How We Inspect Custom CNC Machined Parts Before Shipment
CNC machining quality inspection is an important part of producing accurate and reliable custom parts. Even when a part is produced by CNC equipment, tool wear, material variation, incorrect offsets, or improper clamping may affect the final dimensions.
At iPrecision CNC, parts are inspected according to customer drawings, tolerance requirements, material specifications, and surface finish requirements before shipment.
Drawing Review Before Production
Before machining begins, we review the customer’s 2D drawings, 3D models, and technical requirements.
The review normally covers:
When dimensions or technical requirements are unclear, we confirm them with the customer before production. This helps reduce manufacturing errors and delays.
First Article Inspection
After the first part is completed, important dimensions are measured before continuing production.
Dimensions Commonly Checked
The inspection may include:
The first article inspection helps verify the CNC program, tooling, fixture, and machining sequence. When an adjustment is required, it can be completed before the remaining parts are produced.
In-Process Inspection
For batch production, inspection continues during machining.
Dimensions may gradually change because of tool wear, temperature, or material differences. Important features are therefore checked at suitable intervals during production.
For example, shaft diameters may be checked during CNC turning, while hole positions and pocket depths may be checked during CNC milling.
In-process inspection helps identify dimensional changes before they affect the complete production batch.
Final Dimensional Inspection
After machining is completed, the finished parts receive a final inspection according to the drawing.
Different measuring tools are selected according to the part size, geometry, and tolerance.
Common Inspection Tools
We may use:
General dimensions may be measured with calipers, while tighter dimensions normally require more accurate measuring tools.
Thread and Hole Inspection
Threads and holes are common features in CNC machined parts.
Thread size, pitch, depth, and condition are checked according to the drawing. Precision holes may also be inspected for diameter, depth, position, countersink, or counterbore requirements.
Blind holes are cleaned before inspection to remove chips or machining residue.
Surface and Appearance Inspection
In addition to dimensional inspection, the surface condition of the parts is checked.
The visual inspection may include:
Parts with cosmetic surfaces require additional attention because scratches or contact marks may affect their final appearance.
Inspection After Surface Finishing
Some parts require anodizing, powder coating, polishing, nickel plating, or other surface treatments.
After surface finishing, the parts are checked again for appearance and important dimensions. Coating thickness may affect holes, threads, and fitting surfaces, so these areas must be protected or inspected carefully.
Packaging Inspection
Before shipment, the parts are cleaned, counted, and packed according to their material, size, weight, and surface condition.
Parts are separated when necessary to prevent direct contact during transportation. Steel parts may also require rust protection.
The outer packaging is checked to ensure that the parts are properly protected against scratches, impact, movement, and moisture.
Conclusion
CNC machining quality control should begin before production and continue throughout the manufacturing process.
Drawing review, first article inspection, in-process measurement, final dimensional inspection, appearance inspection, and packaging checks help reduce production risks and ensure that finished parts meet customer requirements.
At iPrecision CNC, we manufacture custom metal and engineering plastic parts based on customer drawings, 3D models, or samples.
Need Custom CNC Machined Parts?
Send us your drawings, 3D models, material requirements, quantity, tolerances, and surface finish specifications. Our team will review your project and provide manufacturing feedback and a quotation.