If you want to buy a shearing machine that can handle metal cutting tasks perfectly, make sure you understand that you are not buying a "candy" but a machine worth tens of thousands of dollars. Especially if you need to import it from another country, imagine the frustration if your new sheet metal shearing machine arrives and doesn't meet your needs or has issues—addressing these problems can be time-consuming and costly.

So take 10 minutes to read this article, which will tell you the 5 most important things you need to know about shearing machines including type of shear, capacity, productivity enhancement options, and safety.

Why You Should Read This Guide?

First of all, you need to know that shearing machines are usually divided into two types through the difference of the drive system: the guillotine (also known as the slider unit) and the swing beam. After determining which drive system to choose, you need to confirm the specific model according to the material, length, and thickness of the workpiece to be processed.

Metal Shearing Machine Design

The guillotine metal shearing machine, as illustrated in (Figure 1), employs a drive system that powers the moving blade in a nearly parallel position to the fixed blade throughout the cutting stroke. This design ensures a straight and precise cut, ideal for high-precision applications. A key component of the guillotine design is the gibbing system, which maintains the blade beams in proper alignment as they move past each other. This system is essential to prevent misalignment and ensure consistent cutting quality, especially when dealing with thicker materials. However, the blades do not last long because they are directly exposed to shear forces and need to be replaced frequently.

In contrast, the swing beam metal shearing machine, shown in (Figure 2), utilizes a different approach. This design uses one of the drive systems to pivot the moving blade downward on roller bearings. This pivoting action eliminates the need for gibs or ways to maintain blade position. The simplicity of this design not only reduces maintenance requirements but also enhances the machine's durability and reliability. Swing beam shearing machines are often preferred for their high-speed operation, making them ideal for mass production scenarios. Choose it if you need to cut thin sheets on a large scale.

Drive Systems of Metal Shearing machine

Evaluating of Metal Shearing Machine

Evaluating Metal Shears for Optimal Performance

When evaluating metal shears, several factors must be considered to ensure the machine meets the specific requirements of the fabrication job. These include the capacity, material specifications, and the rake angle of the blade.

Capacity Considerations

One of the primary considerations is the shearing machine's capacity, which must match the material requirements of the job.

Mild Steel Capacity: Typically rated for steel with a tensile strength of 60,000 pounds per square inch (PSI).

A-36 Steel Capacity: Rated for steel with a tensile strength of 80,000 PSI.

Stainless Steel Capacity: Generally lower than that for mild or A-36 steel.

Aluminum: Certain grades of aluminum may require as much power to shear as steel.

It's crucial to compare the fabricator's material specifications against the machine's listed capacities. When in doubt, consult the shear's manufacturer to confirm capacity and suitability.

Importance of Metal Shearing Machine's Rake Angle

The rake angle, which is the angle of the moving blade as it passes the fixed blade, significantly influences cut quality.

Lower Rake Angle: Generally provides better cut quality, reducing issues like bow, twist, and camber in shorter pieces (up to 4 inches long). However, it requires more power.

Higher Rake Angle: Requires less power but may compromise cut quality.

Variable Rake Angle:Some guillotine-type machines offer a variable rake, allowing the angle to be adjusted to suit the length and type of material being cut.

Fixed Rake Angle: Typically provides a consistent quality cut for specific material thicknesses.

Adjustable Rake Angle: Offers flexibility for better cuts on a range of material thicknesses and lengths. For example:

A fixed 1-1/3-degree rake angle is better for a 3-inch strip of 1/4-inch thickness. A variable rake angle of 1 to 3 degrees can provide better cuts on thinner materials like 24-gauge at 1/2-inch strip.

General Guidelines for Rake Angle and Material Thickness

A good cut is typically expected on a strip that is at least eight times the material thickness (e.g., a 2-inch strip of 1/4-inch steel).

Variable rake machines are more suited for shops handling thicker materials (1/2 inch and higher). Adjusting the rake angle in these machines allows for better cuts across a range of thicknesses and materials.

Productivity Enhancements in Shearing Machines

Many metal shearing machine users rely on essential standard features and optional accessories to enhance their productivity. These enhancements can lead to labor savings, improved material flow, increased accuracy, better cut quality, and, most importantly, improved safety. Here are some key productivity-enhancing features:

Squaring Arms

• Function: Used for squaring the sheet for a trim cut.
• Additional Use: Can also support longer sheets and assist with front gauging.

Support Arms

• Function: Support material in front of the machine.
• Additional Use: Can be used for measuring the cut part with proper front gauging stops.

Stops

• Types: Swing stops and disappearing stops.
• Function: Used for front gauging the material. Disappearing stops are widely used as they allow plates to be fed over them and then pop up when the material is clear.

Programmable Backgauges

• Function: Allows setting the backgauge dimension and potentially controlling other accessories.

Sheet Support Device

• Location: Typically behind the blades.
• Function: Holds up the material to prevent sagging and ensure an accurate cut. Operates in a sequence to clamp and support material during cutting.

Manual or Power Front-Operated Backgauge

• Function: Adjusts the backgauge dimension to control the size of pieces behind the blades.

Different Blade Materials

• Purpose: Provides maximum blade life based on the type of material being cut.

Manual Blade Gap Adjustment

• Function: Allows setting the blade gap for different material thicknesses and types from one side of the machine.

Power Blade Gap Adjustment

• Function: Adjusts the blade gap using a motor, often controlled by a computer based on material parameters.

Ball Transfers

• Function: Facilitates movement of plates on the machine’s table, especially useful for thicker materials.

Conveyor/Stacker/Scrap Separator Unit

• Function: Moves material to a stacking unit or returns it to the front for another cut. Separates trim cut or scrap material from usable material.

Front Return Unit

• Function: Conveyor unit that feeds material back to the front for subsequent cuts.

Manual One-Shot Lube System

• Function: Manually lubricates specific points on the machine.

Automatic Lube System

• Function: Automatically lubricates points on the machine systematically.

Gap in Frame for Slitting

• Function: Allows cutting parts longer than the blade length.

Light Beam/Shearing Line

• Function: Helps align the material with the blade for accurate cuts based on a scribed line.

Pads on Hold-Down

• Function: Prevents marring the material during the hold-down process.

Vibration Isolation Pads

• Function: Facilitate installation of the shear, especially in situations where a large pit is impractical.

Stroke Adjustment

• Function: Allows the operator to set the length of the cut.

High-Speed Devices

• Function: Increase the number of strokes per minute for higher productivity.

Ensuring Safety in Shear Operation

The safe and proper operation of all metal fabricating machinery by properly trained personnel is essential, and shears are no exception. These potentially dangerous machines must be operated in compliance with all federal, state, and local regulations, as well as the manufacturer's instructions.

Built-In Safety Enhancements

Shears should come equipped with several safety features to protect operators:

Point-of-Operation Guards: These guards protect operators from the dangerous points where the cutting occurs.

Warning Labels: Important for indicating potential hazards and must remain in place.

Rear Guards and Light Curtains: Additional safety enhancements required for some operations, especially when there is a larger opening under the guard for material thickness.

Material Handling Techniques

Proper material handling is critical for both feeding parts into the machine and removing them from the back. This minimizes the risk of accidents and ensures smooth operation.

Use of Mirrors

Depending on the size and design of the shear, mirrors are often mounted on the machine. This allows operators to see around the machine, enhancing their awareness of the surroundings and improving safety.

Lockout/Tagout Procedures

Implementing proper lockout/tagout procedures during repairs or blade changes is crucial. This ensures that the machine is completely powered down and cannot be accidentally activated.

Maintaining a Clean Work Area

Keeping the work area clean and free of debris is fundamental for safe operation. A cluttered workspace can lead to accidents and reduce efficiency.