Fundament of MAG Welding

What is MAG Welding

MAG welding is a type of arc welding process that uses a continuously fed consumable wire electrode and an active shielding gas to protect the weld pool from atmospheric contamination. The active gas, typically a mixture of argon, carbon dioxide, and sometimes oxygen, reacts with the molten metal to influence the weld’s mechanical properties and appearance.

Differences Between MAG and MIG Welding

While MAG welding is often confused with Metal Inert Gas (MIG) welding, the key difference lies in the type of shielding gas used. MIG welding employs inert gases like argon or helium, which do not react with the weld pool. In contrast, MAG welding uses active gases that can chemically interact with the molten metal, affecting the weld’s characteristics.

Advantages of MAG Welding

• Versatility: Suitable for welding a wide range of materials, including carbon steel, stainless steel, and some aluminum alloys.
• High Deposition Rates: Allows for faster welding speeds and higher productivity.
• Good Weld Quality: Produces strong, clean welds with minimal spatter.
• Ease of Automation: It can be easily automated and used in robotic welding systems.

Limitations of MAG Welding

• Gas Sensitivity: The choice of shielding gas can significantly impact weld quality, requiring careful selection.
• Equipment Cost: Initial setup costs can be higher compared to other welding processes.
• Skill Requirement: Requires a certain level of skill and experience to achieve optimal results.

Key Knowledge Areas in MAG Welding

Shielding Gases in MAG Welding

The choice of shielding gas is critical in MAG welding, as it directly affects the weld’s mechanical properties, penetration, and appearance. Common shielding gas mixtures include:

• Argon-CO2 Mixtures: Typically 75% argon and 25% CO2, which provides a good balance between weld quality and cost.
• Argon-Oxygen Mixtures: Often used for stainless steel welding, with oxygen content ranging from 1% to 5%.
• Ternary Mixtures: Combinations of argon, CO2, and oxygen, tailored for specific applications and materials.

Electrode Selection

The electrode used in MAG welding is a consumable wire that serves as both the filler material and the conductor for the welding current. Key considerations for electrode selection include:

• Material Compatibility: The electrode material should match or be compatible with the base metal.
• Diameter: Thicker electrodes are used for higher deposition rates, while thinner electrodes are suitable for finer, more precise welds.
• Coating: Some electrodes are coated with copper to improve conductivity and reduce oxidation.
  

Welding Parameters

Several parameters must be carefully controlled to achieve optimal weld quality in MAG welding:

• Voltage and Current: These determine the heat input and arc stability. Higher voltages and currents generally result in deeper penetration but may increase spatter.
• Wire Feed Speed: Controls the rate at which the electrode is fed into the weld pool, affecting deposition rate and weld bead geometry.
• Travel Speed: The speed at which the welding torch moves along the joint. Faster travel speeds can reduce heat input but may lead to insufficient penetration.
• Gas Flow Rate: Ensures adequate shielding of the weld pool. Insufficient gas flow can lead to porosity, while excessive flow can cause turbulence and contamination.

Welding Techniques

Different welding techniques can be employed in MAG welding, depending on the application and desired outcome:

• Short Circuit Transfer: Suitable for thin materials and out-of-position welding, characterized by low heat input and minimal spatter.
• Globular Transfer: Involves larger droplets of molten metal, resulting in higher deposition rates but increased spatter.
• Spray Transfer: Produces a fine spray of molten metal droplets, offering high deposition rates and deep penetration, ideal for thick materials.
• Pulsed Spray Transfer: Combines the benefits of spray transfer with reduced heat input, making it suitable for a wide range of materials and thicknesses.

Joint Design and Preparation

Proper joint design and preparation are essential for achieving strong, defect-free welds:

• Joint Types: Common joint types include butt joints, lap joints, T-joints, and corner joints.
• Edge Preparation: Beveling or chamfering the edges of thicker materials can improve penetration and weld quality.
• Cleaning: Removing rust, oil, and other contaminants from the joint area is crucial to prevent defects like porosity and inclusions.

Safety Considerations

MAG welding involves several safety hazards that must be addressed to protect the welder and ensure a safe working environment:

• Electrical Hazards: Proper grounding and insulation are essential to prevent electric shock.
• Fumes and Gases: Adequate ventilation and respiratory protection are necessary to avoid inhalation of harmful welding fumes and gases.
• UV Radiation: Welding produces intense ultraviolet (UV) radiation, requiring the use of appropriate protective gear, such as welding helmets with UV filters.
• Fire Hazards: Flammable materials should be kept away from the welding area, and fire extinguishers should be readily available.

Applications of MAG Welding

Automotive Industry

MAG welding is widely used in the automotive industry for manufacturing vehicle frames, body panels, and exhaust systems. Its high deposition rates and ability to weld thin materials make it ideal for mass production.

Construction and Infrastructure

In construction, MAG welding is employed for structural steelwork, pipelines, and heavy equipment. Its versatility and ability to produce strong, durable welds are essential for ensuring the integrity of large-scale structures.

Manufacturing and Fabrication

MAG welding is a staple in manufacturing and fabrication shops, where it is used to produce a wide range of products, from machinery components to consumer goods. Its adaptability to different materials and thicknesses makes it a valuable tool for custom fabrication.

Shipbuilding

The shipbuilding industry relies on MAG welding for constructing hulls, decks, and other critical components. The process’s ability to handle thick materials and produce high-quality welds is crucial for ensuring the safety and durability of ships.

Repair and Maintenance

MAG welding is also commonly used for repair and maintenance work, such as fixing cracks, reinforcing structures, and replacing worn-out parts. Its portability and ease of use make it a practical choice for on-site repairs.

Troubleshooting Common Issues in MAG Welding

Porosity

Porosity, or the presence of gas pockets in the weld, can weaken the weld and lead to failure. Common causes include:

• Contaminated Base Metal: Ensure the joint area is clean and free of rust, oil, and other contaminants.
• Inadequate Shielding Gas: Check for proper gas flow rates and ensure there are no leaks in the gas supply system.
• Moisture in the Electrode: Store electrodes in a dry environment and use them within their recommended shelf life.

Spatter

Excessive spatter can lead to a messy weld and increased post-weld cleanup. To reduce spatter:

• Optimize Welding Parameters: Adjust voltage, current, and wire feed speed to achieve a stable arc.
• Use the Correct Shielding Gas: Ensure the gas mixture is appropriate for the material and welding conditions.
• Maintain Proper Contact Tip Distance: Keep the contact tip at the correct distance from the workpiece to ensure consistent arc length.

Lack of Fusion

Lack of fusion occurs when the weld metal does not properly bond with the base metal, resulting in weak joints. To prevent this:

• Ensure Proper Joint Preparation: Bevel or chamfer the edges of thicker materials to improve penetration.
• Adjust Welding Parameters: Increase heat input by adjusting voltage, current, or travel speed.
• Maintain Correct Torch Angle: Keep the welding torch at the appropriate angle to ensure proper heat distribution.

Cracking

Cracking can occur due to excessive stress, improper cooling, or incompatible materials. To minimize cracking:

• Preheat the Base Metal: Preheating can reduce thermal stress and prevent cracking in thick or high-carbon materials.
• Use Low-Hydrogen Electrodes: Low-hydrogen electrodes can reduce the risk of hydrogen-induced cracking.
• Control Cooling Rates: Allow the weld to cool gradually to minimize residual stress.

Innovations in MAG Welding

Pulsed MAG Welding

Pulsed MAG welding is an advanced technique that alternates between high and low current levels, allowing for better control over heat input and weld pool dynamics. This technique is particularly useful for welding thin materials, out-of-position welding, and achieving high-quality welds with minimal spatter.

Double-Wire MAG Welding

Double-wire MAG welding involves using two wire electrodes simultaneously, significantly increasing deposition rates and welding speeds. This technique is ideal for high-productivity applications, such as heavy fabrication and shipbuilding.

Hybrid Laser-MAG Welding

Hybrid laser-MAG welding combines the precision of laser welding with the versatility of MAG welding. This innovative technique offers several advantages, including deep penetration, high welding speeds, and reduced heat input, making it suitable for a wide range of applications, from automotive manufacturing to aerospace.

Automated and Robotic MAG Welding

Automation and robotics have revolutionized MAG welding, enabling consistent, high-quality welds with minimal human intervention. Automated MAG welding systems are widely used in industries such as automotive, aerospace, and heavy manufacturing, where precision and repeatability are critical.

Conclusion

MAG welding is a versatile and efficient welding process that offers numerous benefits for a wide range of applications. By understanding the fundamental concepts, key knowledge areas, and practical techniques outlined in this guide, welders can achieve high-quality results and optimize their welding processes. Whether you are working in the automotive industry, construction, manufacturing, or any other field, mastering MAG welding will enhance your skills and contribute to the success of your projects.

A Welder‘s Guide to Metal Active Gas (MAG) Welding最先出現(xiàn)在SogaWorks。

In this article, I’ll share my thoughts and experiences to help you understand why aluminum stamping is essential in production. In addition, you will also find all the other information you are searching for right here, such as the types, benefits, applications, and common problems of aluminum metal stamping.

Therefore, if you need custom aluminum stamping services, please don’t hesitate and contact us. We are fully prepared to meet all of your stamping requirements with both flexibility and precision.

Definition: What is Aluminum Metal Stamping?

As a metalwork technique, aluminum stamping uses a stamping die and a press to put pressure on an aluminum sheet or bar, which makes it bend and change shape so that the desired final shape and size can be achieved. This manufacturing process is usually carried out in a cold state; hence it is also known as cold stamping. Aluminum metal stamping usually uses the raw material of sheet or strip; hence it is also known as aluminum sheet stamping.

While aluminum sheet metal stamping refers specifically to the process of stamping as applied to aluminum sheet. The term places more emphasis on the fact that the starting material is in the form of a flat sheet.

Types of Metal Stamping Process

Metal stamping refers to a wide range of industrial techniques. You may use these stamping techniques to shape aluminum sheet metal into any shape. The primary processes for stamping aluminum are listed below.

Blanking

The blanking aluminum stamping process involves cutting a section from an aluminum sheet using metal stamping tooling (dies).

Characteristics

• Removes a section of the aluminum sheet to form the desired shape.
• Similar to punching but typically removes a complete part from the sheet.

Applications: Manufacturing of flat parts for automotive, aerospace, and electronics industries.

Piercing

The piercing aluminum metal stamping process uses punches and dies to create holes or notches in aluminum sheets.

Characteristics

• Creates holes or notches.
• A metal sheet is punched to form a shape, often for mounting or assembly purposes.

Applications: Creating holes for fasteners in automotive, appliance, and structural components.

Coining

The coining aluminum stamping is a bending technique where the aluminum sheet is placed between a punch and die, and force is applied to form a shape.

Characteristics

• The aluminum sheet is stamped between punch and die.
• Can form shapes like L, V, or U depending on the requirements.
• Typically used for fine details.

Applications: Precision components in electronics, appliances, or automotive parts.

Deep Drawing

The deep drawing aluminum metal stamping involves pushing aluminum into a cavity to form deep depressions in the material, typically under tensile force.

Characteristics

• Forms deep parts, often used for shaping containers or hollow objects.
• Stretching of the material can be a challenge and must be managed.

Applications: Manufacturing of deep-drawn parts such as cans, containers, or automotive body parts.

Embossing

The embossing aluminum stamping process involves forming a raised or recessed pattern on the aluminum surface by pressing tooling with the desired design.

Characteristics

• Used to create designs or patterns on aluminum surfaces.
• Commonly used for decorative purposes or branding (nameplates).

Application: Decorative components, nameplates, logos, and branding in electronics and signage.

Flanging

The flanging aluminum metal stamping process uses specialized tooling to create flanges or flares on the aluminum surface.

Characteristics

• Creates an outward bend (flare) or inward bend (flange) on the edges of aluminum parts.
• Important for joining or sealing parts together.

Application: Applications requiring joining or sealing, such as ducts, automotive parts, or frames.

Aluminum Alloy for Metal Stamping

Metal stamping employs a wide range of metals and alloys to create high-performance components with remarkable accuracy and repeatability. There are a range of metals suitable for metal stamping process, including aluminum, copper, brass, nickel, titanium, steel, stainless steel, and so on. This part will guide you on why to choose aluminum alloys as the metal stamping materials and take you to have an allover look at the aluminum grades for metal stamping.

The Reason to Choose Aluminum Alloy for Metal Stamping

Choosing the appropriate material is critical to obtaining the intended performance and lifetime of the stamped item. We choose the suitable metal based on the part’s needs, which include strength, durability, and corrosion resistance. Other considerations include the part’s intended application, operational environment, and cost limits. So why do we choose aluminum?

As we all know, aluminum is lightweight but sturdy, corrosion-resistant, and possesses high thermal and electrical conductivity. With these characteristics, aluminum is an ideal material for a wide range of applications, from complex electronic components to durable automotive parts.

Lightweight, yet Strong

Aluminum has an outstanding strength-to-weight ratio, which is one of its most notable characteristics. This means that aluminum components are strong enough to endure significant stress and strain while remaining light enough to contribute to product weight reduction.

This feature is critical in industries such as aerospace and automotive, where weight reduction can contribute to increased performance and fuel efficiency.

Malleable and Formable

Aluminum is highly malleable, which means it can easily form into a variety of shapes without breaking. This feature is very useful in stamping procedures, allowing for the creation of complex parts with detailed designs.

Conductivity

Aluminum is a powerful heat and electricity conductor, making it a suitable material for electrical components and heat exchangers. Aluminum’s use in the food and beverage business stems from its non-toxic properties.

Corrosion Resistance

Aluminum naturally creates a protective oxide covering, making it extremely corrosion resistant. This feature is extremely useful in areas where moisture, chemicals, or salt are prevalent, ensuring the longevity and durability of aluminum parts.

Grades of Aluminum Used for Metal Stamping

There are a lot of aluminum alloy grades suitable for metal stamping. The decision will be based on your individual application requirements. Most aluminum grades are ideal for any metal stamping operation. To comprehend aluminum grades for any metal stamping, please see the table below.

The table above does not suggest that these are the only alloying metals/nonmetals in aluminum grades. Of course, there are more metal elements.

Normally, the “xxx” represent numbers. For example, in the 5xxx family, we may find aluminum 5052, which is suitable for metal stamping.

In general, several aluminum alloys are available for stamping. The specific needs of each application will determine the choice. Let’s look at some common aluminum grades you can use for metal stamping:

Industries Using Aluminum Stamping Parts

Today, tons of industries rely on aluminum-stamping parts for a variety of applications. You can find stamped aluminum parts in many industries, including automotive, aerospace, medical, maritime, lighting, construction, electrical, and electronics.

Aerospace Industry

In aircraft, weight is an important consideration. Aluminum’s lightweight properties, along with its strength, make it suitable for aviation components. Aluminum stamping elements, from the fuselage to the wings and internal mechanics, contribute to a lighter aircraft, improving fuel efficiency and performance.

Automotive Industry

The automotive industry is continually looking for methods to improve efficiency and safety. Automobile frames, panels, and engine components use aluminum-stamped parts.?They give the necessary strength without adding weight, resulting in improved fuel economy and lower emissions. Automotive parts use aluminum stamping to create metal brackets for fender assemblies, door panels, airbags, instruments, and more.

Electronics

Aluminum’s outstanding electrical conductivity and heat dissipation properties make it ideal for electronic components. From electrical device housings to computer heat sinks, aluminum stamping provides performance and longevity in the electronics industry.

Medical equipment

Precision is essential in medical equipment; therefore aluminum stamping is critical. Surgical tools, diagnostic devices, and patient-handling equipment use lightweight, corrosion-resistant aluminum parts where hygiene and dependability are crucial.

Construction and architecture

Builders and architects use aluminum stamping to create components like frames, panels, and structural supports. Its corrosion resistance and visual appeal make it a popular choice for modern architectural designs.

Food and beverage industry

Aluminum’s non-toxic properties and corrosion resistance make it ideal for food and beverage containers and equipment. Its capacity to retain warmth is also useful in cooking and storage applications.

Conclusion

Aluminum stamping is a versatile metal production technology that incorporates numerous operations and techniques. The finest thing is that you may produce hundreds of parts based on your production requirements.

For firms and manufacturers trying to stay ahead, adopting aluminum metal stamping is a wise decision. If you’re ready to explore the possibilities that aluminum stamping has to offer, now is the time to take action. SogaWorks, as one of the most reliable aluminum stamping parts manufacturers, will assist you in achieving high-quality, precision-stamped aluminum components. Please contact us if you have any questions.

Aluminum Metal Stamping: Types, Process, Applications, and Industries最先出現(xiàn)在SogaWorks。

This paper discusses the different types of tolerances with a focus on classification and specific uses in engineering.

What is Tolerance in Engineering?

Tolerance is the allowed deviation of the actual size, shape, or position of a part from its ideal size, shape, or position. In the process of manufacture, because of such factors as machine accuracy and operation procedure, the actual size of the part cannot completely meet the design requirement. In that case, A range of deviation is allowed to ensure good functionality and interchangeability of parts. The tolerance value is equal to the difference between the upper and lower allowable values.

Let’s take an example to illustrate what tolerance is. Suppose you are processing a metal round bar with a length of 100mm. Even if you intend to process all of them into the same shape, it is impossible to process all of the metal bars into exactly 100mm because of deviations in size and shape. Although designers and manufacturers have been working to reduce such deviations, they still cannot reduce the deviations to zero.

Such deviations in size and shape basically fluctuate up and down around the target value. Therefore, depending on the use of the metal bar, the upper limit allowable value (+1mm) and the lower limit allowable value (-1mm) allowed relative to the target size are determined. The difference between these two values (2mm) is called tolerance.

Types of Tolerance

There are 4 types of tolerances: Dimensional tolerance, geometric tolerance, and fit tolerance. Each type of tolerance focuses on different aspects of a part to ensure that the part has the appropriate functionality in different working environments.

Dimensional Tolerance

Dimensional tolerance refers to the tolerance applied to the dimensions marked in the drawing, dimensional objects such as length, distance, position, angle, size, aperture, fillet and chamfer, etc. It is used to indicate tolerances different from general tolerances. Unlike general tolerances, dimensional tolerances have no clear standards and can be arbitrarily specified according to the designer’s intention, but the range of achievable tolerances is limited depending on the processing method, etc. Dimensional tolerances include 2 types, bilateral tolerances and unilateral tolerances.

Bilateral tolerance

Bilateral tolerance refers to the allowable variation of a dimension that exists within a specified range on either side of the reference dimension. In other words, the dimension may vary in both the upper and lower directions relative to the reference dimension.

Example of bilateral tolerance: If the basic size of a hole is 10mm and the bilateral tolerance is ±0.05mm, then the actual dimension range of the shaft is 9.95mm to 10.05mm.

Unilateral tolerance

Unilateral tolerance, however, refers to the allowed variation of a dimension to be on only one side of the basic dimension; that is, the acceptable tolerance range is limited to one direction.

Example of unilateral tolerance: If the basic size of a hole is 10 mm and the unilateral tolerance is +0.05mm, then the actual size range of the hole is from 10.00 mm to 10.05mm.

Geometric Tolerance

Geometric tolerance not only addresses the dimensions of the component but also delineates the precision concerning the shape, position, and orientation of the part. It guarantees the fidelity of the geometric configuration stipulated in the design of the component and is typically implemented with attributes such as straightness, flatness, roundness, and positional accuracy. The primary purpose of geometric tolerance is to maintain the precision of both the shape and position, thereby preventing issues related to improper fitting of the components.

Geometric tolerances can be divided into four categories: form tolerance, orientation tolerance, location tolerance, and runout tolerance, which in total consists of 13 types.

Linearity

Linearity is the allowable deviation from a straight line over a specified length or surface. It is used to define how much a feature of a part can vary from being perfectly linear.

Example of linearity: In a given plane, the line segments to be inspected shall lie between two parallel lines at a distance of 0.1mm.

Flatness

Flatness is a geometrical condition that defines the deviation of a surface from an ideal plane. It provides a metric of how much the surface deviates from ideal flatness, and thus it represents the homogeneity of a surface over its whole area.

Example of flatness: This surface shall be between two parallel planes separated by only 0.3 mm.

Roundness

Roundness, also commonly called circularity, is the geometric condition that defines the extent to which the form of a feature, such as a cylinder, hole, or sphere, departs from a perfect circle in any given cross-section.

Example of roundness: The outer circumference of any cross-section of a shaft cut perpendicularly shall fall between two concentric circles just 0.1mm apart on the same plane.

Cylindricity

Cylindricity is a geometrical condition that measures the extent to which the form of a cylindrical feature conforms to that of an ideal cylinder. It measures the uniformity of the surface both along the length and around the circumference of the cylinder.

Example of cylindricity: The target plane has to be in between two coaxial cylinders only 0.1 mm apart.

Profile of line

The profile of a line is the condition required to retain the perfect form of a curve of any shape on a prescribed plane of a part. Profile tolerance of a line The allowable deviation of the actual contour line of a non-circular curve.

Example of profile tolerance of a line: The projected profile on any cross-section parallel to the projection plane shall lie between the two envelopes created by a circle of diameter 0.03 mm, centered on the line that has a theoretically exact profile.

Profile of plane

Profile of a plane is the condition of maintaining the ideal shape of any curved surface on a particular part. The profile tolerance of a plane is the permissible variation of the actual contour line of a non-circular curved surface from the ideal contour surface.

Example of profile tolerance of a plane: The destination plane should lie between two envelope planes created by a sphere with a diameter of 0.1 mm, whose center is on the plane having a theoretically perfect profile.

Parallelism

Parallelism is the acceptable variation (deviation) of a feature (e.g., surface, axis or line) with regards to being parallel from a designated reference (e.g. a datum plane, axis, or line). Whilst, it looks like flatness has been discussed again, parallelism involves datum(reference plane or line).

Example of parallelism: The plane identified by the indication arrow must be parallel to datum plane A and lie between two planes that are only 0.05 mm apart in the direction of the indication arrows.

Perpendicularity

Perpendicularity is a geometric condition that assesses the degree to which a feature, such as a surface, axis, or line, aligns at a right angle (90°) to a reference feature, which may include a plane or axis.

Example of perpendicularity: The plane represented by the indicating arrow shall be located between two parallel planes that are perpendicular to datum plane A, with a diameter of 0.03 mm.

Angularity

Angularity is a geometric condition that measures the amount that a feature, such as a surface, line, or axis, is oriented at an assigned angle, other than 90° (perpendicularity) or 0° (parallelism), with respect to a reference datum.

Example of angularity: The plane indicated by the indication arrow shall be theoretically exactly angled by 45 degrees to the datum plane A and between two parallel planes only 0.3 mm apart in the direction of the indication arrows.

Position

Position is used to find the exact location of a component’s point, line, and surface relative to a reference.

Example of position: The center of the circle shown by the indication arrow shall be within a circle having a diameter of 0.1 mm.

Coaxiality

Coaxiality ensures that the axis of a cylindrical feature, such as a shaft, hole, or tube, coincides exactly with the axis of a reference datum.

Example of coaxiality: The axis of the given cylinder shall lie within a cylinder that uses datum axis line A as its axis and has a diameter of 0.03 mm.

Symmetry

Symmetry measures the evenness with which a feature, or set of features, is distributed about a central reference axis, plane, or point.

Example of symmetry: The center plane marked shall be between two parallel planes symmetric to datum center plane A and separated from each other by 0.05 mm.

Runout

Runout measures the total deviation of a feature’s surface when it rotates about a reference axis. There are two kinds of runout: circular runout and total runout.

Circular runout: This is a measurement of how much the surface of a rotating part varies at a given cross-section or plane perpendicular to the axis of rotation.

Total runout: This is the measurement of the variation existing on the whole surface of a rotating component down its longitudinal axis. It combines the effects of circular runout with those caused by straightness or taper irregularities.

Fit Tolerance

Fits are the relationships between the tolerance zone of pairing holes and shafts at the same basic size. Or we can say that fits are the clearance between the hole and shaft pairing. The clearance can be both positive and negative. The size of the clearance determines whether the two paired parts can move or rotate independently of each other or, are temporarily or permanently connected.

There are three types of fits: clearance fit, transition fit, and press fit(interference fit).

Clearance fit: The tolerance zone of the hole is above that of the shaft, in other words, the hole is larger than the shaft.

Press fit: The tolerance zone of the hole is below that of the shaft, in other words, the shaft is larger than the hole.

Transition fit: The tolerance zones of the hole and shaft overlap. Any pair of holes and shafts may achieve a clearance or a press fit.

For PDF of types of tolerance, Click Here to Download >>

Conclusion

Engineering tolerances have a fundamental place in design and manufacturing, as only high-quality parts are supposed to be produced. Parts that can be assembled at the right precision and function properly, even after certain variations inherent in any manufacturing, must be achieved. Tolerances contribute to product consistency and reliability by defining the allowable variations in size and form. Understanding the different types of tolerances—dimensional, geometric, and fit—is very important for an engineer or manufacturer to be able to set proper tolerance levels for the various components, given the functional requirements of the final product. Be it the precision of aerospace components or the fitment of automotive parts, mastering the application of tolerances forms an integral part of proficient engineering and superior manufacturing.

What are Engineering Tolerances and How are They Classified?最先出現(xiàn)在SogaWorks。

What is Passivation?

Passivation is a process that uses a strong oxidizing agent to create a dense, protective oxide layer on a metal’s surface. In stainless steel, passivation involves using an acidic solution to remove surface iron and other contaminants. This treatment forms a thicker layer of chromium oxide, which greatly improves the stainless steel’s resistance to corrosion.

History of Passivation

In the 1800s, the chemist Christian Friedrich Sch?nbein discovered the effects of passivation on metals. He immersed iron in concentrated nitric acid and compared it to iron that had not been treated. The treated iron was virtually chemically unreactive compared to the untreated iron.

As welding and passivation of stainless steel became more popular, the environmental and safety impacts of using nitric acid became more apparent.19 In the early 1900s, a German brewing company found citric acid to be a safer, non-toxic alternative to passivation. In 1990, citric acid had replaced nitric acid in many applications in large quantities. Today, both acids are used in modern passivation processes.

What Does Weld Passivation Do？

Stainless steel is primarily made of iron, chromium, and nickel. Chromium provides its corrosion resistance: when chromium is exposed to oxygen, it forms a thin layer of chromium oxide on the stainless steel’s surface, protecting the iron underneath from rust. During welding, however, localized heating can damage this protective oxide layer, making the weld area more susceptible to contamination. Without passivation, environmental contaminants, like chlorides, can react with exposed iron on the surface and initiate corrosion. Once corrosion begins, it can spread through the weld area and into the entire component.

Passivation helps slow or prevent corrosion in 2 ways. First, It allows iron and iron oxides to dissolve more readily than chromium and its oxides, this process removes the iron-rich layer and increases chromium concentration at the surface. Second, Passivation enhances the oxidation process of chromium to form a thicker inert oxide layer, which protects the underlying metal from environmental contaminants.

After fabrication and welding, passivation is the next critical step for stainless steel parts. Key benefits of weld passivation include:

• Removing contaminants from the weld surface
• Extending the lifespan of both the weld and the entire component
• Forming a protective chemical barrier against rust and corrosion

Weld Passivation Methods

Weld passivation can be divided into several types according to their operations.

Pickling paste

Pickling passivation paste is a viscous liquid (gel), which is mainly made of nitric acid, hydrofluoric acid, corrosion inhibitor, thickener, etc. in a certain proportion. It is applied to the weld seam and washed off after about 30 to 60 minutes.

Washing off the paste is particularly challenging, as the resulting wastewater is highly polluting and cannot be directly washed down the drain. Instead, the wastewater must be carefully collected and taken to a disposal facility. Over the years, the harmful effects of pickling paste have drawn increasing attention from workplace safety authorities, leading to stricter regulations around its use. While pickling paste does create a corrosion-resistant weld seam, it leaves a matte appearance on treated areas, often requiring an additional polishing process, which adds time to the process. Although pickling paste is widely used, we anticipate that modern, safer alternatives, such as electrochemical weld cleaning, will become more prominent—a shift that benefits both human health and the environment.

Dip and spray pickling

Dip pickling and passivation involve dipping the whole piece into a bath with pickling fluid. The items will get a nice, evenly pickled surface on both their internal and external surfaces. Since the items are completely immersed, this method is highly effective with tubes and workpieces with narrow areas and corners that are difficult to reach manually.

Spray pickling is advantageous for very large items, as the pickling fluid is sprayed onto the surface and rinsed off, usually after 30-60 minutes. Due to the environmental laws and safety requirements, spray pickling is performed by professionals who collect and dispose of the acids and wastewater.

Spray pickling is often used if the item is too big for dip pickling. It can also be performed with a mobile pickling plant, where a professional will spray pickle the item on-site if it is too complicated to move.

Electrochemical weld passivation

Electrochemical weld cleaning and passivation is a highly effective way of removing oxides from stainless steel welds. The method combines phosphorus-based acids and electricity in a process that results in instantaneous cleaning and passivation.

Phosphoric acids are non-toxic and can be found in fizzy drinks and common household cleaning items – and are not even remotely as harmful as the pickling paste. There is no need to clean the surface with water which makes your process much simpler – you will avoid all the hassle with wastewater disposal.

Process of Weld Passivation

Taking the weld passivation of stainless steel 304 as an example, the main operation steps are:

1. Pretreatment

Before pickling and passivation treatment, the surface of 304 stainless steel needs to be pretreated. The pretreatment methods include degreasing and cleaning, etc., and the purpose is to remove the residual grease and contaminants on the surface.

2. Passivation

Put the 304 stainless steel in the pickling agent and soak it. The pickling agent will dissolve the surface oxide scale and weld spot. The pickling time needs to be determined according to the actual situation, generally controlled between 5-30 minutes.

Or, apply passivation paste to the weld and let it stand for 15 minutes to 60 minutes;

3. Neutralization

Use an alkali solution to neutralize the acidic passivation liquid remaining on the surface to avoid corrosion caused by acid residues and damage to the passivation film. For parts with complex structures such as fine seams, 5% sodium hydroxide can be used for neutralization.

4. Drying

According to the conditions, use methods like wiping or blowing to make the parts dry.

When to Consider Weld Passivation

After welding, cutting, and any other CNC machining operations are done, the passivation process can begin. Stainless steel is inherently corrosion and rust-resistant, but several different processes can introduce potential contaminants that will inhibit the formation of the protective oxide layer during the manufacturing process. This is the time to introduce passivation to improve the corrosion resistance of the weld area.

Some of the factors that may inhibit oxide film formation and reduce the corrosion resistance of stainless steel parts include:

• Foreign matter such as dirt, dust, oil, swarf, and coating materials.
• Different sulfides are added to stainless steel to make it more machine-friendly.
• Iron chips can be embedded in stainless steel from blades, discs, and other cutting tools during the cutting process.

If stainless steel parts are painted or powder coated, passivation is not necessary.

Quality Testing of Weld Passivation

There are several methods for testing the effectiveness of passivation, but it’s important to note that not all methods are suitable for every stainless steel grade. Various testing methods are outlined in ASTM International standards, including:

• ASTM A380: This standard describes best practices for cleaning, descaling, and passivating stainless steel parts, equipment, and systems.
• ASTM A967: This standard details passivation test methods and acceptance criteria, as well as procedures to ensure effective passivation.
• Water immersion test: In this test, the passivated component is submerged in distilled water to detect impurities, such as free iron, on the anode surface.
• Salt spray test: This test evaluates the corrosion resistance of stainless steel by placing the specimen in a salt spray chamber filled with 5% sodium chloride (NaCl) solution at a temperature of 95°F.
• High humidity test: This test requires specialized laboratory equipment, including a humidity chamber maintained at 97% (±3%) humidity and a temperature of 100°F (±5°F) for a minimum of 24 hours. The test piece must be immersed in acetone or methanol and then dried in an inert atmosphere or dehydrating container.
• Blue point test: Prepare a solution by mixing 1 gram of potassium ferrocyanide (K?Fe(CN)?) with 3 ml of nitric acid (65%–85%) and 100 ml of water (preferably prepared on-site). Soak filter paper in this solution and apply it to the surface to be tested, or drop the solution directly onto the surface. Observe the surface condition within 30 seconds; if no blue precipitate appears, the treatment is deemed successful. Rinse the test solution off after the assessment.

Conclusion

Weld passivation is an essential process that is used to enhance the corrosion resistance of stainless steel after welding, and this process ensures their longevity and reliability in various applications. As industry standards evolve, safer alternatives like electrochemical cleaning are becoming increasingly popular, providing environmentally friendly options compared to traditional pickling methods.

Weld Passivation: Enhancing Corrosion Resistance in Stainless Steel Welding最先出現(xiàn)在SogaWorks。

This article will discuss what laser cutting is, how it works, its advantages and disadvantages, and its applications.

What is a laser cutter?

Laser cutting is one of the thermal cutting processes. It employs a focused high-energy laser beam to irradiate and heat the blank piece and makes the heated materials quickly melt or vaporize, and then shapes them into the desired geometry by movement of the beam.

An almost parallel laser beam is generated in the laser source; a mirror is used to direct the laser beam towards the cutting head; and a lens is used at the cutting head to focus the laser beam. The focused, high-energy laser beam shines on the surface of the workpiece, rapidly heating the workpiece and melting the material. Auxiliary gas is used to protect and cool the focusing lens and clear molten metal.

Types of laser cutter

Laser cutting machines can divided into 3 types by the lasers they employ：

• Fiber laser cutter: The fiber laser machine converts electricity into light through the SPI/IPG laser, and then irradiates the high-energy laser beam onto the surface of the blank piece through the cutting head, vaporizing the irradiated material instantly. A fiber laser cutter is mainly used for metals like stainless steel, carbon steel and aluminum alloys.
• CO2 laser cutter: The CO2 laser cutter uses CO2-based gas to generate a laser beam to cut or engrave materials. In this cutting process, auxiliary gas such as oxygen or argon is used to increase cutting speed and clean the material surface. The CO2 laser cutter is mainly used for non-metal materials like plastics and glasses.
• Crystal laser cutter: Crystal laser cutting machines use Nd: YAG (neodymium-doped yttrium aluminum garnet) and Nd: YVO (neodymium-doped yttrium vanadate), usually the former is more commonly used, to generate laser beams to cut and engrave materials.

Summary of the different laser cutter

How does a laser cutter work?

The Laser cutter uses a high-energy laser beam to molten or evaporate the material, thereby cutting and shaping the parts. Its workflow can be summarized into 4 parts:

1. Generate a laser: A laser beam is generated by a laser generator, this is a process like turning on a flashlight.
2. Enables the laser to be focused: The laser light passes through a series of optical elements, such as lenses and mirrors, which focus it onto a very small spot with extremely high energy density.
3. Cut the material: The focused laser beam hits the surface of the material, which is melted or vaporized by the laser, creating a small hole. The laser cutter moves along a planned path to shape the desired geometry.
4. Blow away the extra material: The laser cutter often uses something called an “auxiliary gas”, such as oxygen or nitrogen, to blow away any extra material in the cutting area, keeping it clean and helping to speed up the cutting process.

Suitable Materials

The compatibility of a material with laser cutting methods depends on its physical and chemical properties. Materials with low reflectivity, thermal conductivity and chemical stability can be processed using laser cutting. The common types of materials for laser cutting include metals, plastics, and wood.

Metals

Metals are the common materials used in laser cutting. Since metal materials have a high absorption rate of laser beams, high-quality cutting results can be achieved. Laser cutting of metal materials has the advantages of fast speed, high precision, and small heat-affected zone, and is widely used in automobile manufacturing, machinery manufacturing, aerospace and other fields. the common metals for laser cutting include:

• Aluminum: Such as 5052, 5074.
• Stainless steel: Such as 304, 316L
• Copper: such as C110
• Carbon steel
• Titanium

Plastics

Not all plastics are suitable for laser cutting processes. The plastic needs to be able to absorb laser energy without excessive melting or harmful emissions. The common plastics for laser cutting include:

• Acrylic
• PEEK
• Nylon
• PE

Wood

Laser cutting is ideal for prototyping with wood and creating complex furniture parts and artistic designs. It has a very small kerf (kerf width).

Different materials react differently to laser cutting, and understanding the suitability of a material helps us choose the right cutting machine.

Inappropriate materials

As mentioned above, some materials are difficult to use for laser cutting if they have all or one of the following characteristics, including high reflectivity, easy combustion, and toxic emissions. Some inappropriate materials include:

• Carbon fiber
• ABS
• PVC
• PTFE
• HDPE
• Fiberglass
• PC
• PP

Advantages

The advantages of laser cutting technology are obvious. Some of these advantages are discussed below:

High precision and accuracy

The accuracy of laser cutting depends not only on the laser itself but also on the accuracy of the motion system. Typical tolerances for laser cutting range from 0.003mm to 0.006mm, other cutting tools tolerance levels range from 1mm to 3 mm or even higher.

Modern high-end laser cutting machines use linear motors and optical scales to achieve a positioning accuracy of ±0.001mm in some cases.

Contact-free processing

Laser cutting is a contact-free process, which means there is no physical contact between the cutting tool and the material. This reduces wear on the cutting equipment and reduces the risk of contamination. The result is cleaner, with minimal material deformation. Due to its non-contact nature, laser cutting can process fragile or easily deformed materials.

Fast cutting speed

For example, with 2KW laser power, the cutting speed of 8mm thick carbon steel is 1.6m/min; the cutting speed of 2mm thick stainless steel is 3.5m/min, with a small heat-affected zone and minimal deformation.

Wide range of cutting materials

Compared with oxyacetylene cutting and plasma cutting, laser cutting can cut a variety of materials, including metals, non-metals, composite materials, leather, wood, fiber, etc. However, different materials have different laser cutting compatibility due to their thermophysical properties and laser absorption rates.

Disadvantage

Limited by the power of the laser and the size of the equipment, laser cutting can only cut small to medium thickness plates and tubes.

As the thickness of the material increases, the cutting speed decreases significantly.

Laser cutting equipment is expensive and requires a large one-time investment.

Applications

Since laser cutting has some unmatched advantages over other processes, such as high precision and short processing time, it is widely used in many industries.

Outdoor advertising

In the outdoor advertising industry, metal materials are frequently used. The use of laser cutting to process metal materials, and fonts can improve the visual effect of advertising materials, and improve the efficiency of production and processing so that the advertising company to increase profits.

Sheet metal fabrication

Due to its high level of flexibility, fast cutting speed, high cutting efficiency and short working cycle, laser cutting has made it highly favored in the sheet metal fabrication industry. Laser cutting requires no cutting force and there is no tool wear, in addition, the laser cutting slit is usually narrower and has a high level of automation.

Automotive

In the automotive industry, some accessories such as car doors and exhaust pipes will have some extra corners or burrs after processing. If they are processed manually or in traditional ways, it is difficult to ensure accuracy and efficiency. Using a laser cutting machine can easily solve the corner and burr problems in batches.

Kitchen utensils

In the kitchenware industry, range hoods and gas appliances usually use a large number of sheet metal panels. Traditional processing methods have the disadvantages of low work efficiency and high mold consumption, which not only consumes a lot of resources but also restricts the development of new products. Using laser cutting machines to process kitchenware products has extremely fast cutting speed and high cutting accuracy, which can improve processing efficiency and effectively improve the yield rate of range hoods and gas appliances.

Fitness equipment

Fitness equipment is mainly made of pipes. The use of laser cutting machines can quickly process pipes and complete the production and assembly of fitness equipment more quickly.

Laser cutting design guidelines

Keeping these design tips in mind can help you achieve better laser cutting results and save costs.

What is The Laser Cutter: Basic Explained最先出現(xiàn)在SogaWorks。

Bending is a process used to deform metal using force and bend it in the desired direction to create a specific shape. It is done using rolling machines and press brakes. There are several types of rolling machines, and they can roll sheet metal into different shapes within certain ranges.

There are various sheet bending methods:

• V-bending: This is where the bending tool provides the force needed to bend the metal material (placed on top of the V-die) at the desired angles. This technique can bend steel plates with no change in their positions.
• Roll bending: This technique bends steel sheets into curved forms or rolls. It employs the press brake and a hydraulic press and three rollers to achieve that desired curve. It is ideal for cones, tubes and other hollow-shaped materials.
• U-bending: This process of bending is similar to the v-bending. The only difference is that it utilizes an U-die and the final parts are U-shaped.
• Rotary bending: This technique bends metals to create sharp edges. It is an excellent option for bend angles that are greater than 90°.
• Wipe bending: It uses a die to measure the radius of the sheet’s bend.

Bending is best for materials that are malleable, but not hard or brittle. It is a good choice for spring and mild steels, aluminum 5052 and copper.

Sheet Metal Bending Design Guidelines

In order to achieve better manufacturing results, You should consider the following factors when designing sheet metal parts.

Tolerance

Sheet metal fabrication tolerances refer to the acceptable deviations of sheet metal part features required for accurate and consistent installation and integration.

For sheet metal parts, we use ISO 2768-c to ensure that geometric and dimensional elements are properly controlled.

Bending Radius

The minimum bend radius can vary depending on the materials. When the radius is less than recommended, it can lead to material flow in soft material and fracturing in hard material. To ensure bending strength, the bending radius of sheet metal should be greater than the minimum bending radius of the material. the following table shows the minimum bending radius of various sheet metal materials. t represents the thickness of sheet metal.

The standards of each manufacturer may be different. It is recommended that the standard be reasonably chosen based on the actual situation.

Bending Height

The bending height should be at least twice the thickness of the sheet metal plus the bending radius, that is, H ≥ 2T + R. If the bending height is too small, the sheet metal will easily deform during bending, and it will be difficult to get the ideal shape and dimensional accuracy.

Bending Allowance

If you are bent sheet steel the neutral axis is shifted toward the inner surface that is bent. The K-factor represents the relationship between the location of the neutral axis (t) about the thickness of the material (MT) which is used to determine your bend’s allowance(K-factor= t/MT). The ideal K-factor ranges from 0.3mm to 0.5mm.

Bending Relief

When a bend is too close to the surface on the adjacent edge, the material tends to break. To avoid tearing, bend relief should be cut in the component. The length of the relief must be larger than the radius of the bend, and the width should be at least equal to the material’s thickness.

Curl Features

Curling is the process of adding a hollow circular roll on the edge of a sheet. Curls are generally employed to eliminate sharp edge and ensure that they are safe to handle. It is suggested that:

• The outside radius of a curl should be at least 2x the thickness of the material.
• The size of the hole must be at minimum equal to the curl’s radius plus the thickness of the material derived from the curly feature.
• A bend must be at least equal to the diameter of the curl plus 6 times the thickness of the material of the curl feature.

Hems Features

Hems are folds that are re-attached to the metal, made into the shape of a U shape. Hem features are typically utilized to give strength to the piece and also to join parts. The three major kinds of hems that industrial and design professionals should be aware of include open Hem, closed, as well as teardrop-shaped hem.

• Closed hem: Closed hem is closed tightly with no gaps. The inner diameter should be equal to the thickness of the material(D=T), and the length of the return hem should be at least 6x the thickness of the material(H ≥ 6T).
• Open hem: This hem has a small gap or space that leaves the fold open. The recommended return length should be at least 4x the thickness of the material(H ≥ 4T).
• Tear drop hem: This kind of hem is an elongated teardrop. The inside diameter must be at least equal to the thickness of the material(D=T) and a return length of at least 4x the thickness(H ≥ 4T).

Holes & Slots

Holes or slots placed near bends tend to deform during the bending. To ensure a successful bending result, it is suggested to keep holes from bends by at minimum 2.5x the thickness of the material (T) plus the bend radius (R). When using slots for bending, it’s suggested to place it at least 4x the thickness of the material plus the bend radius away from the bend.

Slots and holes that are too close to the edge of the part can cause an issue related to bulging. It is suggested to leave a gap of at least 2x the thickness of the sheet between the extruded holes and part edge.

Start Your Sheet Metal Projects

At SogaWorks, we offer high-precision, fast, and quality sheet metal fabrication, forming and bending, services for the creation of sheet metal parts made of aluminum, stainless steel, steel, copper alloys, and many others. To get an instant quote, upload your models on our instant quoting platform.

Design Guide For Sheet Metal Bending最先出現(xiàn)在SogaWorks。