Usage & Operation Views: 48

First-piece inspection is the critical quality gate for countersunk hole work - never skip it. When: 1. After a tool change (new or reground); 2. After a material change (new batch, different grade); 3. After parameter changes (speed, feed, depth); 4. After a shift change; 5. After restart following a stop; 6. First run of a new product or process. Items to check: 1. Angle: use an angle gauge or countersink gauge, tolerance within +/-1 degree; confirm it matches the screw (metric 90, US 82). 2. Depth: measure with a depth gauge, tolerance within +/-0.1mm; the key test is test-fitting the screw - after tightening the head should sit flush or 0.1mm below the surface - not protruding, not too deep. 3. Diameter: caliper the maximum countersink diameter, tolerance within +/-0.2mm; confirm the screw head fits fully without interference. 4. Concentricity: check the countersink is centered on the pilot hole with no visible offset; a test-fitted screw that does not tilt means good alignment. 5. Surface quality: visually check the countersink cone for vibration marks, burrs, chipped edges or scratches; feel the hole edge for sharpness. 6. Thread: if tapping, test the screw - smooth entry, no stripped or loose threads; thread depth per spec. 7. Assembly: actually assemble with the screw - smooth driving, firm when tightened, flush head, good appearance. Process: 1. Machine the first piece; 2. Check every item above; 3. If all pass, fill out the first-piece inspection record; 4. Only then run the batch; 5. Keep the first piece as a reference sample at the work station; 6. Spot-check every 10-20 pieces during production. Notes: 1. Do first-piece inspection seriously - not as a formality; 2. If the first piece fails, find the cause, adjust and re-machine until it passes; 3. Keep records for traceability; 4. Calibrate gauges regularly; 5. Train inspectors on the standards. Remember: first-piece inspection is the first and last line of defense for quality! Skipping it can lose a whole batch! Lihao Technology provides a first-piece inspection template to help you build a proper system.