Exothermic welding process and application points of exothermic solder powder

(1) Factors affecting the welding effect
A good solder joint surface is full of light, no pores, and slag inclusions. After cutting, the profile is a whole without pores and flaws. The factors affecting the welding effect are the cleanliness of the mold and the object to be welded. If the dust, grease, oxides or other deposits on the surface of the object to be welded must be removed, it can be cleaned and polished before welding, otherwise the welding after welding The electrical and mechanical properties of the point will be affected. Another major factor affecting the welding effect is moisture or moisture. Since mold, solder powder and the object to be welded may adsorb moisture, how to prevent or remove moisture is the most important step that must be taken during welding. If the residue left in the mold is not completely removed, the surface of the solder joint will be unsmooth and not bright.

In summary, note the main points:
1 drive off the water vapor (can be baked with a blowtorch)
2 cleaning the soldered object,
3 cleaning mold

(2) Precautions for application of exothermic solder powder
1 Each solder powder corresponds to one solder joint, and the solder powder grade should correspond to the mold. It should be carefully checked before use.
2 Solder powder has been protected by multiple layers for its moisture resistance when it leaves the factory, but it is recommended to keep it safe from moisture.
Characteristics and advantages of exothermic welding:
(1) The current interception flow at the welding point is equal to the wire;
(2) The solder joint is permanent and will not cause high resistance due to looseness or corrosion;
(3) The solder joint is like copper, but is tougher than copper itself and is not affected by corrosive products;
(4) The solder joint can withstand repeated large surge (fault) currents without degradation;
(5) The welding operation method is simple and easy to use;
(6) The equipment is light and convenient to carry;
(7) When welding, no external power source or heat source is required;
(8) The quality of the weld can be checked from the appearance; it can be used for welding copper, copper alloy, copper-plated steel, various alloy steels including stainless steel and high-resistance heating heat source materials.
Prepare the exothermic welding connection before use:
(1) Bake the drying mold with a heating tool (spray lamp or drying box) before each start to remove moisture.
(2) Clean the mold after each use, use a soft brush or other soft objects to avoid damage to the mold.
(3) Check the tightness of the contact surface of the mold to prevent the copper liquid from leaking out of the gap during operation.
(4) The mold clamp is used to open and close the mold. The tightness of the mold clamp has an effect on the welding effect. Please carefully check the mold clamp before the welding starts and make appropriate adjustments.
(5) The mold is made of graphite, which is relatively fragile and cannot withstand throwing and strong impact. Therefore, it is not allowed to force the solder beyond the mold size into the mold, or use hard materials and tools to remove the residue.

(6) The service life of the exothermic welding mold can generally reach 50-100 times or more.