CNC Machining Glossary
This CNC machining glossary provides a deeper technical reference for engineers, buyers, and manufacturers working with precision CNC machine shops. It covers advanced terminology related to CNC Swiss turning, 5 axis CNC milling, CNC milling, CNC turning, and quality control and inspection. These terms reflect real world shop floor processes, programming considerations, and inspection standards used in high tolerance manufacturing environments.
A
Adaptive Machining: A CNC process that automatically adjusts feed rates and cutting parameters in real time based on tool load and material conditions.
Allowance: Extra material intentionally left on a part for finishing operations such as grinding or honing.
B
Back Working: Secondary machining operations performed on the rear side of a part, commonly used in CNC Swiss turning.
Broaching: A machining process that removes material using a toothed tool, sometimes integrated into CNC turning for internal features.
C
Chip Load: The thickness of material removed by each cutting edge per revolution, critical for tool life and surface finish.
Climb Milling: A milling technique where the cutter rotates in the same direction as the feed, improving finish and tool longevity.
Closed Loop Control: A CNC control system that uses feedback from encoders to ensure precise positioning and repeatability.
D
Deburring: The removal of sharp edges or residual material after machining to meet safety and quality requirements.
Dwell Time: A programmed pause in tool movement to improve surface finish or dimensional accuracy.
E
End Mill: A rotary cutting tool used in CNC milling to machine slots, pockets, and complex profiles.
Encoder: A feedback device that tracks machine axis position and speed for precise motion control.
F
Fixture Offset: A programmed reference point that aligns the machine coordinate system with the workholding setup.
Form Tool: A cutting tool shaped to produce a specific contour in a single pass, often used in CNC turning.
G
G Code: The programming language used to control CNC machine movements, speeds, and functions.
Grinding Allowance: Additional material left for post machining grinding operations.
H
Hard Turning: CNC turning of hardened materials, typically above 45 HRC, as an alternative to grinding.
Heat Affected Zone: Area of material altered by heat during machining or secondary processes.
I
Interpolation: Coordinated movement of multiple machine axes to create circular or complex paths.
In Process Inspection: Measurement of parts during machining to detect deviations before completion.
J
Jig: A custom device that guides cutting tools and ensures consistent part positioning.
K
Kinematics: The study of motion in CNC machines, especially important in 5 axis machining accuracy.
M
Machining Center: A CNC milling machine capable of automatic tool changes and multi axis movement.
Material Removal Rate: The volume of material removed per unit of time during machining.
O
Orthogonal Cutting: A cutting condition where the tool edge is perpendicular to the direction of motion.
P
Post Processor: Software that converts CAM output into machine specific G code.
Probing: The use of touch probes to measure part features directly on the CNC machine.
R
Repeatability: The ability of a CNC machine to return to the same position consistently over multiple cycles.
Runout: Deviation of a rotating tool or spindle from true concentric rotation.
S
Simultaneous 5 Axis Machining: Continuous movement of all five axes during cutting to produce complex geometries.
Spindle Load: The amount of power being used by the spindle, monitored to prevent tool failure.
T
True Position: A GD&T tolerance defining allowable variation of a feature location.
Tool Life Management: Tracking and controlling tool usage to prevent unexpected wear or breakage.
V
Vibration: Oscillation during cutting that can negatively affect surface finish and dimensional accuracy.
Z
Zero Offset: The reference point from which all CNC machining coordinates are calculated.