9 Point Calibration System of Needle/Metal Detection Machine

 

In the garment and apparel industry, metal detecting machines are generally utilized to detect needles and small metal parts that may have been accidentally lodged in finished garments. Shipping garments with needles, sharp or other unwanted metal objects could result in blacklisting or heavy financial losses for the factories and bad publicity, product recall, financial losses and legal actions for brands. 

Needle detection is also an integral part of the garment manufacturing companies that produce apparel for babies or kids. Generally, conveyor type metal detection machines are recommended and used.

Calibration of Metal Detection Machine

Conveyor detectors should be calibrated to 1.0-1.2 mm/customer’s standard ferrous object detection. 

The 9 Point calibration ensures that the equipment is functioning correctly and operating at the correct sensitivity (1.0, 1.2mm or as per customer’s standard).

• The 9 Point calibration must be done a minimum of 2 times per shift or every time when the machine is out of power/switched off by a certified and trained operator. It is recommended to do it every hour.

• Proper documentation of calibration should be maintained. 

Tools Required For Calibration 

Metal/ needle detector test card and stand

The procedure of Metal Detection Calibration

1. The 9 Point Calibration check on the detector is done by dividing the metal detector conveyor belt into 3 zones.

2. The Calibration Card, supplied by machine vendor, should be passed through each of these zones at three different height levels.

	Left	Center	Right
Top	A7	A8	A9
Center	A4	A5	A6
Bottom	A1	A2	A3

3. The Detector sensitivity must be set at a level which is less than the customer’s requirement (1, 1.2mm etc.).  

4. The Calibration Card should be placed on the conveyor belt and passed through each zone and A, B and C readings to be recorded on a 9 Point Calibration Report.

Recording Results

The 9 Point Calibration Report should be marked as follows

Y /ok/✓- if the needle detection activates (alarm sounds, the light activates and the machine stop or reverses the card) when the Ferrous Calibration Card is passed through the search head.

N/Not ok/X – if the needle detector has no reaction (no alarm sound/light/reverse movement of belt) when the Ferrous Calibration Card is passed through the search head.

• If there is no reaction during the 9 point Calibration procedure and report is fail (even a single reading/result fails) the operator must stop the machine and call the supervisor. The product should not be tested with such a machine.