Welding processes use direct current (dc), alternating current (ac) or pulsed current. Power-Sources are generally classified as constant current, constant voltage and waveform control or pulse welding. That qualifier (constant) must be understood as a useful simplification, not as an absolute value.
What are the factors to be considered when choosing a welding process?
When multiple choices are available to select welding process to accomplish a particular joint it is essential to base the final decision on sound reasoning which generally involves the following considerations: 1. Technical Considerations 2. Production Considerations 3. Economic Considerations. 1. Technical Considerations:
What are the power requirements for arc welding?
Arc welding requires special electric power of low voltage and high current with desirable characteristic to produce and sustain an arc capable of making a good weld. Power sources may be rotating type or static type (transformer or rectifier). Electronic control with feedback (thyristor control) is popular. Output could be AC, DC or both.
What is the best welding process for sheet metal?
Material thickness plays a vital role in selecting a welding process. For example, sheet metal ( < 3 mm in thickness) can be welded best by resistance welding, oxy-fuel gas welding, gas metal arc welding (GMAW), GTAW, flux- cored arc welding (FCAW), laser welding, ultrasonic welding, and low power EBW.
What are the different types of welders?
Most welders can be classified into one of three categories: the do-it-yourselfers (DIY), farmers/ranchers, and general contractor. The following recommendations will help guide your decision and break down welding technology and applications.
What are the factors that must be considered when choosing a welding process?
To evaluate the welding process most appropriate for the job at hand, the following factors would typically be considered:Type of material being welded (see table below)Thickness of the material.The welding position.Type of welding power source and the amount of current available.Time requirements.Working conditions.
What are the three factors to be consider in the selection of electrode?
Base metal thickness, shape and joint fit-up. Welding position.
What four variables can the welder select before welding begins?
VARIABLES IN SMAW (Stick) WELDINGWelding Current.Arc Length.Angle of Electrode.Speed of Travel.Selection of Electrode.
What factors determine the operating parameters of the electrode?
The four important parameters are the welding current, wire electrode extension, welding voltage and arc travel speed. These parameters will affect the weld characteristics to a great extent. Because these factors can be varied over a large range, they are considered the primary adjustments in any welding operation.
Which of the following should be considered when choosing a welding electrode?
What factors should be considered when selecting an electrode size? the skill of the welder, the thickness of the metal and welding codes or standards.
What are the 5 essentials in welding?
ESSENTIALS FOR PROPER WELDING PROCEDURESCorrect electrode size.Correct current.Correct arc length or voltage.Correct travel speed.Correct electrode angle.
What are the 3 types of welding?
There are four main types of welding. MIG – Gas Metal Arc Welding (GMAW), TIG – Gas Tungsten Arc Welding (GTAW), Stick – Shielded Metal Arc Welding (SMAW) and Flux-cored – Flux-cored Arc Welding (FCAW).
What are the 4 things you need before welding?
You should always have the proper safety equipment before you even begin — the most important things that you should have include safety glasses, welding gloves, an auto-darkening helmet (to protect your eyes from the flash), and a fire-resistant jacket.
How do I choose a welding machine?
List of Top 5 Tips to Choose the Best Welding Machine#1)Assess the nature of the metal. Usually, welding is done only on carbon steel. ... #2)Establish the ideal amperage. ... #3)Choose an ideal site for welding. ... #4)Refer to the specs sheet. ... #5)Analyze compressed-gas requirements, if any.
What is the main factor that determines the type of electrode to be used?
The type of electrode used depends on the specific properties required in the weld deposited. These include corrosion resistance, ductility, high tensile strength, the type of base metal to be welded, the position of the weld (flat, horizontal, vertical, or overhead), and the type of current and polarity required.
What factor should be considered when selecting an electrode size?
Electrode size – Electrode size should depend on the electrode type, welding position, joint preparation, base metal thickness, and skill of the welder.
What two factors determine the size of the welding cable?
To choose the right size welding cable you need to know the current levels you'll be working with and the duty cycle for each weld. The more amps you use, or the longer the duty cycle, the bigger welding cable you'll need. Larger welding cable sizes will be less flexible than smaller welding cable sizes.
What is the main factor that determines the type of electrode to be used?
The type of electrode used depends on the specific properties required in the weld deposited. These include corrosion resistance, ductility, high tensile strength, the type of base metal to be welded, the position of the weld (flat, horizontal, vertical, or overhead), and the type of current and polarity required.
Why do we have to consider the type of metal in the selection of electrode?
The first step in choosing an electrode is to determine your base metal composition. Your goal is to match (or closely match) the electrode composition to the base metal type, which will help ensure a strong weld.
How would you select the correct electrode size?
Generally the size of the electrode that should be used depends on the thickness of the part to be welded. For thin metals the electrode is only slightly larger than the metal to be welded. For example if a plate is of 2.0 mm thick the electrode of 2.5 mm should be used.
What factors must be taken into consideration in selecting the correct diameter welding wire?
The primary consideration in choosing welding wire diameter is the thickness of the material being welded. If you select wire that is too small for the material, the welding process is inefficient, costing time and production as the welder has to spend more time completing the weld.
Material being welded
The first consideration when buying a welding machine is the type of material (s) it will be used on. Welders are versatile tools adaptable to many applications, but the type of material being welded is critical to know. weldingnearyou.com can guide you a lot in this case. Metal material that can be welded includes:
Thickness of material being welded
The different materials that can be welded come in a variety of thicknesses. Depending upon the material, the thickness will determine the amount of power required to produce the desired weld. Simply put, the thicker the material, the more voltage and amperage a welder must be able to produce to create a strong, clean weld across the surfaces.
Welding position
The angle at which the weld is being applied is an important factor when deciding on a welding machine’s specifications. Welds laid down on flat, horizontal surfaces are very different than welds on vertical or angled surfaces. Wire flow rates, gas or chemical mixes, and other factors are important to consider when welding positions vary.
Types of Metal Welding Machines
There are three types of metal welding machines. Each is designed and engineered to work on a variety of materials with many optional features available to customize welding methods. Depending upon the type of material being welded, each welding machine has distinct features and benefits that can aid in producing the right results.
Other considerations
There are other considerations to take into account when buying a welding machine. These are the five most important areas to think about:
What are the considerations when multiple choices are available to select welding process to accomplish a particular?
Article shared by : ADVERTISEMENTS: When multiple choices are available to select welding process to accomplish a particular joint it is essential to base the final decision on sound reasoning which generally involves the following considerations: 1. Technical Considerations 2. Production Considerations 3. Economic Considerations.
How does the shape of a component affect the selection of a weld?
The shape and size of a component can affect the selection of a welding process. For example, big sized components or complex shapes are difficult to handle for EBW due to the nature of its operation and the size of the vacuum chamber required. Similarly all shapes cannot be welded by friction welding. Thus, in such cases the selection may be confined to the arc welding processes only.
Why is preheating used in welding?
Preheating is also employed to weld non-ferrous metals of higher thermal conductivities to ensure proper fusion between weld and the parent metal.
Why do welding stations need exhaust systems?
In case excessive smoke is generated in the process it may necessitate the use of more effective ventilation or require the installation of exhaust system for an individual welding station to avoid interference in operations of the surrounding units.
What happens when the thermal conductivity of a material is too low?
If the thermal conductivity of the material is too low, as is the case with stainless steels, it results in excessive accumulation of heat in and around the weld pool resulting in differential heating with consequential development of residual stresses.
Why is position capability not important in welding?
In shop welding, position capability may not be of much importance because the products and assemblies can be turned to the most advantageous position for welding. For field welding particularly of big structures it is not possible to turn them to the best welding position. For example, for fabrication of an oil storage tank it requires to be welded using mainly vertical and horizontal welding positions.
How is structural fabrication accomplished?
Structural fabrications are accomplished by joining many small and even large sized sections and plates to build huge structures. Due to the size and shape of the final structure the welding systems are normally shifted to the job site.
What type of power is needed for arc welding?
Power Sources for Arc Welding Processes: Arc welding requires special electric power of low voltage and high current with desirable characteristic to produce and sustain an arc capable of making a good weld. Power sources may be rotating type or static type (transformer or rectifier). Electronic control with feedback (thyristor control) is popular.
What is the OCV of a power source?
It is the voltage across output terminal of the power source when there is no welding. In case of constant current source, OCV is high and ensures easy arc starting. Higher the OCV, better is the arc stability. IS : 4559 restricts OCV to 100 V to avoid danger of shock to welder.
What is solid state power?
Solid state power sources in comparison to conventional power sources are considered to be more efficient, have fast response characteristics and are must for some special jobs, particularly the applications performed with the aid of robots. In pulsed arc welding, a high power spray of small droplets is produced and this can be directed in any direction.
What is a rule out for a weld?
Weld Specifications. Rule out a process if it does not provide the weld properties specified by the code governing the work.
What to look for when welding a metal joint?
The first thing to look at is whether your weld joint is large or small, whether the joint is out-of-position or not, and whether the base metal is thick or thin.
What is the purpose of penetration in welding?
Penetration varies with the joint. With some joints, penetration must be deep to provide adequate mixing of the weld and base metal and with others it must be limited to prevent burnthrough or cracking.
What are the four terms used to describe the needs of a joint?
In welding, the needs of any joint are expressed in four terms: Fast-Fill (high deposition rate), Fast-Freeze (the joint is out-of-position – overhead or vertical), Fast-Follow (high arc speed and very small welds), and Penetration (the depth the weld penetrates the base metal)
What are the conditions that limit the usefulness of a particular process?
Base-Metal Conditions . Rust, oil, fit-up of the joint, weldability of the steel, and other conditions must be considered. These factors could limit the usefulness of a particular process.
What happens if a process bottlenecks?
Production Bottlenecks. If the process reduces unit fabrication cost, but creates a production bottleneck, its value is lost. Highly complicated equipment that requires frequent servicing by skilled technicians may slow up your actual production thereby diminishing its value.
Should prejudice be included in the selection process?
Human prejudice should not enter the selection process; otherwise objectivity is lost – when all other things are equal, the guiding criterion should be overall cost.