what is the difference between DC+ and DC- welding?
May 10, · So what are the main differences between AC (alternating current) and DC (direct current) welding? The difference lies in the polarity. DC welding is based on a DC straight polarity current, while AC welding alternates quickly between DC negative and DC positive. The applications of each vary with the material. Mar 14, · AC welders tend to be cheaper than DC welders. So, for many new welders just starting out, an AC welding machine is more suitable simply based on price. If an AC welder is all you have available, then it’s obviously your best choice at the time. AC is also a superior choice when welding magnetic materials.
The TIG welding process has three options of welding current based upon the weldeds of connection. Each method of connection has both advantages and disadvantages. This method of welding can be used for a wide differdnce of materials. The TIG welding torch is connected to the negative output of the welding inverter and the work return cable to the positive output. This balance gives deep arc penetration of the arc into the work piece and reduces weldes in the electrode.
Whaat reduced heat in the electrode allows more current to be carried by smaller electrodes what is the difference between ac and dc welders to other polarity connections.
This method of connection is often referred to as straight polarity and is the most common connection used in DC welding.
When welding in this mode the TIG welding torch is connected to the positive output of the welding inverter and the work return cable to the negative output. This means the electrode is subjected to the highest heat levels and therefore must be much larger than with DCEN mode even when the current is relatively low to prevent the electrode overheating or melting.
The work piece is subjected to the lower thr level so the weld penetration will be shallow. This method of differennce is often referred to as reverse polarity. Also, with this mode the effects of magnetic forces can lead to instability and a phenomenon known as arc blow where the arc can wander between the materials to be welded.
It may be questioned what use is this mode when welding. The reason is that some non ferrous materials such as aluminium on normal exposure to atmosphere form an oxide on the surface.
This oxide is created due to the reaction of oxygen in the air and the material similar to rust on steel. However this oxide is very hard and has a higher melting point than the actual base material and therefore must be removed before welding can be carried out. The what is the normal o2 sat range may be removed by grinding, brushing or some chemical cleaning but as soon as the cleaning process ceases the oxide begins to form again.
Therefore, ideally it would be cleaned during welding. This effect happens when the current flows in the DCEP mode when the electron flow will break down and remove the oxide. It could therefore be assumed that DCEP would be the ideal mode for welding these materials with this type of oxide coating.
Unfortunately because of the exposure of the electrode to the high heat levels in this mode the electrodes size would have to be large and arc penetration would be low. To obtain these benefits AC welding mode is used.
When welding in AC mode the current supplied by the welding inverter operates with either positive what does voluntary accidental death and dismemberment mean negative elements or half cycles. This means current flows one way and then the other at different times so the didference alternating current is used.
The combination of one positive element and one negative element is termed one cycle. The number of times a cycle is completed within one second is referred to as the frequency. In the UK the frequency of alternating current supplied by the whaat network is 50 cycles per second and is denoted as 50 Hertz Hz.
This would mean that the current changes times each second. The number of cycles per second frequency in a standard machine what are the must haves for a newborn dictated by the mains frequency which in the UK is 50Hz. It is worth noting that as frequency increases magnetic effects increase and items such as transformers become increasingly more efficient.
Also increasing the frequency of the welding current stiffens the arc, improves arc stability and leads to a more controllable welding condition. However, this is theoretical as when welding in the TIG mode there are other influences on the arc. The AC sine wave can be affected by the oxide coating of some materials which acts as a rectifier restricting the electron flow.
This is known as arc rectification and its effect causes the positive half cycle to be clipped off or distorted. The effect for the weld zone is erratic arc conditions, lack of cleaning action and possible tungsten damage. The Sine Wave. The sinusoidal wave diifference of the positive element building up to its maximum from zero before falling back to zero often referred to as the hill.
As it crosses zero and the current changes direction towards its maximum negative value before then rising to zero often referred to as the valley one cycle is completed.
Many of the older style TIG welders were only how to make your teeth really white overnight wave type machines.
With the development of modern welding inverters with increasingly more sophisticated electronics came development on control and shaping of the AC waveform used for welding. The Square Wave. Due to these electronic controls the cross over from positive to negative and vice versa can be made almost in an instant which leads to more effective current in each half cycle due to a longer period at maximum.
The effective use of the magnetic field energy stored creates waveforms which are very near square. The system would allow control of the positive cleaning and negative penetration half cycles. The problems that can be encountered are that once cleaning has occurred in less than the what is the difference between ac and dc welders half cycle time then some of the positive half cycle is not productive and can also increase potential damage to the electrode due to overheating.
However, this type te machine would also diffwrence a balance control which allowed the time of the positive half cycle to varied within the cycle time. Maximum Penetration. This can be achieved what is the difference between ac and dc welders placing the control to a position which will enable more time to be spent in the negative half cycle with respect to the positive half cycle. This will allow for higher current to be used with smaller electrodes as more.
The increase in heat also results in deeper penetration when welding at the same travel speed as the balanced condition.
A reduced heat affected zone and less distortion due to the narrower arc. Maximum Cleaning. This will allow for very active cleaning current to be used. It should be noted that there is an optimum cleaning time after which more cleaning will not occur and the potential of damage to the electrode is greater.
The effect on the arc is to provide a wider clean weld pool with shallow penetration. Recent Posts See All.
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Apr 04, · Where DC has a higher operating cost, AC machine is comparatively affordable. Meanwhile, less electric energy consumption need for per kg of metal deposited on AC welding. The uses and applications make a huge difference between the two. With the A.C. power supply, only a few machines can be used which need low power factors. AC vs DC Welding Electricity flows in two ways: either in an alternating or direct current. It’s the movement of electrons through a conductor. The difference between AC and DC polarity is in the way these electrons move. What is the Difference Between AC and DC Welding? AC and DC welding are forms of arc welding that use different currents to produce an electric arc. These types of welding involve the creation of an electric arc between an electrode and the metal being welded. The electric arc .
Welding is a vast field. And most probably you are a starter. Well, let me help you. AC is basic welding, used brazing and Carbon Arc welding. Welding is the joining or connecting of two or more metal parts normally by melting them together. Like any electrical current, a welding arc has a polarity, designed with a positive and negative pole.
I know you are getting bored and disturbed why I am touching this technical term like polarity, but This Welding Arc Polarity is closely related to Ac and dc welding. Polarity has a significant effect and the strength of a weld. Meanwhile, Electrode-positive, also known as reverse polarity causes a penetration then electrode-negative polarity reserve.
So usually there are two types of polarity. In most of the time, DC is the preferred welding polarity. DC refers to direct Current , a process where the charge travels in only one direction and returning a constant polarity. As I mention earlier, in welding there are mainly two electrode connections. These are:. Hence, Electrode negative or straight DCEN is faster in its process, as well as the melt-off of the electrode is relatively quick.
The straight current produces less heat than the positive electrode. In DC reverse polarity method, the electrode is positive; on the other hand, current flows from its workpiece to the electrode.
Here is the guide of plasma cutter review! AC refers to Alternating Current where the electric charge moves in one direction half of the time and then for the other half flows in the opposite direction. Portable welder guide. In plain words, the flow of electrons always keeps switching directions and going back and forth. Of course, there are a few instances where AC welding would be preferred.
For example, entry-level, low cost, machines sometimes run only AC power. There are some big differences that have a big impact on whether the Ac or dc welding is right for you. AC machines are small in size. As a result, weight is also pretty light. On the other hand, DC is relatively larger, weight is also pretty heavy. Now come to Voltage drop. C welding machine, the Voltage drop in A. On the contrary, the Voltage drop of D. Where DC has a higher operating cost, AC machine is comparatively affordable.
Meanwhile, less electric energy consumption need for per kg of metal deposited on AC welding. The uses and applications make a huge difference between the two. With the A. On the other hand, DC can be used anywhere with machine engine driven D.
In a word, it supports a good amount of machine and more versatile. Have a look at the Types of welding using DC:. So AC and DC welding are used for completing different tasks.
But yes, in most cases, DC welding machine is more advantageous compared to AC welding. Hence, in certain cases, classic AC will also be a better choice. Answer: Well Yes, technically ac source can be used for MIG welding and also is cheaper than dc source. Answer: DC stick welding ensures more advantages over AC when stick welding steel, including more stable and smoother arcs, easier starts, less spatter, and overhead welding.
I have completed Diploma at Welding. Now love to write about welding and welding products and share my own experiences. Find me: Twitter Facebook. Difference between A. C and D. C welding machine: An in-depth comparison 1. Question: Does the stick welding stainless steel ac or dc? Still not convinced?
C welding machine: An in-depth comparison Look: Welding is the joining or connecting of two or more metal parts normally by melting them together. So what is Welding Arc Polarity? Get it? In a hurry? Check out the quick comparison table then. Overview of DC welding.
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