1) Plant Design for Welding Electrode Manufacturing:

WESPEC can design a welding electrode manufacturing plant based on your requirements. This plan will include a detailed calculation of all your requirements for the production of the best quality product. The main topics are as below:

1-Factory design and construction (land and buildings)

2- Power requirements (electrical, gas, water)

3-Determine the machine needed and design of plant lay out.

4- Specify laboratory equipment required or outsourcing.

5-Specify the equipment needed to carry.

6-Man power requirement.

7-Working Capital Management for welding electrode production factory.

Note: If You already have a Welding Electrode Factory, WESPEC can help you Produce a Quality Product Depending on Your Capabilities.

2) Review Relevant Production Standards:

It is necessary to find out what are the standards for determining the quality of a welding electrode. This is because we guarantee the final quality of the product and its compliance with relevant standards.Also By knowing the standard code of the product you intend to produce, the WESPEC will provide an accurate estimate of the raw materials required, the production process, and how to test the final product.

For instance E308L-15 has these relevant standards as follows:

3) Review Relevant Formulation & Specification of Welding Electrode:

The Technical Documents used by WESPEC to produce high-quality welding electrodes are as follows:

• Formula of Dry and Wet Mix: The exact weight of each coating component in the formula, as well as the precise amount of binder.
• Specification of Raw Materials (Powders, Binders, Wire): Detailed technical specifications of each raw material.
  • For powdered materials: chemical analysis, particle size analysis, and other specifications such as density, LOI, etc.
  • For core wire: specifications include chemical analysis and mechanical properties such as tensile strength, yield strength, and elongation, as well as permissible geometric dimensions.
  • For binders: detailed information including chemical analysis of silicate compounds and technical details such as viscosity, Baume, molar ratio, weight ratio, etc.
• Production Instructions: Comprehensive technical information for the production of welding electrodes, including wet and dry mixing times, wet dough specifications, press pressure, electrode geometric dimensions, drying and baking temperatures and times, etc.

WESPEC Customers Receive a Document Entitled “WELDING ELECTRODE PRODUCTION KNOW-HOW”.(Click Here)

3-1) Wire : The exact specifications of the wire include the chemical analysis, with the maximum, minimum, and typical values of each element shown in the specification sheet. The mechanical properties of the coiled wire, with a diameter of 5.5 mm or 6.5 mm, are also mentioned in this specification sheet.

3-2) Powder: Each welding electrode can contain, on average, 10 to 20 types of minerals, chemicals, metals, and ferroalloys. The specification sheet for each powder includes detailed properties such as chemical analysis, sieve analysis, density, and humidity, as shown in the figure.

3-3) Binder: The main task of the binder is to adhere the required powder coating to the wire surface of the welding electrode. This group of materials primarily consists of sodium and potassium silicate compounds. The specification sheet for these raw materials includes precise properties such as chemical analysis, density, viscosity, molar ratio, and Baume, as shown in the figure.

Depending on the situation, this raw material is supplied in three forms: liquid, lump, and powder. In its liquid state, the adhesive is ready for use in the production process, whereas in the lump and powder states, it requires processing before use.

4) Prepare of Raw Material based on spec

WESPEC knows the qualified raw material suppliers for Welding Electrode Manufacturing from around the world. We can help you in purchasing raw materials based on Described Know-How.

5) Qc of Raw Materials for Welding Electrode Manufacturing

It is necessary to test materials before welding electrode manufacturing. All the materials need to be tested and each item of results should compare with its specification range. each number inserted in this sheet will compare with the related specification.

As shown in the image below, a variety of machines are required for testing the quality of raw materials. Each of these machines comes with its own instructions for testing raw materials. Of course, all these tests are necessary when 120 types of electrodes are targeted for production. You can either purchase some of these testing machines and use them within the manufacturing plant or reduce costs by outsourcing the material testing process to approved laboratories.

5-1) Chemical Analysis:

Different methods are available to determine the quantitative and qualitative analysis of the elements and compounds present in the raw materials:

•XRF

•XRD

•Atomic Absorption

•Carbon/Sulphur

•Oxygen/Nitrogen

•ICP

5-2) Grain Size Test (Sieve Analysis):

After the acceptance of chemical properties, another critical parameter that significantly affects the quality of the powder is grain size. Different methods are available to control grain size. For coarse powders, sieve analysis is used, while for fine powders, the laser particle size method is more common. The results are evaluated using the grain size graph.

5-3) Physic-Chemical Tests:

Other parameters that affect the quality of raw materials are as follows

(if needed on the spec sheet)

•Density &Bulk density

•LOI (loss of ignition)

•ASH

•Humidity or moisture (physical water & chemical water)

•Stabilize range (SR)

•Viscosity

•Baume

•Molar ratio

As an example, the moisture parameter of covered electrodes, measured as physical water (water released at 120°C), varies depending on the type of electrode. For basic electrodes like E7018, it should be less than 0.4% wt, whereas for cellulosic electrodes like E6010, it should be more than 4% wt. This parameter is also important for fluxes, which will be described in the relevant section.

In addition, viscosity and Baume are critical parameters for binders.These properties are controlled using specialized equipment.

The stabilization range is another critical parameter for some powders, such as low-carbon ferromanganese. It is measured using specific methods that analyze the amount of gas released and the degree of discoloration.

5-4) Mechanical Tests:

These tests are used to determine the mechanical properties of primary coiled wire. In this test, the initial wire, with a diameter of 5.5 mm or 6.5 mm, is cut into 40 cm lengths and tested using a tensile testing machine. The results of the tensile test provide a reliable measure of the wire’s performance in the drawing and cutting process to achieve the desired diameter and length.

6) Welding Electrode Manufacturing Production Stages:

Read This Article and This to know more about the important parts of the welding electrode production line.

6-1) Drawing, Straightening, and Cutting:

The primary feed for Welding Electrode Manufacturing is metal coils. These coils are mainly produced by the hot rolling method from ingots produced in the steel plant.

Coiled wires have different encodings in standards. These coils are classified into (non-low-medium-high) alloy steel groups as well as stainless and non-ferrous steel such as nickel, aluminum, cobalt, etc.

Coiled wires have different encodings in standards. These coils are classified into (non-low-medium-high) alloy steel groups as well as stainless and non-ferrous steel such as nickel, aluminum, cobalt, etc.

The Carbon Steel SWRY11 wire in the JIS G3503 standard is one of the most widely used wires that can be used in the production of many electrodes, including E6013,E7018,E7024,E6010. Initial coils are usually are in one or two ton weights. The general steps of the Drawing process are illustrated in flowchart.

In recent years, advancements in technology have resulted in drawing machines with various mechanisms that significantly enhance the quality of the final wire. In general, dry drawing is commonly used in electrode production plants. The image below provides an overview of this process. For details on the latest technologies in this field, refer to the Morgan-Koch Company website.

As mentioned in the flowchart, the output of the drawing and cutting process is the core wire used in the manufacturing of covered electrodes. The appearance characteristics of this core wire are critical; if they are not properly maintained, issues may arise during the pressing of the coating onto the wire’s surface. The primary issue is the wire becoming stuck in the transfer nozzle leading to the covering area.

It is crucial that the wire is thoroughly cleaned after the drawing process is complete and cut to the appropriate length. When it comes to cleaning ferrous wires during the wire drawing process, there are a few key methods we use in the industry to ensure a clean, high-quality surface. Each method has its purpose depending on the condition of the wire and the type of contaminants we’re dealing with. Methods such as Acid cleaning, Mechanical Cleaning, and Washing in the Detergent tub, or Ultrasonic Cleaning before or during the process.

As mentioned earlier, the reduction of the wire diameter is achieved using wire drawing machinery. For example, in the SWRY11 wire drawing process to produce E7018 electrodes with a final diameter of 2.5 mm, the desired diameter can be achieved through six steps of drawing. It is also necessary to use different lubricants to reduce die friction with the wire, facilitate the drawing process, and extend the service life of the dies. Sodium and calcium-based lubricants are widely used in wire drawing.

Once the wire reaches the proper diameter, the wire straightening process is performed. The resulting wire must be free of bending and deflection. The final step is to cut the wire to the desired length. Wire lengths are typically 350 mm and 450 mm.

6-2) Dry & Wet-mixing for Preparing The Flux

At this stage, all approved powders in the warehouse are weighed according to the formulation using either a manual or automatic system and then proceed to the dry mixing stage. The wet mixer may be separate from the dry mixer, or a single mixer can be used for both stages.

The duration of the dry mix depends on the type of mixer and the nature of the formulation. For some formula groups, extended mixing times can cause material adhesion, leading to mixing failures. However, for electrode types such as cellulosic electrodes, special attention must be given to the mixing conditions due to the significant physical differences between cellulose powder and metal powders like manganese. This ensures a homogeneously mixed flux.

The wet mix is achieved by adding a precise amount of binder and water to the dry powder mixture. The mixing times for both dry and wet processes are specified in the electrode manufacturing instructions. The output of this stage is a paste-like flux.

6-3) Extruder

Depending on the type of extruder, the mechanism of production at this stage will be as follows:

6-3-1) Vertical extruder

In this machine, the paste enters the cylindrical vertical chamber which will be directed to the extrusion die location. The advantage of this method is that more paste will be used at a single charge of the device, which will speed up production.The problem of this method is that at low rates production.

6-3-2) Horizental extruder:

In this method, the paste from the wet mix is first inserted into the briquetting slug press and then prepared briquette will charged into the horizontal extruder.

The advantage of this method is low rate and higher precision of production and its disadvantage compared to the previous one is low speed production. Because unlike the previous method the briquette making  is also required before the extruder unit.Types of electrode extruder machineries (figure H1).

6-3-3) Mechanism of Cover Pressing on Wire:

In general, the performance of all extruder machines is the same but there are differences between paste feeding.All of these devices are operated by die proportional to the size required, and the force applied to the die in the extruded chamber with outlet nozzle. An overview of this process based on the type of coating. (figure H1-1).

As shown above, there are two types of extruders for Welding Electrode Manufacturing, The mechanism of operation of these two models is the same.at these machines by applying the pressure behind the flux, the coating process is performed on the wire surface.

The difference between the two models is the applied force on the flux. In the screw model, the applied force is low and it is possible to produce simple electrodes like E6013 in high capacity. but in hydraulic system extruders, the applied force on the flux is made by hydraulic force and capable to produce special electrodes. 

The hydraulic extruders are designed in two types: vertical and horizontal .in the vertical model the capacity is more than horizontal type but has some problems in the production of several models of covered electrodes.

In the figures below, the types of horizontal and Vertical hydraulic extruders are shown:

6-4) Centering & Brushing and Printing

After the extrusion process on the wire, the pressing force throws the electrode on the conveyor, running the electrode forward, and first the concentricity of the coating is controlled by the operator with a specific testing machine. The product then enters the tip and nip brushing unit and is then guided to the printing unit.

Usually, at the beginning of the production, the core wire is not located in the center of the coating, and this leads to the production of an electrode that does not have a good welding performance.

In order to adjust the wire to be placed in the center of the coating, the operator needs to adjust the horizontal and vertical axis of the nozzle with a simple but smart method.(this method is described in below picture)

At the end, the electrode is  placed on the carriage for rest and transfer to the furnace or directly into the furnace via the same conveyor.These manufacturing methods will be performed in accordance with their own instructions.

The importance of the physical properties of the electrode such as the concentricity of the wire and the geometry of the electrode tip and nip and the other parameters is very important in the final quality of this product. All of these parameters are listed in the Physical Specifications Sheet of the electrode for each product.(Fig L1)

6-5) Baking

The important issue in the baking of welding electrode is that the importance of uniform baking in all coating distances from the core wire. For example, in the case of incorrect baking, it causes the electrode surface to bake but does not occur in the substrates. Therefore, electrode baking can be similar to baking a cake(figure H15). Each electrode requires a different baking method depending on its nature, actually, it depends on the nature of the coating.

6-6) Packing

After baking, the products will be ready for packaging and delivery to the customer. The electrode packaging will vary depending on their nature. For example, cellulosic electrodes require metal cans that can keep coating moisture.

basic electrodes are packed in completely different conditions in order to prevent moisture penetration, their packs usually are sealed and resistant to any moisture and atmospheric conditions. Another group of electrodes, such as rutile electrodes, are packaged in cardboard cartons and plastic laminates because of the less importance of the moisture problem than basic electrodes. another group of electrodes will vacuum because of the sensitivity of the coating to the impact(Figure N1).

7) Verify the Quality of the Finished Product:

A very important issue in the Welding Electrode Manufacturing process is the quality plan. this instruction involves all steps. This control is performed at all stages before, during and after production Summary of this quality plan is as follows:

The tests used to verify the quality of a product are divided into two groups:

1-Tests defined by standards

2-Tests defined by the manufacturer

7-1) Tests defined by standards:

Valid global standards for each product provide precise definitions of the tests required and the range of accepted results.(see figures below for stainless steel covered electrode E308-L15,defined by AWS standard)

7-2) Tests defined by the manufacture 

Each manufacturer, in addition to trying to get the test results in the standard optimum range, tries to add features to the product as per the customer’s requirements and also design tests based on these features.

The product that is produced is evaluated according to a valid method in order to check the quality of the product before its final use. This concept is called the standard for coated electrodes, which was developed by the leading industrial countries in this field. One of the most reliable standards is the American Welding Society, for example, the AWS A5.1 standard for the E7018 electrode is Published by this institute. Here you can read the complete description of the steps to perform quality tests of this product.

7-3) Final Product Tests:

At this stage it is necessary to perform all tests defined in the relevant standards as well as defined tests in special conditions. Different groups of welding electrodes are classified in many standard systems. Among the most important international standards for different welding electrodes are AWS-ISO-DIN-EN-BS (see figures below) :

7-3-1) Humidiry of Electrode Covering:

The moisture content of the electrode after the final sintering as mentioned above is a very important qualitative parameter. For example, the moisture content of basic electrodes should always be below 0.6%, generally the presence of moisture is harmful, while the cellulosic electrodes require a moisture content above 4%. This item is commonly referred to H2O 120 (physical water that exits at 120 ° C) and H2O 1000 (chemical water which exits at 1000 ° C).

7-3-2) Welding Performance and Visual Test:

This test examines welding in different parameters such as shape of beads, penetration rate, convexity and concavity of weld, slag detachment, porosity, gas holes, undercut, spatter ,etc. The qualitative properties investigated in this test will vary greatly depending on the type of electrode. For example, low spatter and slag separation are important in basic electrodes, whereas in cellulosic electrodes, the penetration rate is much higher and more important. the control properties of welding according to the type of electrode are among the documents of quality control unit. (Figure P1).

7-3-3) Destructive and Non-Destructive Tests:

As mentioned, each electrode has its own quality parameters defined in related standard . The standard also provides definitions of the limits for test results and how to perform.These tests are described below:

7-3-3-1) Destructive test of weld metal:

.Tensile test 

.Impact test 

.Hardness test 

.Bend test 

.Wear test 

.Fatigue test

.CTOD

.Hydrogen tests 

7-3-3-2) Non Destructive test of weld metal:

.VT

.PT

.MT

.UT

.RT (figure S1&S1-1)

7-4) Chemical and phase analysis of weld metal:

.XRF (figure Z1).

.XRD

.CS (Carbon & Sulphur).

.Atomic  Absorption.

.ON (Oxygen & Nitrogen )

.Spectrophotometry (figure Z1)

7-5) Microstructural study tests:

.Microstructural study with light microscope (FIG N20)

.Microstructural study with SEM (FIG N30)

.Microstructural study with TEM (FIG N40)

7-6) Corrosion and erosion tests

these tests are vary and only requires that are defined by the relevant standards or are able to pass these tests as required by the customer.

Note:

Producers do not need to supply all of these testing equipment. they can outsource them to laboratories.

the frequency of sampling, reporting, and refining the results of these tests in the implementation of the quality management system will be fully performed by the WESPEC.

This Article is Written by Milad Bamdad.
Last Update: December,2024 

Contact us for More Information about Welding Electrode Manufacturing:

Email:contact@wespec.net

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