You’ll find that sheet metal thickness affects your final project at every stage, from procurement to processing. If you find that your projects often fail to meet client requirements due to sheet metal thickness, this article will guide you through the basics of selecting the optimal sheet metal thickness. Only the optimal sheet metal thickness can produce the most perfectly processed product.
What Is Sheet Metal?
Sheet metal is a metal that is smelted and cast into a plate-like material and then pressed into a thin metal plate.Sheet metal materials are typically single metals like aluminum or copper, but can also be created through alloying or coating, such as aluminum alloys or galvanized steel. Sheet metal is a crucial raw material in the fabrication industry. Different sheet metals, due to their varying properties, are often processed and applied in diverse fields, such as sheet metal enclosures, arcade game cabinets, and metal brackets.
Sheet Metal Thicknesses for Different Materials
Internationally, the most commonly used unit for sheet metal thickness in the manufacturing industry is millimeters. Some countries, such as the United States and Canada, use feet or gauges to record sheet metal thickness. Here, we’ll show you the thickness ranges of common sheet metal materials using millimeters as the standard:
Steel Plate:
- Thin Steel Plate: 0.3 mm to 3 mm
- Medium Thickness Steel Plate: 3 mm to 6 mm
- Thick Steel Plate: Over 6 mm
Stainless Steel:
- Thin Stainless Steel Plate: 0.5 mm to 2 mm
- Medium Thickness Stainless Steel Plate: 2 mm to 5 mm
- Thick Stainless Steel Plate: Over 5 mm
Aluminum Plate:
- Thin Aluminum Plate: 0.2 mm to 3 mm
- Medium Thickness Aluminum Plate: 3 mm to 6 mm
- Thick Aluminum Plate: Over 6 mm
Copper Plate:
- Thin Copper Plate: 0.1 mm to 1 mm
- Medium Thickness Copper Plate: 1 mm to 3 mm
- Thick Copper Plate: Over 3 mm
Galvanized Steel Plate:
- Thin Galvanized Steel Plate: 0.4 mm to 2 mm
- Medium Thickness Galvanized Steel Plate: 2 mm to 5 mm
- Thick Galvanized Steel Plate: Over 5 mm
Aluminum Alloy Plate:
- Thin Aluminum Alloy Plate: 0.5 mm to 3 mm
- Medium Thickness Aluminum Alloy Plate: 3 mm to 6 mm
- Thick Aluminum Alloy Plate: Over 6 mm
Thickness Gauge Tools
Depending on the accuracy of the measurement, the tools you need to measure the thickness of sheet metal will also vary to a certain extent. Calipers, micrometers, and ultrasonic thickness gauges are the three most widely used and applicable tools in the world, so sheet metal buyers generally choose them. They have their own advantages and disadvantages, and you can choose according to your actual situation:
- Calipers- Less expensive and easier to use, but you can get an error by measuring not perpendicular.
- Micrometer: The accuracy range can reach ±0.01 mm or higher; but be careful about the measurement force, otherwise it will cause deformation of the plate
- Ultrasonic thickness gauges: These are non-destructive and accurate, but the instrument cannot touch the metal sheet and thus requires a couplant to transmit sound waves.
What is Gauge in Sheet Metal Fabrication?
Gauge : Initially, gauge was primarily based within the UK to measure the diameter of metallic wires. It was later largely used in the United States and Canada for sheet metal thickness. These days, most countries have switched over to millimeters (mm) and even inches as the standard — but Gauge is still predominant in North America, particularly within industries such as steel, aluminum or copper.
How to Read a Sheet Metal Gauge Thickness Chart
Gauge is a standard for measuring the thickness of sheet metal materials. Gauge has no direct correlation to feet or millimeters. It’s like a universal industry number. For the same material, the larger the gauge number, the thinner it is. Furthermore, different metal materials, even if they have the same thickness, will have different gauge numbers. For more information, please refer to the thickness comparison table below:
Common Sheet Metal Thickness Conversion Table
(US Standard Gauge – Steel, Stainless Steel, Aluminum)
Gauge | Steel （mm / inch） | Stainless Steel （mm / inch） | Aluminum （mm / inch） |
10 | 3.416 mm / 0.1345″ | 3.404 mm / 0.134″ | 2.588 mm / 0.102″ |
12 | 2.769 mm / 0.1094″ | 2.775 mm / 0.109″ | 2.052 mm / 0.081″ |
14 | 1.994 mm / 0.0785″ | 2.032 mm / 0.080″ | 1.628 mm / 0.064″ |
16 | 1.519 mm / 0.0598″ | 1.588 mm / 0.0625″ | 1.290 mm / 0.051″ |
18 | 1.214 mm / 0.0478″ | 1.270 mm / 0.050″ | 1.024 mm / 0.040″ |
20 | 0.953 mm / 0.0375″ | 0.889 mm / 0.035″ | 0.812 mm / 0.032″ |
Recommended Default Sheet Metal Tolerance
In sheet metal fabrication, “default tolerances” are acceptable dimensional variations when specific tolerances are not given on the drawing. These values are typically based on industry standards, such as ISO 2768 or ASME Y14.5, combined with manufacturing experience. Typical ranges are tighter for flat laser-cut parts (±0.10-0.20 mm / ±0.004-0.008 in) and looser for welded assemblies (±0.50-1.00 mm / ±0.020-0.040 in). Choosing the right default tolerance helps balance cost, manufacturing efficiency, and product quality while avoiding unnecessary rework or disputes.
How to Choose Sheet Metal Thickness?
Based on the factors that influence sheet metal thickness, the key to finding the perfect thickness is to avoid the mistakes mentioned earlier. You can analyze each step of the manufacturing process to decide on the right thickness.
1.Find a Standardized Unit and Tool for Thickness Measurement
The first and most important step is to promptly adjust the units when receiving orders from different countries. Pay attention to the “Gauge vs. mm/inch” conversion, as this is where many people fail. For example, if a US customer says “16 gauge,” the actual thickness isn’t 1.6mm, but 1.519mm.” Whether to use the customer’s unit or a universal unit, this is something you both need to communicate and confirm. This will determine the success of your subsequent collaboration.
2. Select Based on Application Scenario
When communicating with your customers, you should clarify the intended use of the sheet metal. For example, use thicker sheet metal for corrosion resistance, lightweight sheet metal for aerospace applications, and more durable sheet metal for harsh environments. These requirements should be confirmed in advance.
3. Eliminate Errors Through Design Disassembly
You can avoid some issues caused by sheet metal thickness during your design process. Use 3D design software to disassemble the entire product so that each component and structure is clearly visible. Create a production checklist with the material and thickness of each component. If you discover any unreasonable design structures, discuss replacement plans with the customer promptly. Besides thickness, consider the clearances and bend radii required for structural coordination. This way, you can avoid the awkward situation of “it works in theory, but it doesn’t work in practice” when selecting thickness.
4. Eliminate Problems through Material Properties
As a professional in procurement or fabrication, you need to understand the properties of each material. You need to understand the factors that affect sheet metal thickness. Refer to ASTM/ISO/JIS thickness and tolerance standards to estimate errors in advance. If the actual data falls within your estimated range, production can proceed. If the data is inaccurate, you need to contact the supplier to investigate the situation and replace the sheet metal with the correct thickness before continuing with the next steps.
5. Select Based on Sheet Metal Processing Procedures
Finally, you’ll need to be familiar with the product processing process. Thick plates are more prone to burrs, thermal deformation, and dross after cutting, so perform surface treatment (such as grinding and deburring). Thin plates are prone to discoloration or deformation after cutting, so prepare a mold for the desired shape. For more details, please refer to the “Process on the metal can change material selections” section above.
Why Material Thickness Matters
The advantages and disadvantages of sheet metal thickness can impact the outcome of a fabrication project. For example, in aerospace engineering, sheet metal in many critical areas requires extreme lightness, as the weight of even a small component can determine the success or failure of a rocket launch.
The advantage of thin sheet metal is its ease of fabrication, which is crucial in the sheet metal fabrication industry. From sheet metal to finished product, a product undergoes multiple steps, including cutting, stamping, bending, welding, polishing, and assembly. The thicker the sheet metal, the more difficult it is to fabricate. From an economic perspective, thinner sheet metal is also cheaper. If the structure allows, choosing a thinner sheet can save you money on your project.
Although thicker sheet metal is more expensive and difficult to fabricate, thicker sheet metal plays an irreplaceable role in certain applications. For example, due to its strength and durability, thicker sheet metal is less susceptible to bending and provides stronger support for the entire product structure. This can extend the lifespan of sheet metal parts. Because of its impact resistance, if you need sheet metal for an exterior structure, thicker sheet metal will be more resistant to impact, truly protecting the equipment or products within. Furthermore, because it’s more stable, you’ll find that when testing sheet metal of the same size, thicker sheets are less affected by temperature, experiencing less change from thermal expansion and contraction.
Difficulties in sourcing certain thickness material.
Procuring materials is one of the most important parts of a project. Knowing what’s ahead could help you avoid tangles, stay on course and make it though with ease. Here are some issues that could crop up.
Using different units of measurement: Your customer may have a system that differs from yours and something like gauge sheet metal thickness in North America you work in millimeters.
Difference in tolerance: Manufacturing processes can lead to tiny variations in final thickness. This becomes an even greater problem for overseas projects, however, when standards and expectations differ from location to location.
Cost: Price is always a major factor, as the same material may be more or less expensive depending on where it is sourced from.
Lead time: Certain thicknesses are out of standard, so not every supplier has them in stock. Finding the right material may need special orders or searching to locate a suitable supplier in time.
The Influence of Sheet Metal Thickness on Processing Technology
A piece of sheet metal undergoes multiple processing steps before it becomes the final product we desire. The thickness of the sheet metal is crucial to the success or failure of the process. Here, we’ll discuss each process step separately:
Cutting: Thicker sheet metal is more difficult to cut. Inadequate cutting machine power can result in problems such as incomplete cutting, rough cuts, or burnt edges. However, thinner sheet metal vibrates, affecting cut accuracy.
Stamping: Similar to cutting, thicker sheet metal requires heavier equipment. Inadequate equipment can cause incomplete punching, die jamming, and even damage to the mold or equipment. Conversely, too thin sheet metal can cause edge deformation.
Bending: If the bending angle is too shallow, thicker sheets can experience springback or breakage due to the heavy bending force. Conversely, thinner sheets are easier to shape, but can also leave creases due to poor control of force and angle.
Welding: Thick sheets cannot be burned through, while thin sheets are prone to burning through.
Conclusion：
Choosing the right sheet metal thickness is more than a technical detail, it’s the backbone of a successful manufacturing project. From understanding gauge systems and tolerances to considering industry requirements and processing limitations, every decision impacts strength, cost, manufacturability, and performance. By aligning your material selection with design intent, production capabilities, and procurement realities, you can avoid costly issues and create products that meet both functional and aesthetic goals. In metal fabrication, precision at the outset ensures excellence at the finish.
FAQS
What Issues Might Arise if the Precise Material Gauge isn’t Considered in a Design
As you can easily see from the above description, if the potential for sheet metal thickness tolerances isn’t accounted for during design, sourcing the specific thickness can be challenging, leading to numerous problems. The first is processing. Excessively thick sheet metal can result in inappropriate nut lengths, ultimately preventing a tight connection. The second is assembly. A panel-mounted design can only accommodate sheets of precisely the right thickness. Too thick won’t fit, and too thin will cause looseness. The third is cost. If you replace the material, the original material will be wasted, and you need to consider whether your profit margin can cover the loss from this error. Finally, there’s the issue of efficiency. Whether redesigning or replacing the sheet metal, these solutions take time, but the customer’s delivery deadline is fixed. If the customer doesn’t accept your proposal, you risk losing the customer.
Examples of How Choosing the Right Sheet Metal Gauge Made a Significant Difference in a Project?
We previously worked on an EV charger enclosure whose outer frame had material thickness fluctuations that exceeded design tolerances, preventing precise alignment of the panels and internal modules. We promptly communicated with the client and replaced the outer frame with high-precision cold-rolled steel with a tighter thickness tolerance. This significantly improved the first-pass assembly success rate and reduced rework time. The client also highly praised our service, and we secured a long-term partnership.
