Many improvements in the automotive manufacturing process follow the principle of “winning by volumeâ€. This is why the use of custom tools in automotive machining is almost as common as standard tools, while the requirements for processing flexibility are relegated to secondary positions. The demanding process for shortening the processing cycle, even a few seconds of time saving, is one of the fundamental driving forces for the continuous improvement of the automotive processing technology. It is also the unremitting pursuit of shortening the processing time, making the special tool in the automotive processing technology. The continuous optimization process plays a pivotal role.
In the evolution of automotive processing technology, tool manufacturers are constantly under pressure from automotive manufacturers, and every time they are required to launch a better solution than existing products. Nowadays, standard tools that can satisfy the same type of machining are being developed and developed by Hanyang Technology Co., Ltd., and the share of automotive processing applications is increasing. This is an increasingly obvious trend. More use of standard tools can reduce production costs and provide better delivery reliability.
This article will focus on the following three cutting applications, from which we will see that the latest tools not only meet the requirements of the automotive industry to improve processing efficiency, but also ensure the safety of processing.
Turning: Turning machining is widely used in the machining of automotive parts. In turning, steel shafts and disc parts are roughed and finished under various conditions. The requirements for part quality are also different, but the requirements for processing beats are always the most important. In the traditional machining process, in order to ensure the surface roughness of the workpiece, the feed rate of the tool is limited, and the machining time cannot be further shortened.
Milling: Milling of cast iron parts is extremely common in the machining of automotive parts. In this field, the contact and sealing surfaces of the cylinder and the housing are both milled. In traditional machining processes, machine downtime and tool unreliability often reduce machining efficiency, especially in roughing and semi-finishing operations.
Thread turning: Threading requires high quality. Once the threading process is going to be too bad, the production has to stop. Threading has very strict requirements on the shape of the cutting edge of the threaded tool, especially to maintain accurate positioning of the cutting edge. In the past, the low positioning stability of the threaded insert in the insert pocket was a factor limiting the increase in production efficiency.
Turning with a new generation of tools
In the turning process, the use of Wiper can change the basic law of cutting. The tip radius of a conventional turning tool tends to produce a scalloped blade on the surface of the workpiece. The tool feed and the tool nose radius are directly related to the cross-sectional height of the scalloped blade, which determines the surface quality of the turning. The wiping edge of the wiper wipes the top of the scalloped blade created by the tip. Of course, the concept of light repair in turning also needs to be continuously developed by reducing the length of the wiper to avoid damaging the shape of the machined surface and creating excessive cutting forces. At the same time, the blade needs to control the chip and can be directly mounted like a normal blade.
The Wiper was originally developed to increase the feed rate to twice the conventional blade while maintaining the same surface roughness during turning. Or, under the condition of keeping the feed rate constant, the surface roughness of the workpiece is increased by twice. Obviously, between these two possibilities, different combinations of feed and surface roughness improvement can be established, and the resulting increase in production efficiency of part turning is considerable.
The principle of the wiper technology is based on a large set of corner radius and a small set of fillet radii. There is a circular arc radius for the tip of a conventional blade cutting edge. For this reason, the wiper blade must conform to the standard ISO blade standard. It also has a nominal tool nose radius and the radius of the arc is the same for various machining applications. In addition, the wiper blade must be easy to set up and use, with no major changes in programming and tool nose radius compensation.
The first wiper blade for turning was first introduced by Sandvik Colaman in 1997. This insert features a blade geometry for roughing to ensure the strength of the tip. At the same time, this blade has a long enough wiper to use a higher feed rate. The length of contact between the cutting edge and the workpiece must be balanced with the appropriate chipbreaker geometry for smooth cutting and low cutting forces.
Next, the new type of wiper blade was developed for finishing, and the limit on the amount of cutting is more stringent. Based on a medium-sized bladed groove, this blade has a sharper cutting edge and a larger positive rake angle, which is safe and reliable at high feed rates. The two first-generation wiper blades (WM and WF) have similar workpiece surface roughness forming characteristics, but the groove shapes are different and the influence on tool life is different.
Compared with conventional blades of the same specification, the cutting force of the first generation of the polishing blade is only increased by about 5%, which means that only in the case of extreme instability, it will be negatively affected by the shape of the wiper blade, for example. Turning of the slender shaft, even with conventional blades, and special care must be taken in accordance with the recommended cutting parameters. The high feed rate of the wiper blade stabilizes certain processes and overcomes the tendency to vibrate by selecting a smaller tip.
Along with the widespread use of wiper blades and the assessment of surface quality measurements, the impression that the wiper blade causes vibrations changes. Compared with the bright surface produced by the conventional tool tip, Hanyang Technology Co., Ltd., the appearance of the dark surface after the turning of the light has become associated with high surface quality. The larger wiper tip radius provides very satisfactory stability during the turning process and also makes the Wiper groove the preferred finishing insert for general turning of various workpiece materials.
The wiper blade has another important effect in turning: it improves chip breaking in many processes. Part of the reason is because the Wiper geometry is designed for good chip control at low feed rates and smooth chip breaking at high feed rates, so chip control is optimal for a wide range of applications.
Recently, the polishing blades for turning have required new developments, especially in the automotive industry. Part of the reason is that the surface quality generated by the first generation of the wiper blade is insufficient at high feed rates. Increasing the nominal radius of the wiper cutting edge aligns with the surface quality requirements in production. However, for R&D work, the challenge is that the actual length of the wiper required for high feed rates is limited.
Today, the well-designed new generation of wiper technology correctly combines the nominal radius with the number and size of the fitted radii, which ensures the correct finishing and smooth transition of the wiper with the rest of the cutting edge. The key to the new wiper edge structure is the perfect combination of cutting geometry and chipbreaker shape for optimum cutting results.
A new generation of wiper technology must increase the surface roughness of the workpiece, and the feed rate should be at least equal to the current level. Any vibration generated by the new wiper blade must be lower than the first generation wiper blade. As a result of the development of the new wiper blade, a new wiper-shaped WMX has been created. The new wiper-edge WMX exhibits excellent cutting results that reduce the tendency to vibrate, can be found by monitoring the level of noise generated during machining, or from the shape of the chips produced during machining.
The new generation of wiper-edge WMX has a wider range of applications than the original wiper blades or standard inserts used in many turning operations in the automotive industry, while covering the range of original inserts. Using a higher feed rate will develop the potential for increased productivity - reducing processing time by 30%. If the surface roughness of the workpiece is used as the standard industrial automation network for the replacement of the blade, the new generation of the wiper-shaped WMX prolongs the tool life due to the significant improvement in blade wear. The new wiper insert conforms to the basic shape of ISO standard inserts and is easy to set up and use. As the original intention of developing a new generation of wiper-edge WMX, to improve the surface roughness level of the machined workpiece, the new blade WMX insert has been shown to achieve better surface quality (Ra 0.8) at the maximum feed rate. At slightly lower feed rates, WMX can produce surface roughness below Ra0.5.
The existing first generation of wiper blades (WM and WF) will continue to exist as a complementary trough for WMX. The WM geometry features a sturdy cutting edge that is a safer and more reliable solution for intermittent cutting of parts; WF is suitable for finishing, for example when the depth of cut is less than 0.5 mm or when a sharper cutting edge is required And when improving chip evacuation control during finishing.
The design purpose and processing effect of the wiper depends on whether the cutting edge is parallel to the feed direction. In some cutting applications, the wiper blade has minor drawbacks that require programming adjustments. When the part has a taper greater than 5 degrees, the wiper cutting edge can still be cut, but without its excellent lightening effect. In order to achieve the same surface quality, the feed rate must be lowered to the recommended value for a conventional tip radius blade.
Similarly, in the case of reverse machining, the wiper cutting edge does not adequately eat the knife, so the feed rate must be reduced from the high feed rate of the wiper blade to the recommended value for the conventional tip radius blade. As an alternative to the manual input of these variable feed rates, there is currently a programming software that can support the above applications.
Most of the turning operations are external turning and face turning, which means that the wiper blade can significantly reduce cutting time, improve surface quality and improve chip evacuation as well as increase safety through a strong cutting edge. Evaluate the turning process at hand, see the possibilities of using the wiper technology, and then optimize the process with the wiper technology to get a lot of benefits.
In the normal turning process, changing the conventional blade to a wiper blade on the same tool holder can directly reduce the machining time while maintaining excellent and consistent surface quality. The new generation of wiper blade WMX has truly developed the wiper technology. At the same time, there is no special restriction on high stability requirements, and it has a smooth chip breaking effect at high feed rate. It is the first choice and versatile solution.
Milling - from roughing to finishing
Cast iron milling is an important part of the manufacture of engine and housing parts. In engine manufacturing, the right geometry, good surface finish, and zero waste in total quality assurance are absolutely important goals. However, in the face of increasing cost pressures, they are eclipsed. In order to meet all of the above requirements, we need reliable and efficient tools and solutions, such as roughing and finishing of the cylinder and cylinder head planes.
For foundries or other primary subcontractors, roughing is usually part of the blanking process and metal removal rates are the most important factor. Finishing combines all the requirements for high efficiency, high reliability and high quality. One of the most challenging processes is face milling of the combustion surface, which is often the final step in the machining of the cylinder shape.
In the automotive industry, cast iron is a widely used workpiece material. Gray cast iron still dominates, and by weight it is several times that of ductile iron and other types of cast iron. Recently, the continuous development of materials and production has helped expand the use of compacted graphite iron (CGI), tempered ductile iron (ADI) and a range of alloy cast irons, increasing the range of cast iron processing materials. The cast iron cylinder liner can also be combined with an aluminum alloy cylinder, which makes milling more difficult.
In order to improve the production efficiency and reliability of the processing technology, a series of cast iron milling solutions have been launched recently.
Sandvik Coromant has long been leading the introduction of automotive-specific milling cutters and cap milling cutters for automatic wire milling in large-scale production. Recently, more and more flexible wires or single machining centers are used to process small quantities of cast iron parts and automotive parts, which means that 80% of milling cutters are in the range of 63 to 160 mm. This reflects the increasing variety of cast iron milling available today, ranging from small batches and light machining in small machining centers to roughing and finishing on automated wire or heavy machining centers in large-scale production.
In the development of new tools for roughing and semi-finishing, the objectives to be achieved include improvements in tool feed range, cutting force, workpiece breakage, burr formation, surface quality and noise level.
The improvement starts with increasing the lead angle from the conventional 45 degrees to 65 degrees, which brings, for example, a more brisk cut of the milling cutter, which can be closer to the advantages of fixture processing. However, a slightly larger lead angle increases the tendency of the workpiece to collapse when the tool is cut out because of the large radial cutting forces and the effect of the flake graphite structure in the cast iron material. In fact, the replacement tool judgment criteria often must be set according to the limits of the workpiece chipping. Therefore, in order to cope with the possible cracking effect of the large lead angle, a new 65 degree cutter blade shape has been designed, which makes the tool more advantageous when it exits the cutting.
In addition, the new geometry on the eight cutting edges also causes the cutting force to be more toward the support locating surface of the blade. At the same time, a portion of the blade geometry forms eight positive rake angle chip formers that are positioned in an optimal manner on both faces of the support blade.
Although the cutting force in cast iron machining is relatively low, it is often amplified by high frequency due to the distribution of the cutting force on the largest possible area during the milling of large contact faces, so the good support of the cutter and the blade during cast iron cutting becomes critical. The blade groove of the 65 degree insert has a good radial and axial support surface and extends all the way to the cutting edge of the insert, which allows the insert to handle heavy-duty cutting and resist deformation, so the tool has a high life span. Cutting safety.
For this new cast iron face milling cutter CoroMill 365, the face milling cutter body has an oversized tool support surface that allows the milling cutter to obtain maximum flange support from the machine tool spindle for added stability. The use of a screw clamping insert facilitates tool handling and wedge clamping is used for ultra-tight pitch bodies. Coolant is an integral part of cast iron cutting. The new face milling cutter body has a continuous coolant passage that allows coolant to reach each blade for maximum cooling.
Increasing the feed rate and surface quality are essential features of the tool, which require ultra-compact pitch, axial mounting accuracy of the blade cutting edge, and the wiper blade. While providing high cutting safety, these ever-increasing performance requirements have to be met, which has been successfully implemented in the development of new cutting tools that combine proven milling tool concepts.
The CoroMill face milling cutter range with replaceable toolholders now offers semi-finishing, finishing and roughing solutions for cast iron and aluminium cylinders, cylinder heads and housings. Tool-cutter milling cutters based on proven concepts like CoroMill 245 and Century have been widely recognized when tool pitch, accuracy, clamping and reliability are decisive factors.
Toolholder design and the positioning, adjustment and locking of the blades create significant differences in processability and performance. The use of standard toolholders on standard and custom bodies provides more effective teeth count – which is critical to increasing productivity and surface quality. The control of the axial position of each holder determines the surface quality and the consistency of the body, ensuring the level of use of any replacement or sister body. Therefore, the strict positional limitation and stability of the tool holder on the body is combined with good coarse and fine adjustment, which is the basis of tool performance. Good design accuracy, combined with the toothed interface of the tool holder, the extremely small blade positioning and the wiper blade technology, have brought the performance and quality consistency of the new milling cutter to a new level.
The interchangeability of the tool holders greatly enhances the safety and durability of the machine, reducing the cost and inventory of large diameter tools. The weight of large diameter tools during cutting is a problem, so the presence of CoroMill Century aluminum cutters makes tool replacement and clamping easier. Some tool-clamping cutters have been exposed to the risk of damage to the machined surface quality due to chipping, and now the accelerated coolant is forcibly punched out from the newly designed independent cooling ports on each tool holder, effectively cutting the chips away from the machining area. Greatly improved processing safety.
Many automotive milling processes are sensitive and subjective, so it is important to ensure that there are sufficient knives with options when investing in large diameter tools that represent large tooling costs. By using the standard CoroMill blade inserts on CoroMill holders, many different insert types are available for large diameter milling cutters, including the use of wiper blades in several locations. This means that there are many choices of inserts on the tool holder, from the latest generation of coated carbide grades (in combination with specific geometries) to more specialized tool materials such as silicon nitride ceramics, cubic boron nitride and PCD. blade. Such large diameter tools are preferred over existing applications. This adds flexibility to tool selection and combination, making it easier to find the best machining solution.
The interchangeable toolholder concept of CoroMill 365 face milling cutters and large diameter face milling cutters represents two important advances in machining technology for the automotive industry.
Thread turning with I-Lock technology
When it comes to problems in thread turning, the micro-displacement of the indexable insert is considered to be one of the common causes of accidents. Slight movement of the cutting edge during the cutting process tends to result in prematurely shortened tool life, no performance consistency and unsatisfactory machining results.
However, recent breakthroughs in blade technology have found a way to accurately position the blade on the shank and have achieved dramatic changes in cutting edge stability. This breakthrough opens the door to a harder, more durable blade material that reliably reduces cycle times.
In thread turning, many problems that lead to poor performance and unsatisfactory machining results are often caused by negligence in the basics of common metal cutting, such as minimizing tool overhang, maximizing tool stability, and centering the cutting edge. It is most suitable for the application of cutting parameters and the selection of the most suitable tools and processing methods. Other specific problems with thread turning include the depth of cut per pass, the different methods of radial feed, and the blade tilt angle required to obtain a sufficiently large blade back angle, which is based on the pitch and diameter of the thread and the helix angle. to make sure.
As the most typical feature of the thread, thread profile and tooth profile error are the most common causes of quality failure in thread machining, or may be caused by tolerance or surface roughness. When this happens, the life of the cutting edge usually ends prematurely. One of the main reasons for the formation of incorrect thread profiles so far is the lack of stability of the blade on the shank. The micro-movement of the blade also has some adverse consequences that lead to a shortened tool life. One of the main consequences is the chipping of the cutting edge, especially at the tip radius. By selecting an alternative clamping screw, for example, it is usually necessary to replace the quick-change screw with a U-shaped screw, the stability can be improved to some extent. But until now, it has been difficult to resolve the complete fixation of the blade on the blade holder.
The second factor is the beginning and end of each pass in thread turning, which means that the magnitude and direction of the cutting force changes abruptly. These are the most sensitive movements during the machining process and are susceptible to the risk of blade displacement. The tip of the threaded jaw on the blade forms a lever with the screw, forcing the cutting edge to slightly change position and deform the support point in the blade slot. During the thread turning process, alternating axial forces are generated at the beginning and end of each pass, and the balance is offset after the cut and during the cut. This alternating axial force acts on the blade from different directions, creating a tendency for the blade to move back and forth.
The third factor, any change in the type of thread, means that the cutting force varies in size and even direction, but the blade size does not have to vary with the thread profile to provide different levels of support in the blade holder. And the same blade size will have a different pitch, which means that a large pitch blade does not have more support than a small pitch blade. If the blade size changes as the thread profile and pitch change, the blade and shank specifications will have to become much more than expected.
Therefore, the main consequence of the cutting edge displacement is the generation of thread tolerances and minor cracking of the blade cutting edge. If the tool is not stopped after machining a defective thread profile, tool wear will increase more quickly. As the cutting edge wears, the insert will withstand greater cutting forces and thus further displacement, thereby accelerating the failure. In fact, the replacement of the blade due to the displacement is more frequent than the replacement of the actual blade. The precise positioning of the cutting edge is critical in terms of thread quality consistency in the process.
Another aspect of blade positioning is repeatability. In order to avoid time-consuming machine setup and to minimize or eliminate the occurrence of scrapped parts, the easy and precise positioning of the insert in the shank is important. Under normal circumstances, the blade should not be indexed as far as possible during the pass to avoid the threaded surface. If the blade needs to be indexed during the pass, the precise positioning of the blade is maintained and realized. Acceptable processing results are key. In combination with this, taking into account the impact of machine downtime, it is also important to perform blade indexing between the two passes quickly and easily.
The production efficiency of thread turning is largely related to the number of passes required for the thread turning tool to complete the thread profile. If the number of passes is too large, and the depth of cut is insufficient, excessive tool wear and frictional heat are caused, resulting in rapid flank wear and plastic deformation. Small depths of cut also often have an adverse effect on chip formation, creating thin, unmanageable chips. Less passes require a greater depth of cut, but the cutting edge is subject to more load. By optimizing the number of passes, the time required to machine the full thread is reduced and the cutting edge is improved. The large depth of cut produces a higher cutting force, which increases the tendency of the blade to shift in the seat, which again emphasizes the need for reliable positioning of the blade.
Another typical feature of a thread is the pitch, which in some cases may be the cause of component errors. Most pitch errors come from CNC errors, and when the machine, control unit, setup, and programming errors have been eliminated, the stability of the indexable insert in the shank and the effect of the tool lateral feed on the pitch can be made. Evaluation. The pitch of the thread is an element of the design of the part. Normally, the fine thread has stricter tolerance requirements. In terms of cutting, it takes more to machine the fine thread due to the smaller number of threads per unit millimeter or inch (feed rate). Long time. However, the larger the pitch, the higher the feed rate and the greater the cutting force required, which also requires very stable blade positioning.
Due to the fragility of the cutting edge in thread turning, the insert needs to be as hard and wear-resistant as possible, and is not susceptible to brittle fracture, and there is no risk of chipping during processing. In modern machining, a large amount of cutting heat is generated at the cutting edge, forcing the tool to have the ability to resist plastic deformation. After plastic deformation, it is followed by rapid flank wear. If the same cutting edge continues to be used, There is a crack in the cutting edge. Plastic deformation of the cutting edge is the biggest obstacle to improving efficiency through cutting speed in thread turning. Inappropriate blade material allows the cutting edge to be quickly scrapped to produce an unacceptable thread, followed by a broken cutting edge. In general, the proper number of passes and the flank wear at the expected blade life are the goals of thread turning.
However, in order to withstand the mechanical load, especially the mechanical load of the threaded tip, the blade needs to have a certain strength, and the blade material also needs a small amount of reasonable toughness. This requirement is extremely obvious for machining internal threads. The boring process is always accompanied by the problem of tool vibration, knife and chip removal, so proper toughness plays a decisive role in blade performance and reliability.
Eliminating the micro-displacement of the insert in the insert pocket provides the possibility of using new tool materials, and the development of the insert material does not require much consideration for processing instability. As a result, the latest developments in fine-grained insert base technology provide a unique matrix with high red hardness, making tools with sharp cutting edges resistant to plastic deformation, such as thread turning, cutting and grooving, and solid carbide end mills. . The GC1125 is a new PVD coated grade optimized for thread turning of steel and also performs well on other workpiece materials. It increases production efficiency by using higher cutting speeds - in thread turning it is often not possible to use higher cutting speeds due to the limitations of tool material properties. The matrix of GC1125 is very hard and does not use any gradient technique because its inherent toughness provides sufficient cutting edge strength.
The PVD coating is a new multi-layer titanium aluminide coating with cutting edge ER treatment and insert geometry for high edge safety. As mentioned above, the outer blade tip of the blade is prone to plastic deformation, and the blade portion of the thread crest is more likely to be worn due to flaking and sticking, thereby forming a built-up edge. GC1125 is a PVD coating that better eliminates these trends and flank wear. The flank wear typically occurs along the cutting edge that is machined to form a threaded surface. It is a complement to the thread turning universal material GC1020 and can be used to optimize the productivity of the threading process. Other complementary threaded inserts include a very sharp, uncoated grade H13A for heat resistant alloys, titanium alloys and certain cast irons. CB20 is a cubic boron nitride material for thread turning of hard materials.
Therefore, for a number of reasons, the positioning and locking quality of the thread turning insert in the shank insert groove plays a decisive role in achieving high production efficiency, safe operation and consistent part quality. With the past method of blade locking and positioning, it has been impossible in many cases to fasten the blade in the blade slot. The fixing of the blade, the clamping of the blade and the easy indexing mean a compromise, and the limitations of the blade manufacturing method have hindered the possibility of breaking the traditional method.
The development of the blade positioning and locking concept of the CoroThread 266 thread turning tool brings greater safety, longer tool life and higher productivity. The CoroThread 266 accurately and securely positions the blade even during cutting or indexing, which is an important breakthrough for thread turning.
The CoroThread 266 thread turning tool series meets the requirements for higher stability compared to conventional blade clamping system tools. The shims are very important for the thread turning process and have been redesigned to provide a safe basis for the blade to be fixed in the shank. The blade provides the blade with the necessary secure and precise positioning through the two solid contact faces in the blade holder and the side-mounted screws. This is a convex, precision rail interface on which the corresponding blade is positioned.
The blade clamping screw attaches the blade to the rail and rests radially against a contact surface, providing high stability and accurate positioning. When cutting, the guide rails supporting the blade are subjected to cutting forces, and there is no risk of damage to any blade support points of the blade holder. The positioning rail is perpendicular to the feed direction.
For accuracy, the CoroThread 266 has a high repeatability, ensuring a cutting edge axial (feed direction) of ±0.05 mm for Class M tolerance inserts and ±0.01 mm for E-class tolerance inserts. The iLock rails facilitate the speed and clamping of the indexing of the inserts, and the contact pattern and clearance of the rails are critical to their performance. The shape and positioning of the guide rails has been extensively developed to set precise bearing points between the blade and the blade, while the new blade manufacturing technology keeps the support points consistent. This technology eliminates the misalignment of the blade holder, which improves blade clamping.
In summary, the development of tools in the three areas of turning, milling and thread turning directly meets the requirements of automotive manufacturers for improved processability, improved safety and quality consistency in high volume production. With the improvement of the absolute stability of the cutting edge as one of the main success factors of cutting, the new development of the tool holder, the indexable insert and the positioning technology between the two has completely overcome the existing limitations and lead the machining of the automotive industry. To be more efficient.
In the evolution of automotive processing technology, tool manufacturers are constantly under pressure from automotive manufacturers, and every time they are required to launch a better solution than existing products. Nowadays, standard tools that can satisfy the same type of machining are being developed and developed by Hanyang Technology Co., Ltd., and the share of automotive processing applications is increasing. This is an increasingly obvious trend. More use of standard tools can reduce production costs and provide better delivery reliability.
This article will focus on the following three cutting applications, from which we will see that the latest tools not only meet the requirements of the automotive industry to improve processing efficiency, but also ensure the safety of processing.
Turning: Turning machining is widely used in the machining of automotive parts. In turning, steel shafts and disc parts are roughed and finished under various conditions. The requirements for part quality are also different, but the requirements for processing beats are always the most important. In the traditional machining process, in order to ensure the surface roughness of the workpiece, the feed rate of the tool is limited, and the machining time cannot be further shortened.
Milling: Milling of cast iron parts is extremely common in the machining of automotive parts. In this field, the contact and sealing surfaces of the cylinder and the housing are both milled. In traditional machining processes, machine downtime and tool unreliability often reduce machining efficiency, especially in roughing and semi-finishing operations.
Thread turning: Threading requires high quality. Once the threading process is going to be too bad, the production has to stop. Threading has very strict requirements on the shape of the cutting edge of the threaded tool, especially to maintain accurate positioning of the cutting edge. In the past, the low positioning stability of the threaded insert in the insert pocket was a factor limiting the increase in production efficiency.
Turning with a new generation of tools
In the turning process, the use of Wiper can change the basic law of cutting. The tip radius of a conventional turning tool tends to produce a scalloped blade on the surface of the workpiece. The tool feed and the tool nose radius are directly related to the cross-sectional height of the scalloped blade, which determines the surface quality of the turning. The wiping edge of the wiper wipes the top of the scalloped blade created by the tip. Of course, the concept of light repair in turning also needs to be continuously developed by reducing the length of the wiper to avoid damaging the shape of the machined surface and creating excessive cutting forces. At the same time, the blade needs to control the chip and can be directly mounted like a normal blade.
The Wiper was originally developed to increase the feed rate to twice the conventional blade while maintaining the same surface roughness during turning. Or, under the condition of keeping the feed rate constant, the surface roughness of the workpiece is increased by twice. Obviously, between these two possibilities, different combinations of feed and surface roughness improvement can be established, and the resulting increase in production efficiency of part turning is considerable.
The principle of the wiper technology is based on a large set of corner radius and a small set of fillet radii. There is a circular arc radius for the tip of a conventional blade cutting edge. For this reason, the wiper blade must conform to the standard ISO blade standard. It also has a nominal tool nose radius and the radius of the arc is the same for various machining applications. In addition, the wiper blade must be easy to set up and use, with no major changes in programming and tool nose radius compensation.
The first wiper blade for turning was first introduced by Sandvik Colaman in 1997. This insert features a blade geometry for roughing to ensure the strength of the tip. At the same time, this blade has a long enough wiper to use a higher feed rate. The length of contact between the cutting edge and the workpiece must be balanced with the appropriate chipbreaker geometry for smooth cutting and low cutting forces.
Next, the new type of wiper blade was developed for finishing, and the limit on the amount of cutting is more stringent. Based on a medium-sized bladed groove, this blade has a sharper cutting edge and a larger positive rake angle, which is safe and reliable at high feed rates. The two first-generation wiper blades (WM and WF) have similar workpiece surface roughness forming characteristics, but the groove shapes are different and the influence on tool life is different.
Compared with conventional blades of the same specification, the cutting force of the first generation of the polishing blade is only increased by about 5%, which means that only in the case of extreme instability, it will be negatively affected by the shape of the wiper blade, for example. Turning of the slender shaft, even with conventional blades, and special care must be taken in accordance with the recommended cutting parameters. The high feed rate of the wiper blade stabilizes certain processes and overcomes the tendency to vibrate by selecting a smaller tip.
Along with the widespread use of wiper blades and the assessment of surface quality measurements, the impression that the wiper blade causes vibrations changes. Compared with the bright surface produced by the conventional tool tip, Hanyang Technology Co., Ltd., the appearance of the dark surface after the turning of the light has become associated with high surface quality. The larger wiper tip radius provides very satisfactory stability during the turning process and also makes the Wiper groove the preferred finishing insert for general turning of various workpiece materials.
The wiper blade has another important effect in turning: it improves chip breaking in many processes. Part of the reason is because the Wiper geometry is designed for good chip control at low feed rates and smooth chip breaking at high feed rates, so chip control is optimal for a wide range of applications.
Recently, the polishing blades for turning have required new developments, especially in the automotive industry. Part of the reason is that the surface quality generated by the first generation of the wiper blade is insufficient at high feed rates. Increasing the nominal radius of the wiper cutting edge aligns with the surface quality requirements in production. However, for R&D work, the challenge is that the actual length of the wiper required for high feed rates is limited.
Today, the well-designed new generation of wiper technology correctly combines the nominal radius with the number and size of the fitted radii, which ensures the correct finishing and smooth transition of the wiper with the rest of the cutting edge. The key to the new wiper edge structure is the perfect combination of cutting geometry and chipbreaker shape for optimum cutting results.
A new generation of wiper technology must increase the surface roughness of the workpiece, and the feed rate should be at least equal to the current level. Any vibration generated by the new wiper blade must be lower than the first generation wiper blade. As a result of the development of the new wiper blade, a new wiper-shaped WMX has been created. The new wiper-edge WMX exhibits excellent cutting results that reduce the tendency to vibrate, can be found by monitoring the level of noise generated during machining, or from the shape of the chips produced during machining.
The new generation of wiper-edge WMX has a wider range of applications than the original wiper blades or standard inserts used in many turning operations in the automotive industry, while covering the range of original inserts. Using a higher feed rate will develop the potential for increased productivity - reducing processing time by 30%. If the surface roughness of the workpiece is used as the standard industrial automation network for the replacement of the blade, the new generation of the wiper-shaped WMX prolongs the tool life due to the significant improvement in blade wear. The new wiper insert conforms to the basic shape of ISO standard inserts and is easy to set up and use. As the original intention of developing a new generation of wiper-edge WMX, to improve the surface roughness level of the machined workpiece, the new blade WMX insert has been shown to achieve better surface quality (Ra 0.8) at the maximum feed rate. At slightly lower feed rates, WMX can produce surface roughness below Ra0.5.
The existing first generation of wiper blades (WM and WF) will continue to exist as a complementary trough for WMX. The WM geometry features a sturdy cutting edge that is a safer and more reliable solution for intermittent cutting of parts; WF is suitable for finishing, for example when the depth of cut is less than 0.5 mm or when a sharper cutting edge is required And when improving chip evacuation control during finishing.
The design purpose and processing effect of the wiper depends on whether the cutting edge is parallel to the feed direction. In some cutting applications, the wiper blade has minor drawbacks that require programming adjustments. When the part has a taper greater than 5 degrees, the wiper cutting edge can still be cut, but without its excellent lightening effect. In order to achieve the same surface quality, the feed rate must be lowered to the recommended value for a conventional tip radius blade.
Similarly, in the case of reverse machining, the wiper cutting edge does not adequately eat the knife, so the feed rate must be reduced from the high feed rate of the wiper blade to the recommended value for the conventional tip radius blade. As an alternative to the manual input of these variable feed rates, there is currently a programming software that can support the above applications.
Most of the turning operations are external turning and face turning, which means that the wiper blade can significantly reduce cutting time, improve surface quality and improve chip evacuation as well as increase safety through a strong cutting edge. Evaluate the turning process at hand, see the possibilities of using the wiper technology, and then optimize the process with the wiper technology to get a lot of benefits.
In the normal turning process, changing the conventional blade to a wiper blade on the same tool holder can directly reduce the machining time while maintaining excellent and consistent surface quality. The new generation of wiper blade WMX has truly developed the wiper technology. At the same time, there is no special restriction on high stability requirements, and it has a smooth chip breaking effect at high feed rate. It is the first choice and versatile solution.
Milling - from roughing to finishing
Cast iron milling is an important part of the manufacture of engine and housing parts. In engine manufacturing, the right geometry, good surface finish, and zero waste in total quality assurance are absolutely important goals. However, in the face of increasing cost pressures, they are eclipsed. In order to meet all of the above requirements, we need reliable and efficient tools and solutions, such as roughing and finishing of the cylinder and cylinder head planes.
For foundries or other primary subcontractors, roughing is usually part of the blanking process and metal removal rates are the most important factor. Finishing combines all the requirements for high efficiency, high reliability and high quality. One of the most challenging processes is face milling of the combustion surface, which is often the final step in the machining of the cylinder shape.
In the automotive industry, cast iron is a widely used workpiece material. Gray cast iron still dominates, and by weight it is several times that of ductile iron and other types of cast iron. Recently, the continuous development of materials and production has helped expand the use of compacted graphite iron (CGI), tempered ductile iron (ADI) and a range of alloy cast irons, increasing the range of cast iron processing materials. The cast iron cylinder liner can also be combined with an aluminum alloy cylinder, which makes milling more difficult.
In order to improve the production efficiency and reliability of the processing technology, a series of cast iron milling solutions have been launched recently.
Sandvik Coromant has long been leading the introduction of automotive-specific milling cutters and cap milling cutters for automatic wire milling in large-scale production. Recently, more and more flexible wires or single machining centers are used to process small quantities of cast iron parts and automotive parts, which means that 80% of milling cutters are in the range of 63 to 160 mm. This reflects the increasing variety of cast iron milling available today, ranging from small batches and light machining in small machining centers to roughing and finishing on automated wire or heavy machining centers in large-scale production.
In the development of new tools for roughing and semi-finishing, the objectives to be achieved include improvements in tool feed range, cutting force, workpiece breakage, burr formation, surface quality and noise level.
The improvement starts with increasing the lead angle from the conventional 45 degrees to 65 degrees, which brings, for example, a more brisk cut of the milling cutter, which can be closer to the advantages of fixture processing. However, a slightly larger lead angle increases the tendency of the workpiece to collapse when the tool is cut out because of the large radial cutting forces and the effect of the flake graphite structure in the cast iron material. In fact, the replacement tool judgment criteria often must be set according to the limits of the workpiece chipping. Therefore, in order to cope with the possible cracking effect of the large lead angle, a new 65 degree cutter blade shape has been designed, which makes the tool more advantageous when it exits the cutting.
In addition, the new geometry on the eight cutting edges also causes the cutting force to be more toward the support locating surface of the blade. At the same time, a portion of the blade geometry forms eight positive rake angle chip formers that are positioned in an optimal manner on both faces of the support blade.
Although the cutting force in cast iron machining is relatively low, it is often amplified by high frequency due to the distribution of the cutting force on the largest possible area during the milling of large contact faces, so the good support of the cutter and the blade during cast iron cutting becomes critical. The blade groove of the 65 degree insert has a good radial and axial support surface and extends all the way to the cutting edge of the insert, which allows the insert to handle heavy-duty cutting and resist deformation, so the tool has a high life span. Cutting safety.
For this new cast iron face milling cutter CoroMill 365, the face milling cutter body has an oversized tool support surface that allows the milling cutter to obtain maximum flange support from the machine tool spindle for added stability. The use of a screw clamping insert facilitates tool handling and wedge clamping is used for ultra-tight pitch bodies. Coolant is an integral part of cast iron cutting. The new face milling cutter body has a continuous coolant passage that allows coolant to reach each blade for maximum cooling.
Increasing the feed rate and surface quality are essential features of the tool, which require ultra-compact pitch, axial mounting accuracy of the blade cutting edge, and the wiper blade. While providing high cutting safety, these ever-increasing performance requirements have to be met, which has been successfully implemented in the development of new cutting tools that combine proven milling tool concepts.
The CoroMill face milling cutter range with replaceable toolholders now offers semi-finishing, finishing and roughing solutions for cast iron and aluminium cylinders, cylinder heads and housings. Tool-cutter milling cutters based on proven concepts like CoroMill 245 and Century have been widely recognized when tool pitch, accuracy, clamping and reliability are decisive factors.
Toolholder design and the positioning, adjustment and locking of the blades create significant differences in processability and performance. The use of standard toolholders on standard and custom bodies provides more effective teeth count – which is critical to increasing productivity and surface quality. The control of the axial position of each holder determines the surface quality and the consistency of the body, ensuring the level of use of any replacement or sister body. Therefore, the strict positional limitation and stability of the tool holder on the body is combined with good coarse and fine adjustment, which is the basis of tool performance. Good design accuracy, combined with the toothed interface of the tool holder, the extremely small blade positioning and the wiper blade technology, have brought the performance and quality consistency of the new milling cutter to a new level.
The interchangeability of the tool holders greatly enhances the safety and durability of the machine, reducing the cost and inventory of large diameter tools. The weight of large diameter tools during cutting is a problem, so the presence of CoroMill Century aluminum cutters makes tool replacement and clamping easier. Some tool-clamping cutters have been exposed to the risk of damage to the machined surface quality due to chipping, and now the accelerated coolant is forcibly punched out from the newly designed independent cooling ports on each tool holder, effectively cutting the chips away from the machining area. Greatly improved processing safety.
Many automotive milling processes are sensitive and subjective, so it is important to ensure that there are sufficient knives with options when investing in large diameter tools that represent large tooling costs. By using the standard CoroMill blade inserts on CoroMill holders, many different insert types are available for large diameter milling cutters, including the use of wiper blades in several locations. This means that there are many choices of inserts on the tool holder, from the latest generation of coated carbide grades (in combination with specific geometries) to more specialized tool materials such as silicon nitride ceramics, cubic boron nitride and PCD. blade. Such large diameter tools are preferred over existing applications. This adds flexibility to tool selection and combination, making it easier to find the best machining solution.
The interchangeable toolholder concept of CoroMill 365 face milling cutters and large diameter face milling cutters represents two important advances in machining technology for the automotive industry.
Thread turning with I-Lock technology
When it comes to problems in thread turning, the micro-displacement of the indexable insert is considered to be one of the common causes of accidents. Slight movement of the cutting edge during the cutting process tends to result in prematurely shortened tool life, no performance consistency and unsatisfactory machining results.
However, recent breakthroughs in blade technology have found a way to accurately position the blade on the shank and have achieved dramatic changes in cutting edge stability. This breakthrough opens the door to a harder, more durable blade material that reliably reduces cycle times.
In thread turning, many problems that lead to poor performance and unsatisfactory machining results are often caused by negligence in the basics of common metal cutting, such as minimizing tool overhang, maximizing tool stability, and centering the cutting edge. It is most suitable for the application of cutting parameters and the selection of the most suitable tools and processing methods. Other specific problems with thread turning include the depth of cut per pass, the different methods of radial feed, and the blade tilt angle required to obtain a sufficiently large blade back angle, which is based on the pitch and diameter of the thread and the helix angle. to make sure.
As the most typical feature of the thread, thread profile and tooth profile error are the most common causes of quality failure in thread machining, or may be caused by tolerance or surface roughness. When this happens, the life of the cutting edge usually ends prematurely. One of the main reasons for the formation of incorrect thread profiles so far is the lack of stability of the blade on the shank. The micro-movement of the blade also has some adverse consequences that lead to a shortened tool life. One of the main consequences is the chipping of the cutting edge, especially at the tip radius. By selecting an alternative clamping screw, for example, it is usually necessary to replace the quick-change screw with a U-shaped screw, the stability can be improved to some extent. But until now, it has been difficult to resolve the complete fixation of the blade on the blade holder.
The second factor is the beginning and end of each pass in thread turning, which means that the magnitude and direction of the cutting force changes abruptly. These are the most sensitive movements during the machining process and are susceptible to the risk of blade displacement. The tip of the threaded jaw on the blade forms a lever with the screw, forcing the cutting edge to slightly change position and deform the support point in the blade slot. During the thread turning process, alternating axial forces are generated at the beginning and end of each pass, and the balance is offset after the cut and during the cut. This alternating axial force acts on the blade from different directions, creating a tendency for the blade to move back and forth.
The third factor, any change in the type of thread, means that the cutting force varies in size and even direction, but the blade size does not have to vary with the thread profile to provide different levels of support in the blade holder. And the same blade size will have a different pitch, which means that a large pitch blade does not have more support than a small pitch blade. If the blade size changes as the thread profile and pitch change, the blade and shank specifications will have to become much more than expected.
Therefore, the main consequence of the cutting edge displacement is the generation of thread tolerances and minor cracking of the blade cutting edge. If the tool is not stopped after machining a defective thread profile, tool wear will increase more quickly. As the cutting edge wears, the insert will withstand greater cutting forces and thus further displacement, thereby accelerating the failure. In fact, the replacement of the blade due to the displacement is more frequent than the replacement of the actual blade. The precise positioning of the cutting edge is critical in terms of thread quality consistency in the process.
Another aspect of blade positioning is repeatability. In order to avoid time-consuming machine setup and to minimize or eliminate the occurrence of scrapped parts, the easy and precise positioning of the insert in the shank is important. Under normal circumstances, the blade should not be indexed as far as possible during the pass to avoid the threaded surface. If the blade needs to be indexed during the pass, the precise positioning of the blade is maintained and realized. Acceptable processing results are key. In combination with this, taking into account the impact of machine downtime, it is also important to perform blade indexing between the two passes quickly and easily.
The production efficiency of thread turning is largely related to the number of passes required for the thread turning tool to complete the thread profile. If the number of passes is too large, and the depth of cut is insufficient, excessive tool wear and frictional heat are caused, resulting in rapid flank wear and plastic deformation. Small depths of cut also often have an adverse effect on chip formation, creating thin, unmanageable chips. Less passes require a greater depth of cut, but the cutting edge is subject to more load. By optimizing the number of passes, the time required to machine the full thread is reduced and the cutting edge is improved. The large depth of cut produces a higher cutting force, which increases the tendency of the blade to shift in the seat, which again emphasizes the need for reliable positioning of the blade.
Another typical feature of a thread is the pitch, which in some cases may be the cause of component errors. Most pitch errors come from CNC errors, and when the machine, control unit, setup, and programming errors have been eliminated, the stability of the indexable insert in the shank and the effect of the tool lateral feed on the pitch can be made. Evaluation. The pitch of the thread is an element of the design of the part. Normally, the fine thread has stricter tolerance requirements. In terms of cutting, it takes more to machine the fine thread due to the smaller number of threads per unit millimeter or inch (feed rate). Long time. However, the larger the pitch, the higher the feed rate and the greater the cutting force required, which also requires very stable blade positioning.
Due to the fragility of the cutting edge in thread turning, the insert needs to be as hard and wear-resistant as possible, and is not susceptible to brittle fracture, and there is no risk of chipping during processing. In modern machining, a large amount of cutting heat is generated at the cutting edge, forcing the tool to have the ability to resist plastic deformation. After plastic deformation, it is followed by rapid flank wear. If the same cutting edge continues to be used, There is a crack in the cutting edge. Plastic deformation of the cutting edge is the biggest obstacle to improving efficiency through cutting speed in thread turning. Inappropriate blade material allows the cutting edge to be quickly scrapped to produce an unacceptable thread, followed by a broken cutting edge. In general, the proper number of passes and the flank wear at the expected blade life are the goals of thread turning.
However, in order to withstand the mechanical load, especially the mechanical load of the threaded tip, the blade needs to have a certain strength, and the blade material also needs a small amount of reasonable toughness. This requirement is extremely obvious for machining internal threads. The boring process is always accompanied by the problem of tool vibration, knife and chip removal, so proper toughness plays a decisive role in blade performance and reliability.
Eliminating the micro-displacement of the insert in the insert pocket provides the possibility of using new tool materials, and the development of the insert material does not require much consideration for processing instability. As a result, the latest developments in fine-grained insert base technology provide a unique matrix with high red hardness, making tools with sharp cutting edges resistant to plastic deformation, such as thread turning, cutting and grooving, and solid carbide end mills. . The GC1125 is a new PVD coated grade optimized for thread turning of steel and also performs well on other workpiece materials. It increases production efficiency by using higher cutting speeds - in thread turning it is often not possible to use higher cutting speeds due to the limitations of tool material properties. The matrix of GC1125 is very hard and does not use any gradient technique because its inherent toughness provides sufficient cutting edge strength.
The PVD coating is a new multi-layer titanium aluminide coating with cutting edge ER treatment and insert geometry for high edge safety. As mentioned above, the outer blade tip of the blade is prone to plastic deformation, and the blade portion of the thread crest is more likely to be worn due to flaking and sticking, thereby forming a built-up edge. GC1125 is a PVD coating that better eliminates these trends and flank wear. The flank wear typically occurs along the cutting edge that is machined to form a threaded surface. It is a complement to the thread turning universal material GC1020 and can be used to optimize the productivity of the threading process. Other complementary threaded inserts include a very sharp, uncoated grade H13A for heat resistant alloys, titanium alloys and certain cast irons. CB20 is a cubic boron nitride material for thread turning of hard materials.
Therefore, for a number of reasons, the positioning and locking quality of the thread turning insert in the shank insert groove plays a decisive role in achieving high production efficiency, safe operation and consistent part quality. With the past method of blade locking and positioning, it has been impossible in many cases to fasten the blade in the blade slot. The fixing of the blade, the clamping of the blade and the easy indexing mean a compromise, and the limitations of the blade manufacturing method have hindered the possibility of breaking the traditional method.
The development of the blade positioning and locking concept of the CoroThread 266 thread turning tool brings greater safety, longer tool life and higher productivity. The CoroThread 266 accurately and securely positions the blade even during cutting or indexing, which is an important breakthrough for thread turning.
The CoroThread 266 thread turning tool series meets the requirements for higher stability compared to conventional blade clamping system tools. The shims are very important for the thread turning process and have been redesigned to provide a safe basis for the blade to be fixed in the shank. The blade provides the blade with the necessary secure and precise positioning through the two solid contact faces in the blade holder and the side-mounted screws. This is a convex, precision rail interface on which the corresponding blade is positioned.
The blade clamping screw attaches the blade to the rail and rests radially against a contact surface, providing high stability and accurate positioning. When cutting, the guide rails supporting the blade are subjected to cutting forces, and there is no risk of damage to any blade support points of the blade holder. The positioning rail is perpendicular to the feed direction.
For accuracy, the CoroThread 266 has a high repeatability, ensuring a cutting edge axial (feed direction) of ±0.05 mm for Class M tolerance inserts and ±0.01 mm for E-class tolerance inserts. The iLock rails facilitate the speed and clamping of the indexing of the inserts, and the contact pattern and clearance of the rails are critical to their performance. The shape and positioning of the guide rails has been extensively developed to set precise bearing points between the blade and the blade, while the new blade manufacturing technology keeps the support points consistent. This technology eliminates the misalignment of the blade holder, which improves blade clamping.
In summary, the development of tools in the three areas of turning, milling and thread turning directly meets the requirements of automotive manufacturers for improved processability, improved safety and quality consistency in high volume production. With the improvement of the absolute stability of the cutting edge as one of the main success factors of cutting, the new development of the tool holder, the indexable insert and the positioning technology between the two has completely overcome the existing limitations and lead the machining of the automotive industry. To be more efficient.
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