How to Inspect After CNC Machining? These 4 Methods Are Most Commonly Used

1. Coordinate Measuring Machine (CMM): "Full-Dimension Precision Inspection" for Complex Parts

• Inspection Scope: Measures dimensional accuracy (e.g., hole diameter, distance, angle) and geometric tolerances (e.g., roundness, coaxiality, flatness) with a precision of ±0.001mm, meeting the strict ±0.005mm requirements of aerospace parts;
• Operation Logic: A probe touches the part surface to automatically collect 3D coordinate data, which is compared with the CAD model to generate a deviation report. It supports "one-click inspection" for batch parts, avoiding manual reading errors;
• Applicable Scenarios: First-article inspection of new products, periodic sampling inspection in mass production (e.g., 1 piece inspected for every 50 pieces), and orders requiring customers to provide "full-dimension inspection reports."

2. Roughness Tester: "Micron-Level Control" of Surface Quality

• Inspection Principle: A diamond stylus slides across the part surface to record contour fluctuation data, calculating parameters such as Ra and Rz. Medical implants require Ra≤0.4μm, and automotive gearbox gears require Ra≤0.8μm;
• Operation Points: Select the "key working surface" of the part (e.g., seal groove, mating surface) for inspection, avoid sampling in areas with burrs or scratches, and maintain stable stylus pressure (usually 0.75mN) to ensure data accuracy;
• Advantages: Portable roughness testers can be used directly in the workshop, and it takes only 10 seconds to inspect one point, suitable for rapid surface quality screening of batch parts.

3. Vision Measuring Machine: "Efficient Visual Inspection" of 2D Dimensions

• Inspection Method: Place the part on an optical platform, a high-definition camera captures the surface image, and software automatically identifies features such as edges and holes to measure 2D dimensions (length, diameter, spacing) with a precision of ±0.002mm;
• Efficiency Advantage: Supports "simultaneous inspection of multiple parts" (e.g., 10 mobile phone middle frames at a time), completing all dimension measurements within 1 minute—5 times more efficient than caliper inspection, and avoiding manual alignment errors;
• Special Functions: Can inspect surface defects (e.g., scratches, missing corners) and generate image reports, facilitating traceability of problem causes (e.g., debris residue during CNC machining).

4. Hardness Tester: "Basic Verification" of Material Mechanical Properties

• Inspection Type: Select based on part material—Brinell hardness tester (HB) for aluminum alloy parts, Vickers hardness tester (HV) for stainless steel and titanium alloy parts. Medical parts need to meet the HV250±10 standard;
• Operation Notes: Polish the part surface (roughness Ra≤1.6μm) before inspection to avoid the oxide layer affecting readings, and select "non-working surfaces" (e.g., part edges) for inspection to avoid damaging the appearance;
• Associated Value: Hardness inspection can indirectly verify whether the "wrong material is used" (e.g., using industrial aluminum as aerospace aluminum). An automotive parts factory once discovered that the supplier sent the wrong material through hardness inspection, avoiding 1,000 defectives from entering the assembly line.

Why Are These 4 Methods "Most Commonly Used"?