards the self-centering chuck.
Important: Depending on the tool feed direction, compensation factors must be considered, as shown in the drawing above the scale diagram:
- Compensation Factor "A": Multiplier x1
- Compensation Factor "B": Multiplier x1.5
- Compensation Factor "C": Multiplier x2
In the case of multiple operations being performed simultaneously, the sum of each result must be calculated.