To meet the needs of the automotive industry, tool manufacturers have also introduced milling cutters for milling cast iron and other materials. Existing automotive parts are hardened to increase productivity and reduce costs. For machining hardened ferrous metals, milling cutters with CBN or ceramic inserts are available.
First, Valenite develops QC milling inserts to meet the needs of the automotive industry
In the early automobile production line, each station had to complete one process in a fixed time. Then, the workpiece is transferred to the next station. This transfer can only be performed after the slowest process is completed. At this time, the cutting speed, feed rate and number of passes are fixed in each process, and a certain process needs to be changed. The knife has to stop the entire production line, so the impact of tool life on production efficiency is very prominent. Reiterman, product development manager at Valenite, proposed that the tool life is half a class, one half class is not good, and the tool life can reach a class steadily, so that the minimum requirements after the tool change is off work. The next goal is to increase tool life to 2, 3 or 4 shifts.
The use of high-hardness, high-strength tool materials, industrial automation network copyright, coupled with appropriate coatings, to extend tool life first. However, Reiterman believes that improving tool geometry also increases tool life, especially when milling cast iron. He pointed out that the automotive industry processes a range of alloy cast irons, including gray cast iron and ductile iron high density ductile iron. These cast irons have different processing characteristics. The gray cast iron contains a network of hard structures and is brittle. When machining, the tool is prone to chipping. The ductile iron high-density ductile iron has certain plasticity and can produce iron filings, but when the tool is cut out The workpiece will also produce "flanging", which will result in damage to the tip. Reiterman also pointed out that the same workpiece casting process is different, and its processing performance is also different. For example, a thin section and rapid cooling can result in a particularly hard, difficult-to-machine surface for the casting. In addition, the processing properties may vary depending on the batch of different batches of the casting batch.
Valenite's new development for machining cast iron QC milling inserts with four cutting edges, the cutting edge has a positive rake angle, and there are several cutting edge arcs between the main cutting edge and the minor cutting edge. The wiper blade is specially designed at the secondary cutting edge.
When milling or shallow deep milling, the size of the tool tip arc is critical. In this case, the radius of the tool nose arc should be larger than the depth of the cut, which results in a main angle between the tool nose arc and the workpiece, which plays a good role in avoiding chip edge chipping when machining cast iron. The sharp blade is very sensitive to vibration during the processing of cast iron and is prone to chipping. Therefore, the cutting edge of the tool nose arc should be sharpened and rounded. On the other hand, the wiper action is used to remove the "crest" of the feed tool mark, and the honing reduces the cutting edge cutting ability - making it less sharp and causing the surface to be swollen. The positive value of the front corner of the QC blade can effectively reduce the cutting force and facilitate chip removal. According to the material characteristics of the workpiece, it is convenient to customize the most suitable milling cutter body to reduce cutting force, reduce heat accumulation and extend tool life. Different cast iron milling processes, using QC inserts, can increase tool life.
Second, Iscar developed for the automotive industry Auto2000 milling cutter
Automotive production has undergone a digital transformation from the use of ancient rigid production lines to today's advanced flexible manufacturing systems. For the car itself, there is a trend of diversification of energy. This change directly affects the selection of materials for automotive parts. Therefore, the automotive industry is looking for tools that are both easy to use and adapt to a variety of metal materials. To this end, Iscar has developed a new range of milling cutters for the automotive industry, called the Auto2000 milling system. Its characteristics, the positioning of the blade axial height of the blade seat ring fine grinding, which can save a lot of tool adjustment re-adjustment time. The tool can be used for finishing, semi-finished gray cast iron, and ductile iron commonly used in the malleable cast iron industry. The maximum depth of cut is 5mm. The blade is octagonal Hanyang Technology Co., Ltd. Each blade has 16 cutting edges and has a positive rake groove in the axial direction, which reduces the cutting force. In addition, the rear of the tool tip has a wiper to improve the surface quality of the workpiece.
Third, the use of ceramic blades for milling
On the modular production line or flexible machining unit (FMC), it is easy to adjust the cutting parameters by means of numerical control technology, which is more conducive to giving full play to the full potential of advanced tools. Marshall, manager of milling cutters at Kennametal, says that for milling gray cast iron, the best choice for silicon nitride is to get the highest productivity. Even at 760 to 1370 m/min cutting speed, the feed rate of the tool life is comparable to that of cemented carbide.
After the National Precision Products Company (NPP) tried the Fx-perfect blade made of Kennametal's silicon nitride Kyon3500, it believed that the tool life was still improved after the feed rate was increased by 3-4 times compared with the cemented carbide tool. For example, with a φ25.4mm solid carbide end mill, 300 pieces can be machined in one regrind, and more than 2000 pieces/edge or 16,000 pieces/piece can be processed with a Kyon3500Fix-perfect insert face milling cutter with φ76mm.
According to NPP, ductile iron is more difficult to machine than gray cast iron, and the cutting speed needs to be adjusted. When the metal removal rate per tooth is the same as that of the gray cast iron, the spheroidal graphite cast iron has a cutting speed of v=730m/minnc.qoos.ipi, and the gray cast iron has a cutting speed of v=914~1219m/min. Silicon nitride Kyon3500 tool material has superior performance, although its price is more expensive than cemented carbide, but the productivity increase is far more effective than the tool cost increase. The key machine power stiffness is sufficient. Although ceramics can be used for milling to achieve high cutting speeds and long tool life, if the depth of cut reaches 3.8 mm, the machine power can reach 20 hp without moving. Therefore, only a small cutting speed can be reduced, and this does not give full play to the superior performance of the ceramic.
Fourth, the geometric angle of the milling cutter is improved
According to NPP's experience, when the machine power is insufficient, the correct choice of tool geometry can also expand the production capacity of low-power machines. For example, conventionally, cast iron milling cutters have a negative axial radial rake angle (double negative angle milling cutter), and this negative geometric angle makes the cutting edge relatively strong. On the contrary, the positive and negative angle milling cutters (axial positive rake angle, radial negative rake angle) cut smoothly, which also reduces the machine power requirements and makes it easier to use advanced tool materials.
According to the use of the blade grade, the edge of the milling cutter blade can be sharp, and the chamfer can be ground from 0.013mm to 0.076mm. For the Kyon3500 ceramic blade, a 20° chamfer is ground and the chamfer width is 0.2mm to prevent the chip from being damaged by the chip at high speed.
Kennametal's Fix-Perfect system is a collection of different positive and negative angle combinations. Its characteristics are as follows: Since the blade adopts the vertical type, the lower part of the blade has strong physical support, which increases the blade strength. The negative axial rake angle causes the cutting force to be directed toward the main shaft and the milling cutter works stably. Moreover, the negative axial rake angle enables the earliest cut into the workpiece "impact point" to leave the tool tip and protect the tool tip.
The Fix-perfect cutter has a squeegee blade for roughing and finishing. The surface roughness is up to 32 (contour root mean square deviation), which reduces one finishing and reduces cycle time.
Fifth, the tool should adapt to the changes of various parts of the car
Because cast iron is very hard and has a high compressive strength and can be cast into a very complex shape, it has been used to make other parts of automotive engine casings. Later, CAFE (Corporate-average-fuel-efficiency) and so on, began to reduce the amount of heavy alloys on light vehicles. In 1980, according to the American Foundry Association, household cars controlled 600 pounds of cast iron. By 1999, the average had dropped by nearly half to 325 pounds, and is expected to drop to 230 pounds in 2006. On the other hand, the aluminum industry analysis predicts that automotive aluminum parts will rise by 50% in five years, from 250 pounds per vehicle in 2000 to 380 per vehicle in 2005.
For the mass production of aluminum parts, polycrystalline diamond (PCD) tools are required. The main cause of chip PCD tool damage during machining.
To keep the cutting edge of the PCD tool intact, it is best to distribute the cutting load evenly to each milling cutter. Therefore, precision adjustment (especially axial) is an important means of extending the life of the PCD cutter. For example, the Ingersoll milling cutter Flex-Lok insert allows fine adjustment of the vertical insert and then secures the insert with a barrel screw. In this way, each blade on the milling cutter is load balanced for maximum tool life.
Processing aluminum alloy has special requirements on tool geometry. Aluminum alloys for aviation industry should use large positive rake angle cutters because of their high viscosity and low silicon content. For aluminum alloys with high silicon content, it is not necessary to use too much. The sharp front is the front corner, but should be stable and durable. Therefore, most automotive manufacturers use aluminum alloys with a small axial radial positive rake angle.
First, Valenite develops QC milling inserts to meet the needs of the automotive industry
In the early automobile production line, each station had to complete one process in a fixed time. Then, the workpiece is transferred to the next station. This transfer can only be performed after the slowest process is completed. At this time, the cutting speed, feed rate and number of passes are fixed in each process, and a certain process needs to be changed. The knife has to stop the entire production line, so the impact of tool life on production efficiency is very prominent. Reiterman, product development manager at Valenite, proposed that the tool life is half a class, one half class is not good, and the tool life can reach a class steadily, so that the minimum requirements after the tool change is off work. The next goal is to increase tool life to 2, 3 or 4 shifts.
The use of high-hardness, high-strength tool materials, industrial automation network copyright, coupled with appropriate coatings, to extend tool life first. However, Reiterman believes that improving tool geometry also increases tool life, especially when milling cast iron. He pointed out that the automotive industry processes a range of alloy cast irons, including gray cast iron and ductile iron high density ductile iron. These cast irons have different processing characteristics. The gray cast iron contains a network of hard structures and is brittle. When machining, the tool is prone to chipping. The ductile iron high-density ductile iron has certain plasticity and can produce iron filings, but when the tool is cut out The workpiece will also produce "flanging", which will result in damage to the tip. Reiterman also pointed out that the same workpiece casting process is different, and its processing performance is also different. For example, a thin section and rapid cooling can result in a particularly hard, difficult-to-machine surface for the casting. In addition, the processing properties may vary depending on the batch of different batches of the casting batch.
Valenite's new development for machining cast iron QC milling inserts with four cutting edges, the cutting edge has a positive rake angle, and there are several cutting edge arcs between the main cutting edge and the minor cutting edge. The wiper blade is specially designed at the secondary cutting edge.
When milling or shallow deep milling, the size of the tool tip arc is critical. In this case, the radius of the tool nose arc should be larger than the depth of the cut, which results in a main angle between the tool nose arc and the workpiece, which plays a good role in avoiding chip edge chipping when machining cast iron. The sharp blade is very sensitive to vibration during the processing of cast iron and is prone to chipping. Therefore, the cutting edge of the tool nose arc should be sharpened and rounded. On the other hand, the wiper action is used to remove the "crest" of the feed tool mark, and the honing reduces the cutting edge cutting ability - making it less sharp and causing the surface to be swollen. The positive value of the front corner of the QC blade can effectively reduce the cutting force and facilitate chip removal. According to the material characteristics of the workpiece, it is convenient to customize the most suitable milling cutter body to reduce cutting force, reduce heat accumulation and extend tool life. Different cast iron milling processes, using QC inserts, can increase tool life.
Second, Iscar developed for the automotive industry Auto2000 milling cutter
Automotive production has undergone a digital transformation from the use of ancient rigid production lines to today's advanced flexible manufacturing systems. For the car itself, there is a trend of diversification of energy. This change directly affects the selection of materials for automotive parts. Therefore, the automotive industry is looking for tools that are both easy to use and adapt to a variety of metal materials. To this end, Iscar has developed a new range of milling cutters for the automotive industry, called the Auto2000 milling system. Its characteristics, the positioning of the blade axial height of the blade seat ring fine grinding, which can save a lot of tool adjustment re-adjustment time. The tool can be used for finishing, semi-finished gray cast iron, and ductile iron commonly used in the malleable cast iron industry. The maximum depth of cut is 5mm. The blade is octagonal Hanyang Technology Co., Ltd. Each blade has 16 cutting edges and has a positive rake groove in the axial direction, which reduces the cutting force. In addition, the rear of the tool tip has a wiper to improve the surface quality of the workpiece.
Third, the use of ceramic blades for milling
On the modular production line or flexible machining unit (FMC), it is easy to adjust the cutting parameters by means of numerical control technology, which is more conducive to giving full play to the full potential of advanced tools. Marshall, manager of milling cutters at Kennametal, says that for milling gray cast iron, the best choice for silicon nitride is to get the highest productivity. Even at 760 to 1370 m/min cutting speed, the feed rate of the tool life is comparable to that of cemented carbide.
After the National Precision Products Company (NPP) tried the Fx-perfect blade made of Kennametal's silicon nitride Kyon3500, it believed that the tool life was still improved after the feed rate was increased by 3-4 times compared with the cemented carbide tool. For example, with a φ25.4mm solid carbide end mill, 300 pieces can be machined in one regrind, and more than 2000 pieces/edge or 16,000 pieces/piece can be processed with a Kyon3500Fix-perfect insert face milling cutter with φ76mm.
According to NPP, ductile iron is more difficult to machine than gray cast iron, and the cutting speed needs to be adjusted. When the metal removal rate per tooth is the same as that of the gray cast iron, the spheroidal graphite cast iron has a cutting speed of v=730m/minnc.qoos.ipi, and the gray cast iron has a cutting speed of v=914~1219m/min. Silicon nitride Kyon3500 tool material has superior performance, although its price is more expensive than cemented carbide, but the productivity increase is far more effective than the tool cost increase. The key machine power stiffness is sufficient. Although ceramics can be used for milling to achieve high cutting speeds and long tool life, if the depth of cut reaches 3.8 mm, the machine power can reach 20 hp without moving. Therefore, only a small cutting speed can be reduced, and this does not give full play to the superior performance of the ceramic.
Fourth, the geometric angle of the milling cutter is improved
According to NPP's experience, when the machine power is insufficient, the correct choice of tool geometry can also expand the production capacity of low-power machines. For example, conventionally, cast iron milling cutters have a negative axial radial rake angle (double negative angle milling cutter), and this negative geometric angle makes the cutting edge relatively strong. On the contrary, the positive and negative angle milling cutters (axial positive rake angle, radial negative rake angle) cut smoothly, which also reduces the machine power requirements and makes it easier to use advanced tool materials.
According to the use of the blade grade, the edge of the milling cutter blade can be sharp, and the chamfer can be ground from 0.013mm to 0.076mm. For the Kyon3500 ceramic blade, a 20° chamfer is ground and the chamfer width is 0.2mm to prevent the chip from being damaged by the chip at high speed.
Kennametal's Fix-Perfect system is a collection of different positive and negative angle combinations. Its characteristics are as follows: Since the blade adopts the vertical type, the lower part of the blade has strong physical support, which increases the blade strength. The negative axial rake angle causes the cutting force to be directed toward the main shaft and the milling cutter works stably. Moreover, the negative axial rake angle enables the earliest cut into the workpiece "impact point" to leave the tool tip and protect the tool tip.
The Fix-perfect cutter has a squeegee blade for roughing and finishing. The surface roughness is up to 32 (contour root mean square deviation), which reduces one finishing and reduces cycle time.
Fifth, the tool should adapt to the changes of various parts of the car
Because cast iron is very hard and has a high compressive strength and can be cast into a very complex shape, it has been used to make other parts of automotive engine casings. Later, CAFE (Corporate-average-fuel-efficiency) and so on, began to reduce the amount of heavy alloys on light vehicles. In 1980, according to the American Foundry Association, household cars controlled 600 pounds of cast iron. By 1999, the average had dropped by nearly half to 325 pounds, and is expected to drop to 230 pounds in 2006. On the other hand, the aluminum industry analysis predicts that automotive aluminum parts will rise by 50% in five years, from 250 pounds per vehicle in 2000 to 380 per vehicle in 2005.
For the mass production of aluminum parts, polycrystalline diamond (PCD) tools are required. The main cause of chip PCD tool damage during machining.
To keep the cutting edge of the PCD tool intact, it is best to distribute the cutting load evenly to each milling cutter. Therefore, precision adjustment (especially axial) is an important means of extending the life of the PCD cutter. For example, the Ingersoll milling cutter Flex-Lok insert allows fine adjustment of the vertical insert and then secures the insert with a barrel screw. In this way, each blade on the milling cutter is load balanced for maximum tool life.
Processing aluminum alloy has special requirements on tool geometry. Aluminum alloys for aviation industry should use large positive rake angle cutters because of their high viscosity and low silicon content. For aluminum alloys with high silicon content, it is not necessary to use too much. The sharp front is the front corner, but should be stable and durable. Therefore, most automotive manufacturers use aluminum alloys with a small axial radial positive rake angle.
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