Welder World Blog

Posts Tagged ‘Techniques’

It is obvious that Arc welding is considered as the major and an essential part of all the industries involved in designing and infrastructure. But what arc welding is? It is a process of fusing two metals by applying intense heat. This welding type used welding power supply in order to create an electric arc between base material and electrode. And, the final product that develops contain all the properties, just as in metals. The term arc welding is named because the heat that is used during the process of melting the metal at the juncture of joining is caused by an electric arc. With the help of a mechanically guided electrode, carrying the current between tip and the joint leads to cause of electric arc. Listed here are some of the arc welding tips and techniques for the beginners.

- Safety Precautions
Remember that before commencing with any of the welding methods, you need to adopt proper safety precautions. During welding harmful UV rays and sparks are produced that can damage eyes and skin, so it is important to wear safety glasses to get rid of any kind of damage. Also, wearing helmets during arc welding is mandatory. After all, self protection is a must to reduce risk of fire accidents and electric shocks. So before starting with arc welding, make sure that you have every safety gear ready with you.

- Rod and Arc Setting
This is the one of the most crucial and important parts of this procedure. And, if you are starting with this welding type for the very first time then it is better to do it on a rusty metal work as it is much more tolerant to the rusty surfaces. Also, make sure that your current setting should be in the correct position. And, if you are making use of 2.55mm rods, then make sure to use only 80 amps current supply. Also, polarity settings have to be adjusted. Polarity setting is done in such a way that the rod is positive and the earth is negative.

- Arc Welding Process
At first you need to turn on the welding machine. An electric arc is being generated when the welding rod comes in contact with the juncture of fusion. Generally, Tap Starting and Scratch Starting, are used for the process of electric arc generation. In Tap starting method, an electrode is used to tap on the work that removes excessive flux from electrode tip, which meanwhile creates an electric contact to generate the arc. While in scratch starting method, the rod is made to scratch against the surface of the work slightly and as the spark is generated, the rod can be lifted off. Also, remember not to put extra pressure in the method, because through this the rod might get stuck to the work medium.
Stick welding is known as the process that makes use of a covered electrode called stick. Also, known as Shielded Metal Arc Welding or SMAW, stick welding is the most widely used method today than other welding methods. But, now the question is how do they work?

The equipments used:

Stick welder contains circuitry inside the machine, which enables to carry a specified amount of voltage, therefore creating an arc. And, this is the reason why these welders are sometimes referred to as ARC welders. Totally relying on the application as well as on the machine, the current can be either alternating or direct current. The circuit board, which is present inside the welder enables it to ground the negative to the positive by creating heat without burning the electronics.

Shielded Metal Arc Welding (SMAW)

The welding procedure with the help of stick is called shielded metal arc welding or SMAW. The welding stick is a metal, which is coated with a flux material that burns off when the arc is struck, thereby creating a gas that protects the weld created. This type of welding is the most preferred method for the purpose of large metal structures like building framework, etc., because of its versatility and penetration ability. Although, today, other welding process like Flux-cored welding, or wire feed, is gaining more popularity, but stick welding still dominates the field.

The Weld:-

Factually, there are two types of leads that occurs in a stick welder. One lead is the negative clamp, and the other is the positive lead. In positive lead, the consumable metal stick is placed, while the negative lead is clamped on to the metal that is to be welded. During the process, when positive lead containing the stick comes in contact with the metal, an arc is created that further burns into the metal surface. Throughout the arc burning process, the stick is also burned, which thereby creates the weld. And, this is why welding is considered different than that of soldering process.

Safety Measures

While getting indulged in the process of welding, it is imperative to consider certain safety precautions to get rid of the risky environment. Always make sure to wear a welding hood when striking an arc. It is known that harmful UV rays are produced during the welding that can lead to burn in the eyes, so it is advisable to wear suitable goggles during welding. Also, wear leather welding gloves and a long-sleeved leather jacket, as well as heavy footwear and jeans. Remember, to remove all the inflammable materials from the work area before welding. So, consider the safety measures in order to get clean and successful welding.

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Welding technology in the electronics assembly occupies an extremely important position. General Welding divided into two categories: one is mainly applied to through-hole electronic components and PCB welding? Wave, the so-called wave (wavesoldering) that is soft solder melting solder by electric pump or electromagnetic pump jet peak into the design requirements of the solder, so that pre-printed board with electronic components by solder wave crest to achieve components with the PCB solder pad or pin end of the mechanical and electrical connection between the soft soldering welding; the other is mainly applied to surface mount components and PCB welding? reflow (reflowsoldering), also known as re-flow soldering, reflow soldering is through the so-called re-melted pre-assigned to the PCB pad of soft solder solder paste, solder-side components for surface mount or pin and the PCB pad mechanical and electrical connections between the soldering, to achieve a certain reliability of the circuit functions. With surface mount components in electronic products widely used surface mount reflow soldering techniques and technology into a major technology. Its main technology features: The flux of metal to be welded surface cleaning (removal of oxide), to make good on the solder wetting; supply of molten solder to wet the metal surface; in the solder and welding metal intermetallic compounds formed between ; also enables micro-soldering.

Reflow soldering is in advance of PCB Welding parts (pad) cast proper and appropriate forms of solder paste release surface mount components, solder reflow using an external heat source to the welding required by the group or by point welding. Reflow and wave soldering in comparison with the following features:

1, do not like the wave soldering components as needed to direct immersion in molten solder, so parts are subject to the thermal impact;

2, reflow the site only need to solder on the cast, a significant reduction in the use of solder;

3, solder reflow can control who discharge to avoid defects such as bridging the generation;

4, when the components have a certain deviation from posted up here, because the role of molten solder surface tension, cast in the correct position as long as the solder, reflow soldering can automatically correct this minor error, so that components fixed in position on;

5, can use local heating source, which can be used in the same substrate for different reflow soldering process;

6, solders are generally not mixed with impurities, the use of solder paste for reflow solder can be formed to maintain the right.

Reflow soldering techniques are classified according to heating methods are: vapor phase reflow, infrared reflow, infrared hot air reflow, laser reflow, hot air reflow soldering, and tools such as heating.

Reflow temperature curve theory: From the temperature curve (see Figure 1) of reflow principle: When the PCB into the heating zone (dry zone), the solder paste in the solvent, the gas evaporate, while the flux solder paste wetting pad component terminal and pin, solder paste softening, collapse, covering the pad, the pad, component pins and oxygen separation; PCB into the heat zone, so that PCB and components are fully preheated suddenly into the welding zone against PCB excessive heat damage to PCB and components; when PCB into the welding zone, the temperature rose rapidly to reach molten solder paste, liquid solder pad on the PCB, components and pin ends wet , diffusion, overflow or return mixed to form the solder joint; PCB into the cooling zone, so that solder solidification, to complete the soldering.

Temperature curve is critical to ensure welding quality, the actual temperature curve and solder paste temperature profile of the temperature slope and the peak temperature should be consistent. 160 temperature rise before the speed control in 1 / s ~ 2 / s, if the temperature slope too fast, on the one hand and the PCB heating component fast, easy to damage the components, could easily lead to PCB deformation; the other hand, solder paste in the solvent evaporation rate is too fast, easily spilled metal components, resulting solder ball. Peak temperature is set higher than the melting temperature of solder paste 20 ~ 40 or so (for example, the melting point of solder paste Sn63/Pb37 183 , the peak temperature should be set at about 205 ~ 230 ), back (again) flow time for the 10s ~ 60s, the peak temperature is low or back (re) flow time is short, will not fully welded, solder paste does not cause serious melting; peak temperature is too high or back (re-) long stream, resulting in oxidation of metal powder, affect the welding quality, and even damage to components and PCB.

Reflow temperature profile, and back under the principles of the reflow soldering machines currently on the market are generally simple four-zone reflow machine, there are six large, eight-or 12-zone reflow soldering machine, which model QHL320A reflow soldering machine 20 programmable temperature control, the equivalent of 20-zone reflow machine, it will return the temperature curves, and thus more precise temperature control, more fitting ideal reflow profile to achieve optimal welding.

Where good welding quality protection? QHL320A reflow machine in addition to full compliance with reflow in the control of outside temperature curve, but also allows users to truly understand the principle of reflow soldering. QHL320A reflow machine with the functions of large transparent window, users can have transparent windows throughout the entire welding process control, solder paste can be observed simultaneously in the whole state of the welding process changes, easy to find the problems in the welding process, through the parameters adjustments to improve, to ensure good quality of welding. Meanwhile QHL320A reflow soldering machine for small desktop machine, all-static soldering, effectively prevent a large-scale multi-zone reflow machine crawler transfer resulting from small vibrations, the vibration may be in the flow of molten solder paste soldering area state of the small space between IC (Such as distance 0.5mm) and components (such as 0603,0402 and 0201, etc.) affect the welding, leading to the drift component, solder balling, solder bridges welding defects, and all welding is still completely avoid these potential defects.

Set back (again) reflow soldering temperature profile of the authority:

1, according to the temperature curve using the solder paste to set. Different metal content of the solder paste has a different temperature profile, solder paste manufacturers should be provided in accordance with the temperature curve of the specific product set back (again) reflow soldering temperature profile;

2, under the PCB material, thickness, whether the multilayer, size, etc.;

3, under the surface mount board carrying components of the density, size and availability of components of BGA, CSP and other special components set.

4, according to the specific equipment, such as: the length of heated area, plus

Learn what tig welding is from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk

Learn what tig welding is from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk

Learn the basics of welding from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk

Learn the basics of welding from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk

Learn the basics of welding from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk

Learn what tig welding is from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk

Learn the basics of welding from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk

Learn what tig welding is from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk