High-speed machining of micro tools

Micro-tools refer to milling cutters. The diameter of the drill does not exceed 0.25 inches (6.35 mm). The high-speed machine does not have a clear definition of absolute parameter parameters, but the more practical definition means that the high-speed spindle is required to be very complicated or fine. Machining.

The spindle speed of the machine tool exceeds 25,000 rpm.

As the manufacturing industry moves toward miniaturization, product sizes are declining and varieties are becoming more and more abundant. Therefore, the use of micro-tools is becoming more and more common. But the efficient and economical use of these small tools requires both the use of specially designed equipment and the willingness to move from conventional machining methods to new tools. This is mainly due to the fact that the spindle of a conventional CNC machine cannot meet the requirements of high-speed machining of small-diameter tools. Even if speed requirements are met, the spindle will be overloaded for a long period of time and add undue load to the equipment. For example, a tool having a diameter of fewer than 0.5 inches (12.7 mm) runs at a speed lower than or equal to 1000 rpm in a conventional CNC machining center, resulting in improper feed rate, broken tool, and the like. Often, people attribute tool breaks to operator errors, improper machining parameters, or worse reasons simply because of the small tool relationship. The fact is that the traditional machine tool spindle load and cutting force are large, and the high speed required, the chip is effectively discharged from the cutting groove.

Three prior art

The best way to perform efficient machining with small tools involves three levels of the process. These three interrelated elements include high speed machining technology, optimized micro tool design, and low viscosity coolant.

◆High-speed processing technology:

The smaller the tool, the more efficient it is to machine high-quality parts and avoid tool breakage. High-frequency spindles with speeds up to 6000 rpm are ideal for milling, drilling, tapping and engraving with micro-tools.

This technology uses high speed, small cutting steps, but significantly improved feed rate. For example, pass your hand through the burning candle. If your hand moves too slowly, it will leave enough time for the flame to cause damage, but if your hand passes through the flame very quickly, there is no time for the flame. To hurt your skin. The same principle applies to the high speed machining of micro tools. With a rapid movement, there is not enough time for the heat to act on the part, causing problems. During machining, the tool continuously cuts the chips from the workpiece, producing about 40% of the heat from the friction on both sides of the tool and 20% from the deformation (bending) of the chips. Therefore, approximately 60% of the heat is concentrated in the chips. High-speed machining strives to reduce heat in the chips and achieve clean cutting. Improving the quality of the process requires better cooling of the tool, reduced cutting forces, and low vibration. The high speed spindle reduces the chips to less than 0.005 inches (0.13 mm). This small chip load greatly reduces the friction between the tool and the material. The result of high-speed 1 low cutting force is reduced heat generation and reduced tool deflection. The machine can process thinner-walled workpieces, resulting in lower heat generation, excellent surface and edge quality, and higher precision. As a result, the workpiece is easily clamped due to the low cutting force. Because it is possible to use a modular vacuum table that is easier to set up, it is convenient to change batches. (especially thin flat plates plus [materials, even more so.)

◆ Optimize tool design:

Changing large diameter tools to small geometries produces unacceptable feed rates and surface finishes. When the tool diameter becomes smaller and the spindle speed increases, the requirements of Knife County should be changed. The traditional use of inserting J-pieces is no longer suitable for machining with micro-tools. This is mainly due to the increase in speed rather than the diameter. The increase in speed requires a better combination of the tool and the space left for the chips, ensuring that the chips can be discharged and prevented from accumulating. Effective machining with small tools requires special tools for high speed machining to optimize the tool. The right micro-tool geometry, combined with a high-speed spindle and ideal coolant, completely eliminates the need for subsequent deburring and grease removal.

◆Low viscosity coolant:

High-speed machining essentially reduces heat build-up and typically requires coolant to cool fast-moving micro-tools. Companies that specialize in high-speed machining with small tools know that coolants used in traditional CNC equipment are not ideal in this new situation, which is an excellent example of the need to jump out of the existing thinking-frame when using high-speed machining.

Small tools with complex geometries and extremely high rotational speeds require coolants and lubricants with lower viscosity than water. The low viscosity is required because the coolant needs to reach the edge of the tool even at high spindle speeds. Emulsions have a higher viscosity than water, so they are not effective lubricants for high speed machining with micro tools. However, some coolant micro-injection systems can use ethanol, which is commonly produced in sugar fermentation processes and typically has a lower viscosity than water. Ethanol has a low evaporation point and can be used as a very effective cooling and lubricant for efficient processing. Moreover, conventional coolants are all petroleum-based, and the waste liquid needs to be properly treated, and the ethanol only needs to be volatilized, thereby saving the cost associated with waste disposal. Furthermore, ethanol does not leave residual material on the processed product, thereby eliminating costly degreasing work.

Machine power

Using a micro tool is not as easy as finding a fixture to clamp a small tool onto a conventional CNO machine 40 taper spindle. Because the spindle is designed to accommodate large tools such as 3-inch fly knives for deep cutting of high-density substrates. In that case, the cutting will form a large moment and the cutting force, and the small tool will be easily broken, which will reduce the production efficiency and increase the cost in the long run. At this point, the operator's only option is to reduce the speed and feed rate to the creep state, which is very inefficient because the machining cycle is too long. “A vivid, perhaps somewhat funny, metaphor is to compare a semi-powered double-row minivan with a sports car. The reality is that you don’t compare the two or compare them. Why? Because of the truck design, It is to have the power and strength to pull or drag heavy goods, and the sports car is designed for speed and mobility.

In essence, traditional CNC manufacturers who boast the ability to run micro-tools, and car manufacturers put spoilers and racing stripes on bulky SUVs, and then claim that the car has the same performance as Porsche. Just as you can't expect to install spoiler and racing stripes on the SUV, it can behave like a sports car. You can't load a high-speed spindle on a cumbersome traditional machine, and then expect it to be highly efficient and high-speed machining with micro tools. same. When designing a machine, you can choose one of two directions. That is, you can design the machine to be a large motor, high-speed, low-cutting spindle for micro-tools, or to create a spindle with a lightweight, high speed, and low cutting force dedicated to micro-tools. Of course, both types of machine tools can be used for a variety of purposes, such as milling, drilling, tapping, slotting, etc. But the so-called versatility is also limited to this. Ultimately, if processing efficiency and quality are important and both large and small parts need to be machined, the result is that two different machines need to be installed in the same shop. Although it may seem like a repetitive investment in equipment, the cost can quickly be achieved through efficiency and versatility associated with return on investment (ROI).

Recycled. You can produce parts better, faster, and more economically.

solution

If high-speed machining centers are considered separately, the best way to machine with micro-tools is to use equipment that combines the above advantages of high-speed machining technology, optimized micro-tool design, and low-viscosity coolant. If you combine the three factors, you can bring unimaginable processing speed and product quality. However, the advantages are not limited to this, and the process can completely eliminate secondary work such as deburring and degreasing. Here, two examples of high-speed machining can be cited, as Datron machines can do. First: a 0.25-inch (6.35 mm) single-edged knife, cutting 6061 aluminum, cutting depth 1/8 inch, processing speed 45000 rpm, cooling with ethanol, feed rate 250" / min. Second, with 1 / 8 "Double-blade high-speed cutting tool (HSC+), processing 6061 aluminum plate with low helix angle, depth 1/8", processing speed 50000 rpm, ethanol cooling, feed rate 200" / min. High-speed machining has certain rules to follow. First, avoid overheating of the spindle, because it will aggravate wear and damage, and greatly reduce the service life of the spindle; "half the maximum diameter of the tool in the Z-axis direction: with a smaller step, Higher feed rate: Finally, move quickly to dissipate the heat from the chips.

In conclusion

In short, use the right tools to get the right job. The golfer will not use the No. 1 woods on the greens and will not use the putters to kick the ball. Conventional machine tools have low speeds and high spindle cutting forces, which cannot meet the requirements for efficient cutting of small tools. Only high-speed machine tools for micro-tool machining can meet the high-efficiency and high-quality machining of the most complex and small parts according to specific needs. High-speed machining with micro-tools has the advantages of low cutting force, less tool breakage, less heat accumulation, high surface finish, no need for deburring and degreasing, and low tool vibration. Spindles with speeds between 25,000 rpm and 60000 rpm, with smaller tools, resulting in better part quality and shorter machining times. Datron's machine range offers these advantages, giving users the benefits and helping manufacturers improve efficiency and product quality when machining small parts with micro tools. Our machine tools are typically 40" x 27" x 8", and are available in other sizes.

Deshengrui Machinery is a professional CNC manufacturing and sheet metal fabrication company, including CNC machining services, CNC turning service, CNC milling services, CNC drilling services, laser cutting services, stamping services, die casting service, iron casting service and steel forging service.