Reasonable selection of micro-tool coating 2

“The coarse particles in the coating are completely unacceptable for micro-size processing,” says Liu. “When the coating is deposited using a cathodic arc process, the coarse particles of the metal phase will eventually stick to the surface of the coating. Since the micro- Remove the coarse particles by polishing, as is usually done for larger cutters.

Liu suggested that the ion-arc process can be replaced by the ion sputtering process provided by CALLOY. The ion splash is more suitable for depositing a micro-tool coating because it can deposit a smooth thin coating with no coarse particles and the coating thickness can be maintained between about 1 and 2 μm.

Liu added. The coating of cemented carbide end mills is mainly to improve the productivity. Especially for those tools used to cut difficult-to-machine materials. “If you properly coat the carbide cutting tool will improve its performance, the same for any other carbide cutting tools.”

Regardless of the technical difficulty of coating micro-tools, many commercial coating companies are hesitant about the coating of such tools, but also because of the fragile knife in the course of operation is easy to be damaged. According to Liu, in the coating process, at least three steps to the implementation of the tool, first, the tool removed from the packaging one by one, and transferred to the cleaning rack; the second is to transfer the tool to the fixture fixture; Third, the tool back into the packaging, so that shipped back to the manufacturer there. “If the coating is sent in good condition and you are damaged during the coating process, you will need compensation.

If the miniature tool manufacturer has its own coating equipment, this will not be a problem. But most manufacturers do not have such equipment. So can only rely on external resources that may be more or less damaged some of the tools. Liu estimates that there is difficulty in coating operation and coating technology. About 95% of the micro-tools are not coated.

CALLOY Tool Company outsourced the coating of its micro-tools to other companies, and Liu said it was difficult to find a company that could handle the fragile micro-tools and be willing to coat them. “The smaller the tool size, the more the coating company It is possible to damage it. “

What’s the FPC?

What is general fpc1?

We all know that if it is a general-purpose fpc1, they are an ideal way to make threads on the fpc2 mill, and, in most metals, it can be used.

What is high performance fpc2?

High performance fpc4 is provided by fpc3, which can be used on most metals, but ideally for threaded aluminum and stainless steel components. The cutting tools are made of fpc5, and the titanium carbide coating is the characteristic of it, and the bottom of the bottom, the spiral is 40 degrees.

What is fpc5 conical tool?

Fpc8 and fpc7 are tools that can be affordable and portable. All you can use is a 32 JT tree and a match to give up.

What is fpc9 tool system -fpc8 cone tool

Below are the contents of fpc9 and drill chuck.

Fpc5 is used to install key and keyless drill clips. We can see that for many typical drilling applications, as an option is affordable, and it also has generality and hold a series of bit size can be placed with a drill.

Fpc7 cone fpc0, and compatible keying and keyless drill CARDS are all owned by us. If you want to order, the size of your drill chuck size with the corresponding arbor match is what you need to do. Only for the drill bit is fpc9, for milling or other side cutting loads are not supposed to be, because the chuck from fpc5 is often dissected by these types of cuts. Below are the features of fpc1 milling cutter: it is single-ended, has a fixed length, and is plated with titanium.

Two kinds of flute, most of which are designed for general use, are fpc5, including steel. A dark gray fpc5 coating is made of these cutting tools and is well known for its heat resistance and hardness.

Reasonable selection of micro-tool coating 1

“The tool coating is particularly beneficial for the processing of hard-to-machine materials.” Those harder materials contain large amounts of nickel and cobalt, which usually require processing with a coating tool. “However, for other materials it can not be so Say.

“It is certainly not necessary or necessary to force the use of the coating when cutting aluminum or plastic, and cutting aluminum with uncoated cutting tools has become a practice.” But there are exceptions, that is, the production workshop that wants to minimize the tool change. In this case, the use of PVD deposition of ZrN or TiB2 coating is more appropriate.

Coating systems and service providers also agree that the TiB2 coating is suitable for cutting aluminum alloys, but only for workpiece materials with a silicon content of less than 10%. He said that when the silicon content in the aluminum alloy is higher than 10%, TiB2 coating is difficult to effectively prevent the workpiece material and tool material bonding and transfer. Therefore, when the silicon content is higher than 10%, in view of the abrasive material of the workpiece, should be used CVD diamond coating tool.

Most coating companies apply cathodic arc deposition technology to a variety of coatings because they can evaporate and deposit more than 90% of the target onto the tool, compared to other methods, Liu said. Material waste is rare. “In addition, the kinetic energy associated with the process gives the coating a good adhesion.”

The disadvantage of the cathodic arc deposition process is that coarse particles are produced when the smooth coating is deposited. Liu described the coarse particles as “molten droplets”, which is a commonly used coating element, titanium. It’s almost like a little bit of splashing droplets. This droplet may not hinder the chip control of the larger tool, but when the tool size is getting smaller, its negative effect becomes more and more obvious, at this time, the tool coating business needs to adjust the process. Minimize droplet size or avoid droplets. Liu added that there is also a choice, that is, after coating to maintain the integrity of the coating under the premise of removing the droplets.

Liu said that if these coarse particles maintain the same basic size, the surface texture of the tool will become smooth, it is possible to catch the chips and squeeze the chips together.

Reduce cutting heat

With regard to the heat generated during micro-cutting, some university researchers have come to different conclusions. Purdue University’s research suggests that micro-cutting tools do not produce large amounts of cutting heat. This is because the micro-cutter needs high-speed rotation, and any heat is immediately taken away by the chips. These chips are very small. But with a large surface area ratio.

The effect of the coating is not to take away the heat, because the heat generated is very small. Processing, the spindle speed range of 250,000 ~ 750,000r / min (depending on the workpiece material and load conditions), the tip temperature of 27 ~ 33 ℃.

Dr. Rob Robinson, a former Purdue University doctor who worked with Jackson on the coating study, agrees that “the coating designed to reduce and take away the heat at the macro scale is completely unnecessary at the microscopic scale because at the microscopic scale , Cutting heat is not the cause of tool wear, the main reason is the mechanical force (rather than heat) caused by mechanical wear. Therefore, he pointed out that the coating for micro-tools only need to be used to improve the wear resistance of the tool.

In order to determine the temperature rise during micro-processing, Purdue University researchers conducted a finite element calculation. The relatively low melting point (such as sulfur, calcium, potassium, etc.) in the processed material was studied. “If you see a melting point (such as a small molten droplet) when processing an element with a melting point of 50 ° C, you can say that the cutting temperature is about 50 ° C. But we do not see any signs of melting,” Robinson explains. , So we conclude that micro – scale cutting does not produce a lot of cutting heat.

Due to the low cutting temperature, no coolant is required for processing, but researchers at Purdue University lead compressed air to the cutting zone. To help chip removal and to accelerate the oxidation of the workpiece material. “If the metal is not rapidly oxidized, the friction coefficient increases (even with the coating tool),” Jackson explains. “This leads to an increase in temperature, because it produces metal and metal bonds rather than metals and oxides Of the bond “.

Vertical milling of aluminum 2

Aluminum is easy to bond with cemented carbide is the reason for the large axial thrust when cutting with uncoated cutting tools. Vertical milling is an intermittent cutting process. Since the cutting edge cuts only the workpiece in the 180 ° rotation range, there is little continuous chip breakage. In the case of dry cutting, uncoated end mills occasionally produce continuous chips, because a newly generated chip adheres to the surface of the chip flute. In the next new chip is pushed to it, basically with it after being washed away. Pfefferkorn said, “there must be enough force to make the chips push each other.”

Micro-milling test also found. Diamond-coated end mills are more regular and more uniform on the machined surface, while the surface finish of the m-coated tool is not uniform, indicating that a large amount of cutting heat is generated during the cutting process. Said Carpick. “The heat generated in the cutting has a great impact on micro-tools, especially in high-speed machining”

The research paper points out that these performance enhancements are only available if the durability of the diamond coating is long enough. Approximately 80% of the fine grain diamond coated tools and 40% of the nano-diamond coated tool have peeled off the coating, which usually occurs after a few minutes of cutting. The original coating tool after the peeling of the coating or exhibits a performance similar to that of the uncoated tool, or abruptly fails. therefore. The next step is to study how to improve the adhesion of the coating.

Vertical milling of aluminum

According to Carpick, the team’s focus is on the use of coated micro-end mills to process 6061-T6 aluminum materials because the industry wants to increase the use of the material in the manufacture of various parts, including engine blocks. In addition, aluminum is easy to bond to the carbide cutter, but not easy to bond to the diamond tool because the diamond friction coefficient is small, less cohesive. For cutting tests. Researchers installed an electric drive and high-speed spindle with ceramic bearings on the Haas TM-1 CNC milling machine. In all tests, the speed of the high-speed spindle was 4000 r / min, given a feed rate of 500 mm / min. Performance Micro Tool provided a miniature end mill for the test. The test was used for cutting, but there was a set of humidity control systems with two nozzles blowing moist air through the tip. “The humid processing environment significantly reduces tool friction and wear,” Carpick said.

“When cutting, the cutting force applied to the diamond coating tool is lower than the cutting force at the time of cutting with the uncured carbide cutting tool under the spray cooling conditions of the cutting fluid.

Pfefferkorn said. Whether or not the cutting fluid is sprayed, the aluminum scrap is adhered to the uncoated tool.

Analysis of cutting force and axial thrust data in the paper “Micro-end mill performance analysis of diamond coating” shows that the use of uncoated end mills, 0.5 ~ 1μm thick fine grain diamond-coated end mills and 200mm thick nano-diamond coated end mill dry milling 6061-T6 aluminum, the required cutting force size has improved significantly: the main cutting force and axial thrust from the uncoated tool 2.14N (± 0.85N) and 4.40N (± 0.44N) to 0.49N (± 0.09N) and 0.34N (± 0.04N) of the fine grain diamond coating tool, while the nanometer diamond coating tool progresses to reduce the cutting force and axial thrust To 0.18 N (± 0.07 N) and 0.17 N (± 0.02 N). These data show that the cutting force of the coated tool and the axial thrust are more balanced, while the uncorrected tool axial thrust is twice the cutting force. The reduction in cutting force is due to the smaller friction and adhesion of the diamond coating.

Calloy USA Microdrill production line

The company has introduced its Calloy USA microdrill production line to the north American market. According to the company, the quality of the product line and its competitive pricing make it an attractive project. Located in Europe, the plant has been providing sophisticated products since 1928. For years, Calloy USA for the Swiss watch industry has been about microprecision.

Standard product size starts. 1mm(0.0039) to 3mm (0.118), in the hss-e-8% cobalt and 10% microgranular solid carbide, including the pilot point, 4-5-x D, 5-7 X D and 6-7 X D (high performance) series. Order the product within 2-3 weeks (10 pieces).

The Sec tool introduced the company’s new AM1 and AM2 polycrystalline diamond (PCD) drilling RIGS for composite manufacturing. It is reported that the new diamond cutting-edge technology to eliminate cutting fiber in the composite processing or layered problems, and make the company successfully developed the industry’s first three PCD groove geometry (AM1) used for composite drilling. AM1 and AM2 PCD are designed to provide the sharpest and most powerful cutting edges available now, using reliable PCD techniques. These techniques can be sharper than the PCD coating, and when the coating is applied, the package cuts the edge and produces a blunt effect. The additional advantages of new solid PCD include high cutting speed, long knife life, low friction, excellent thermal conductivity, multiple sharpening ability and high process reliability.

“In compound processing, sharp edges are very hard to cut in all materials,” says Scott Turner, the company’s marketing manager. If not cut, these fibers will eventually lead to wear and premature replacement of the material. In addition, sharper cutting tools have less pressure on materials, less stress, and less toughness.

In order to effectively utilize the “ordinary” composite material, the third flute on AM1 provides high level of stability, but also reduces vibration and improves roundness. Similarly, AM1’s domed tip applies a biangular geometric shape that reduces uncut fibers and reduces layering in composite applications. It is impossible to grind these highly complex geometries using conventional brazing or similar PCD techniques.

Micro tool coating points

Pfefferkorn argues that, in fact, the geometric characteristics of the micro-tool are not as precise as desired, “the radius of the cutting edge of the miniature end mill is already greater than we would expect from the chip load produced during cutting.”

In addition to working with researchers with experience in hot-wire CVD deposition, the team chose this deposition process because the thickness of the coating deposited by other CVD methods, such as plasma-based deposition processes, The multi-material is deposited on the tip, Pfefferkorn says, “Growing a sphere on a sharp cutting edge like a dog’s bones. I’m not saying that hot wire CVD is the only way to use it, The reason is because it does not produce this ‘dog bone effect’. ”

The coating is not only thinner. And must have good adhesion with the matrix, but also should be continuous and smooth, although the latter feature is difficult to quantify. “We are trying to eliminate the limitations of building suitable models for smoothness,” says Carpick. “So we can not know exactly how smooth the coating needs, and we think that a little bit rough may be useful because it may Helping to prevent the workpiece material from sticking to the tool.

Since the nanocrystalline diamond coating can be very thin, it can be adapted to the surface morphology of the substrate, including the grinding of the tool grinding and the cracks caused by the etching process. The micron grain coating can cover these surface defects. Pfefferkorn said, “micro-tools have been quite rough, we do not need to make them more rough.”

Processing of Micro tool coating

To the cobalt treatment, the need to selectively etching out the most appropriate amount of cobalt, and not too much to weaken itself is very thin micro-cutting tool In order to prevent the removal of too much drilling and affect the integrity of the tool, Weight ratio) must not exceed 6% to 8%. “We cut all the cobalt in the thin surface to prevent it from affecting the growth of the diamond,” says Pfefferkorn, “and we minimize the effect of tool integrity by controlling the depth of the etch.”

The paper points out that the research team at the University of Wisconsin-Madison conducted a seeding operation after completion of the etching: the use of ultrasonic treatment in acetone, the use of nano-diamond powder on the matrix deposition of diamond particles. The introduction of the grain played a role in positioning, where the diamond began to grow (ie nucleation). Nano-diamond powder agglomeration leads to uneven seeding and uneven growth of diamonds. Therefore, the researchers used ultrasonic cleaning in alcohol solutions to ensure that large grains were removed to achieve uniform seeding.

Then, using the hot-wire chemical vapor deposition system designed and fabricated by the research team, nano-grain and fine-grained diamond were grown on the tool. Carpick confirmed that the grain size of nanocrystalline diamond was 10 to 100 μm, Particle size greater than 100nm, less than 300nm). The deposition system comprises a deposition chamber in which the tungsten wire at a temperature of at least 1800 ° C is filled with a shielding gas (particularly methane diluted in hydrogen).

The thickness of the coating obtained by deposition is about 60 to 200 m. The average tool has a diamond coating thickness of 2μm or more, which is too thick for micro-tools because the radius of the cut edge of the uncoated micro-tool is often less than 1μm. “The thickness of the coating used for large-scale tools is not suitable for micro-tools, it will passivate the tool and thus greatly reduce its cutting performance,” Carpick said.

Find a better micro-tool coating

Since the coating of the cutting tool is beneficial to the processing of the macro size, there may be reason to deduce that the tool coating is also advantageous for small size machining. If the coating is properly applied and the coating thickness is thin enough to pass the microcrystalline edge, some researchers may agree with this view. However, these researchers have not yet finalized whether the micro-tool coating is conducive to processing, as well as the best way to coat.

In order to understand how to more effectively the micro-tool coating, some universities are carrying out relevant research. This paper is a study of the University, including the deposition of diamonds and other coatings on micro-tools, the selection of preferred coating methods, and the study of different workpiece materials on the coating tool response.

Application of an increasing number of diamond coatings

One of the challenges for diamond coatings is the adhesion of the coating to the tool surface. A team of researchers from the University of Wisconsin-Madison, the University of Pennsylvania and the Argonne National Laboratory has deposited a layer of transition on micro-end mills to enhance the adhesion of diamonds, And deionized water were tested on a 300 μm double-slot micro-end mill. According to Flank E. Pfefferkorn, assistant professor of mechanical engineering at the University of Wisconsin-Madison, one of the purposes of this test is to create a mechanical link between the cemented carbide substrate and the diamond coating.

Pfefferkorn and Robert W. Carpick, Associate Professor, Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania (who was dedicated to the study of diamond coatings at the University of Wisconsin-Madison) and his graduate students and partners in the paper titled “Diamond Micro Milling cutter: the ability to micro-size aluminum cutting “papers pointed out that the cobalt binder can enhance the toughness of the tool, but will weaken the diamond coating and the bonding strength between the matrix, and by limiting the formation of nuclei and inhibit the diamond Grow. “The main reason for removing the drill from the surface of the substrate is that it hinders the growth of the diamond,” Pfefferkorn said.