V-tec veined rotary cutting tools, including helical end mills and drills, are PCD-coated using a high-pressure and high-temperature process that allows polycrystalline diamond (PCD) to be directly sintered into the veins that form complex geometric shapes. While PCD Cutting Carbide Inserts is typically only available in flat segments, this process allows the end mills and drills to be offered in solid-body helical geometries that are free of braze joints?that may be prone to failure, making it possible to machine highly abrasive materials, the company says. Non-ferrous application materials include composites, aluminum alloys, copper alloys, metal matrix composites, ceramics, graphites, carbides, friction materials, green ceramics and magnesium. ? According to the company, the advantages Helical Milling Inserts of the helical end mills and drills include providing a broader application range, lower production costs, improved productivity and workpiece quality, improved tool life, lower machine setup costs and reduced inventory quantities. Cutting edge sharpness and retention are said to improve surface finishes, while the helical geometry of the tools are said to lower tool forces and support better chip evacuation. The end mills and drills are designed with increased thermal conductivity and lower coefficient of friction to result in less heat buildup and adhesion.
During NC programming, the programmer must determine the cutting dosage for each process and write it in the program as an instruction. Cutting dosage includes cutting speed, back engagement and feed speed. Different cutting dosages are required for different processing methods.
1. the selection principle of cutting dosage
When roughing, it is generally based on improving productivity, but economical and processing costs should also be considered. In the case of semi-finishing and finishing, cutting efficiency, economy and processing cost should be considered on the premise of ensuring processing quality. The specific values should be based on the machine manual, the cutting dosage manual, and the experience.
Starting from the durability of the tool, the selection order of cutting dosage is. first determine the back engagement, then determine the feed, and finally determine the cutting speed.
2. Determination of back engagement
The back engagement is determined by the stiffness of the machine tool, the workpiece and the tool. When the stiffness is allowed, the back engagement should be equal to the stock amount of the workpiece as much as possible, which can reduce the number of passes and increase the production efficiency.
How to determine the principle of back engagement.
(1) When the surface roughness value of the workpiece is required to be Ra12.5μm~25μm, if the stock amount of CNC machining is less than 5mm~6mm, the rough processing can meet the requirement once. However, when the margin is large, the rigidity of the process system is poor, or the machine power is insufficient, the feed can be divided into multiple times.
(2) When the surface roughness value of the workpiece is required to be Ra3.2μm~12.5μm, it can be divided into two steps of roughing and semi-finishing. The back engagement during roughing is the same as before. After roughing, leave a balance of 0.5mm~1.0mm and cut it off during semi-finishing.
(3) When the surface roughness value of the workpiece is required to be Ra0.8μm~3.2μm, it can be divided into three steps. roughing, semi-finishing and finishing. The back engagement during semi-finishing takes 1.5mm~2mm. The back engagement is 0.3mm~0.5mm during finishing.
3. the determination of the feed
The feed is mainly based on the machining accuracy and surface roughness requirements of the part and the material of the tool and workpiece. The maximum feed speed is limited by the stiffness of the machine and the performance of the feed system.
How to determine the feed speed.
1) When the quality requirements of the workpiece can be guaranteed, in order to improve production efficiency, a higher feed speed can be selected. Generally, it is selected in the range of 100 to 200 m/min.
2) When cutting or machining deep holes or machining with high speed steel tools, it is advisable to choose a lower feed speed, generally in the range of 20 to 50 m/min.
3) When the processing accuracy and surface roughness are high, the feed speed should be selected to be smaller, generally in the range of 20 to 50 m/min.
4) When the tool is taking the idle stroke, especially when the distance is “return to zero”, the highest feed speed set by the machine numerical control system can be selected.
4. the determination of the spindle speed
The spindle speed should be selected based on the allowed cutting speed and the workpiece (or tool) diameter. Its calculation formula is.
n=1000*v/π*D
v—-cutting speed, in m/min, determined by the durability of the tool;
N—-spindle speed, the unit is r/min;
D—-diameter of work piece or tool diameter in mm.
The calculated spindle speedn is finally selected according to the machine manual to have a speed that is relatively close to the machine.
In short, the specific value of cutting dosage should be determined by analogy based on machine performance, related manuals and practical experience. At the same time, the spindle speed, depth of cut and feed speed can be adapted to each other to form the optimal cutting dosage.
5. the reference formula
1) back engagement (ap)
The vertical distance between the machined surface and the surface to be machined is called the back engagement. The back engagement is the engagement measured by the cutting point base point and perpendicular to the working plane. It is the depth of the turning tool into the workpiece for each feed, so it is called depth of cut. According to this definition, as in the horizontal to cylindrical lathe, its back engagement can be calculated as follows.
Ap=(dw-dm)/2
In the formula ap—-back engagement(mm);
Dw—-surface diameter of the workpiece to be machined (mm);
Dm—-The surface diameter (mm) of the workpiece has been machined.
Example 1. The diameter of the surface to be machined is known to be Φ95mm; now the feed car is Φ90mm in diameter and seek back engagement.
Solution. ap=(dw-dm)/2=(95-90)/2=2.5mm
2) feed (f)
The relative displacement of the tool and the workpiece in the direction of feed movement per revolution of the workpiece slot milling cutters or tool. According to the direction of the feed, it is divided into horizontal feed and transverse feed. The horizontal feed refers to the feed along the direction of the lathe bed rail, and the transverse feed refers to the feed perpendicular to the direction of the lathe bed rail.
Feed speed v f is the instantaneous velocity at which the selected point on the cutting edge moves relative to the workpiece feed.
Vf=f*n
Where vf—-feed speed(mm/s);
N—-spindle speed(r/s);
f—-feed(mm /s).
3) cutting speed (vc)
The instantaneous velocity of the main motion of the selected point on the cutting edge relative to the workpiece.
Vc=( π*dw*n)/1000
In the formula vc—-cutting speed (m/min);
Dw—-surface diameter of the workpiece to be machined (mm);
n—-Workpiece speed (r/min).
In tungsten carbide inserts the calculation, the maximum cutting speed should be taken as the standard. For example, when the machine is used, the value of the surface diameter to be machined is calculated because the speed is the highest and the tool wears the fastest.
Example 2. The outer diameter of the workpiece with a diameter of Φ60mm, the selected lathespindle speed is 600r/min, and vc
Solution. v c=( π*d*w*n)/1000=3.14x60x600/1000=113 m/min
In actual production, it is often known as the diameter of work piece. According to the workpiece material, tool material and processing requirements, the cutting speed is selected, and then the cutting speed is converted into lathespindle speed, in order to adjust lathe, the following formula is obtained.
n=( 1000*vc)/π*dw
Example 3: On the CA6140 horizontal lathe machine Φ260mm pulley outer circle, select vc is 90m / min, find n.
After calculating the lathespindle speed, the value close to the nameplate should be selected, that is, n=100r/min is selected as the actual speed of lathe.
6.?summary
The three factors of cutting dosage are the general term for cutting speed (vc) , feed (f),feed speed (vf), and back engagement (ap).
1.back engagement ap(mm)
ap=（dw-dm) / 2
2.feed f(mm/r)
vf=f*n
3.cutting speedvc(m/min)
vc=( π*dw*n)/1000
The Carbide Inserts Website: https://www.estoolcarbide.com/product/cnmm190624-cnmm646-turning-inserts-high-quality-carbide-cutting-tool-for-machine-tools/
In order to stay competitive in their industries, manufacturers must always be on the lookout for new ways to provide value while keeping cost to a minimum. That is one of the duties of David Zurowski, Dihart carbide group leader at Komet of America Inc. (Schaumburg, Illinois). When the company needed to produce complex tools at higher production rates, he knew its existing Carbide Turning Inserts grinders could not keep up with the task. By investing in a universal cylindrical grinding machine from Junker (Elgin, Illinois), Komet was able to decrease production time while providing the same, high-quality products.
Established in 1918, the Komet Group is a full-line supplier of drilling, boring, reaming, threading and milling tools. With a total workforce of 1,600, the privately held company manufactures reamers, cutting rings and rapid-set heads with carbide and cermet blades. Led by President and CEO Jan Pflugfelder, Komet of America and its 140 employees are dedicated to the design and manufacturing of special indexable tools, polycrystalline diamond tools and reamers.
With a growing demand for complex tools, Komet needed to manufacture at higher production rates without sacrificing quality. The company tungsten carbide inserts determined that its existing grinders could no longer keep up with effectively producing its multi-step tools. In particular, tools with a flat diameter and back taper caused a major production bottleneck because the grinders required an extra setup to adjust the table to match the angle.
Komet began searching for a solution that would remove this extra setup as well as grind the tools in one clamping to simplify the process. Moreover, the company needed the grinding machine to be delivered in a short amount of time and to be able to accommodate a diamond grinding wheel. To meet these requirements, Komet searched for a CNC grinding machine with a freely programmable B axis that could accurately and efficiently grind parts. According to the company, Junker’s Lean Selection allround stood out because it offers a rigid B axis with 0.0001-degree resolution that is capable of grinding all the tapers Komet needs to manufacture its tools. Along with the crucial B axis, the flexibility of the grinding machine set Junker apart from the competition, the company says.
Mr. Zurowski says Komet selected a grinder with a choice of two grinding spindles because “we believe that we will have fewer limitations having one wheel per side and more clearance for our complex tools.” The machine was also available in a short delivery time and at an appealing price point, he says.
In addition to the proper mechanical features, the company sought a custom-designed grinding program to reduce the amount of air grinding. The carbide inserts ground on each reamer are set at common intervals along the diameter, meaning the grinding surface is interrupted. After several discussions about the problem, Junker suggested using its gap detection acoustic sensor to control the workhead speed. Now, when the grinding spindle detects air grinding, the workhead rotates quickly until the next carbide insert is detected. At each insert, the workhead slows to the “grind” setting then speeds up again to the “air” setting when finished grinding. This is designed to ensure the best cycle time.
In April 2015, the Junker Lean Selection allround arrived at Komet and was up and running shortly thereafter. With machine operation in full swing, the company immediately noticed significant savings in production times. Mr. Zurowski says that setting back the taper with the B axis has been easier, hassle-free and faster for operators. “In setup, we save around 30 to 35 minutes,” he says. The grinder’s flexible design not only provides significant savings in setup time, but it also reduced running time by 5 to 10 minutes per part. The freely programmable B axis enables the operator to grind continuously without having to change out the grinding wheel.
Despite the improved run time and setup time, Komet detected a final inefficiency after installation. Some parts required a wheel change in order to grind multiple features, making wheel-change time a critical factor in throughput. To improve change-over time and prevent potential quality issues when mounting a new wheel, the company implemented Junker’s three-point grinding wheel mounting system, which reduces wheel change-over times to less than 20 minutes and guarantees a wheel concentricity of less than 2 microns. Now that the system is installed, the company says it is experiencing a further reduction in setup times, improved grinding times and even better part quality.
“From our experience in grinding reamers and the way we set up and run the Junker, our finished product is the same quality despite a reduction in production time, which is what we were looking for,” Mr. Zurowski says.
Komet uses the same grinding wheels as it previously did, but the company says that setup is simpler, change-over is faster, and grind time is reduced. The machine is equipped with the JUWOP/LS programming system, in which the graphically supported data entry and to-scale representation on the screen are designed to make machine programming easy with little or no training.
Today, the company produces high-quality reamers with greater efficiency and at competitive costs for a quality/value proposition, Mr. Zurowski says. The economical and flexible Junker Lean Selection allround gives the tool supplier the freedom to manufacture a wide range of parts with high quality and precision as it aggressively seeks to expand its markets and provide new applications to its customers.
The Carbide Inserts Website: https://www.estoolcarbide.com/product/tungsten-carbide-inserts-turning-inserts-on-lathes-tnmx110616-tnmx150916-using-for-peeling/
TDM Systems has introduced TDM Cloud Line, a cloud-based Carbide Milling Inserts solution for tool data management that enables manufacturers to fast feed milling inserts access tool data wherever, whenever. The key advantage of the solution is that users can download and manage data from thousands of tools without having to purchase them, according to the company. Users can test alternative tools during the product design process and select the best tool for the job. Data from the cloud is available anywhere and ready for immediate usage in the virtual cutting process.
Other benefits include easy tool database setup, prepared and tested tool data for immediate use, provisioning of correct CAM data, manufacturer-independent tool assembly, statistical evaluation, and a structured and configurable user interface.
Not only introduction of graphene carbon nanotubes comes, but also new carbon nanomaterials and their auxiliary mechanisms！
Fullerene, carbon nanotubes (CNTs, Carbon Nanotubes) and graphenes (Graphene) are popular carbon nanomaterials in recent years. Currently, five scientists have won the Nobel Prize in this field. Why are carbon nanomaterials widely sought after? For example, bicycles made of carbon fiber-added steel are only a fraction of the weight of ordinary bicycles because of the very small mass of carbon atoms and the chemical bonds between carbon atoms or between carbon atoms and other atoms. Very strong. Therefore, materials mixed with carbon nanometers usually have better mechanical properties and lighter overall weight.
First principles are widely used in physics, chemistry, and materials science. Material design, material prediction, interpretation experiments, etc. are inseparable from the first-principles calculation, because the first principle starts from the Schr?dinger equation and requires very few parameters to calculate most of the material properties of the material very accurately; Further combined with the adiabatic assumption, it can also be used to simulate molecular dynamics. In the field of carbon nanomaterials, first-principles calculations are widely used because the electronic correlation of carbon atoms is very weak, and the first-principles calculations can often make very accurate predictions.
This article will introduce some new types of carbon nanomaterials that differ slightly in the way carbon atoms are combined and arranged in well-known fullerenes, carbon nanotubes, and graphene. These subtle differences can be reflected in the final material properties but can vary greatly. A small difference in the arrangement of carbon atoms can translate into large differences in material properties, which is where carbon nanomaterials attract many materials scientists, physicists, and chemists.
1.Hybridization and dimension
There are two main ways to hybridize carbon atoms to carbon nanomaterials: sp2 or sp3. In the sp2 hybrid mode, each carbon atom forms three molecular orbitals uniformly distributed in a plane at an angle of 120 degrees, and an out-of-plane p-orbit, commonly known as pz orbital; the most typical carbon nanomaterials It is a famous graphene. In the sp3 hybrid mode, each carbon atom forms four molecular orbitals that are evenly distributed in space, roughly forming the shape of a regular tetrahedron from the body to the four vertices. A typical solid material represents a diamond, but A typical representative of the world of nanomaterials is Adamantane. Adamantane is a representative of a whole family of materials, and a molecule contains a core of the diamond structure. If it contains multiple cores of diamond structure, then this family of materials will become Diamondoid. Figure 1: Typical carbon nanomaterials classified according to hybridization (sp2, first row; or sp3, second row) and material dimensions.
The above is just hybridization, or rather, a mainstream choice that a single carbon atom can make when forming a nanomaterial. When many carbon atoms are combined, in addition to hybridization, they can choose to expand in any direction. Is it a zero-dimensional material or a high-latitude material? The above chart 1 lists various representative materials according to hybridization and dimension.
One-dimensional materials in sp3 hybrid mode lack a typical. Readers familiar with relevant research may think of Polyethylene, but in terms of individual molecules, polyethylene molecules lack some long-range configuration rules, or long-range order, and lack the cravings usually in carbon nanomaterials. Mechanical strength.
2.carbon nanowires
Looking at the material below, is it a bit interesting? Is it solid or macromolecule?
This new type of carbon nanomaterial is both a sp3 hybrid of carbon atoms and a one-dimensional composition of carbon atoms. At the same time, their cross sections are not like a traditional linear organic molecule, but have multiple chemical bonds. Pass through the cross section. This means that these materials are close to diamond insulators in terms of electronic properties. They are far superior in mechanical properties to traditional linear organic molecules, and their mechanical strength is close to that of carbon nanotubes or graphene. Theoretical calculations do confirm these [1], they are called carbon nanowires, or diamond nanothreads.
Is this new material with a strange shape just a theoretical expectation, or can it be actually prepared? It seems that such materials need to start surface milling cutters from the synthesis of small organic molecules, after a small to large process, but experimentally [2] is through a process from large to small, starting from the solid state of benzene, after 25GPa high pressure The role of the original sp2 hybrid chemical bond becomes a sp3 hybrid chemical bond under high pressure, thereby transforming the three-dimensional molecular crystal into a one-dimensional carbon nanomaterial.
Long-range ordered one-dimensional nanowires are shown in the example of Figure 2; unordered structures may often be obtained in actual experiments. This figure shows a disordered structure and the results of scanning tunneling microscopy of carbon nanowire crystals obtained in experiments.
3.Applying first-principles calculations
First-principles calculations perform well in predicting the properties of materials. Combining experimental results rod peeling inserts often leads to more in-depth perspectives on the interpretation of experimental results. In the synthesis of diamond carbon nanowires, due to the harsh experimental conditions, the high pressure of 25GPa needs to be realized in a very small diamond anvil cell (DAC), so the experimental synthesis of materials lacks long-range order, experimental results At first glance, there is a lot of disorder interference. The theoretical calculations can help us distinguish whether the composition contains the new materials we expect.
In theory, we have become a carbon nanowire structure. After adding a certain disorder by introducing the Stone-Wales chemical bond rotation, we can use the theoretical calculation to do the atomic position relaxation and then obtain the optimal structure with the lowest energy. Accurate theoretical calculations can give the distance between atoms in a material, or calculate the radial distribution function in a material. Comparing the theoretical results with the experimental results in Figure 4. It not only confirms that the experimental composition is in agreement with the theoretical structure, but also discerns which atomic structures correspond to the peak resolution of the experimental results.
Figure 4. Comparison of the radial distribution function (RDF) of experimentally synthesized nanowires with the simulated radial distribution function of theoretically generated carbon nanowire structures.
The first principle calculation gives the optical properties of the material. Raman spectroscopy is often a reliable means of characterizing experimental compositions because it does not have to destroy the experimental composition, and spectral peaks can tell us what molecular vibrational modes have Raman activity. One method of calculating the Raman spectrum by density functional theory is to first calculate the dielectric constant of the molecule, and then perform a small displacement of the atom position along the eigenmode of the molecular vibration to calculate the change of the dielectric constant. With the advanced computing power of modern computers, we can now easily calculate the Raman activity of a molecule to determine which structural units are present in the experimental composition. Figure 5 shows a characteristic structural unit included in the synthesis results of carbon nanowires by calculation and analysis of Raman spectroscopy.
Figure 5. Comparison of experimental Raman spectra of carbon nanowires with theory.
4. Functionalization
An important feature of carbon nanomaterials is the ability to add various functional groups to them. As long as some small organic molecules are replaced in the preparation stage of the synthetic preparation. In the carbon nanowire material, a simple method involves replacing the hydrogen atom (H) in the reactant with a chlorine atom (Cl), or replacing the carbon atom therein with a nitrogen atom (N) and a boron atom (B). It can be functionalized to change its electronic properties, phonon properties, thermal properties or mechanical properties. Figure 6 shows several typical nanowire structures formed by replacing hydrocarbon groups with nitrogen atoms [4].
The study of replacing benzene with an initial reactant containing a nitrogen atom to synthesize nanowires is published in the article [3]. This replacement is a complete replacement instead of doping, using pyridine (pyridine, C5NH5) instead of the benzene ring to participate in the reaction, the reaction process is still similar to the use of high pressure diamond ballast, the sp2 hybrid carbon is converted into sp3 hybrid carbon And complete the transformation of small molecules into one-dimensional materials.
Using the principle of first principles, we can study by two methods, in which the carbon nanowire material of that structure is synthesized. One is to compare the characterization properties of all candidate structures with experiments, such as Raman spectroscopy, XRD, and so on. The other is naturally sorted by their energy. In calculating the energy of carbon nanowires, their molecular structure and periodicity must be optimized first. However, this one-dimensional material has a characteristic that they have a helical structure, which creates some difficulties in calculation.
If you replace the macromolecules that are truncated at both ends, the energy calculation must be inaccurate; if you use periodic boundary conditions, how do you determine the helix angle? A feasible trick is to select several helix angles for calculation [2]. Each angle is different, which means that the length of a structural repeat period is different along the one-dimensional structure. After calculating a number of different helix angles, the average energy per structural unit (or average per atom) is obtained, and a simple quadratic regression fit is performed on the helix angle. The implicit assumption of quadratic regression fitting is that the effect between two adjacent structural elements is approximately spring-like. Although this is not a completely true hypothesis, it can still capture the main force between adjacent units, because in carbon nanomaterials, covalent bond forces between adjacent atoms and adjacent structural units are used. The Hooke’s law of the spring is approximate.
Figure 6. Four typical diamond carbon nanowires decorated with nitrogen atoms from the literature[4]
5.Mechanical strength
Carbon nanomaterials have a lot of wonderful electrical properties, but now they are widely used in their mechanical lightness: light atoms, strong bonding. Carbon nanowires have the basic unit of diamonds. Will they also have enough strength? Simply put, yes. As shown in Figure 7, the calculations show that the carbon nanowires have a Young’s modulus between 800 and 930 GPa, which is comparable to natural diamonds (1220 GPa). Of course, the mechanical strength of this one-dimensional material is directional. This is both a disadvantage and an advantage: this material concentrates all mechanical strengths in one direction. Some even imagine that this carbon nanowire can be used to make a cable for a space elevator.
Figure 7. Young’s modulus of three different types of diamond carbon nanowires from reference [5].
6.Conclusion
Diamond carbon nanowires have recently joined the large family of carbon nanomaterials with a strict one-dimensional structure and high mechanical strength. In the research process, with the help of powerful computing power, through the first-principles calculation, the possible carbon nanowire atomic molecular structure can be studied, and the interpretation of experimental results can be assisted, and the experimental results can be analyzed in depth. Carbon nanowires, as well as many other interesting new features of carbon nanostructures, are waiting for more theoretical calculations and experimental verification to explore.
