A CNC shearing machine cuts sheet metal to specified dimensions through controlled blade movement and workpiece positioning. Its operation involves CNC command input, drive system control, blade clearance adjustment, and position feedback. Understanding the machine's cutting capacity, positioning accuracy, and drive system helps buyers and engineers evaluate its suitability for different production requirements.
How a CNC Shearing Machine Works
CNC command processing
The CNC system receives the programmed cutting dimensions and relevant material and process settings. Based on the machine configuration, it controls the cutting cycle and positions the backgauge to establish the required cutting length.
Blade movement and workpiece positioning
The drive system, which may use hydraulic components, a servo motor, or a mechanical drive depending on the machine design, moves the upper blade through the cutting stroke.
At the same time, the backgauge positions the sheet metal at the required distance from the blade. Accurate positioning helps maintain consistent cut dimensions across multiple workpieces.
Blade clearance adjustment
The clearance between the upper and lower blades affects the cutting edge quality and the amount of deformation around the cut. Incorrect clearance can cause excessive burrs, tearing, or deformation.
The original guidance gives the following reference ranges:
For thicker sheets, blade clearance is approximately 5% to 8% of the material thickness.
For thinner sheets, blade clearance is approximately 2% to 3% of the material thickness.
These percentages are starting references from the source material, not universal settings. The appropriate clearance depends on material thickness, strength, blade geometry, and the machine manufacturer's recommendations.
Position and pressure feedback
Depending on the machine configuration, limit switches and pressure sensors provide information about blade position and cutting force. The CNC system uses available feedback signals to monitor machine operation and identify deviations.
The actual feedback functions and automatic correction capabilities depend on the sensors, controller, and drive system installed on the machine.
Key Parameters of a CNC Shearing Machine
Cutting capacity
Maximum cutting thickness
This parameter specifies the maximum material thickness the machine can shear under its rated conditions. It is commonly stated for Q235 low carbon steel.
For example, a machine designated 16 × 3200 is generally rated to cut Q235 steel up to 16 mm thick, with a maximum cutting length of 3200 mm. Actual capacity may differ when processing stainless steel or other materials with different strength characteristics.
Maximum cutting length
The maximum cutting length is the usable length of the cutting line. It should match the dimensions of the sheets being processed and the required production range.
Rated cutting force
Rated cutting force indicates the machine's available cutting capacity under specified conditions. It affects the maximum thickness and material strength the machine can handle, together with blade clearance, cutting angle, and other design factors.
Accuracy parameters
Backgauge repeatability
Backgauge repeatability describes how consistently the backgauge returns to a programmed position. The original material gives the following examples:
| Machine category | Reference repeatability |
|---|---|
| Higher-end machines | ≤ ±0.05 mm |
| Standard machines | ≤ ±0.1 mm |
These are indicative figures from the source material, not universal performance classifications. Actual repeatability should be verified against the manufacturer's specifications and test conditions.
Cutting straightness
Cutting straightness describes the deviation of the cut edge from a straight reference line.
The original material cites a straightness limit of ≤ 0.1 mm over a length of 2.5 m for low carbon steel. However, this figure should not be attributed to GB/T 14349-2008, which is not the applicable shearing machine accuracy standard.
The relevant current standard is GB/T 14404-2024, Plate Shears: Testing of Accuracy. The applicable tolerance should be confirmed from the standard's relevant inspection provisions and the machine's acceptance criteria.
Drive system parameters
Drive type
The drive system influences the machine's cutting force, operating characteristics, and maintenance requirements.
Hydraulic drives are commonly used for heavy duty machines and applications involving thicker sheet metal.
Mechanical drives can offer a relatively economical solution, depending on the machine design and production requirements.
Servo driven systems can suit applications requiring responsive control, precise positioning, or frequent operating cycles.
The actual performance depends on the machine structure, control system, and rated capacity rather than the drive type alone.
Cutting cycles per minute
This parameter indicates how many cutting cycles the machine can complete in one minute under specified operating conditions. It affects potential production throughput.
Actual output also depends on sheet size, material thickness, backgauge movement, loading and unloading time, and the selected cutting sequence.
Selecting a CNC Shearing Machine
Machine selection should begin with the material grade, maximum sheet thickness, cutting length, required dimensional accuracy, and expected production volume. The drive system and cutting speed should then be evaluated against these requirements.
Check rated cutting capacity and accuracy data under comparable test conditions. A machine's maximum thickness or nominal cycle rate alone does not establish whether it can meet the required production quality and throughput.
Custom Precision Machining for Industrial Equipment
Hansheng Automation provides custom precision machining based on customer drawings for a range of industrial applications. Our work includes precision components for yacht equipment and RC racing cars, as well as nonstandard parts for tobacco packaging machinery and filling machinery. Each component is manufactured according to the supplied drawings and the specific dimensional and structural requirements.
