Sheet Metal Assembly Techniques: From Welding to Fastening

23 Jun.,2025

 

Sheet Metal Assembly Techniques: From Welding to Fastening

Sheet metal assembly involves joining multiple metal parts to create a finished product or components. Whether you’re building a rugged piece of industrial equipment or assembling a compact enclosure for electronic systems, the method of assembly plays a role in durability, cost, and lead time.

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At EZG Manufacturing, we work with businesses that need more than just parts; they need fully assembled solutions. Backed by decades of experience and equipped with advanced fabrication tools, we provide everything from precision cutting to finished assemblies.

Below, we break down the most common sheet metal assembly techniques, how they’re used, and where they provide the most value.

What Is Sheet Metal Assembly?

Sheet metal assembly is the process of taking cut and formed metal components and fastening them together using various techniques. These parts can range from flat patterns to fully shaped brackets, panels, or structural elements. The goal is to turn individual sheet metal components into a reliable final product.

Different projects require different techniques depending on the material (such as carbon steel or stainless steel), the assembly environment (from aircraft assembly facilities to construction sites), and functional needs like weight, part count, or corrosion resistance.

From Flat Sheet to Final Form: Common Sheet Metal Assembly Techniques

1. Welding Techniques

Welding is one of the most reliable ways to assemble metal components. At EZG, we use both MIG and TIG welding to join parts depending on the thickness, material, and desired finish.

  • MIG welding uses a continuously fed wire and shielding gas. It’s ideal for structural jobs and high-volume production.
  • TIG welding uses a tungsten electrode and offers finer control. It’s best for stainless steel or components with visible seams where aesthetics matter.

Welding works by applying intense heat to melt the edges of the metal pieces, fusing them together as they cool and solidify. Each method creates a strong bond, often stronger than the base metal itself.

Our team includes AWS-certified welders and robotic welding systems for consistent results on both small and large batch orders.

2. Mechanical Fastening (Rivets, Bolts, Screws)

Mechanical fastening is often the preferred solution when:

  • You need access to parts later
  • Dissimilar metals are being joined
  • Welding would cause thermal distortion or material issues

This method involves drilling or punching holes into parts and inserting hardware such as rivets, bolts, or sheet metal screws. These fasteners can create either permanent or removable joints, depending on the application.

  • Rivets are ideal for permanent joints and commonly used in aerospace and transit industries.
  • Bolts and screws allow for disassembly and are perfect for enclosures, inner fender assemblies, or components requiring regular maintenance.

At EZG, our technicians use assembly riveters, hand tools, and precision drilling to prepare threaded holes and mounting points, giving clients the flexibility they need in both prototyping and full production.

3. Adhesive Bonding

Adhesive bonding is a great option when welding or fasteners could interfere with aesthetics, introduce distortion, or aren’t compatible with certain materials. It’s commonly used to join:

  • Thin sheet metal sections
  • Dissimilar materials (like metal to plastic)
  • Panels needing smooth finishes without visible fasteners

This method involves applying industrial adhesive or epoxy between surfaces, which is then cured using time, heat, or pressure to form a durable bond. Adhesives also distribute stress more evenly across the bonded area, making them well-suited for lightweight or vibration-prone designs.

While not the solution for every project, adhesive bonding is ideal for custom applications that demand flexibility or uniform stress distribution.

4. Hemming and Folding

Hemming is the process of folding the edge of a sheet metal part over itself to create a rounded, reinforced edge. This not only improves strength and safety but also offers a cleaner appearance than raw edges.

Using a press brake or hemming tool, we perform:

  • Open hems for lighter-duty strength
  • Closed hems for increased rigidity and alignment

This technique is frequently used in:

  • Automotive manufacturing
  • Appliance housings
  • Flat pattern assemblies

Hemming helps reduce sharp edges, increase stiffness, improve multi-panel alignment, and even reduce part count, making it a cost-effective way to prep components for final assembly.

5. Tab and Slot Assembly

This technique uses precisely cut tabs and slots to lock parts together before final fastening. It’s often paired with welding or bonding and is:

  • Fast to assemble
  • Great for alignment and fixturing
  • Ideal for laser cutting applications

Tabs fit tightly into slots, holding components together during final assembly and reducing the need for clamps or jigs. This self-fixturing approach is especially helpful in projects requiring high repeatability or tight tolerances.

Thanks to EZG’s in-house laser cutting capabilities, we frequently use this method to speed up assembly time, particularly for high-volume or repeat builds.

6. Clinching (Press Joining)

Clinching mechanically interlocks two layers of sheet metal without any added hardware or heat. Using a punch and die, it forms a dimple that locks the metals together.

Benefits include:

  • No thermal distortion
  • Tight, corrosion-resistant joints
  • Minimal surface preparation

Clinching is often used in:

  • HVAC systems
  • Automotive subassemblies
  • Sheet metal enclosures with high part counts

This technique is ideal when speed, cleanliness, and cost-efficiency are key concerns.

7. Stud Insertion and PEM Fasteners

When your project needs components that mount circuit boards, covers, or brackets, stud and PEM fasteners provide reliable threaded attachment points.

We insert PEM studs, standoffs, and nuts directly into metal sheet parts before final assembly.

These are used in:

  • Electromechanical assemblies
  • Control panels
  • Machine enclosures

Our CNC presses support high-speed insertion and consistent placement across parts, helping you maintain tolerances and fit.

8. Modular and Electromechanical Assembly

Modern designs often combine sheet metal parts with electronics, wiring, or plastic elements. EZG’s team supports complete electromechanical assembly, including:

  • Mechanical buildout from flat pattern to box
  • Wire routing and subcomponent mounting
  • Integration of access panels, connectors, and fasteners

The process includes mounting PCBs, connecting wires to terminals, and installing hardware, all within metal enclosures fabricated in-house. This eliminates the need to coordinate with separate vendors for mechanical and electrical integration.

This is a common need in fields like medical, construction technology, and industrial automation, where a single source for both fabrication and assembly reduces complexity.

9. Powder Coating and Finishing

Assembly isn’t complete until your parts are finished and ready for use. At EZG, we offer in-house powder coating and wet paint booths to meet your appearance, durability, or spec requirements.

Powder coating involves spraying electrostatically charged powder onto metal surfaces, which is then cured in an oven to form a tough, uniform finish. It protects against corrosion and wear, and allows for consistent color and texture across production runs. Our finishing services help maintain the look and function of your sheet metal products from the inside out.

Benefits of in-house finishing services:

  • Eliminate the need to transport parts between vendors
  • Speed up the assembly process
  • Protect sheet metal products from corrosion or wear

This full-service model saves time and helps maintain quality throughout the entire production cycle.

Choosing the Right Sheet Metal Assembly Technique

Choosing the best assembly method depends on:

  • Material type (carbon steel, aluminum, stainless steel)
  • Application requirements (load, vibration, temperature)
  • Production volume (prototypes, short runs, or high-volume production)
  • Design complexity and part access needs (access requirements, part geometry)

At EZG, our engineers assist with design reviews and can adapt sheet metal designs to suit faster production or easier assembly. 

Why Work with EZG Manufacturing?

EZG Manufacturing isn’t just a fabrication shop, we’re a complete production partner. With over 120,000 sq. ft. of manufacturing space, heavy lifting capabilities, and advanced tools like our 10k fiber laser and 350-ton brake press, we’re built for projects ranging from a single metal part to full complex assemblies. We handle everything from laser cutting and welding to finishing and custom property creation. 

From flat pattern to final product, our goal is to give you one point of contact and a finished product that’s ready for use.

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Sheet Metal Box : 12 Steps (with Pictures) - Instructables

Sheet Metal Box

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Introduction: Sheet Metal Box

This is a great project to make if you are new to working with sheet metal. At this point in my class all of our sheet metal projects have been very simple with, at most, one bend. But, when we get to the this project my students always have a hard time trying to think through how to construct something from one piece of flat material. They begin to understand a little better when I relate what we are doing to an unfolded cereal box but until they work through making this box it usually doesn't make sense to them. This project makes them stretch their problem solving muscles by making them think through the correct order of operations to end up with a quality little container.

My students start off not liking this project as it really steps up the level of difficulty from our previous two projects but they end feeling very accomplished and finally coming to the conclusion the project wasn't really that hard to begin with. Plus, they like that they've finally made something that they can use and take home.

In this Instructable I'm going to walk you through how to make one of these simple sheet metal boxes!

If you are just beginning to work with sheet metal I recommend also checking out my two previous sheet metal Instructables. They cover how to make SHEET METAL DOG TAGS and SHEET METAL VISE JAW COVERS.

Step 1: Video Walkthrough

If you prefer watching over reading the video above covers the step by step instructions for this fabrication project in under eight minutes.

Step 2: Tools and Materials

Tools and Equipment

  • Ruler
  • Try Square (Any square would work fine)
  • Scratch Awl
  • Aviation Snips
  • Foot Shear (optional)
  • Sheet Metal Break
  • Bar Folder (optional)
  • Spot Welder

Materials

  • Sheet Metal ( I used 22 gauge)
  • Layout Fluid (optional)
  • Sand Paper
  • Spray Paint (optional)

Step 3: Planning

Before we begin we need a plan of action. If you can't visualize how the flat pattern for a box should look with sheet metal, find an old shoe box or cereal box and unfold it. The patterns for a cardboard box will look very similar to what you need to plan out for the sheet metal box.

The box I have my students create in class ends up being 5.5" x 2" x 3.5". To make things easy for my students I designed our classroom box so it would be able to work on the size of a standard 8.5" x 11" piece of paper. This size allows my students to practice their layout pattern and folding on paper before they move to metal. If your plan works on a paper mock up it should work on sheet metal.

I've included a picture and a pdf file of the plans I use in my class. Feel free to use it exactly as dimensioned or just use it as a template for your own size of box.

Terms to know:

There are are couple of terms that you'll want to know to help you understand the plans if you haven't worked with sheet metal before.

Hem - A section of your metal that has been rolled over onto itself. The hems will be located on the top edges of your box to provide a nice smooth rounded edge instead of a sharp, jagged one.

Tab - An additional piece or strip of metal that will be used in assembling or holding the sheet metal to the desired form.

Step 4: Mock Up (OPTIONAL)

Making a mock up out of cheap material is always a good practice to have when building something you are unfamiliar with doing. I have my students create their box out of paper first before I allow them to move on to working with the sheet metal. The process I show my students for laying out their pattern on paper is the exact same process they will use when they move on to the real deal. When you are finished with your mock up and it is the same size as what you planned; your work with sheet metal should go pretty smooth. If your mock up comes out with uneven sides, the corners don't connect, or its too small/large, then it will probably be a good idea to go back to the planning phase and make some revisions to your idea.

The order of operations for this step are as follows:

  1. Measure and mark your hem length from one edge of your paper.
  2. Draw a line parallel to the edge you measured from through your marked measurement.
  3. Repeat steps one and two for all the edges of your paper
  4. Measure and mark your hem plus your side length from one edge of your paper.
  5. Draw a line parallel to the edge you measured from through your marked measurement.
  6. Repeat steps four and five for all the edges of your paper
  7. Label the areas of the paper that will be used.
  8. Measure and mark your tab length off of one your sides.
  9. Draw a line parallel to the line you measured from to create square for your tab
  10. Repeat steps 8 and 9 for all of your tab locations.
  11. Label your tabs
  12. Draw roughly 45 degree lines to angle off your hems and tabs
  13. Cut out any part of your paper that is not labeled.
  14. Fold along your lines until you have a box.

Step 5: Cut to Size

Once you are prepared to work with your metal the first step you will need to take is to get your stock piece to the needed size. Using your plans measure and mark your overall size measurements on your metal. It is important to mark your lines nice and straight, a square will help you with that. If you do end up marking your lines slightly at and angle you will have a much harder time having your box come out as you planned.

For this step I used a foot shear to cut my metal to size. A foot shear made this step quick and easy and left me with nice clean edges on my metal. If you do use a foot shear be sure you line up your marked lines in the correct spot on your shear before cutting. I have included a picture showing how my marked line is right off the edge of the table of my shear, which will give me the exact measurement I want on my cut. A foot shear isn't necessary, as you could also do this step with hand snips.

The order of operations for this step are as follows:

  1. From the edge of your metal measure and mark your needed overall size dimensions.
  2. Use a square and scratch awl to mark straight lines through your marks.
  3. Cut along your marked lines to get your metal to the needed size.

Step 6: Layout

Now that your metal is to the correct size, it is time to mark your layout pattern onto the metal. I recommend using a square for this step if you have one, it will ensure you get as straight as marked lines as possible. Overall this is the same process as making the mock up, if you decided to complete that step. Just take your time and make sure the lines you are marking are correct and the way you want them to be. Below I've included the order of operations I have my students use.

The order of operations for this step are as follows:

  1. Measure and mark your hem length from one edge of your metal.
  2. Scratch a line parallel to the edge you measured from through your marked measurement.
  3. Repeat steps one and two for all the edges of your metal.
  4. Measure and mark your hem plus your side length from one edge of your metal.
  5. Scratch a line parallel to the edge you measured from through your marked measurement.
  6. Repeat steps three and four for all the edges of your metal.
  7. Measure and mark your tab length off of one your sides.
  8. Scratch a line parallel to the line you measured from to create a rectangle for your tab.
  9. Repeat steps 7 and 8 for all of your tab locations.
  10. Label all the areas on your metal that will be used for the box.
  11. Scratch 45 degree lines to angle off all of your hems and tabs.

Step 7: Cut to Shape

With your layout marked it is time to use aviation snips to cut your metal to shape. Overall this step is pretty easy, but using snips on metal can be a real grip strength workout. The biggest mistake my students make is going to fast and they end up cutting off one of their tabs. Take your time and make sure you are cutting the areas that are supposed to be cut.

The order of operations for this step are as follows:

  1. Use your aviation snips to cut your metal to shape.

Step 8: Clean Connection Areas

When you spot weld the box together you want as clean of connection between the metal as possible. That means before you start doing any bending you will want to clean up the portions of your metal where the spot welds will be located. It will be much easier to clean up your tabs and sides of your box now before you bend. To do this you will want to sand off the layout fluid and any oil and grease on the metal. This will allow you to have a clean metal to metal connection when we spot weld which will give us the strongest connection possible.

To do this just get some emery cloth or some 80 grit sand paper and clean off the inside and outside of your metal wherever your tabs will overlap your sides.

Step 9: Make Hems

As stated earlier hems are just a section of your metal that has been rolled over onto itself. The hems will be located on the top edges of your box to provide a nice smooth rounded edge instead of a sharp, jagged one. To do this step I will be using a bar folder but the process can be done with a sheet metal brake as well. Your goal with your hems is to have your doubled up layer of metal be flat without any bubbles or dents. The key to getting your hems correct is to use a tapping, not a heavy hammering, motion while also keeping your hammer head flat against your metal. If you use too much force or have your hammer head slightly angled you will end up with dents across your hems. Just like all the steps of any project you do, take your time and pay attention.

The order of operations for this step are as follows:

  1. Insert your metal into your bar folder up to your marked hem line.
  2. Pull your handle to fold your metal over 180 degrees
  3. Remove your now folded metal from the bar folder and place it back on the fold table with the fold facing up.
  4. Pull your handle again to the 180 degree position to better flatten your double layered portion of metal.
  5. Repeat steps 1-4 for all other hems.
  6. Place your hem on an anvil/solid surface and use your hammer to completely flatten your hems.
  7. Repeat step 6 for all other hems until all hems are completely flattened.

Step 10: Bend Into a Box

You are almost done. Once the hems have been made the next step is to bend your metal into a box. You will be working with a sheet metal brake to complete this step. The goal here is to clamp your brake teeth right on your lines. If your line is clamped down at an angle to your brake teeth, you will bend your metal at an angle and your box will not come out as you hope. Also, you will need to move some teeth on your break or you will not be able to fold your metal correctly. Move the teeth on your break around until you have a setup where you can insert your shorter side underneath so your tabs won't be crumpled during bending.

The order of operations for this step are as follows:

  1. Use your clamping bar handle to lift up the teeth of your brake.
  2. For this step the line you should be using should be the line that will bend your side and tabs at the same time. In my example it would be my "Long Side" line. Slide your metal piece underneath the teeth and line your marked line up with the edge of the teeth.
  3. Lower the clamping bar handle down to clamp your metal into place.
  4. Use your bending leaf handles to slowly fold your sides and tabs to 90 degrees.
  5. Return your bending leaf to neutral position and lift up your teeth to remove your bent metal.
  6. Repeat steps 1-5 for the opposite side of your box.
  7. Flare out your tabs slightly so your sides and tabs are not perfectly aligned. Use a vise or some pliers for this.
  8. Go back to the break, lift up the folding leaf, and insert your unfolded sides under your correctly positioned teeth.
  9. Clamp down on top of your marked line, with your teeth and line parallel to each other.
  10. Use your leaf handles to bend your sides slowly up to 90 degrees or until you can go no further without damaging your box.
  11. Lift up your teeth and remove your folded side.
  12. Repeat steps 8-11 for the opposite side of your box.
  13. Lightly bend your tabs back closer to the edge of your sides. I use a vise for this but you could also use a hammer to tap them back into place as well.

Step 11: Spot Weld

You now have a box! But without some form of fastening/assembly the box can be unfolded or deform pretty easily. To keep it in the shape you want it we need to make some sort of connection between your tabs and the sides of your box. For this I am going to spot weld the tabs to the sides of the box. If you don't have a spot welder, mechanical fasteners would work fine as well. Something like pop rivets or machine screws is what I would recommend if you wanted to go that route. You already prepared your metal for this process in a previous step, so all that is left is to actually spot weld. Please be sure to wear all the required and proper PPE (Personal Protective Equipment) when using the spot welder. Our spot welder owners manual recommends safety glasses, a face shield, gloves, closed toed shoes, and long pants.

The order of operations for this step are as follows:

  1. Position your box between the electrodes where you need to weld. This area should be on your tabs.
  2. Pinch down on your metal by slowly pressing down on your foot pedal and be sure you have your electrodes correctly positioned.
  3. When you are ready press your foot pedal all the way down and hold until your spot welder cycle is finished. You should hear the electricity cycle on and then off. Keep the pedal pressed down until you hear the cycle end.
  4. Release the foot pedal and reposition your box to the next spot that needs welded.
  5. Repeat steps 1-4 until your box is completely fastened together.

Step 12: Finished!

You now have a nice little container to use around the shop! If you feel the need for a lid, like I show in some of the pictures, just repeat the same process but make the box slightly bigger overall, but only design it to have about half the height.

For painting I used just regular spray paint that can be used on metal. Be sure to clean your metal up before painting by sanding it clean of oil and rust. Then be sure to wipe away any dust or metal shavings left behind after the clean up.

This Instructable I found to be more challenging to explain just through texts and pictures. If you need further explanation on a given step just leave me a questions in the comments below and I'll try to answer to the best of my ability.

If you make a box, let me know!

Enjoy creating and learning!

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