May. 26, 2025
Not all sheet metal parts are created equal, and the most important factor in the success of a sheet metal part is the material it’s made from.
The type of metal a sheet metal part is made from must be chosen carefully to ensure that the part meets fabrication requirements during manufacture and performance requirements in its final application. Picking the wrong material can cause part or whole product failure, low yields, high costs, poor performance or a number of safety issues.
Imagine a safety critical structural part failing due to improper material selection, and you have an idea of one potential concern. If you imagine products having to be recalled, at a high cost, due to in-use failure you have an idea of another potential concern.
The process of selecting the material for a sheet metal part can be complex because of the sheer number of factors involved. The issue is something that requires careful consideration.
The most important questions to answer when selecting a material for sheet metal parts are:
Fig. 1: Sheet Metal Parts at Komacut
In this guide, we'll look at the most common sheet metal materials used and go over the factors that need to be considered when choosing the right material.
There are many types of sheet metal, and each type has its benefits and drawbacks that must be considered when selecting a material for a project. The different properties different materials have make them suitable for different applications.
We will explore the types of sheet metal materials used at Komaspec and give examples of real-life uses for each of them.
Mild or Low Carbon Steel
Mild steel is by far the most commonly used material for sheet metal fabrication. The relative strength it has, combined with the ease of fabrication and relatively low cost compared to stainless steel or aluminum, means that it’s suitable in plenty of applications. These steels can be used to create a wide variety of custom steel parts. Automotive body panels, furniture and structural parts are common examples of mild steel in application.
Mild Steel Pros
Mild Steel Cons
Stainless Steel
Stainless steel is an alloy containing chromium, which provides good corrosion resistance and improved strength. Stainless steel is great in outdoor applications or other applications in which parts might be exposed to rust or corrosive chemicals. It’s also useful in applications that need more hardness than mild steel. As well as this, it is non-magnetic and non-sparking, making it ideal for medical instruments.
Fig. 2: Mill Finish – Stainless Steel
Stainless Steel Pros
Stainless Steel Cons
Galvanized Steel
When steel is galvanized, a layer of zinc is bonded to its surface. This method serves as a cost-effective way to build a high level of corrosion resistance into the material. In turn, this reduces the potential for rusting prior to fabrication and the need for additional surface finishing. Galvanized steel is perfect for things like fencing and other outdoor frameworks that are exposed to the weather.
Fig. 3: Cold Galvanized Steel
Galvanized Steel Pros
Galvanized Steel Cons
Aluminum
Aluminum has many wonderful qualities. Its primary qualities are its high level of resistance to rust and its reduced weight, being one-third of the weight of steel. It is less strong than other materials, but this can sometimes be overcome through design. In some applications, aluminum can also be designed to be equally as strong as steel.
Because of its lack of strength, aluminum may often not be able to handle the same stresses as steel. As such, you might want to contact our representatives at Komaspec to help you decide if aluminum is suitable for your intended use or not.
Fig. 4: Aluminum RAL
Aluminum Pros
Aluminum Cons
Spring Steel
Spring steel is a very resilient material containing manganese and high concentrations of carbon. It is designed to bend or flex under load and to return to its original shape when the load is removed. This makes it an excellent choice for making latching mechanisms, drive belts and, of course, springs.
Spring Steel Pros
Spring Steel Cons
For more info about each of the sheet metal materials Komaspec offers, including specific physical properties and surface finishing options, you can refer to the sheet metal material selection on our website.
Order and track sheet metal components online through Komaspec's on-demand sheet metal fabrication platform.
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The costs that come with sheet metal parts fabrication begin with the cost of the raw material. Costlier materials, such as aluminum, stainless steel, and copper, can provide superior performance compared to cheaper materials, such as mild steel and galvanized steel. Still, they obviously come with a higher price tag.
In some cases, a cheaper metal will be suitable for a job and will provide adequate performance at a lower cost. For example, if aluminum is too expensive for a part that requires light weight and corrosion resistance, galvanized steel might be a better choice.
Ultimately, choosing the right material will mean weighing up performance requirements and the cost constraints of a project.
The table below shows a rough outline of how much each material costs. We can see that, while aluminum is twice as expensive as steel per kg, stainless steel is nearly five times more costly. Titanium is much more expensive again and is used sparingly in products such as jet engines, where the extra strength it provides is crucial.
Fig. 5: Material Cost Per Kg (USD)
The Difficulty in Comparing Material Costs
When considering which sheet metal material to buy for a project based on cost, there’s more to consider than just the price of a material per kg. You have to weigh material cost per kg against the design and performance goals of the project. Not all sheet metal is created equal in strength, weight, and appearance.
Stainless steel is stronger by weight than aluminum, for example, meaning that designs can be adapted. Thinner stainless steel can be used for a tank or vessel than it can for an aluminum one, for example.
Cost Increase of Custom Steel Parts
Custom design requirements often impact the price of steel sheet metal parts. This is because custom designs often require more intricate processes and skills to manufacture, increasing the cost of labor and materials.
Custom metal parts fabrication often also requires additional processes, such as welding, cutting, and bending, which can also increase the cost of the parts. They may require the use of specialized tools and equipment to construct correctly as well.
Understanding the mechanical properties different sheet metals have and the effect these properties have in application is critical to selecting the right material. There are many physical qualities inherent in different metals, and each one can be used to serve a different purpose.
Some of the most essential mechanical factors to consider in the material selection process include:
Strength of Sheet Metal Parts
Material strength is often the most widely used metric in determining material suitability. It is measured according to how much load a material can withstand before it bends out of its original shape. This bending is also known as plastic deformation.
There are two ways of looking at the strength of a material when it comes to choosing one for manufacture. Considering each separately may give a different outcome in decision making.
Strength By Cost
This simply considers how strong a material is in respect to how much it costs. Titanium is an example of a material with a high cost to strength ratio, and mild steel is an example of the opposite.
For metal enclosures or tanks that require large amounts of high strength material at low cost, for example, low-carbon (mild) steel would generally be considered the ideal material.
Strength By Weight
This considers how strong a material is in relation to its mass (or weight). Gaining high strength with lightweight materials is important in certain applications. In airplanes, for example, reducing weight is essential, and aluminum is often a good choice.
Strength to weight properties are also assessed by looking at specific strength.
Interestingly, in a comparison of aluminum, carbon steel, and stainless steel, the aluminum alloy has the highest specific strength (ASM Material Data Sheet), despite having the lowest tensile strength.
Fig. 6: Tensile Strength vs. Specific Strength
Also referred to as formability, this is the ability of a material to be stretched without cracking or breaking. If a material is highly ductile, it will withstand a large amount of stretching. Stretching commonly occurs in manufacture when a tight radius is formed during a metal stamping or folding process.
Fig. 7: Sheet Metal Materials at Komaspec
A simple way to visualize ductility is to imagine a material acting as a spring - the greater the elasticity of a material, the better its ductility. One thing to note is that this flexibility can be increased using a metal-forming process called annealing.
Corrosion Resistance
Corrosion occurs when a metal deteriorates as a result of the action of air, moisture or a chemical. The most common form is rust, which happens when iron in a material reacts with the oxygen and moisture in its surroundings. Good corrosion resistance (Metals - Corrosion Resistance to Aggressive Fluids) is a crucial factor in sheet metal selection because corrosion can weaken steel in a surprisingly short period of time if the conditions are right.
Fig. 8: Corrosion From Aggressive Fluids
The two main factors that help reduce corrosion are:
What is the Best Material for Corrosion Resistance?
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Stainless Steel
Stainless steel contains chromium, which forms a thin film of chromium oxide on its surface, protecting it from corrosion. Stainless steel can become discolored, or it can rust if there is long term exposure to the elements. It is particularly vulnerable to corrosion where there are high salt concentrations. However, the resistance is greatly superior to mild steels.
Bimetal corrosion is a risk with stainless steel and must be considered when mating with other parts or fasteners.
Aluminum
A lightweight alternative to steel, aluminum is a naturally non-reactive metal that will not corrode in the presence of air or water.
Aluminum can be somewhat vulnerable to corrosion when in contact with concrete, however, and there’s also a risk of bimetal corrosion. Both of these problems can be overcome through anodizing or painting.
Modified Mild Steel
Using galvanized mild steel could be a great alternative if cost is a factor. The Zinc coating gives a layer of protection at lower cost. Be aware, however, that when galvanized mild steel sheets are cut, the edges are exposed and will be vulnerable to rust.
Mild Steels
Mild carbon steels without secondary finishing will rust rapidly in the presence of moisture or salt. In fact, unprotected steel sheets can begin to rust even before fabrication, which often leads to the need for deburring or chemical treatment to remove rust before surface finishing.
Rust can be so severe, in some cases, that it impacts the final part appearance even after painting. Parts can appear “mottled” or like they have a blotched surface when this happens.
Sheet metal part fabrication processes involve procedures such as cutting, bending, and joining sheets of metal. These procedures create different configurations of sheet metal to create custom steel parts. Each material has its own specific advantages and disadvantages in the fabrication process that need to be considered.
Laser Cutting
Laser cutting is a precise and reliable method for cutting all different types of metal. This method is a great option in many different situations. However, it’s particularly useful where speed and precision are important, such as in the automotive industry. Lasers are also useful for cutting thicker materials, for making complex cut-outs and for making very clean cuts.
Shiny metals, such as aluminum and copper, are more difficult to cut, although it is still possible to cut these materials with a laser. The minimum / maximum thickness which can be cut, however, varies depending on the material type, which in the case of very thick or very thin material, may limit potential choices.
Bending
There are two factors that have an impact on bendability:
Some materials can be bended more easily than others and with more success in application. It’s worth noting, however, that even within the same material, there can be differences in bendability between different grades. If ductility is important, for example, the series aluminum is best avoided as the hardness of the material can result in micro-cracks and part failure duing bending.
Generally speaking, aluminum is commonly considered a good choice where sheet metal bending is required.
Designs with tight bend radii and low tolerances will mean that a more bendable material is required. For more about bend design, read our article on sheet metal design guidelines. Very stiff materials (i.e. medium carbon or stainless steels) may require larger reliefs are larger bend radii vs mild steels and aluminum parts.
Fig. 9: Metal Bending at Komacut
Weldability
Welding is one of the most common methods for joining and manufacturing metal components. This process uses a high-powered and highly controlled electric arc to heat base metals to the point where they melt. They are then joined and solidify as almost one piece.
The weldability of sheet metal will depend on the type of filler metal used, the process used and the material makeup of the sheet.
Mild carbon steels are highly weldable with a variety of processes, are generally finished with secondary processes which help to resolve discoloration of the base material. Aluminum requires TIG welding, which can be more time and cost intensive than MIG, and the material is more vulnerable to deformation and discoloration due to heating during the welding process. Stainless is also weldable, but requires TIG or special robotic welding equipment and may need passivation or secondary processes to hide discoloration from the welding process.
Fig. 10: Robotic Welding at Komacut
Different materials have different properties when it comes to surface finishing. Not all materials are compatible with all surface finishing options, such as anodization being largely specific to aluminum, or the difficulty of electropolishing mild steel parts.
For which options are available for various sheet metal materials, please see the table below or explore in greater detail in our surface finishing article.
Finish Corrosion Resistance Coating Thickness Abrasion ResistanceTable 1: Surface Finishing: Corrosion, Thickness, Abrasion
Finish Carbon Steel Stainless steel Aluminium Application Visual Requirements Thickness Corrosion resistance Mill Finish Internal Parts or Parts with Subsequent Processing Low-Visual - - Antirust Oiling Parts with Subsequent Processing Low-Visual - 24 Hours NSS Brushed Indoor Med-Visual - - Anodized Indoor / Outdoor High-Visual - - Mircro-Polishing Indoor / Outdoor High-Visual - - Passivation Indoor / Outdoor Med-Visual 0.5 to 15μm - Zinc Plating Indoor / Outdoor Low-Visual 5 to 25μm 48 to 94 Hours NSS E-Coating Indoor / Outdoor Low-Visual 5 to 25μm 96 Hours NSS Powder Coating Indoor / Outdoor High-Visual 70 to 150μm 480- HoursTable 2: Metal Finishing Guide
The application of the part often determines the finishing requirements. Some reasons for wanting an enhanced surface finish include:
Because these aspects are critical to quality for many applications, it’s important to think about these requirements when selecting a material.
Aesthetics
Polishing is a common technique used to create a high-quality look that’s pleasing to the eye. The process involves progressively removing all surface imperfections to give a metal part a shiny finish.
Fig. 11: Surface Finishing
Polishing for Sheet Metal Parts
Stainless steel can be brought to a mirror finish and is very durable; aluminum is less durable and can take longer to reach the same finish. It is not possible to create a durable polished surface on mild steel.
Hygienic Sheet Metal Parts
Sheet metal parts are often used in both the food industry and medical settings. The material chosen must be resistant to the build-up of bacteria and other contaminants.
Stainless steel, for example, is a popular choice for sheet metal products because it is non-porous and resistant to corrosion. This eliminates the need for potentially toxic paints and other coatings.
Additionally, stainless steel can be easily cleaned and sterilized using various chemical and thermal methods. This makes it an ideal choice for food-grade products and medical instrumentation.
Stainless steel 316, for example, is widely used for food service or medical equipment due to its excellent resistance to chemical cleaning agents, acids and other corrosion.
Durability for Sheet Metal Parts
Durability is the main factor that affects a material’s resilience to dents, scratches and bending. Also important in hygienic environments, the durability of a material affects how well it can withstand harsh environments without needing to be repaired or replaced.
Stainless steel is a great option if a part needs to resist scratching and be easy to repair. When scratched, it does not cause possible contamination with aluminum oxide. Aluminum, along with copper, will resist scratches and deformation very poorly.
Mild steel is another durable material, but the paints and coating needed should be considered as they can often lead to the same problems with contamination.
Material finishing requirements will help determine the best material choice for any particular part. For more about different types of finishing, read this guide.
As we mentioned in a former blog post, there has been significant consolidation and subsequent closings of many small to mid-size companies in the plastic injection molding, metal stamping, precision machining, and metal fabrication industries since . From the first part of the current decade, when the economy regained some of its strength and began building momentum, to the present day, certain industries began thriving and achieving record profits, like the automotive industry; demand for fabricated components, especially metal fabricated components, is at an all-time high.
Today, a considerable number of companies across industries can perform fabrication of some sort, however, there is limited capacity among premier metal fabrication companies, globally. With this in mind, procurement professionals are left with major challenges to locate and source capable metal fabrication supply partners.
Before deciding on the best supply partner for metal fabrication services, remember to be aware of all aspects of the parts and assemblies and to look at each option from multiple angles.
Sourcing the right metal fabrication supply partner is challenging because of both internal and external factors. Supply partners, across commodities, are often selected based solely on cost, a result of corporate procurement teams’ cost initiatives that focus on, and reward, cost reductions above all other key performance indicators (KPIs).
While cost remains critical in any sourcing activity, large or small, one could argue that overall capabilities, experience, and quality are equally as important and should be weighted as part of the decision criteria, accordingly. Before moving forward with a metal fabrication supply partner, a procurement professional must have a though-out supplier development process that ensures the following considerations are met and the results meet company goals.
The metal fabrication industry has evolved in the last decade. Metal Fabrication, by definition, is the building of metal structures by cutting, bending, and assembling processes. Metal fabrication capabilities vary from company to company. Some focus on larger production runs at a lower cost, while others focus on low volume with greater options for customization. In today’s world, the more capabilities that a company offers, the more appealing they are to any procurement professional. The right metal fabrication company will offer services such as cutting, stamping, forming, extruding, bending, assembling, etc. Truly capable players will offer value-adding services such as welding, plating, heat treating, coating, painting, etc.
When comparing suppliers, it is extremely rare for a supply partner to only provide one service. This common discovery is why it is so essential for a procurement professional to find the right metal fabrication partner and why leading procurement professionals are not making sourcing decisions with a supplier attitude, but instead with a supply partner mentality.
When considering the capabilities of a potential metal fabrication supply partner, a procurement professional must analyze and evaluate every offering that partner provides or has the capacity to provide. One must ask, “Is this potential supply partner capable to meet all my business needs, and more, without the risk of problems during prototype runs or production?” Below are a few common, yet extremely vital questions a procurement professional should ask regarding the capabilities of any metal fabrication company that is being considered for a program:
Which metal fabrication services do they offer and specialize in?
There are many different types of metal fabrication capabilities for a given component. It is important for a procurement professional to understand the many types of metal fabrication processes that a potential supply partner can offer. This is not only helpful for understanding of the supply partner, but it may help to save on total program costs. The most common metal fabrication processes are described below:
What materials does the potential supply partner work with and what can they suggest?
There are many different materials that can be fabricated, most notably steel and aluminum variants. Certain supply partners specialize in the different material types so it is important to know not just what your potential supply base is capable of, but also what each supplier is known for and specializes in. It is also important for the potential supplier partner to understand all material variants and alternatives. Many projects or products will be designed in other areas of the world and will kick off development builds in those regions, with the end goal to have production sourced in another region. In this case, it is always helpful to work with a metal fabrication partner that understands material equivalents (EN, SAE, etc.) and can suggest alternatives that are more available in the production region. The most common raw materials used by metal fabrication companies include plate metal, formed or expanded metal, tube stock, welding wire or rod, casting, etc.
What production services are offered by the potential supply partner?
Procurement professionals need to inquire on the specific production services and/or secondary operations that are offered by the potential supply partner. Some programs will require simple fabricated parts and others full, finished and tested assemblies. The following is a list of important questions to ask regarding production services:
What design capability does the potential supply partner have?
It’s one thing to take a prototype through production, but what if design services are necessary? Not all metal fabrication companies offer these services or provide them as a one of their core competencies. Ask each company in consideration whether they can work based on a drawing (digital or printed), whether they can translate the drawings to shop drawings, and whether they are capable of starting from scratch without the help of an initial design provided. Getting these questions answered upfront eases communication with supply partners throughout the entire process.
Metal fabrication is an art. Not everyone can fabricate metal components or assemblies; experience is key. No matter the industry, metal fabrication requires experience both at the individual level and the company level. A procurement professional must be assured that the potential metal fabrication supply partner has sufficient experience to avoid costly mistakes.
Ask metal fabricators about their knowledge as it relates to industry codes and regulations. For automotive companies, being knowledgeable, experienced, and certified in various ISO/TS standards is recommended, and in many cases required for certain OEMs and Tier Is. ITAR is a common certificate for the defense industry and so on. Be sure to have potential supply partners describe how operations have continuously improved over the years to be as efficient and safe as possible. Ask about similar projects they have completed and parts they have fabricated. Further, do not hesitate seek references from past customers. A good metal fabrication company will have plenty that are willing to speak on their behalf and will welcome this due diligence.
As a rule of thumb, one should always strive to get at least three quotes from highly qualified potential supply partners. Once attained, compare costs across the board as it relates to the program. Attaining an apples-to-apples comparison amongst metal fabrication companies is not always easy. One company might use a higher quality material or more precise cutting tools, where fewer costly mistakes are expected in the long term. Some are priced higher because they are smaller shops that offer more customized services or less common metal fabrication process. While bulk can be cheaper, it might not be right for a given project. Certain projects and designs will require metal fabrication processes that may offer higher tooling costs and lower piece costs, or vis versa. It is important to understand the full program costs before rushing into any sourcing decision.
Make sure that the RFQ sent to each supplier details the specifics of exactly what is needed. The supplier development initiatives and Supplier Capabilities Assessments, that should be sent to each potential supply partner along with the RFQ, should also down-select many of the unknowns and discrepancies. Also, a procurement professional must be cognizant of supply partner location as that may negate the cost savings of a less expensive quote.
There are many items a sourcing professional should be cognizant of and consider before choosing a metal fabrication supply partner. There must be full awareness on the bigger picture and not just the short-term cost savings or avoidances. Too often supply partners are chosen for the wrong reasons or for short-term gains. Understanding a potential metal fabrication supply partner’s capabilities, experience, quality, and costs will put you and your company in the best position to win for the long term.
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