miracle sheets revie
2 posts
Jun 30, 2025
7:54 PM
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Undercutting in machining is the deliberate removal of material from a concealed or recessed area of a workpiece, forming a negative profile that cannot be reached by a straight tool approach. This technique enables crucial functional and assembly features—such as snap-fits, retaining grooves, and clearance pockets—that enhance product utility and reduce post-machining operations.
The process begins in design, where engineers specify the undercut’s geometry—depth, width, angle, and radii—on technical drawings. Machinists then translate these into CNC toolpaths, selecting specialized undercut cutters or angle heads. Machining under an overhang requires complex motions: for instance, in 5-axis milling, the spindle tilts so the cutter’s cutting edge can reach beneath the adjoining surface. Alternatively, live tooling on a turning center uses angled holders to machine grooves under the workpiece’s flange.
Undercutting also appears in gear manufacturing and broaching: here, broach tools with multiple successive teeth cut deeper under the blank in staged passes, forming precision keyways or internal profiles. Gear undercuts in involute teeth ensure proper tooth thickness and root fillet, avoiding stress concentrations and potential tooth breakage.
A central challenge of undercutting in machining is maintaining surface finish and dimensional accuracy. Restricted access leads to poor chip evacuation, risking recutting and surface damage. High-pressure coolant, air blasts, or segmented toolpaths mitigate this by clearing chips between passes. Additionally, machinists choose high-gradient carbide cutters with polished flutes to reduce chip adhesion.
Inspection of undercut features requires creative metrology. Air gauges detect subtle depth variations, while optical comparators and borescopes provide visual confirmation. For critical aerospace or medical parts, CMM probes map the undercut profile in 3D, verifying compliance with design intent.
In essence, undercutting in machining transforms design complexity into tangible functionality. By blending advanced tooling, multi-axis capabilities, and rigorous inspection, manufacturers produce parts that perform reliably and assemble efficiently.
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