Sheet metal fabrication creates long-lasting metal parts from a variety of materials, such as stainless steel, aluminium, titanium, brass, copper, bronze, and so on. Its thickness ranges from wispy leaves to light foil to a heavy plate. Cutting, stamping, bending, punching, shearing, forming, welding, revetting, drilling, and tapping are all examples of sheet metal prototyping. They can be plain flat sheets, etched, embossed, corrugated, ribbed, or perforated.
Its applications range from automotive to transportation to medical devices, aerospace, appliance manufacturing, consumer electronics, industrial furniture, machinery, and more.
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Advantages of Sheet Metal
Sheet metals are strong, can withstand high pressures, and are malleable. Second, they can be shaped into any shape.
In terms of cost, sheet metal has a significant advantage over other types of metal fabrication. When it comes to mass production, sheet metal fabrication is highly scalable. While the initial setup can be costly, the price per piece drops rapidly as volume increases.
How Does Sheet Metal Work?
Sheet metal fabrication technology is evolving, and materials, equipment, and tooling are becoming more specialised than ever before.
Sheet metal can be cut, stamped, punched, sheared, formed, bent, welded, rolled, riveted, drilled, tapped, and machined. Brushing, plating, anodising, powder coating, spray painting, silk screening, and other marking options are available for the components. Parts can also be riveted, screwed, or welded together to form complex assemblies.
Types of Sheet Metal Materials
Materials used in sheet metal fabrication vary widely. Strength, hardness, flexibility, and resistance to corrosion are all commonly desired properties for metals used in sheet metal fabrication. Below are the most commonly used materials.
| Standard stainless |
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It is the most commonly used type of stainless.
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| Standard magnetic stainless |
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| Spring-like steels |
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301, 17-4, 1095, and 1075 are all spring-like stainless steels. It will work-harden quickly and must be heated during the formation process to relieve stresses. |
| Aluminum |
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Generally, aluminum is moderately priced, and has several types to choose.
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| Copper & Brass |
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| Electrolytically tough pitch (ETP) copper, either C110 or C101. Cartridge brass is used very few. |
| Cold Rolled Steel (CRS) |
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The alloys 1008 and 1018 are used to smooth the finish of hot rolled steel and to maintain a tighter tolerance when forming. |
| Pre-Plated Steel |
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It is either hot-dip galvanized steel or galvanealed steel, which is galvanized and then annealed. |
Techniques to shape Sheet Metal parts
Flat sheet metal can be shaped in a variety of ways. Deep drawing, hydroforming, spinning, and stamping is examples of hot and cold forming techniques. These are the processes used to make the body panels for modern vehicles and complex-formed objects such as metal sinks and aluminium beverage cans. Many of these techniques are iterative, meaning that the metal is shaped by repeating the process several times to change the shape of the metal in increments.
Cold-forming processes include the following:
Cutting
• Shearing used to be common way to cut sheet steel.
• A punch press is more effective than a laser or a waterjet for cutting simpler parts.Because it can produce parts quickly and efficiently by operating at hundreds of strokes per minute.A complex flat pattern with size-limited stamped features can be created by combining punch and laser cutting.
• CNC laser cutting.There are two types of lasers used. Fiber-optic lasers are used to deliver precise cuts on thinner and more reflective materials. Multi-gas or CO2 lasers have greater power and are better suited for thicker gauges. The cut can be quite complex, with +/- 0.005 in tolerances. or even better
• Photochemical machining fabricate metal parts through precision photolithography and chemistry. The technology’s unique methods make it ideally suited to the production of clean, precise, unstressed and burr free parts.
Bending
Bend shapes can range from gentle curves, such as those along a steel can’s vertical axis, to sharp corners at angles above, below, or right at 90 degrees.These relatively sharp bends are created using press brakes. In a continuous bending operation, rolling and forming methods produce open or closed single-axis curves.
Hemming
Rolling the edge of a metal shape provides a smoother, stronger edge. Hems can be open, with an air space between the folds, or closed, with the folded metal pressed tightly against itself. Curling creates a rounded edge on a piece of metal, which is also known as a barrel hem.This can be used to simply eliminate the sharp edge or to serve a specific operational function, such as holding the pin around which the hinge rotates in the case of a door hinge.
Design Points
Designing for sheet metal fabrication has its own set of criteria that are distinct from other manufacturing methods. The more information about a part’s features and functions available early in the design process, the sooner a manufacturable design may be finalised. If, on the other hand, a design has flaws, a manufacturing provider should be able to point them out and suggest solutions. In some circumstances, the supplier may even have design analysis software that may immediately identify design flaws that need to be addressed.
Some design points to think about:
• Sheet metal fabrication is the most cost-effective option. Consider welding or riveting together parts that can be created with universal tools if a single part becomes too difficult.
• To avoid distortion, features must be placed away from bends because curves strain the metal. A good rule of thumb is 4T, which stands for four times the material thickness.
• Because a press brake bends sheet metal by pushing it into a die with a linear punch, closed geometry cannot be produced.
• Sheet metal tolerances are far more generous than machining or 3D printing tolerances. Tolerances are affected by factors such as material thickness, machine type, and the number of steps in part production.
• A uniform bend radius, such as 0.030 in., should be used across a single part to reduce the number of machine setups and speed up production.
• When possible, keep a standard distance of four times the material thickness from bend to edge. This eliminates the need to remove excess material required to make the bend.
• Welding thin materials can cause bending and cracking. Other ways of assembling are desirable.
• Always consider the manufacturer’s minimum requirements for installation locations and material thickness when utilising PEM hardware.
Finishing Options
Sheet metal can be finished in a variety of ways and purposes. Some finishes protect sensitive materials from rust or corrosion, and others change to the metal’s surface. The following are examples of finishing treatments:
• Sand blasting is the process of cleaning a metal surface by spraying jets of abrasive material at it. It is commonly used on stainless and carbon steel to eliminate impurities and increase adherence before painting.
• Brushing cleans and scores the metal surface with abrasive brushes. It can be used as a final finish on materials such as aluminium and stainless steel.
• Polishing : Metals such as stainless steel, aluminium, and copper can all be treated from polishing. It can be used as a final finish or as a preparation for plating. It is not suitable for painting metals because it does not improve adhesion.
• Powder coating: This is a process where powdered paint is sprayed onto a part and then cures it with heat.This creates a strong, and corrosion-resistant layer that is more durable than standard painting methods. A wide variety of colors are available to create the desired aesthetic.
• Plating can be done electrolytically or electroless. It can prevent corrosion, improve solderability, harden a surface, prevent wear, reduce friction, and aid in paint adhesion. Plating processes include:
– Passivation, a cleaning process that prevents corrosion in stainless steels by removing free irons from the surface of the material.
– Chromate coating, a conductive coating used on aluminum to protect against corrosion.
– Anodizing, an electrochemical process used on aluminum and other non-ferrous metals that provides insulation and prevents corrosion.
– Zinc, a self-sacrificing anti-corrosion coating (applied by galvanizing or galvanealing) for steels and is often combined with a Chromate coating over the zinc.
– Nickel, often a cosmetic coating and can serve as a substrate for plating processes that cannot adhere to a given metal.
– Tin, a solderable, conductive coating.
Applications
Sheet metal is one of the most versatile materials and processes. Because of the features of sheet metal parts, almost all industries rely on some form of sheet metal fabrication. For example:
• Aerospace
• Refrigerators, freezers
• Airplane components
• Brackets
• Electronics
• Automobile parts
• Chassis
• Cabinets
Conclusion
Critical factors such as strength, weight, and cost should be considered when selecting materials and processes for sheet metal fabrication. However, you won’t know whether the design meets your requirements until you receive prototypes and test them. Is it strong enough? Is it light enough? Does it look and feel as it should?
It may take several prototype iterations to produce a part that meets your expectations. The speed at which parts are manufactured and tested becomes a significant factor in time to market.
After prototyping and testing, numerous options exist for producing low-volume, end-use parts. A part can be manufactured in various ways, each with its own set of costs.
