Selection of cutting parameters for end mills in spectacle frame processing

In the processing of spectacle frames, the selection of cutting parameters for end mills needs to comprehensively consider material properties, tool geometric parameters, processing accuracy requirements, and equipment capabilities. The following is a specific analysis:

First, material properties and tool selection

Spectacle frame material

Spectacle frames are usually made of materials such as titanium alloy, memory alloy, stainless steel or acetate fiber, and the cutting performance of different materials varies significantly:

Titanium alloy: It has large elastic deformation and obvious cutting vibration. Therefore, it is necessary to select tools with good rigidity and control the cutting parameters.

Memory alloys: They have a strong tendency to work harden, so a larger rake Angle and a smaller cutting force need to be selected.

Stainless steel: It is prone to built-up edge formation, so sharp cutting edges and suitable cutting fluids should be selected.

Acetate fiber: It is a non-metallic material. Dust is prone to be generated during cutting, so appropriate cutting tools and cutting parameters need to be selected.

Geometric parameters of cutting tools

Rake Angle: Generally, it is taken as 5° to 12°. When processing titanium alloys or memory alloys, the rake Angle can be appropriately reduced (such as -5° to 5°) to enhance the strength of the tool.

Relief Angle: Generally, 13° to 16° is taken to reduce the friction between the rear tool face and the workpiece.

Helix Angle: Usually 26° to 30°, which can improve the stability of cutting.

Number of cutting edges: When performing rough machining, select 2-edge or 3-edge end mills to increase the chip holding space. When performing finish machining, select 4-edge or 6-edge end mills to enhance machining accuracy.

Second, selection of cutting parameters

Cutting speed (Vc

Carbide end mills

Titanium alloy: 30-45 m/min

Stainless steel: 60-90 m/min

Acetate fiber: 100-200 m/min (subject to adjustment according to actual cutting conditions)

High-speed steel end mills

Titanium alloy: <10 m/min

Stainless steel: 12-20 m/min

Feed per tooth (fz)

Rough machining: 0.05-0.15 mm per tooth

Finishing: 0.02-0.08 mm per tooth

When processing titanium alloys or memory alloys, a smaller feed per tooth should be selected to reduce the cutting force.

Axial cutting depth (ap) and radial cutting depth (ae)

Axial cutting depth: It is selected based on the rigidity of the machined area, usually ranging from 0.5 to 2 mm.

Radial cutting depth: Selected based on the tool diameter, it is usually 30% to 50% of the tool diameter.

Third, processing technology and equipment capabilities

Processing technology

Spectacle frame processing usually includes three stages: rough machining, semi-finish machining and finish machining. The cutting parameters of each stage need to be adjusted according to the processing requirements.

When processing small parts (such as mirror legs and nose pads), it is necessary to select end mills with smaller diameters and control the cutting parameters to avoid tool vibration and overcutting.

Equipment capacity

The spindle speed, feed rate and power of a machining center or CNC milling machine must meet the requirements of cutting parameters.

When processing titanium alloys or memory alloys, it is necessary to ensure the rigidity of the equipment and avoid cutting vibration.

Fourth, selection of cutting fluid

Titanium alloys and stainless steel: Extreme pressure cutting fluid or kerosene is recommended to reduce cutting heat and built-up edge.

Acetate fiber: It can be cooled with compressed air to avoid the impact of cutting fluid on the material.

Fifth, suggestions for parameter optimization

Test and Adjustment

Before formal processing, cutting tests need to be conducted and the cutting parameters adjusted according to the actual cutting effect.

Record the optimal cutting parameters under different material and tool combinations to form a processing database.

Tool monitoring

Regularly inspect the wear of cutting tools and replace worn ones in a timely manner to prevent a decline in processing quality due to tool wear.

Equipment maintenance

Ensure that the main shaft, guide rails and feed system of the equipment are in good condition to avoid unstable cutting parameters caused by equipment problems.