What are the reasons for the poor skills of welders? What are the dangers of poor welder welding?

There are two reasons for the poor skills of welders. The first is that there is not enough learning in theory. There is a lack of necessary mastery of the theories of welding materials and welding methods. On the other hand, there is a lack of practical experience. It may be that there is a lack of practical skills, so the skills will be poor.

Poor welder skills are due to many reasons,1Welding parameters (current, voltage) are not taken into account

Phenomenon] many welders in order to pursue the speed of welding, often ignore the importance of current, voltage and other welding parameters, root welding, fill welding, cover welding and other unified welding parameters, this is what we commonly call a parameter to go the world example, in fact, this is the performance of welding operation is not standardized, this phenomenon is not a big problem for ordinary weldments, but for strict requirements of weldments is absolutely impossible.

Improvement] Establish a strict welding process system, strictly formulate welding parameters, welders strictly abide by them, and special products should evaluate the welding process parameters, and can only be used after passing the assessment. In addition, there should be different welding parameters for root welding, filling welding and cover welding, so as to avoid unqualified due to inappropriate and non-standard parameters.

2.The welding speed does not match.

Phenomenon] When welding, do not pay attention to the control of welding speed and welding current, and the diameter of the welding rod and the welding position are used in coordination. For example, when the corner seam of full penetration is under-welded, due to the narrow size of the root, if the welding speed is too fast, the root gas and slag inclusion do not have enough time to discharge, which is easy to cause defects such as unpenetration, slag inclusion and porosity at the root; When the cover is welded, if the welding speed is too fast, it is also easy to produce porosity; If the welding speed is too slow, the residual height of the weld will be too high and the shape will not be neat; When welding thin plates or welds with small blunt edge sizes, the welding speed is too slow, and it is easy to burn through.

Measures] welding speed has a significant impact on welding quality and welding production efficiency, the selection of welding current, weld position (root welding, fill welding, cover welding), the thickness of the weld, the size of the groove to select the appropriate welding speed, in order to ensure penetration, gas, welding slag easy discharge, no burn-through, good forming under the premise of selecting a larger welding speed, in order to improve productivity and efficiency.

The causes and hazards caused by virtual welding.

During the soldering process of circuit boards, especially when making electronic kits or wireless headphone kits, virtual soldering can have a huge impact.

Virtual soldering is mainly caused by oxides and dirt on the surface of the metal to be welded, which makes the solder joint become a connection state with contact resistance, resulting in the operation of the circuit.

Abnormal, there is an unstable phenomenon of good and bad connection, and the noise increases without regularity, which brings major hidden dangers to the commissioning, use and maintenance of the circuit.

In addition, there are also some virtual solder joints that maintain good contact for a long period of time when the circuit starts working, so they are not easy to find. But at temperature,

Under the action of environmental conditions such as humidity and vibration, the contact surface is gradually oxidized, and the contact gradually becomes incomplete. The contact resistance of the virtual solder joint will be induced.

The local heating and local temperature increase further deteriorate the condition of the solder joints that are not in complete contact, and eventually even make the solder joints fall off, and the circuit is completely incorrect.

Regular work. This process can sometimes be as long.

In one or two years, the principle can be explained by the concept of "galvanic battery": when the solder joint is damp, water vapor seeps into the gap.

After that, the water molecules dissolve the metal oxides and dirt to form an electrolyte, and the copper and lead-tin solder on both sides of the virtual solder joint are equivalent to the two electrodes of the galvanic battery, lead-tin soldering.

The material loses electrons and is oxidized, and the copper gains electrons and is reduced. In such a galvanic cell structure, metal loss-making corrosion occurs in the virtual solder joint, and the local temperature occurs.

The elevation exacerbates the chemical reaction, and the mechanical vibrations cause the gaps to widen, until a vicious circle causes the virtual solder joints to eventually break the circuit.

According to statistics, nearly half of the failures of electronic products are caused by poor soldering. However, to have thousands from one.

It is not easy to find the virtual solder joint that causes the fault in the electronic equipment of the solder joint. Therefore, virtual soldering is a major hidden danger to the reliability of the circuit and must be strictly avoided. This is especially important when performing manual soldering operations.

Generally speaking, the main causes of virtual soldering are: poor solder quality; Poor reducibility or insufficient dosage of flux; The surface of the welded area is not pre-cleaned.

Well, the tinning is not firm; The temperature of the soldering iron tip is too high or too low, and there is an oxide layer on the surface; The welding time is not well mastered, too long or too short; Soldering in the solder yet.

When solidifying, the soldering element becomes loose.

The hazards of welding defects to welded components are mainly as follows: (1) Cause stress concentration. The distribution of stresses in welded joints is complex.

Where there is a sudden change in the cross-section of the structure, the distribution of stress is particularly uneven, and the stress value at some points may be many times larger than the average stress value, and this phenomenon is called stress concentration. There are many reasons for stress concentration, and the presence of process defects in the weld is one of the most important factors. The defects of cracks, non-penetration, and other sharp notches existing in the weld make the weld cross-section discontinuous, produce abrupt parts, and will produce a large stress concentration under the action of external force.

When the stress exceeds the breaking strength of the metal material at the front of the defect, the material will crack and fail. (2) Shorten the service life. For components bearing low-cycle fatigue loads, if the size of the defect in the weld exceeds a certain limit, after a certain cycle of cycles, the defect will continue to expand and grow until the component is fractured.

3) Cause brittleness and endanger safety. Brittle fracture is a kind of low-stress fracture, which is a rapid burst fracture of structural parts without plastic deformation, and its harm is great. The quality of the weld has a great impact on the brittleness of the product.

Therefore, the welder must ensure the quality.

Firm welding is the basic quality requirement of welders, it is related to the service life of components, it is related to the life safety of tens of millions of people, and it is related to the level of technology and credibility of a country.

If the welding is not firm, the weldment will be broken and leaked, which will bring damage and danger to people's production and life.

Welding is a manufacturing process and technology that joins metals or other materials such as plastics by means of heat, high temperature or high pressure.