Explore the key parameters of CNC turning of composite materials

Exploration of Key Parameters for CNC Turning of Composite Materials

When CNC turning composite materials, factors such as material properties, tool selection, cutting parameters, and cooling and lubrication need to be taken into account. The following are the key points of specific parameters:

1. Tool materials and geometric parameters

Tool material:

Hard alloy cutting tools: Suitable for most composite materials, they have good wear resistance and strength.

Diamond tools: Suitable for processing high-hardness and wear-resistant non-metallic composite materials, such as carbon fiber reinforced plastic (CFRP), but should avoid cutting ferrous metals.

Ceramic cutting tools: Suitable for high-speed cutting and difficult-to-machine materials, they feature high hardness and heat resistance.

Tool geometric parameters:

Rake Angle: It is selected based on the material properties, generally ranging from 15° to 25°. For composite materials with higher hardness, the rake Angle can be appropriately reduced to enhance the edge strength.

Relief Angle: Take 10° to 14° to reduce the friction between the tool and the machined surface and improve the surface quality.

Main deflection Angle: Take 45° to 90°, and adjust it according to the processing requirements to control the radial cutting force.

The cutting edge inclination Angle is set at 3° to 5°, which is helpful for chip removal and reducing the cutting force.

The radius of the tool tip arc is taken as 1 to 2mm. The rake Angle of the forming tool can be 0° to meet specific processing requirements.

2. Cutting parameters

Cutting speed

Affected by the material of the cutting tool, the material of the workpiece and the processing requirements. For thermoplastics, the cutting speed can be appropriately increased to enhance productivity, but it is necessary to avoid material softening.

For thermosetting plastics or high-hardness composite materials, the cutting speed needs to be reduced to prevent the tool from overheating and wearing.

Feed rate:

Select based on surface quality, vibration and workpiece deformation requirements. A smaller feed rate should be selected during fine machining to ensure the machining quality.

For composite materials that are prone to vibration, the feed rate needs to be further reduced.

Cutting depth:

Select based on the workpiece allowance, rigidity and deformation requirements of the workpiece. During rough machining, a larger cutting depth can be adopted to enhance efficiency, while during finish machining, the cutting depth needs to be reduced to ensure accuracy.

For thin-walled or easily deformable composite material workpieces, the cutting depth needs to be reduced to avoid deformation.

3. Cooling and lubrication

Coolant selection:

It should have good heat transfer performance, chemical stability, lubrication performance and safety.

It should be avoided to react with the components in the composite material to prevent corrosion of the workpiece or tool.

Nozzle position and Angle:

The nozzle should be directly facing the contact surface between the tool and the workpiece to ensure that the coolant is evenly sprayed.

The position and Angle of the nozzle need to be adjusted appropriately to cover the entire contact surface between the tool and the workpiece and improve the cooling effect.

4. Processing strategies and technological measures

Processing sequence:

Adhering to the principle of "rough first, then fine, from the inside out", remove the excess materials first, and then carry out fine processing to ensure accuracy.

For complex composite material workpieces, the processing sequence should be reasonably arranged to avoid vibration and deformation.

Clamping scheme:

Ensure that the workpiece is clamped correctly and stably to avoid displacement or vibration during the processing.

For thin-walled or easily deformable workpieces, special clamping methods should be adopted to enhance rigidity.

Tool Wear and Compensation

Regularly check the wear of cutting tools and replace those that are severely worn in a timely manner.

Appropriate compensation should be made based on the amount of tool wear to ensure processing accuracy.