Repair method of bad electric heating tube

(I) The significance of defective product repair

In the production of electric heating elements, defective products are inevitable. Due to the inconsistency of technology and management level of each factory, the number of defective products varies greatly. In some enterprises with strong technical strength and high management level, the defective rate can be controlled below 0.5%, while in some poor enterprises, the defective rate is 3-5%. If the defective products in production can be repaired and the percentage of defective products is reduced to a minimum, this is the goal pursued by every enterprise. Reducing defective products can not only reduce the loss of the enterprise, reduce costs, and improve the economic benefits of the enterprise, but also save raw materials, auxiliary materials, labor, and meet the delivery requirements.

(II) The possibility of repairing defective products in the production of electric heating elements

Generally speaking, after the electric heating elements are made, it is found that the defective products are difficult to repair, but in practice, we have found that some can be repaired.

1. What types of defective electric heating elements can be repaired:

When the following problems occur in the filler of the electric heating element-magnesium powder, which makes the element defective, this type of electric heating element has the possibility of repair.

A The quality of the original magnesium powder is good. Due to uneven stirring or other reasons during modification, after the electric heating element is made, its tidal resistance is low, about 100MΩ. When the element is placed in the air, the resistance will continue to decrease. When red ink is injected at both ends, the ink can be absorbed. When the tube mouths at both ends are cut open, the red ink absorbed is greater than 2mm.

B During the processing of the electric heating element, the magnesium powder is slightly damaged:

Such as the flange welding at both ends of the oil heater pipe and the water dispenser pipe, the end welding of the water boiler pipe, and the pickling during the electroplating process, (hydrochloric acid, nitric acid) and the immersion of the electroplating liquid.

C Some other situations: such as the electric heating tube has not been furnaced after the tube is made, or has been furnaced, but the furnace temperature is too low or the temperature has reached, but the furnace time is too short, etc.

2. What situations cause defective electric heating elements that cannot be repaired:

A Reasons for magnesium powder: poor quality of the original magnesium powder, high content of ferromagnetic substances and other harmful impurities, too low density or uneven density.

B. Pipe material defects: such as cracks, burrs inside the pipe, bubbles, shrinkage holes, slag inclusions, etc.

C. Problems in the pipe manufacturing process: such as broken heating wire, eccentricity or collision of heating wire and lead rod, etc.