Feed rate (F word) specification in CNC Programming

Introduction

The feed rate tells the machine how fast to move the tool while cutting. It helps control the speed for smooth and safe machining.

When you want the tool to move at a specific speed to cut material properly.

When changing from rough cutting to fine finishing and need a slower feed.

When programming a CNC machine to ensure the tool does not move too fast or too slow.

When adjusting the speed to avoid tool damage or poor surface quality.

When setting up a new machining operation with different materials.

Syntax

CNC Programming

F<feed_rate_value>

The letter F is followed by a number that sets the feed rate.

The feed rate value is usually in units per minute (like mm/min or inches/min).

Examples

Sets the feed rate to 150 units per minute.

CNC Programming

F150

Sets a faster feed rate of 500 units per minute for quicker cutting.

CNC Programming

F500

Sets a slow feed rate of 20 units per minute for delicate finishing.

CNC Programming

F20

Sample Program

This program moves the tool in straight lines (G01) with feed rates set by the F word. The first move uses a feed rate of 100 units/min, the second move continues at 100 units/min, then the feed rate changes to 200 units/min for the last two moves.

CNC Programming

G01 X50 Y50 F100
G01 X100 Y100
G01 X150 Y50 F200
G01 X200 Y100

Important Notes

If you do not specify a feed rate, the machine uses the last set feed rate.

Always choose a feed rate suitable for the material and tool to avoid damage.

Feed rate units depend on machine settings (metric or imperial).

Summary

The F word sets how fast the tool moves while cutting.

Use different feed rates for rough and fine cuts.

Always specify feed rate to control machining speed safely.