How to Assemble Sheet Metal Parts? Exploring 8 Methods

Welcome to this comprehensive guide on sheet metal parts assembly. This blog post aims to delve into the intriguing world of sheet metal assembly, revealing essential techniques and tips that will help improve the efficiency and quality of your assembly process.

What is Sheet Metal Parts?

The term ‘sheet metal parts‘ refers to a vast category of parts made from different types of metal sheets. It’s a phrase you might have come across in various industrial scenarios, but what exactly does it mean? Simply put, a sheet metal part is a component that has been fabricated from a sheet of metal. These sheets are often thin and flat, making them highly flexible for forming into a wide range of shapes.

Sheet metal parts can be manufactured from several different metals including, but not limited to, aluminum, stainless steel, bronze, steel, brass, and copper.

The Basics of Assembling Sheet Metal Parts

Assembling sheet metal parts requires careful planning, precision, and the right techniques.

Firstly, you must have a clear understanding of the design requirements for the assembly parts. This includes the specific dimensions, tolerances, and function of the final assembly. Sheet metal part drawings are essential tools used to detail these requirements, guiding the assembly process and ensuring the parts fit together as designed.

Secondly, the type of sheet metal parts being assembled and their material properties will significantly influence the assembly process. Automotive sheet metal parts, for instance, might require different assembly methods compared to parts used in the electronics or construction industry. Heat shield sheet metal, commonly used in automotive and aerospace applications, may require high-temperature resistant fastening methods.

Fastening methods for sheet metal range from traditional methods like welding, riveting, and screwing to modern techniques such as adhesive bonding. The choice of method depends on several factors such as the type of materials being joined, the desired strength of the joint, the production volume, and cost considerations.

8 Methods to Assemble Sheet Metal Parts

1. Welding

Welding is a popular technique for the assembly of sheet metal parts. The process involves the use of heat to melt the metal parts being joined. A filler material is often added to the joint to form a pool of molten material (the weld pool) that cools to become a strong, permanent bond. When it comes to fastening methods for sheet metal, welding offers robustness and durability that are essential in many industries, including automotive, construction, and aerospace.

There are various types of welding techniques, each with its unique benefits and best use scenarios:

MIG Welding (Metal Inert Gas): MIG welding, or Gas Metal Arc Welding (GMAW), is a common method used for welding sheet metal parts. It involves the use of a continuously-fed electrode wire and an inert shielding gas to protect the weld pool from contamination. This method is well suited for long production runs and is effective with a wide range of metals.
TIG Welding (Tungsten Inert Gas): TIG welding, or Gas Tungsten Arc Welding (GTAW), utilizes a non-consumable tungsten electrode and inert shielding gas. Known for its precision, TIG welding is an excellent choice for detailed work or sheet metal parts requiring a high-quality finish.
Spot Welding: Spot welding is a type of resistance welding used to join sheet metal parts by applying pressure and heat to specific points. This method is fast, efficient, and well suited for mass production tasks, such as automotive sheet metal parts assembly.
Arc Welding: Arc welding, or stick welding, uses an electric current formed between an electrode and the metal parts to melt them, forming a strong bond. This type of welding is highly versatile, effective on a variety of metals and alloys, and is often used in construction and repair work.

2. Riveting

Riveting involves joining sheet metal parts together by way of a rivet – a metal pin or bolt. The rivet is placed into pre-drilled holes of the parts to be joined, and its tail is deformed, either by hammering or using a riveting machine, until it expands to about 1.5 times the original shaft diameter. This creates a permanent mechanical fastening, securely holding the sheet metal parts together.

There are different types of riveting, each serving a unique purpose:

Solid Riveting: This is the oldest and one of the most reliable types of riveting. It involves the use of solid rivets, which are deformed with a hammer or rivet gun. This technique is widely used in aircraft structures due to its superior strength.
Pop Riveting (Blind Riveting): Named for the ‘pop’ sound it makes during installation, a pop rivet is tubular, with a mandrel through the center. A rivet gun is used to pull the mandrel back while deforming the rivet and then snaps off at a predetermined length. This method is commonly used when access to the joint is only available from one side.
Semi-Tubular Riveting: Semi-tubular rivets are similar to solid rivets but have a hole (partially hollow) at the tip. The hole at the end of the rivet reduces the force needed for application by rolling the tubular portion outward.
Oscar Rivets: These are two-piece rivets ideal for joining plastic to plastic, or plastic to metal. They are typically used in automotive applications.

3. Screwing

In this process, specially designed screws are driven into the parts to hold them together, usually with the aid of a screwdriver or power drill. Screwing offers a significant advantage in terms of convenience and speed, and it also allows for disassembly and reassembly, making it ideal for sheet metal assemblies that may require maintenance or adjustments over time.

Several types of screws are used in sheet metal assembly, depending on the specific requirements of the project:

Self-Tapping Screws: These screws have a sharp point and cutting edge thread that can form female threads in the material while being screwed in. They are highly useful for joining thin sheet metals.
Thread Forming Screws: These screws don’t remove material but instead displace it, creating a mating thread in the metal. They provide a stronger hold and are used for thicker sheet metal parts.
Thread Cutting Screws: With a distinct cutting edge, these screws remove material and create a female thread, much like a tap. They are suitable for heavy-duty applications where a strong grip is necessary.
Machine Screws: Typically used with nuts or pre-tapped holes, these screws are useful for assembling components with through-holes. They come in a variety of head styles, like flat head, round head, and pan head, each suitable for different applications.
Small Sheet Metal Screws: These are used for attaching thin, lightweight sheet metal parts. The threads on these screws are designed to hold tightly into the thin metal.

4. Bolting

Bolting is a conventional method used in the assembly of sheet metal parts, and it’s quite similar to screwing. The process involves using bolts and nuts to fasten parts together. Bolts pass through pre-drilled holes in the sheet metal and are fastened with nuts on the opposite side. Bolting is often used in applications that require high-strength fastening or where the assembled parts need to be frequently disassembled and reassembled.

There are several types of bolting methods that can be utilized for sheet metal assemblies:

Hex Bolts: These are often used in construction and repair applications. They have a hexagonal head and machine threads that mate with a nut or a tapped hole.
Carriage Bolts: Characterized by their round head and square neck, these bolts are used in wood to metal fastening, as the square neck grips into the wood to prevent turning.
Flange Bolts: These have a circular flange under the head that acts as a built-in washer to distribute the load. They’re used when the fastening surface cannot accommodate a separate washer.
Eye Bolts: Designed with a loop on one end, they are used for attaching a securing eye to a structure, so a rope or cable can be tied to it.
U-Bolts: These are used to support pipework in construction. The U-shape provides a good grip around the pipe, with the two ends being threaded to accept nuts.
J-Bolts: Shaped like the letter ‘J’, these bolts are often used in structural applications like securing walls to concrete foundations.

5. Soldering

Soldering involves the use of a filler material (solder) to join parts together. The solder, which has a lower melting point than the metal parts being joined, is heated until it melts. It is then allowed to flow into the gap between the parts. As the solder cools, it solidifies and forms a bond between the parts.

The key advantages of soldering include:

Versatility: Soldering can be used on a wide range of metals, making it an ideal method for different sheet metal assemblies.
Precision: It provides a high level of precision, making it suitable for assembly parts requiring meticulous attention to detail.
Low Thermal Distortion: The process involves lower temperatures compared to welding, reducing the risk of thermal distortion and warping of the sheet metal part.

However, it’s essential to note a few disadvantages:

Lower Strength: Soldered joints may not be as strong as welded or brazed joints, especially when under high mechanical or thermal stress.
Skill Requirement: Soldering requires a skilled operator to ensure the correct application and proper bonding of the sheet metal parts.
Potential for Corrosion: If not properly cleaned, the flux used in soldering can cause corrosion over time.

6. Brazing

Brazing is another common method utilized for assembling sheet metal parts. It works similarly to soldering but occurs at much higher temperatures. During the brazing process, a filler metal or alloy is melted and drawn into a capillary formed between two pieces of metal to be joined. As the filler metal cools, it hardens and securely bonds the parts together, forming a sheet metal assembly.

Here are some of the benefits of brazing:

Strong Joints: Brazing can create extremely strong joints, often stronger than the sheet metal parts being joined, resulting in durable and long-lasting assemblies.
Uniform Heat Distribution: The process evenly distributes heat, reducing the chances of distortion or warping of the sheet metal part.
Versatility: Brazing can join a wide variety of metals, including those that are difficult to weld.

However, there are a few drawbacks to consider:

High Temperature: Brazing requires high temperatures, which may not be suitable for certain types of sheet metal parts, especially those that might be negatively affected by high heat.
Skilled Labour: Similar to soldering, brazing requires skilled labor to ensure high-quality and reliable joints.
Cleanliness Requirement: The assembly parts need to be extremely clean for brazing, as any dirt or oxidation can prevent proper bonding.

7. Adhesive Bonding

Adhesive bonding, also referred to as gluing or bonding, is a process wherein an adhesive is used to attach sheet metal parts together, creating a bond that can be surprisingly strong. Unlike some other assembly methods, adhesive bonding doesn’t involve melting and is typically done at room temperature.

The process involves applying the adhesive to the surfaces of the assembly parts to be joined. The adhesive then cures, forming a strong bond between the parts.

Here are some benefits of adhesive bonding:

No Heat or Distortion: Because adhesive bonding is done at room temperature, there is no risk of heat distortion, making it suitable for sheet metal part materials that cannot withstand high temperatures.
Even Stress Distribution: Adhesive bonding spreads the bonding force across the entire joint, reducing stress concentration and providing stronger bonds.
Smooth Finish: Adhesive bonding results in clean, smooth finishes, without the need for further finishing processes.

However, it comes with a few drawbacks:

Curing Time: Adhesives usually require significant time to cure and attain full strength, slowing down the assembly process.
Surface Preparation: Surfaces must be carefully prepared and cleaned for successful bonding.
Temperature Sensitivity: Many adhesives can weaken or fail under high temperatures or in very cold environments.

8. Clinching

Clinching, also known as press joining, is a method of mechanically fastening sheet metal parts without the use of additional components or heat. It involves the deformation of the workpiece(s) to form an interlocking joint.

In the clinching process, the sheet metal parts are positioned between a punch and a die. The punch then applies force, causing the material to flow plastically and form a button-like joint, securely connecting the parts.

Clinching can be broadly classified into three types:

Round Clinching: Here, the punch and die form a round clinch joint.
Square Clinching: In this type, a square clinch joint is formed.
Rectangular or Oval Clinching: These methods create a rectangular or oval clinch joint.

Conclusion

We’ve explored a range of methods, each with their unique advantages and challenges. Remember, the method you choose will depend on various factors, including the type and thickness of the sheet metal, the expected load on the joint, the operating environment, and budget considerations.

For all your sheet metal parts requirements and assembly needs, Chengli Hardware is your trusted partner. We offer a range of services that are designed to meet your unique needs. Visit our website to learn more about our offerings and how we can assist you in your sheet metal assembly projects.

Frequently Asked Questions

What is a sheet metal part?

A sheet metal part is a component formed by an industrial process into thin, flat pieces. These parts are one of the fundamental forms used in metalworking, and they can be cut and bent into a variety of shapes and sizes.

What is the most common sheet metal?

Steel, especially in the form of cold-rolled mild steel, is one of the most common types of sheet metal due to its affordability, strength, and availability.