News

2024/10/11 005｜Application and development of ball End Mill (Part 2)

Application and development of ball End Mill (Part 2)

1. Common milling methods

◼ Copy milling : The ball milling cutter is used to process curved surfaces and complex shapes. The tool moves along a predetermined trajectory to obtain the required three-dimensional curved surface shape. In terms of application, it is often used in mold manufacturing, curved surface parts processing and other operations.

◼ Oblique milling : The tool cuts into the workpiece surface obliquely at a certain angle to achieve high-efficiency material removal. It is suitable for application in large-area curved surface processing, such as rough machining of large molds.

◼ Parallel milling : The tool processes along a path parallel to the workpiece surface. It is suitable for surfaces that are relatively flat or have slight curvature. It is often used in the finishing stage of molds to obtain a smooth surface.

◼ Spiral milling : The tool moves downward or upward in a spiral shape to process continuous curved surfaces, reducing surface contact points and obtaining uniform surface quality. It is suitable for processing internal arcs, cylinders or conical shapes, etc.

◼ Side milling : The side edge of the ball milling cutter is used to process the side or edge of the workpiece. This method can process the vertical and curved parts of the workpiece at the same time. It is often used to modify the contour or edge of the workpiece, such as the side wall of a mold.

◼ Local finishing : For fine processing of local areas, the ball milling cutter only processes a certain part of the workpiece surface to achieve high precision requirements. Application: Used for local detail processing that requires high surface quality, such as key surfaces of molds.

These milling methods combine the characteristics of ball milling cutters and can achieve a variety of processing needs from rough machining to fine machining. They are widely used in mold manufacturing, automotive industry, aerospace, watches, glasses, electronic parts and other fields.

2. How to perform surface processing

The process of curved surface processing by ball milling cutters is mainly realized through its unique hemispherical blade design, so it is very suitable for processing complex three-dimensional curved surfaces and corners. The following are the basic principles and steps of curved surface processing by ball milling cutters:

⚫ Tool selection and setting :
To meet the requirements for processing curved surface shape and accuracy with a suitable ball milling cutter diameter and R angle, you must first set the processing parameters, such as spindle speed, feed speed and cutting depth, to ensure a stable processing process.

⚫ Tool path design :
According to the surface shape and design requirements of the workpiece, simulate and generate tool paths. Commonly used path modes include copy milling, spiral milling and parallel milling. These paths are usually generated using CAM (computer-aided manufacturing) software to ensure that the tool can Follows the workpiece surface precisely.

⚫ Cutting layer by layer :
The ball milling cutter removes material layer by layer through multiple cuts. The infeed depth of each cut is usually shallow to maintain the smoothness and accuracy of the processing. Due to the curvature of the cutting edge of the ball milling cutter, contact during cutting The smaller area helps reduce cutting forces and improve surface quality. (As shown in Figure 02)

⚫ Surface finish control :
The machining of ball milling cutters can achieve high-gloss surface treatment. This is because it can evenly cut away small bumps on the surface of the workpiece, leaving a smooth curved surface. In the finishing stage, a smaller cutting depth and slower feed speed are usually selected to further improve the surface quality.

⚫ Check and fix :
After completing the processing, check the accuracy and smoothness of the surface, and make corrections if necessary. This may include secondary or multiple fine cutting or polishing treatments to meet the final requirements.

※ Advantages of ball milling cutters in curved surface processing -

◼ Fine curved surface processing: Process smooth three-dimensional curved surfaces with high precision, suitable for complex-shaped molds and parts manufacturing.
◼ Diversified processing paths: The tool path can be flexibly designed according to the needs of the workpiece to adapt to different surface characteristics.
◼ Efficient material removal: Material is gradually removed through multiple cuts, which can effectively control errors during the machining process.

In short, ball milling cutters can efficiently and accurately complete various complex curved surface processing tasks with their unique design and flexible processing methods in curved surface processing. The development of ball milling cutters can be traced back to the early 20th century. In modern times, with the advancement of machining technology, excellent results can be achieved for high-precision curved surface processing and complex surfaces.

※ The following two methods are commonly used for curved surface milling -

3. What is R angle? And the importance of the R angle

The R angle is the radius of curvature of the cutting edge of a ball milling cutter, which is the radius of the cutting edge from the center of the tool to the edge of the tool. For ball milling cutters, the R angle usually represents the radius of the hemispherical part of the cutting tool, which determines the cutting speed of the cutting tool. The radius of the curved surface that can be processed at the same time, and the R angle is a very important feature for ball milling cutters.

◼ Precision control: The size of the R angle directly affects the smoothness and accuracy of the processed surface. A smaller R angle can process finer and more precise curved surfaces, while a larger R angle is suitable for processing a wide range of curved surfaces.
◼ Stress distribution: Appropriate R-angle design can optimize the stress distribution during the cutting process, reduce tool wear and extend tool life.
◼ Surface finish: When processing curved surfaces, a suitable R angle can reduce surface roughness and obtain higher surface finish.

4. How to choose the R angle?

◼ According to the requirements of the workpiece: If a very fine curved surface needs to be processed, a smaller R angle should be selected; on the contrary, a larger R angle is suitable for processing larger curved surfaces or roughing stages.
◼ According to material characteristics: For materials with higher hardness or brittleness, choosing a smaller R angle can reduce the cutting force and reduce the risk of chipping, or adjust and design the processing path to adapt to the material.
◼ Processing efficiency: In some cases, choosing a larger R angle can improve processing efficiency, because it can allow larger cutting depths and can also produce finer arcs and corners.

5. Application of R angle in ball milling cutters

Advantages of the R angle of the ball milling cutter in curved surface processing -

In practical applications, the selection of R angle needs to be determined according to specific processing requirements. For example, in mold manufacturing, ball milling cutters with different R angles are often used for step-by-step machining. The large R angle is used for rough machining first, and then the small R angle is used for finishing to achieve high precision and high finish.

6. Dilemma of ball milling cutter

⚫ Lower cutting efficiency: Since the contact area of ball milling cutters is smaller, especially in the center part of the tool, the cutting efficiency is not as good as other types of milling cutters, which may result in longer processing times, especially when roughing large areas.
⚫ Easy to produce tool marks: When the ball milling cutter is processing a curved surface, if the tool path design is improper or the feed speed is uneven, it is easy to leave tool marks on the surface of the workpiece, affecting the surface quality and requiring additional subsequent polishing.
⚫ Limited tool life: Due to the small contact area and low cutting speed, the tip portion of the ball mill is susceptible to concentrated wear, which may lead to shortened tool life, especially when machining hard materials.
⚫ Accumulation of processing errors: During multiple cutting processes, small positioning errors and the accuracy limitations of the machine tool may lead to accumulated errors, thus affecting the accuracy of the final product.
⚫ Not suitable for large feed processing: Ball milling cutters are not suitable for large feed processing, because this will increase the cutting force and lead to tool deformation or chipping, especially when processing materials with higher hardness.

According to the above list, if the cutting points are concentrated at the tip with greater cutting resistance, the blade is likely to chip. Therefore, special attention must be paid during processing, and the various coefficients and spherical rows must also be paid attention to during processing. The chip performance is poor. Improper use may reduce the quality of the machined surface and damage the insert. Therefore, before processing, it is extremely important to select the material of the milling cutter, the manufacturer, demand, and blade design of the milling cutter. Huiyi Precision (S&A TOOL) specially selects three common ball knives for reference :

⚫ If you need a small and compact milling cutter for precision machining.
－You can refer to this one: [ UYB-Two-edge micro-diameter ball cutter ]

⚫ If you need a milling cutter for deep processing and flexible operation.
－You can refer to this one: [ MENB-Two-edge high-hardness long-neck ball cutter ]

⚫ If you need a milling cutter with strong hardness and efficient curved surface production.
－You can refer to this one: [ UXB-Four-edged Ball Cutter ]

7. Solutions and improvements

To resolve these dilemmas, the following measures are often taken -

➤ Optimize tool paths: Use advanced CAM software to design reasonable tool paths to reduce the occurrence of tool marks and improve processing efficiency.
➤ Choose appropriate tool materials and coatings: Use more wear-resistant and harder tool materials and coatings to extend tool life.
➤ Adjust processing parameters: Balance processing efficiency and surface quality by adjusting spindle speed, feed speed and cutting depth.
➤ Post-processing and polishing: When surface smoothness is required, post-processing and polishing will be performed to remove knife marks and improve surface quality.

Generally speaking, these difficulties of ball milling cutters can be alleviated by optimizing processing strategies and rational selection of cutting tools. Although there are shortcomings, its application in complex curved surface processing is still irreplaceable.

8. Future development

Ball milling cutters are multi-functional and changeable tools, and even have many variant designs in recent years. Therefore, with the needs of the times and the continuous advancement of technology, ball milling cutters will usher in more changes in materials, design and applications. Innovation and development:

◼ New material application: In the future, ball milling cutters will use more new materials, such as nanomaterials, cemented carbide, etc., which will not only improve the wear resistance and service life of the cutter, but will also be able to be used in more aspects.
◼ Intelligent manufacturing: Combining the Internet of Things and artificial intelligence technology will enable intelligent monitoring and predictive maintenance of ball milling cutters, further improving production efficiency and processing quality, and also promoting the development of new technologies.
◼ Green manufacturing: Develop environmentally friendly ball milling cutters to reduce energy consumption and environmental impact during processing, strike a balance between environmental protection and nature, and promote the sustainable development of the manufacturing industry.
◼ Precision machining technology: With the advancement of precision machining technology, ball milling cutters will be able to achieve higher precision and more complex shape processing requirements, meeting the application needs of more industries.

As an important tool in modern machining, ball milling cutters have a wide range of applications and development potential. With the continuous innovation of technology, ball milling cutters will play an important role in more fields in the future, matching new types of machine models. Along with the innovation of multi-axis machine tools, ball milling cutters will promote the development of manufacturing industry in a more efficient, smarter and greener direction, allowing the development of milling cutters to continue to be important into the future.

"How far can this milling cutter go? I really want to know......"
"I don't know which milling cutter is suitable for me, it's really confusing......"
"I have a plan that requires additional precision machining, but I don't know how to execute it......"

If you have any questions such as the above or want to know more about the article, you can contact us. "S&A Tool" will provide kind replies and consultations to help you solve your current problems!