Facing-Everything you need to know

Facing is a lathe machining operation in which material is removed from the end face of a rotating workpiece to produce a flat surface that is perpendicular to the axis of rotation.

Facing Operation in Turning (Lathe Machining)

1. What is Facing?

Facing is a fundamental turning operation performed on a lathe to produce a flat, smooth surface at the end of a cylindrical workpiece, perpendicular to its axis of rotation.
It is commonly the first operation carried out to square the end of the job and establish a reference surface.

2. Purpose of Facing

To make the end surface flat and perpendicular to the axis
To bring the workpiece to accurate length
To remove rough or damaged ends
To prepare the surface for drilling, boring, or threading
To improve surface finish and dimensional accuracy

3. Principle of Facing

The workpiece rotates in the spindle.
The single-point cutting tool is fed radially inward, i.e., perpendicular to the axis of rotation.
Material is removed from the outer diameter toward the center.

4. Tool Used for Facing

Single-point cutting tool (right-hand or left-hand)
Tool material:
- High Speed Steel (HSS)
- Carbide tipped tool
- Coated carbide inserts (in CNC lathes)
Tool geometry:
- Proper side rake and back rake
- Adequate clearance angles
- Sharp nose radius for good finish

5. Facing Operation Setup

Workpiece holding
- 3-jaw chuck (most common)
- 4-jaw chuck
- Collet (for precision work)
Tool positioning
- Tool tip must be set exactly at the center height
- Tool should be rigidly clamped in the tool post
Machine settings
- Select appropriate spindle speed
- Choose correct feed rate
- Set depth of cut

6. Steps in Facing Operation

Mount and secure the workpiece in the chuck.
Set the facing tool at center height.
Start the lathe and bring the tool near the outer edge.
Engage the feed to move the tool toward the center.
Continue cutting until the tool reaches or slightly crosses the center.
Retract the tool and stop the machine.
Measure the length and surface finish.

7. Types of Facing

Plain Facing
- Produces a flat surface
- Most common type
Step Facing
- Produces stepped faces at different diameters
Angular Facing
- Produces a surface at a specified angle
Form Facing
- Produces a contoured or profiled face using a form tool

8. Cutting Parameters (Typical)

Cutting speed (V): Depends on material (e.g., mild steel: 25–40 m/min for HSS)
Feed (f): 0.05–0.3 mm/rev
Depth of cut (d): 0.5–2 mm (roughing), 0.1–0.3 mm (finishing)

9. Common Problems & Defects

Defect	Cause	Remedy
Center pip	Tool not crossing center	Move tool slightly past center
Rough surface	Low speed, blunt tool	Increase speed, sharpen tool
Tool chatter	Poor rigidity	Reduce overhang, tighten setup
Non-flat face	Tool height incorrect	Set tool exactly at center