In the mechanical engineering industry, metal cutting is a commonly used processing method. By using cutting tools to remove metal layers (machining residues) on the surface of the workpiece, it helps to form the required parts.
Mechanical cutting tools, also known as metal cutting tools, are mechanical tools with a hardness higher than the hardness of the work piece, with the use of shaping product details by cutting workpieces. to remove excess metal.
These CNC cutting tools are diverse in types, designs, and designs, and they will work when fitted to machine tools such as lathes, milling machines, drills, planers, etc. to perform functions. Specialized machining in mechanics such as turning, milling, drilling, boring, planing, tapping, … helps create and complete details, meeting the needs of assembling, manufacturing or repairing machines and equipment.
Trường An Industrial is an authorized dealer of Sumitomo in Vietnam, providing a wide range of high quality cutting tools of Sumitomo Japan.
General requirements for metal cutting tools
For CNC cutting tools in mechanical processing, they must meet the following requirements to ensure that the machining process is smooth, stable, in accordance with machining requirements, and accurate. and especially avoid unnecessary incidents.
So they have many different shapes and sizes, but basically, metal cutting tools need to meet the following factors:
Hardness: The cutting tool needs to have a hardness higher than that of the workpiece, it must be hard enough to not deform during cutting.
Mechanical strength: is the ability not to break when subjected to pressure during cutting.
Heat resistance: The cutting tool needs to maintain its rigidity and mechanical strength when subjected to heat generated during machining.
Abrasion resistance: Abrasion resistance during cutting.
Common types of mechanical cutting tools
There are many different types of CNC metal cutting tools such as turning cutters, milling cutters, milling stations, drills, reamers, chamfers… used for different processing methods such as turning, milling, drilling, planing, broaching… They are also installed on a variety of machine tools such as lathes, milling machines, drilling machines, planers… to meet different processing purposes.
1. Turning knife
The turning tool is an extremely popular cutting tool used in metal processing, it helps to quickly shape round parts such as smooth shafts, cones, round holes … The turning tool consists of 2 main parts: rolling part and cutting part. The tool holder helps to firmly clamp the lathe tool on lathes, the cutting part is usually made up of replaceable lathe pieces.
Mechanical turning tools are very diverse in types and designs to meet many turning applications, as well as turning needs on materials with different properties. For turning tools, according to different classifications, there will be the following types:
According to the function of the turning tool, there are external turning tools, internal turning tools, threading turning knives, grooving tools, cutting tools, shoulder turning knives, end trimming knives, boring turning tools, and shaping turning tools.
According to the turning direction of the tool during machining, there are left turning tools and right turning tools.
According to the structure of the turning tool, there are round knives, prismatic knives, solid knives, welding knives, and serrated knives.
According to the way of attaching the tool to the workpiece, there are radial cutters and tangential cutters.
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Milling knife
Along with turning tools, milling cutters are also used a lot in mechanical processing, even its application is more than turning tools. Milling cutters are mounted on milling machines or compound machines to perform milling operations.
Milling cutters can be used to create many complex parts, due to the milling mechanism, the milling cutter can quickly remove excess parts on the workpiece to create grooves, holes, threads, gears … machining from rough to perfect the shape of many types of details.
Mechanical milling cutters also have many different classifications, based on their own criteria, we have the following types of mechanical milling cutters.
- Based on the distribution of the tool teeth relative to the tool axis, there are end mills, bridge mills, angle mills, face mills, disc mills.
- According to the structure of the teeth, there are pointed-tooth milling cutters and back-cutting milling cutters.
- According to the direction of the knife teeth there are straight tooth knives, inclined tooth knives, helical tooth knives, sole tooth knives.
- Based on the structure of the whole milling cutter with solid milling cutter, compound tooth milling cutter.
- According to the cutting condition of milling cutters with cylindrical milling cutters, end milling cutters.
- Based on technology features plane milling cutters, slot and step milling cutters, profiled surface milling cutters, gear and thread milling cutters, hole milling cutters, T-groove milling cutters, material cutting milling cutters.
- Based on the method of clamping tools with horizontal cylindrical milling cutters, vertical cylindrical milling cutters.
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Mechanical drill bit
Drill bits are cutting tools used to make holes, drill holes in metal materials in the mechanical industry. The drill bit can be used on large CNC machines or on small hand drills.
The basic structure of the drill bit includes the shank and the working part, but depending on the different applications, the types of drill bits have different designs, structures and sizes. The most common are twist drills, but there are other types of drill bits as follows:
Twist drill bit: this type of drill bit, depending on the design or manufacturing material, coating, torsion … is divided into many types of drill bits such as long drills, flat bottom drills, steel drills, multi drill bits. power, non-ferrous metal drill bits…
Piece drill bit: this has a cutting part that is small cutting pieces that are attached at the top of the drill body.
Interchangeable drill bit: the tip of the drill bit can be removed to replace cutters with different apex angles or replace with a new one when the old one is worn out.
- Centering drill: used to create a positioning hole before drilling with a larger drill, to avoid drilling deviation, often used on curved surfaces.
- Step drill bit: has multiple diameter steps, allowing to drill many holes of different diameters with just one drill bit.
- Hole drill bit: This type of drill is often used to cut large glass holes on thin sheet materials.
- Serrated drill bit: used to drill or to shape on a plate-like surface of the part
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Boring tool
Drill bits are used in mechanical engineering to enlarge a hole after the hole has been made by drilling, reaming or turning methods. In machining, reaming is a finishing operation, ensuring dimensional accuracy and quality of the machined surface.
The reamer includes solid reamers of various shapes and reamers with shanks, reamers and cutting pieces joined together to form a complete reaming system. See also Big Daishowa CK BORING SYSTEM for mounting hole boring head system
5. Cape Taro
The tap (or tap blade, tap knife) is a cutting tool used to create threads by tapping threading. The tap can produce both outer and inner hole threads.
Tapes include the following types:
Based on chips, taps are divided into cutting taps and compression taps.
- The tapping tap creates a thread by cutting the material billet and creating a chip like normal cutting, the chip after creating will be pushed out of the hole.
- Compression taps create threads by using force to deform the material to shape the thread without creating chips.
Based on the usage of the tap, there are machine taps and hand taps.
- Machine taps are used on processing machines such as milling machines, CNC milling machines, tapping drills, specialized tapping machines.. including twist-groove and straight-groove taps (for hole processing only).
- A hand tap is a type used by hand to tap threads. In the past, hand taps were usually a set of 3 trees: rough, semi-finished and fine, but thanks to material technology and improvements in design, current taps only need 1 tree to perform tapping. complete lace.
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Grinder, sharpener
Grinding and grinding bits are collectively known as alloy grinding bits, usually made of Tungsten Carbide (Tungsten Alloy) material, used for grinding, and for shaping product details. The grinding process, which can be done manually or on a machine, is now mainly done on CNC grinding machines, ensuring higher accuracy.
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Hole knife
Hole cutters or hole punches are used to expand holes with many types of holes such as cylindrical holes, step holes, tapered holes, square head holes. The reamer has more cutting edges and higher rigidity than the drill bit, resulting in higher hole accuracy.
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Sharpening knife
The broach helps to extend the inner cylinder and profile faces on the workpiece. It is also used in a number of broaching techniques for plane machining, profiled faces in solids, and mass production. Common types of broaching knives are grooving knives, hole sharpening knives, and profiled surface sharpening knives.
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Beveled knife
The chamfering tool or beveling tip is a cutting tool that uses, as its name suggests, a sharp chamfer of a hole, helping to reshape the edge of the hole in accordance with the machining requirements. There are many names for beveled knives such as open-mouthed nose, flared nose, chamfered drill bit, mouth-hole reamer, etc.
There are also a number of other but less common types of CNC cutters. Cutting tools are increasingly being upgraded and improved in designs and styles to help increase machining efficiency. Especially the manufacturing materials and coatings used on the tools are also much better, with extremely good heat and wear resistance.
Today’s popular cutting tools manufacturing materials
1. Tool steel
Also known as high-quality, high-carbon carbon steel, formerly used very commonly in cutting tools. There are two types of tool steel: carbon tool steel and alloy tool steel.
1.1 Carbon tool steel
Contains 2 main components, iron and carbon, while other elements in tool carbon steel are negligible. The higher the carbon content in the steel, the higher the hardness and durability of the tool, but makes the heat resistance worse.
To achieve the required hardness, heat resistance and wear resistance for cutting tools, the amount of C in tool carbon steel should not be less than 0.7% (usually 0.7 – 1.3%). and low amount of P, S (P < 0.035%, S < 0.025%).
Tool carbon steel has the advantage of high hardness and abrasion resistance, but the limitation is low thermal resistance, when the temperature is 200 – 250oC, the hardness of the cutting tool will be reduced very quickly.
For that reason, today tool steel is no longer used much to make cutting tools, but mainly for low-speed cutting tools (up to 10-12 m/min) such as: planers, skewers, wood cutting tools or hand-processing tools such as hand saws, drills, files, etc.
1.2 Alloy tool steel
Is carbon steel mixed with other metal elements such as tungsten, chromium, vanadium, silicon, manganese, nickel … with the total amount of added elements ranging from 1% to 5% of the total mass of the mixture. This helps to increase the thermal stability of the cutting tool, overcoming the limitation of carbon tool steel.
Depending on the types of elements added and their ratio, the alloy tool steel will vary in hardness, elasticity, mechanical strength, thermal strength, and oxidation resistance. Common tool alloy steels are chromium steel, chromium-manganese-silicon steel, tungsten steel, and chromium-nickel steel.
Although this steel has improved the high temperature resistance of cutting tools, due to the development of new materials, tool steel is currently only used to make tools. low cutting speed.
2. Wind steel
Wind steel is a steel with a high carbon content and the metal elements tungsten (W), molybdenum (Mo), chromium (Cr) and vanadium (V). It has high hardness, wear resistance and heat resistance, which allows cutting tools to work at high speeds without reducing tool stiffness. That’s why wind steel is called “fast-cutting steel” in many countries (for example, in English, it is high speed steel).
The cutting tools are made from high-speed steel with heat resistance up to 500 – 600 C, with cutting speeds up to 50 – 60 m/min.
For common material cutting tools, they are usually made from high-speed steel grades P6M5 (6% tungsten, 5% molybdenum), P6M3 (6% tungsten, 3% molybdenum), P12 (12% tungsten). For cutting tools for stainless steel and alloy steel with high hardness and ductility (in the condition of impact cutting), the steel grades P18KM2, P10K5M3, P9K5, P6M5K5, P12M2K8M3 are usually used. P9M4K8, . . .
3. Hard alloy
This is a material for making cutting tools with very high hot hardness, can withstand temperatures of more than 800 C and can achieve cutting speeds of up to hundreds of m/min. Hard alloys are made up of compounds of carbon and metals such as tungsten, titanium, tantalum, and cobalt as a binder. There are two commonly used hard alloys:
- Tungsten-Cobalt alloy (commonly denoted as BK*): this group is used to make cutting tools for processing brittle materials such as cast iron, brass, hardened steel, and plastics. Cutting speed can reach 200m/min.
- Titanium – Tungsten – Cobalt alloy (commonly denoted T * K *): this group is used for cutting tools for processing ductile materials such as steel, copper. Cutting speed can reach 350m/min.
Currently, people also use three-carbide alloys (Volfram carbide, Titanium carbide and Tantan carbide – denoted TTK) to make cutting tools, this type has higher durability than TK 1.5- 2 times.
Hard alloys are commonly used to make turning/milling chip pieces according to different shape and size standards. To increase the durability of chip pieces, they will be plated on the surface with a thin layer of coating typical of each manufacturer. The cutting speed can now reach 800 m/min or more.
Sumitomo turning chip
Although the performance of hard alloys is shown to be superior to that of mild steel, hard alloys still have the following limitations:
It is not possible to create complex shapes because only simple small pieces can be created (by pressing dough), and at the same time, it cannot be processed into shapes because it is too hard. Therefore, hard alloys are often only used to make simple single-edged cutters.
Relatively high brittleness, easy to break, break and chip under impact load. Currently, this disadvantage is overcome by coatings that increase the mechanical strength of the cutting tool.
Poor thermal conductivity ~50% of steel
4. Other materials
4.1 Ceramic mineral alloy (Ceramic alloy)
This alloy is made from aluminum oxide (Al2O3) – Corundum by crushing, pressing and sintering. Mainly used for making hard alloy-like cutting pieces. Ceramic mineral alloys have the advantages of higher thermal strength and wear resistance than hard alloys, but have higher brittleness and lower mechanical strength than hard alloys.
4.2 Super Hard Materials (CTM)
It is a polycrystalline material made up of Boron Nitrite. It has higher thermal stability than hard alloys and ceramic mineral alloys. Commonly used for plating hard alloy knife pieces or for making abrasive tools for sharpening cutters. Super hard material (CTM) is suitable for processing steel, cast iron, alloy that is difficult to work.
4.3 Synthetic diamonds
Sumitomo end mills covered with synthetic diamonds
Synthetic diamonds can be made in powder or crystal form, they have similar physical properties to pure diamonds in nature. There are two main methods of creating artificial diamonds: the HPHT high-temperature high-pressure method (using extremely high temperature and pressure to recreate the environment similar to the diamond-forming environment in the ground), and the evaporation method. CVD chemical deposition (using chemical vaporization of carbon gas compounds under the action of plasma heat rays to create gas molecule division until only carbon atoms remain to deposit and grow on metal nuclei) diamond available).
Applied more and more in cutting tools, such as diamond sharpening tip, diamond cutting stone, diamond cutter, diamond cutting knife piece, etc., artificial diamond has the advantage of angle nice cutting, improved surface finish, as well as a relatively reasonable price. They are also used as coatings on cutting tools such as turning chips, drill bits, reamers, etc. Artificial diamond knives are mainly used in the finishing of non-ferrous metals, alloys and non-metallic materials.
How to handle when the cutting tool is worn
During the machining process, the cutting will often create friction and impact between the tool and the workpiece, causing the tool to wear out over time. Therefore, at a certain stage, the cutting tools will no longer retain their sharpness, affecting the accuracy and quality in machining.
To handle this problem, you can choose to re-sharpen the knife with specialized grinders or better yet, choose to buy new cutting tools to ensure quality and machining performance.
Notes when choosing to buy cutting tools
To own quality cutting tools, to ensure processing requirements, you need to note the following tips.
- It is advisable to choose metal cutting tools from large, well-known manufacturers in the market.
- Select the parameter of the tool in accordance with the machining mode such as spindle rotation speed, feedrate, cutting speed … suitable workpiece material…
- See the compatibility of the cutting tool with the type of machine you are using.
- Consult experts who have a lot of experience in the profession.
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