Introduction to 1. Resistance Welding

Resistance welding refers to the use of current through the weldment and the resistance heat generated at the contact as a heat source to locally heat the weldment, while pressurizing the welding method.

Resistance welding is a method in which a metal bond is formed by heating the workpiece to a molten or plastic state by the resistance heating effect generated by the current flowing through the contact surface and adjacent areas of the workpiece.

There are four main resistance welding methods, namely spot welding, seam welding, projection welding, butt welding. In these four methods, resistance welding electrodes are required. Our company specializes in the production of resistance welding electrodes, from powder to tungsten and molybdenum products, tungsten and copper bonding to precision machining products, all produced by our company. Combined with many years engaged in the production and supply of welding electrodes, we have rich experience in how to improve the performance and life of products.

1. Spot welding: It is a high-speed and economical welding method, suitable for spot welding of carbon steel plates and stainless steel plates, high-carbon steel saw blades, iron wire products, wire terminals, auto parts, stainless steel products, low-voltage electrical appliances, hardware Lighting, kitchen utensils, small household appliances, hardware and other industries.

The materials used for spot welding are chromium zirconium copper, aluminum oxide copper and beryllium copper, etc. Our company has precision processing capabilities and can process according to drawings.

In addition, the copper-inlaid tungsten and copper-inlaid molybdenum electrodes produced by our company have remarkable welding performance in welding copper wires, copper braided wires, copper sheets, copper tabs, carbon brush holders, gold wires, copper wires, aluminum foils, etc., with small solder joints, high consistency, and long welding times and long service life.

2, seam welding: seam welding is an extension of spot welding, through the roller electrode pressure weldment and continuous rotation of power transmission, forming a continuous weld. Our company produces seam welding electrodes, including molybdenum alloy and tungsten alloy. In addition, our company also produces parallel sealing welding electrode wheels. This electrode is also called sealing cap electrode and tungsten copper sealing welding electrode, which are mainly used to weld packaging devices, optical devices, sensor devices and MEMS devices.

3, projection welding: projection welding is also a form of spot welding, through the use of parts on the original surface, chamfer, prefabricated convex point will be welded to another piece of larger parts. In addition to the projection welding of plate parts, projection welding also includes projection welding of nut and screw parts, wire cross projection welding, tube projection welding and plate T-shaped projection welding.

In the nut projection welding, usually need to use tungsten copper nut electrode. Our company can provide a variety of end faces such as pure tungsten, pure molybdenum, tungsten copper, etc., and the base material is chromium zirconium copper. Made by back casting, the material life is much longer than the chromium zirconium copper nut electrode cover. Our company provides nut electrodes of different specifications. We can provide tungsten-copper nut electrodes directly backed by drawings, and we can also provide tungsten-molybdenum discs or tungsten-copper discs for brazing to customers.

 

Definition, performance and characteristics of 2. resistance welding electrodes

Resistance welding electrode is a part of resistance welding machine that directly contacts the weldment and transmits current to the weldment, which has an important influence on welding quality and efficiency.

Resistance welding electrodes are usually made of metal materials with good electrical conductivity, such as copper, chromium zirconium copper, and tungsten copper. Its shape and size will be designed and manufactured according to the specific welding process and weldment requirements.

In the process of resistance welding, the electrode generates resistance heat through contact with the surface of the weldment, so that the weldment is locally heated to a molten or plastic state, thereby achieving welding. In order to ensure the welding quality, the electrode needs to have the following characteristics:

1. Good conductivity: to ensure that the current can be evenly passed through the electrode to produce a uniform heating effect.

2. Suitable hardness and wear resistance: It can prolong the service life of the electrode with the pressure and friction in the welding process.

3. High temperature resistance: maintain good performance at high temperature and avoid deformation or melting.

4. Easy to maintain and replace: it is convenient to clean and repair the electrode to ensure the stability of welding quality.

In addition, the surface quality of the electrode will also affect the welding quality. The electrode surface should be smooth and flat, free of dirt, oxide layer or other impurities to ensure good contact with the weldment.

 

Selection of electrode materials for 3. resistance welding

Resistance welding is mainly used for the welding of metal materials. For different metals, the electrode materials used are also different.

Tungsten (W)

1. General composition above 99.95%

2. Is the highest melting point of metal (3410°C)

3. High hardness at room temperature and high temperature

4. Sensitive to mechanical and thermal shock and cracking

5. Low reactivity with other metal components

6. High resistance

Tungsten Properties

Composition (%wt.)	Density (g/cm3)	Hardness (HRC)	Conductivity (%IACS)	Class	RWMA	Advantage
Tungsten content ≥ 99.95	19.3	36	30	13	13.743	High temperature resistance
Cerium Tungsten (CeO2:2%)	19.2	—	—	—	—	Low discharge power, good arcing performance, excellent arc ablation resistance, longer service life
Lanthanum tungsten (La2O3: 1-2%)	19.2	—	—	—	—	Low discharge power, easy to process

Molybdenum (Mo)

General composition above 99.95%

1. Very high melting point (2623°C)

2. Mechanical and thermal shock resistance is stronger than tungsten

3. Compared with tungsten, the hardness at room temperature and high temperature is lower

4. Low reactivity with other metal components

5. Electrical and thermal properties and tungsten equivalent

Molybdenum alloy TZM alloy

An alloy made of titanium, zirconium and molybdenum (0.5% Ti, 0.08% Zr, and 99.4% Mo).

1. High melting point

2. Good chemical resistance

3. Compared with pure molybdenum, higher hardness

4. Good thermal conductivity and resistance

molybdenum lanthanum alloy MoLa alloy

Molybdenum lanthanum alloy (MoLa), also known as high temperature molybdenum, is a molybdenum alloy that is doped with rare earth lanthanum to improve the high temperature performance and other properties of molybdenum.

1. High melting point

2. Enhanced creep resistance

3. Compared with pure molybdenum, the high temperature resistance is improved

4. Better electron emission performance

Molybdenum properties

Composition (%wt.)	Density (g/cm3)	Hardness (HRB)	Conductivity (%IACS)	RWMA	Advantage
Molybdenum content ≥ 99.95	10.2	90	30	14.423	Excellent electrical and thermal conductivity
Titanium-zirconium-molybdenum alloy TZM (Ti: 0.5%, Zr: 0.08%, C: 0.02%)	10.17				High heat and creep resistance
Molybdenum-lanthanum alloy Mola (La2O3: 0.1 -1.8%)	10.19				High heat and creep resistance

Copper Tungsten (CuW)

an alloy made of copper and tungsten.

1. Its performance is between copper alloy and tungsten

2. Moderate hardness at high temperature

3. Better conductivity than tungsten and molybdenum

Tungsten copper material performance

Product Name	Copper content%	Density g/cm3 ≥	Conductivity IACS %≥	Hardness HB Kgf/mm2 ≥
50 Tungsten Copper	50±2.0	11.85	54	115
55 Tungsten Copper	45±2.0	12.3	49	125
60 tungsten copper	40±2.0	12.75	47	140
65 Tungsten Copper	35±2.0	13.3	44	155
70 Tungsten Copper	30±2.0	13.8	42	175
75 Tungsten Copper	25±2.0	14.5	38	195
80 tungsten copper	20±2.0	15.15	34	220
85 Tungsten Copper	15±2.0	15.9	30	240
90 Tungsten Copper	10±2.0	16.75	27	260

Silver-tungsten alloy (AgW)

an alloy made of silver and tungsten.

1. Like copper tungsten alloy, silver tungsten is characterized by medium hardness and conductivity at high temperature

2. For welding stainless steel and/or nickel foil

Product Name	Content (%wt.)	Modelnumber (g/cm³) ≥	Hardness (HRB) ≥	Conductivity (%IACS) ≥
Silver Tungsten 65	Tungsten: 65%, balance silver	14.5	75	48
Silver Tungsten 70	Tungsten: 70%, balance silver	14.9	82	45
Silver Tungsten 75	Tungsten: 75%, balance silver	15.4	86	41

Material matching can ensure good spot welding quality. There are also many kinds of electrode shapes, such as R type, P type, F type and CF type.

 

4.The characteristics of different electrode materials are shown in the following table:

electrode material	Main ingredients	Characteristics	Materials for welding
chrome copper	Cu-Cr	Precipitation hardening alloy, with high thermal and electrical conductivity, is a more economical choice.	Soft steel, steel sheet
chromium zirconium copper	Cu-Cr-Zr	Precipitation hardening alloy, with high heat resistance, hardness higher than chromium copper.	Soft steel, steel sheet
alumina strengthened dispersion copper	Cu-Al2O3	The dispersion hardening alloy is softer than chromium copper, but it will not deform after high temperature.	Steel and steel sheet after surface treatment
Tungsten	W	High melting point material, with high heat resistance, low thermal and electrical conductivity.	Copper
Molybdenum	Mo	Compared with tungsten, the wear resistance is poor, but it is more economical and can be used, and it is easier to process.	Copper
Tungsten Copper	U-W type	In terms of thermal and electrical conductivity, it is between tungsten and chromium copper, not easy to bend, and easy to process.	Depending on the electrode
silver tungsten	Ag-W	In terms of thermal and electrical conductivity, it is similar to tungsten copper and can not be used in the occasion of copper alloy.	Depending on the electrode

Our company has many years of service experience in the field of resistance welding, electrode materials and electrode products are sold to domestic and foreign customers. In line with the rich production experience and service experience, we continue to develop new products and improve the performance of materials, products widely praised by customers.