Troubleshooting for Needle detector

Troubleshooting for Needle detector

If you suspect that your machine is malfunctioning, there are several possible causes.
Examine the following points

Belt stains

The belt should be cleaned weekly and often. Since the surface of the belt is relatively dirty due to the product being placed on it, please be conscious of cleaning it. Every day, dust and other debris, including minute amounts of iron, will adhere to it from the outside when it is used. When these accumulate, the machine will react to the iron attached to the belt immediately below the product, even if there are no needles in the product.

The needle detector has two types of sensors: a needle detection sensor that detects whether needles are mixed in, and a photoelectric sensor that detects whether products have been fed in. The needle detection sensor is always in the process of detecting, but the decision to stop the conveyor is made when the photoelectric sensor confirms the product.
In other words, if the photoelectric sensor cannot confirm the product (no product on the belt), the detection sensor does not stop the belt even if there is a detection response.
Since the photoelectric sensors are located on both sides of the conveyor belt at a height of about 5 mm, products that are lower than the position of the photoelectric sensor light, i.e., very thin products (less than 4 mm thick), cannot be checked because the products pass under the light of the photoelectric sensor, and the belt will not stop even if it detects a reaction. The belt does not stop even if there is a detection response.

When belt contamination is detected, one of the needle position detection lamps on the machine’s control panel (8 lamps for HN-600C and 10 lamps for HN-610C/620C) will light up. Alternatively, in the HN-610C/620C, the detection reaction level meter will light up to red. Iron dust on the belt will cause the needle position detection lamp to light periodically as the belt rotates.

Malfunction due to external noise

When a product is placed on the conveyor belt of the needle detector and the product comes to the needle detector sensor, if external noise that disturbs the magnetic field of the needle detector sensor is detected, the belt will stop due to a malfunction caused by the noise. The following are examples of external noise
Electromagnetic clutch motors, sewing machines, cutting machines, packing machines, large transformers, stain removal guns, vacuum motors, elevators, large fans in factories, large moving objects such as trains outside factories, transformers, welding machines, high voltage lines, etc. When using the needle detectors, workers should remove objects such as cell phones, keys, and watches from their bodies. Also, when using a needle detector, hanger racks, and other objects should not pass by the needle detector.
If you suspect that external noise is acting, you must first identify the source of the noise that is causing the problem. Move the needle detector to a different location or move the noise-generating equipment away from the needle detector.
If there is a large fan above the needle detector, the fan should also be turned off during the needle detection.
Even if the source of noise in the plant cannot be identified, for example, if the red light on the monitor comes on when the power switch of the needle detector is turned on and the operation switch is off, it can be determined that the machine is receiving external noise. Or, if you run only the needle detector at night or under conditions where all machines are not turned on, and no noise is detected, then something in the plant is causing the problem.　Run each of the expected machines one at a time under those conditions to determine the cause.

Malfunction due to internal noise

Internal noise from the needle detector is the noise generated by the machine itself, such as the vibration of the machine itself.
The adjuster bolt on the bottom of the needle detector should be fully secured.
A weak floor can also cause vibrations in the needle detector, which can lead to malfunctions. Place a 20 cm square board under the adjuster bolt of the machine to reduce the vibration of itself.
Check the setscrews and other parts of the cover of the needle detector carefully. If the cover is vibrating and contacting the needle detection sensor, it may also cause malfunctions.
If the bearings used in the needle detector are magnetized, this can also cause a malfunction.
A demagnetizer should be used to remove the magnetism from the bearings.

Malfunction due to product defect

Some products may react with the needle detector depending on the type of dye used. In many cases, certain colors will pass through the inspection machine, while other colors will not. In addition, rubber, which is often used in the soles of shoes and other products, may contain a large amount of iron powder. In these cases, there are no broken needles or other fragments in the product. The whole product contains microscopic amounts of iron, and the conveyor needle detector reacts to the total amount of iron. In these cases, even the handheld type often fails to detect the product. A handheld needle detector can generally detect smaller objects than a conveyor needle detector as long as it is pressed against the product, but since the detection area is much smaller, there are even fewer reactants in it, so a handheld needle detector may not be able to detect it.
Also, even NC-measured metal accessories may be more likely to react if the quantity attached to the product is large.

In such cases, it is necessary to lower the sensitivity to the level where no reaction occurs. After adjusting the sensitivity, please pass a test piece of the required needle detection standard and confirm that the needle detector reliably reacts at that level.

*Demagnetization of magnet
The needle detector uses a permanent magnet for the detection sensor. To check the operation of the needle detector, please be sure to run a test piece through it in place before use.

NOTE:
Production of HN-600C was discontinued in February 1997 with the launch of HN-610C/HN-620C.
Production of HN-610C/620C was discontinued in March 2003 with the launch of HN-630C/640C.
Production of HN-630C/640C was discontinued in May 2005 with the launch of HN-650C/660C.
Production of HN-650C/660C was discontinued in September 2008 with the launch of HN-670C/680C.