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Tapping failure reasons analysis

After the first metal part be tapped, we always to check it: if pass the thread gauge inspection? The inspection result is OK, we can do mass production. If it fails, We should consider which reasons cause tapping faiulre.
KYLT provide Metal Machining services for: WEDM, EDM, DRILL, TAPPING, CNC LATHING, CNC MILLING, ALUMINUM / MAGNESIUM / PLASTIC RAPID PROTOTYPES MAKING. 1PCS ORDER IS ALLOWED.


Aluminum CNC machined workpiece
Aluminum CNC machined workpiece

Normally, the following reasons may cause screw thread faiulre:

1) UNQUALIFIED TAP

Tap is wear or bad

2) QUALIFIED DRILLING HOLE (BEFORE TAPPING)

If the hole is too small, because of friction, will increase the difficulty of tapping, while tapping faster wear, and vice versa, the hole is too big, it can easily tap into, but the quality of teeth is very poor, because the diameter of teeth will become larger, relative to the screw nut bonding force is insufficient, easy to slide teeth. In M3 *0.5, the correct hole (general iron) should be between 2.50 and 2.65, if too large, it is not easy. Obtain good quality teeth.

3) MACHINING ANGLE

The tap is not perpendicular to the workpiece.

4) TAP NOT CLEAN

The tap is not clean and the scrap of iron is clamped into it, which leads to the enlargement of teeth.

5)SCREW THREAD NOT CLEAN

The scraps or impurities in the screw thread have not been removed, which results in the unqualified inspection of the thread gauge.

6) LOSE OIL

Tap without oil, too much friction leads to thread rupture.

7) PROBLEM TAPPER

Poor tapping machine and shaking of axle result in disqualification of thread enlargement.

8) INSPECTION FREQUENCY

Inspection with screw gauge every 20 or so in the process (frequency depends on the qualified condition, if the qualified rate is high, the inspection cycle can be lengthened, otherwise it will be shortened. )
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