Cutting strategies for thin-walled parts processed by end mills

When using end mills to process thin-walled parts, it is necessary to comprehensively consider tool selection, optimization of cutting parameters, planning of processing paths and clamping methods to reduce deformation, improve processing accuracy and surface quality. The following is the specific analysis of the cutting strategy:

First, tool selection

Tool type: Give priority to choosing end mills with high rigidity and high wear resistance, such as solid carbide tools or coated tools, to reduce vibration and wear during the cutting process.

Tool geometric parameters:

Rake Angle: Appropriately increasing the rake Angle can reduce the cutting force, but it is necessary to avoid making it too large, which may lead to insufficient tool strength.

Relief Angle: Appropriately increasing the relief Angle can reduce the friction between the tool and the workpiece and improve the surface quality.

Helix Angle: Choosing a larger helix Angle (such as 35° to 45°) can improve chip removal performance and reduce cutting force.

Tool diameter: Select an appropriate tool diameter based on the wall thickness of the part and the machining allowance to prevent excessive tool diameter from causing concentrated cutting force.

Second, optimization of cutting parameters

Cutting speed (Vc) :

High-speed cutting can reduce cutting force, but the appropriate cutting speed should be selected based on the material of the tool and the workpiece.

For instance, when hard alloy tools are used to process aluminum alloys, the cutting speed can reach 200 to 400 m/min.

Feed per tooth (fz) :

Reducing the feed rate per tooth can lower the cutting force, but the processing efficiency needs to be balanced.

When processing thin-walled parts, the feed rate per tooth is generally controlled at 0.02 to 0.1 mm/z.

Cutting depth (ap) and cutting width (ae) :

Adopt the strategy of small cutting depth and large cutting width to reduce the influence of cutting force on thin-walled parts.

The cutting depth generally does not exceed one-third of the wall thickness, and the cutting width can be appropriately increased to improve efficiency.

Third, processing path planning

Layered milling

The total cutting depth is divided into multiple layers for processing. After each layer is cut, the stress of the workpiece is released to reduce deformation.

For example, a part with a wall thickness of 2 mm can be cut in 4 layers, with each layer cut to a depth of 0.5 mm.

Climb milling and reverse milling

Priority is given to the climb milling method, which can reduce the cutting force and improve the surface quality.

Circular interpolation

Circular interpolation is adopted at the corner to avoid sudden stop and start of the tool and reduce vibration and shock.

Fourth, clamping method

Special fixture:

Design special fixtures to increase the rigidity of the workpiece and reduce the vibration during the cutting process.

For example, vacuum suction cups, electromagnetic suction cups or dedicated clamping devices are adopted.

Auxiliary support

Add auxiliary supports at the weak points of thin-walled parts to reduce deformation during cutting.

For example, fill the cavity with wax or low-melting-point alloys to increase rigidity.

Fifth, cooling and lubrication

Cooling method:

High-pressure internal cooling or external cooling is adopted to promptly remove the cutting heat and reduce thermal deformation.

Lubricant

The use of cutting fluid or micro-lubrication (MQL) technology can reduce the friction between the tool and the workpiece and lower the cutting force.

Sixth, optimization of processing sequence

Be rough first and then refined:

First, carry out rough machining to remove most of the allowance, and then proceed with fine machining to ensure dimensional accuracy and surface quality.

Symmetrical machining

For thin-walled parts with symmetrical structures, symmetrical processing methods are adopted to reduce deformation caused by stress concentration.

Seventh, tool wear monitoring

Regular inspection

Regularly inspect the wear of cutting tools and replace severely worn ones in a timely manner to prevent an increase in cutting force due to tool wear.

Tool life management

Establish a tool life management system and set the tool replacement cycle reasonably according to the processing conditions.