Sheet metal cutting techniques

One of the most common processes in sheet metal manufacturing is sheet metal cutting, which is used to divide large sheets into sections, create precisely measured pieces of metal, and create precise perforations. body. In this article we will learn about sheet metal cutting techniques: classification, advantages, applications, common errors and safety notes.

1. What is sheet metal cutting?

• Sheet metal also known as rolled metal pieces have a high surface area to volume ratio and are typically 6 mm (¼ inch) thick or less. Thickness is also the main difference between sheet metal and sheet metal because sheet metal is thicker than that. Most of the operations below can also be performed on both sheet and sheet metal, but many operations can become more complex as sheet thickness increases.
• Cutting is often the first stage in sheet metal manufacturing. You can cut different shapes or structures from rectangular metal sheets to meet design requirements. The main cutting techniques include two types: profileless cutting and profile cutting.
• There are a number of processes that allow complete cutting of sheet metal materials without the need for cutting force. These techniques involve extreme heat, high pressure, vaporization and abrasive blasting to shape sheet metal fabricated parts.

2. Sheet metal cutting technique without shear

2.1 Laser Cutting

Laser cutting of sheet metal involves using a focused laser beam to melt metal in localized areas. Laser cutters are compatible with a wide range of metals, from non-ferrous to mild steel and stainless steel.

This technique involves two subprocesses running concurrently.

• The first involves focusing a high-power laser beam onto a metal plate, which absorbs the heat energy of the laser beam, causing it to vaporize.
• A cutting nozzle then supplies the blowing air for laser cutting. This gas is usually oxygen or nitrogen, which helps prevent the treatment head from splashing and vaporizing during sheet metal manufacturing.
  
  

Laser cutting of sheet metal

Laser cutting applications in sheet metal cutting:

• Creates highly precise and clean cuts, perfect for detailed designs.
• Capable of cutting a variety of metals and thicknesses, including steel, aluminum and titanium.
• Commonly used in industries that require high precision, such as aerospace and automotive manufacturing.
• Provides flexibility in cutting complex shapes and small, intricate parts.

2.2. Plasma Cutting

Plasma cutting is a thermal cutting process that involves metal with an ionized gas called plasma. This method uses significant heat to cut the metal, creating large burrs and oxidation zones near the cutting area. Additionally, it enables faster cutting, high precision and repeatability in sheet metal production.

Plasma cutting tools only work effectively on conductive metal sheets. Therefore, this is one of the most suitable methods for cutting conductive materials of medium aluminum thickness.

Plasma-cutting

Plasma cutting applications in sheet metal cutting:

• Effective for cutting thick metal sheets and plates.
• Widely used in heavy manufacturing, automotive and industrial applications.
• Capable of producing relatively clean cuts with a small heat-affected zone.
• Ideal for large-scale projects where speed is key.

2.3. Water jet cutting

This cutting process involves using high-pressure water streams to cut metal sheets. Waterjet cutting is very versatile and can cut a variety of hard and soft materials using pressurized water and abrasives. It is ideal for cutting soft materials, metal foil, fabric or rubber. At the same time, it is suitable for cutting hard materials such as copper, carbon steel, aluminum and carbon steel.

The pressure involved is typically around 60,000 psi, with a delivery velocity of 610m/s to cut through various types of sheet metal. However, waterjet cutting is a better alternative to laser cutting techniques.

Water jet cutting

Application of waterjet cutting in sheet metal cutting:

• Ideal for materials sensitive to high temperatures as it does not generate heat.
• Capable of cutting complex shapes with high precision.
• Suitable for a wide range of materials, including metals, glass and composites.
• Typically used for projects requiring minimal material deformation and no heat affected zones.

3. Cutting technique with shear

3.1. What is shear cutting?

Shear cutting, also known as die cutting, is a cold mechanical cutting process in which a metal sheet is placed between two sharp blades using guides or stops. The lower blade (or die) remains stationary while the upper blade (or punch) cuts through the metal with one quick strike. Both the die and punch are typically made from tool steel or carbide. The shear force during this process will cause the metal sheet to be stressed, and when the ultimate shear strength of the material is exceeded, the material will be sheared.

There are many different methods for mechanically cutting sheet metal, but the basic one is to use blades to cut between materials. The equipment for this process can be operated in many ways (manually, electrically, pneumatically and hydraulically).

These processes are often more economical for slightly larger-scale production due to longer setup times and costs associated with special tooling and molds. For one-off parts and small runs other cutting processes can be applied, e.g: laser cutting, for example, tends to be more cost-effective.

3.2. Shear cutting

Shear cutting is suitable for high-volume applications and cutting soft materials that do not require a clean finish, such as brass, aluminum and mild steel. This technique cuts straight lines on a metal sheet with a flat surface. The cutting method involves applying a cutting force to a surface, causing the flat metal material to separate at the point of cutting.

This is often the ideal process for creating straight edges on sheet metal with rough edges. It is cost-effective for high-volume operations when producing thousands of parts in short lead times. However, the cutting ability may not be perfect for applications that require a quality finish due to the burrs and material deformation it causes.

3.3. Punching

Punching uses shear force to create holes in a metal sheet. In this sheet metal fabrication process, scrap is removed from the hole, the final product is the material left on the mold.

The hole punch is suitable for creating cutouts and holes of different shapes and sizes. However, using the punching process can take a long time due to the need to match the die and punch knife precisely.

Applications of punching in sheet metal cutting:

• Commonly used to create holes, slots or shapes in sheet metal.
• Essential in mass production to produce parts consistently and quickly.
• Often combined with other processes such as bending or shaping.
• Suitable for a variety of materials, with different thicknesses.

3.4. Blanking

Blanking is an ideal process for economical sheet metal fabrication. It involves removing a portion of sheet metal from a larger portion of the parent material using a blanking punch and die. The punch creates a “punching force” through the metal plate while the die holds the workpiece in place throughout the process.

This process is suitable for economical fabrication of custom parts due to its high repeatability, dimensional control, and excellent accuracy.

Applications of blanking in sheet metal cutting:

• Ideal for producing flat, uniform parts in large quantities.
• Commonly used in the automotive and appliance industries.
• Allows for tight tolerances and clean edges.
• Effective for processing a variety of metals and thicknesses.

3.5. Saw

Saw cuts metal material with a serrated tool to create a series of small cuts in the metal. Saw teeth use cutting force and friction to tear small portions of metal material. Band saws come with a variety of thin, slightly curved teeth suitable for cutting brass, aluminum and other non-ferrous metal sheets.

Horizontal band saws help cut longer bar stock to the desired size. On the other hand, vertical circular saws help make complex cuts that require precise contours on metal parts.

4. What is the simplest technique for cutting sheet metal?

For beginners or those looking for a simple method, hand cutters or tin snips are the easiest tools for cutting sheet metal. They require minimal setup, are cost-effective, and are perfect for cutting thin panels along straight lines or gentle curves.

5. What tools are commonly used to cut sheet metal?

Sheet metal cutting, an important process in many different industries, involves a series of tools, each designed for specific tasks. The right tool not only ensures efficiency but also enhances the precision of the cut. Below is a list of tools commonly used in sheet metal cutting:

Scissors (Hand-held scissors and Electric scissors):

• Handheld shears: Ideal for smaller projects and precision cutting.
• Electric shears: Used for larger projects, providing speed and power for thicker sheets.

Chisel drilling machine

• Perfect for cutting complex shapes and contours.
• Can be used on many different thicknesses and materials.

Chisel and hammer:

• Traditional tools for basic cutting and shaping.
• Requires skill and is mainly used for artistic or small-scale projects.

Cutting machines

• Great for making straight, clean cuts.
• Used in industrial environments for high volume, repetitive tasks.

Refer to the sheet metal cutting machines provided by VISC here

Snips (News Snips and Aviation Snips):

• Tin Snips: Ideal for straight cuts and slight curves on thinner metal sheets.
• Aviation Snips: Designed for more complex cuts and better handling.

Angle grinder:

• Versatile for cutting, grinding and polishing.
• Suitable for thicker and harder metals.

Scroll saw:

• Great for intricate designs and detailed work.
• Provides precision in cutting patterns and shapes.

Electric metal saw:

• Used for heavy cutting operations.
• Provides clean and efficient cuts on thick metal sheets.

6. What are the main parameters in the sheet metal cutting process?

In the complex sheet metal cutting process, several key parameters play an important role in determining the quality, efficiency and feasibility of the operation. Understanding these parameters is essential to achieving optimal results in your metalworking projects.

Material Thickness:

• Indicates the amount of force or energy required to cut.
• Influences the choice of cutting methods and tools.
• Thicker materials often require more powerful cutting techniques such as plasma or laser cutting.

Cutting speed

• Refers to the speed at which the cutting tool or laser moves across the material.
• An important factor that affects both productivity and cutting quality.
• Optimal speed varies depending on material type and thickness.

Output power (for Laser/Plasma cutting):

Setting the machine's capacity is important for efficient cutting of different types and thicknesses of materials.
Higher output power is often required for thicker, harder materials.

Kerf Width:

• The width of the cut or the amount of material removed during the cutting process.
• Kerf affects the final dimensions of the sheet metal part and overall accuracy.
• Narrower cuts result in more material conservation and less waste.

Cutting Tolerance:

• Refers to the allowable deviation in cutting dimensions, which is important for precise manufacturing.
• Tighter tolerances are often required in high-precision industries.

Surface Finish:

• The quality of the cut surface may vary depending on the cutting method.
• Smoother surfaces are often desired for aesthetic and functional purposes.

7. What are some of the most common metals used for sheet metal cutting?

Sheet metal cutting is used on a variety of metals, each with its own characteristics and challenges. Here are some of the most common metals used in this process, along with their common applications:

Steel (Mild steel and carbon steel):

Widely used due to its power and affordability.
Common in automotive parts, construction materials, and appliances.

Stainless Steel:

Known for its corrosion resistance and durability.
Used in medical devices, kitchen equipment and architecture.

Aluminum:

Lightweight and corrosion resistant.
Ideal for the aerospace, automotive and consumer goods industries.

Brass:

Combines workability with a visually appealing finish.
Often used in decorative elements, plumbing and musical instruments.

Copper:

High conductivity and ductility.
Common in electrical components and roofing materials.

Galvanized steel:

The steel is coated with zinc to prevent rust.
Used in outdoor structures, ducts and fences.

Titan:

Exceptional strength-to-weight ratio and corrosion resistance.
Used in aerospace, medical implants, and high-performance auto parts.

Nickel alloy:

High resistance to heat and corrosion.
Used in chemical process equipment and high temperature applications.

Silver, Gold, Platinum:

Precious metals with instrumental applications

Zinc:

Good corrosion resistance and low melting point.
Commonly used in moldings and protective coatings.

Tin:

Soft, pliable and corrosion resistant.
Used in coatings, welding and alloying.

Lead:

Dense and malleable.
Used in radiation shielding and batteries.

Inconel:

A nickel-chromium alloy known for its ability to withstand extreme temperatures.
Used in jet engines, nuclear reactors and chemical processing.

8. Which industries commonly use sheet metal cutting?

Sheet metal cutting is an indispensable process in many different industries, each leveraging the technique for specific applications. Here are ten industries that commonly use sheet metal cutting, along with how they use it:

• Automotive industry: Uses sheet metal cutting to create body panels, frames, and engine parts.
  Aerospace industry: Relies on precision sheet metal cutting for airframe structures, engine components and cabin interior components.
• Construction industry: Use sheet metal for roofing, siding, HVAC systems and structural components.
  Manufacturing of industrial machinery and equipment: Use of sheet metal components in the manufacture of heavy machinery and equipment.
• Electronics industry: Requires precision-cut metal to make housings, frames, and various hardware components.
• Energy sector, including renewable energy: Use cut metal sheets to make parts in power generation equipment, including wind turbines and solar panels.
• Shipbuilding industry: Depends on large-scale sheet metal cutting for hulls, decks and other structural parts of ships.
• Medical Device Manufacturing: Precision-cut sheet metal is needed for surgical instruments, equipment housings, and hospital furniture.
• Consumer Goods and Equipment: Sheet metal cutting is used for the outer shell and internal parts of equipment.
• Railway industry: Uses sheet metal cutting to fabricate train hulls, parts and infrastructure components.
• Defense and military sector: Relies on sheet metal cutting to make vehicle armor, weapons parts, and infrastructure.
• Metal Machining and Fabrication Shops: Use a variety of cutting techniques for custom metal parts and products for a variety of applications.
• HVAC (Heating, Ventilation, and Air Conditioning): Sheet metal is cut for ductwork, vents, and other HVAC system components.
• Sign and advertising industry: Uses sheet metal cutting to create durable and flexible signs and displays.
• Art and Sculpture: Artists use sheet metal cutting to create intricate designs and sculptures.

9. Is the cost of cutting sheet metal high?

Sheet metal cutting costs can vary significantly based on a number of factors. Understanding these factors is essential to estimating the overall cost of your project.

• Design complexity: More complex designs require advanced cutting techniques, which can increase costs.
• Type of metal: Different metals, such as stainless steel or titanium, have different prices and cutting requirements.
• Metal Thickness: Thicker materials often require more powerful cutting tools, resulting in higher costs.
• Cutting method used: Techniques such as laser cutting or waterjet cutting may have different operating costs than traditional methods.
• Production volume: Higher quantities can reduce costs per unit due to economies of scale.
• Level of precision required: Projects requiring high precision may involve additional processes, which impact costs.a
• Machine and tool wear: Frequent replacement or maintenance of cutting tools can add to costs.

10. What are some design considerations for sheet metal cutting?

Designing for sheet metal cutting requires a combination of technical knowledge and creativity. Here are some practical tips for optimizing your designs:

Minimize complex cuts:
Simplify design to reduce cutting time and costs.
For example: Choose straight lines or standard shapes if possible.

Consider material properties:
Choose the metal that best suits your design requirements and cutting method.
For example: Use aluminum for designs that require lightness and flexibility.

Optimize for nesting:
Arrange parts to maximize material usage and minimize waste.
For example: Align similar parts close together on a metal plate.

Allowable Kerf and material deformation:
Adjust the design to account for the width of the cut (kerf) and the possibility of material deformation.
Example: Increase the hole size slightly to compensate for the groove width.

Designed for bending and joining:
If the part requires bending or welding, include appropriate tolerances in the design.
For example: Include bend allowances to ensure accurate final dimensions.

Combined Tolerance:
Design with realistic tolerances to ensure parts fit together as intended.
For example: Specify tolerances in design documents to guide the cutting process.

Avoid sharp corners:
Round the corners to reduce stress concentrations and the possibility of material cracking.
For example: Use rounded or radiused lines on corners instead of sharp corners.

11. Safety tips when cutting sheet metal

When working with sheet metal cutting, safety is paramount. Here are essential safety tips to follow:

• Wear protective equipment: Always wear safety glasses, gloves and hearing protection to protect against flying debris and loud noises.
• Ensure proper ventilation: Work in a well-ventilated area, especially when using methods that create smoke or fumes.
• Use sharp tools: Regularly maintain and sharpen cutting tools to reduce the effort required and prevent accidents.
• Fixing the metal plate: Clamp the metal plate down to prevent movement during cutting, reducing the risk of injury.
• Be cautious with power tools: Handle power tools such as saws and electric grinders with care, making sure they are turned off when not in use.
• Follow Equipment Guidelines: Always operate machinery according to the manufacturer's instructions and safety instructions.
• Keep a first aid kit nearby

12. Common problems and defects when cutting sheet metal

Sheet metal cutting can be fraught with various problems and defects, which can affect the quality of the finished product. Understanding these problems and knowing how to solve them is important.

Common defects and how to fix them:

Buried edges:
The cause is due to blunt cutting tools or incorrect tool alignment.
Fix: Sharpen tools regularly and ensure proper alignment.

Deformation or warping:
Occurs due to excessive temperature during cutting.
Solution: Use appropriate cutting speeds and cooling methods to minimize heat buildup.

Incomplete cuts:
Results from insufficient cutting force or blunt tools.
Solution: Adjust force or power settings and use sharp tools.

Rough surface finish:
Caused by using inappropriate cutting methods or tools.
Solution: Choose the right cutting method and tool for the material and desired finish.

Material waste:
Results from ineffective sample placement or cutting.
Fix: Optimize material usage by better organization and planning.

Incorrect size:
Due to incorrect tool settings or material movement during cutting.
Fix: Ensure correct tool setup and secure material fixation.

Excessive noise:
Created by certain cutting processes or equipment.
Solution: Maintain equipment properly and use sound reduction methods.

Conclusion

Sheet metal cutting is a complex and important process in many industries. Its success depends on understanding and leveraging various cutting techniques, considering factors such as material properties, safety, design complexity and cost. From using the right tools and methods to ensuring safety and addressing common errors, sheet metal cutting expertise shapes the efficiency and quality of the final product.