Two kinds of misoperation caused by skillful repair of needle detector

- Nov 01, 2019-

Two kinds of misoperation caused by skillful repair of needle detector

We usually encounter that in the products of the working substance, sometimes the needle detector will react due to the different types of dyes. For example, in the case of a certain color, almost all of them can pass the needle detector, but in other colors, they can't pass. This is because some dyes contain iron oxide. We need to change the dyes before we can use the needle detector normally.

In addition, the rubber at the bottom of shoes often contains a lot of metal powder. In this case, we can see that there is no broken needle and other metal fragments in the tested product, but because there are many tiny iron, the transfer needle detector will also react to the overall metal content. At this time, the hand-held needle detector may often fail to detect product abnormalities. Because the portable needle detector is pressed on the tested product for detection, it can detect smaller foreign matters than the transport needle detector.

However, in the above cases, although the sensing strength of the hand-held needle detector is relatively high, the area of the needle detector is very small, and the area of the reaction body of the sensor is smaller, so it often occurs that the hand-held needle detector cannot detect foreign matters.

If clothing and other sewing products adopt metal accessories, we should first ensure that the accessories (metal zipper, metal button, metal bead chain, etc.) do not contain iron, cobalt, nickel, the three magnetic metal components.

If these magnetic metals reach a certain content in the accessories, they will not pass the inspection of the needle detector, and the sewing products installed with these accessories will not pass the "fault" phenomenon of the needle detector.

Misoperation caused by external noise

We put the inspected product on the conveyor belt of the needle detector. If the product moves to the vicinity of the needle detector and enters the noise disturbing the magnetic field of the needle detector from the outside, the machine will stop transmitting the inspected product and sound the display.


Generally, there are several situations of external noise as follows:

Large moving objects such as electromagnetic clutch motor, sewing machine, cutting machine, packaging machine, large transformer, decontamination spray gun, ironing table motor, elevator, large fan, railway outside the workshop, welding machine, high-voltage wire, etc.

When using the needle detector, operators must not carry metal objects such as mobile phones, keys, watches, etc., which may cause false alarm of the needle detector. In addition, when the needle detector works, we should avoid carrying the clothes hanger made of metal to pass by.

When there is a large fan on the upper part of the needle detector, the author suggests that the power supply of the needle detector must be turned off when it is working.

When the source of noise in the workshop is uncertain, for example, when the power supply of the needle detector is turned on and the operation switch is turned off, if the display lights red, we can judge whether it is affected by the external noise. At night or when all the power in the workshop is off, only connect the power of the needle detector. If there is no noise effect, we can judge that there are other problems in the workshop production. In the same state, we can start the mechanical equipment that may have an impact one by one and find out the cause.