What is MFDC?

What is MFDC?

MFDC stands for MID FREQUENCY DIRECT CURRENT. This is a control and power supply system that takes an AC power input and converts it into an inverted higher frequency power output. It is inverted and converted a combination of times in the control and transformer to end up with a 400 – 4000 hertz inverted DC output.

Is resistance welding AC or DC?

The resistance welding industry has traditionally used rectified 3-phase AC to create DC power. This method of creating power requires large machines and large transformers, and also lacks the precise process control that many users are seeking.

Why alternating current is most suitable for resistance welding?

Alternating current is found to be most suitable for resistance welding as it can provide any desired combination of current and voltage by means of a suitable transformer. In order to avoid the surface distortion, the portion of the metal adjacent to the weld or joint should not be allowed to be overheated.

Why Copper is used in spot welding?

Copper is used for the electrodes as it has a high thermal conductivity and low electrical resistance compared to most other metals, ensuring that the heat is generated preferentially in the work pieces rather than the electrodes.

Which current is used in resistance welding?

Low-frequency Electric resistance welding Current is then passed between the two edges of the steel to heat the steel to a point at which the edges are forced together to form a bond without the use of welding filler material. Initially this manufacturing process used low frequency A.C. current to heat the edges.

What electrode is used for projection welding?

Copper electrodes are used in projection welding as copper is a good conductor of electricity and heat. The two metal workpieces to be joined are placed between the two electrodes.

What does DC mean in welding?

Direct current
Direct current is an electric current that has a constant polarity flow in a single direction. This current can be positive or negative. With DC welding, since the magnetic field and current of the arc are constant, stable arcs are produced.

Why is welding copper difficult?

Copper alloys have quite different welding characteristics due to differences in thermal conductivity. For example copper, due to its high thermal conductivity, may require substantial preheat to counteract the very high heat sink.

Can you Spotweld copper?

YES, We can weld copper with copper or to any other metal like SS or bi metal alloy using spot welding process. You need to select proper welding electrodes for welding. If you want to weld copper to copper or its alloy , you need to select electrode material based on RWMA Class 13 & 14 .

What are the 3 basic types of resistance welding bonds?

There are three basic types of resistance welding bonds: solid state, fusion, and reflow braze. In a solid state bond, also called a thermo-compression bond, dissimilar materials with dissimilar grain structure, e.g. molybdenum to tungsten, are joined using a very short heating time, high weld energy, and high force.

What are the two types of resistance welding?

There are several different forms of resistance welding (e.g. spot and seam, projection, flash, and upset welding) which differ primarily by the types and shapes of weld electrodes that are used to apply the pressure and conduct the current.

What welding is used to weld metal pieces?

Arc welding is a fusion welding process used to join metals. An electric arc from an AC or DC power supply creates an intense heat of around 6500°F which melts the metal at the join between two work pieces.