Some Reasons That Causing Picking Error Of Nozzle

- Nov 19, 2018-

The smt nozzle is not only the key part of the mounter for picking and placing the absorbed elements, but also the background of the camera when taking photos. It mainly picks the elements by the vacuum adsorption, and put the elements on the coordinate position of the circuit board by blowing.

When the nozzle picks the elements, it is necessary to ensure that the center of the elements, the center of the nozzle and the spatial center of the image obtained should coincide. In fact, the adjustment of the optical vision system is to compensate for the deviation caused by the non-coincidence in actual work.


So what causes picking error of nozzle?

The worn nozzle, deformable nozzle, blocked nozzle and damaged nozzle

All these cause insufficient air pressure leading to the inability to pick components, so it is necessary to check the wear degree of the nozzle regularly and replace the serious worn nozzle.

The influences of feeder, the poor feeding of feeder (damaged feeder gear), the hole of belt not setting on the gear, foreign matter under feeder, the worn spring, deformation and rust of cover plate, spring and other operating mechanism, which results in deviation of components or failure to pick components. Therefore, it should be considered that regular inspections should be processed to avoid wasting a lot of devices.

3. Vacuum negative pressure is insufficient.

When the nozzle pick components, a certain negative pressure is generated at the  nozzle. The negative pressure detection method is generally used to determine whether pick-up of the nozzle is abnormal. When the negative pressure sensor detection value is within a certain range, the machine thinks that the pick-up is normal, conversely, it is not good. The vacuum negative pressure should be above 53.33 kPa when the element is picked, so that there is enough vacuum to pick the element. If the vacuum negative pressure is insufficient, it will not be able to provide enough suction to pick components. We should check the vacuum negative pressure and clean the nozzle regularly. At the same time, we should pay attention to the contamination of the vacuum filter on each mounting head. To replace the blackening filter and ensure the smooth airflow.

4.The influenced by the picking height.

The ideal picking height of the nozzle is to press down 0.05 mm when the nozzle touches the surface of the element. If the depth of the pressure is too deep, the element will be pressed into the trough instead of picking the element. If the picking of a component is not good, the picking height can be adjusted slightly upward, such as 0.05 mm.

5.The problem of incoming components.

The quality problems in package of chip components produced by some manufacturers, such as the large error of tooth hole spacing, the excessive viscous force between tape and plastic film, and the small size of material trough are all possible reasons for the failure to pick the components.