Take a holistic approach
It is important to take into account all the steps, from roughing all the way to finishing, because they are all interconnected, interrelated and interdependent, such as the margin you want to leave for finishing and semi-finishing before starting rough.
In order to ensure a high quality surface finish, the operator needs to remove the appropriate amount of material during the roughing and semi-finishing stages so that the finishing can be carried out with few or fewer errors. Any problem can result in poor surface quality.
Roughing will process most of the blank margin, so that the finishing tool will not have pressure, and the reasonable matching of the roughing margin also prevents premature damage to the finishing tool. Many factories are more willing to roughing the use of more aggressive feed parameters, which may lead to large burrs on the wall of the part, which is difficult to break.
If these burrs are found on a part during a finishing operation, they can be very hard (producing chip nodules), resulting in a very short blade life. Roughing tools should be programmed to remove notched burrs and should provide a good surface to be machined for the finishing stage."
If these burrs are found on a part during a finishing operation, they can be very hard (producing chip nodules), resulting in a very short blade life. Roughing tools should be programmed to remove notched burrs and should provide a good surface to be machined for the finishing stage." How to improve the finish of the turning surface 2023-11-06 10:04:03
In the finishing stage of a turning operation, the last thing an operator wants to do is scrap a part because of poor surface finish quality, and the factory also needs to consider many factors to improve the surface finish and meet customer requirements. The right blade and cutting parameters are essential, but so is taking a holistic approach to producing a better surface finish.
Take a holistic approach
It is important to take into account all the steps, from roughing all the way to finishing, because they are all interconnected, interrelated and interdependent, such as the margin you want to leave for finishing and semi-finishing before starting rough.
In order to ensure a high quality surface finish, the operator needs to remove the appropriate amount of material during the roughing and semi-finishing stages so that the finishing can be carried out with few or fewer errors. Any problem can result in poor surface quality.
Roughing will process most of the blank margin, so that the finishing tool will not have pressure, and the reasonable matching of the roughing margin also prevents premature damage to the finishing tool. Many factories are more willing to roughing the use of more aggressive feed parameters, which may lead to large burrs on the wall of the part, which is difficult to break.
If these burrs are found on a part during a finishing operation, they can be very hard (producing chip nodules), resulting in a very short blade life. Roughing tools should be programmed to remove notched burrs and should provide a good surface to be machined for the finishing stage."
If you look at a functioning machine tool or mild steel turning process, the operator needs to produce a surface finish good enough at an early stage to achieve the necessary surface finish, and if you start working with hardened steel parts, the surface finish that is rough-rolled before heat treatment will greatly affect the final surface finish after heat treatment.
Select the right feed and speed
In finishing, you will use a higher surface feed, so the speed is faster and the feed speed is lower. And, in general, your cutting depth will be smaller. But it's also important that you make sure that the feed speed is consistent with the surface finish you want. If the feed speed is too slow, it will cause excessive friction and premature wear of the blade, resulting in poor surface finish.
The faster cutting speed helps to raise the temperature slightly, resulting in a better surface finish. It also prevents the material from sticking to the top or surface of the tool. Compared to roughing applications, the operator should increase the speed slightly, but not too much, otherwise it will have the opposite effect. If there is a chip on the side of the blade, the feed should be increased.
Many brands tend to slow down compared to roughing applications, which is a common mistake in finishing operations. Increasing speed is necessary to obtain a high quality surface finish.
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How to improve the finish of the turning surface 2023-11-06 10:04:03
In the finishing stage of a turning operation, the last thing an operator wants to do is scrap a part because of poor surface finish quality, and the factory also needs to consider many factors to improve the surface finish and meet customer requirements. The right blade and cutting parameters are essential, but so is taking a holistic approach to producing a better surface finish.
Take a holistic approach
It is important to take into account all the steps, from roughing all the way to finishing, because they are all interconnected, interrelated and interdependent, such as the margin you want to leave for finishing and semi-finishing before starting rough.
In order to ensure a high quality surface finish, the operator needs to remove the appropriate amount of material during the roughing and semi-finishing stages so that the finishing can be carried out with few or fewer errors. Any problem can result in poor surface quality.
Roughing will process most of the blank margin, so that the finishing tool will not have pressure, and the reasonable matching of the roughing margin also prevents premature damage to the finishing tool. Many factories are more willing to roughing the use of more aggressive feed parameters, which may lead to large burrs on the wall of the part, which is difficult to break.
If these burrs are found on a part during a finishing operation, they can be very hard (producing chip nodules), resulting in a very short blade life. Roughing tools should be programmed to remove notched burrs and should provide a good surface to be machined for the finishing stage."
If you look at a functioning machine tool or mild steel turning process, the operator needs to produce a surface finish good enough at an early stage to achieve the necessary surface finish, and if you start working with hardened steel parts, the surface finish that is rough-rolled before heat treatment will greatly affect the final surface finish after heat treatment.
In finishing, you will use a higher surface feed, so the speed is faster and the feed speed is lower. And, in general, your cutting depth will be smaller. But it's also important that you make sure that the feed speed is consistent with the surface finish you want. If the feed speed is too slow, it will cause excessive friction and premature wear of the blade, resulting in poor surface finish.
The faster cutting speed helps to raise the temperature slightly, resulting in a better surface finish. It also prevents the material from sticking to the top or surface of the tool. Compared to roughing applications, the operator should increase the speed slightly, but not too much, otherwise it will have the opposite effect. If there is a chip on the side of the blade, the feed should be increased.
Many brands tend to slow down compared to roughing applications, which is a common mistake in finishing operations. Increasing speed is necessary to obtain a high quality surface finish.
Excessive dimensional tolerances can reduce the contact area between the blade (for example, a WNMG blade) and the slot, causing the slot to move. This causes microvibrations, which have a negative impact on the surface finish.
Determining the correct cutting depth will help the stability of the turning process. Too small a cutting depth causes the tip radius to apply all the force radially to the part, which causes vibration and negatively affects the surface finish.
It is also important not to recommend excessive depth of cutting, as most of the material should be removed during rough and medium machining stages. You usually want a light depth of cut and a low feed speed.
Choose the right brand of knives
The use of branded blades helps to produce better cutting results. Another aspect that can be discussed with the blade manufacturer about new applications will help to determine which blade will produce a high quality surface finish in the turning operation, so as to select the right blade. Machining conditions and part material determine which type of blade is suitable, but some general characteristics can be recommended during the finishing stage.
As long as the part geometry allows, a larger radius is usually preferred when finishing. The larger radius helps smooth the material more effectively, almost like a wiper. With a larger tip radius, you can slightly increase the feed speed while still maintaining a high surface quality. However, in thin-wall applications, smaller tip radii reduce radial cutting forces, which can cause deflection and vibration, which negatively affects surface finish.
The shape of the blade has a great influence on the initial chip formation and surface finish.
The role of polishing edge in machining
The use of branded blades helps to produce better cutting results. Another aspect that can be discussed with the blade manufacturer about new applications will help to determine which blade will produce a high quality surface finish in the turning operation, so as to select the right blade. Machining conditions and part material determine which type of blade is suitable, but some general characteristics can be recommended during the finishing stage.
As long as the part geometry allows, a larger radius is usually preferred when finishing. The larger radius helps smooth the material more effectively, almost like a wiper. With a larger tip radius, you can slightly increase the feed speed while still maintaining a high surface quality. However, in thin-wall applications, smaller tip radii reduce radial cutting forces, which can cause deflection and vibration, which negatively affects surface finish.
The shape of the blade has a great influence on the initial chip formation and surface finish.
Select the appropriate chip-breaker
Choosing the right chip-breaker is also the key point. When the blade is involved in cutting, the top surface of the blade is directly related to the material processing and chip area. So if you get a shallower cut depth at a lower feed speed, the chute will look different than if you get a deeper cut depth at a higher feed speed. You need to choose the right chip breaker for the material, as chip breaker is critical to maintaining a consistently good surface finish, especially on multiple parts.
The thinner the coating, the better
An overlooked aspect of this process is how the grade of the blade affects the surface finish, especially as it relates to the coating.
When it comes to physical vapor deposition (PVD) versus chemical vapor deposition (CVD) coatings, CVD coatings tend to be much thicker than PVD coatings. Compared to thinner coatings, thicker coatings can present a greater challenge in producing high-quality surface finish, every time. Due to the adhesion of the coating, PVD produces a better surface finish than the CVD coating. PVD blades have a complete coating on all surfaces, while chemical vapor deposition reduces the coating on the microgeometry, thereby changing the shape of the microgeometry.
How to control chips
For most turning operations, it is recommended that the high-pressure coolant be directed at the cutting edge. This helps remove chips from the cutting area. Chip control is essential to maintain a high quality finish. Removing chips prevents the tool from touching the chips again, which can damage the cutting edge of the tool. It also prevents chips from curling around the tool and moving on the surface of the workpiece, which can cause scratches or blemishes in polishing.
"The coolant helps keep parts and tools cool so you can cut faster, and if high-pressure cooling is not possible, conventional or internal cooling is the best option."
Coolant is not recommended for all applications. For turning hardened materials - any material exceeding HRC50 - ceramic tool coolant should be avoided as it has a tendency to heat shock the tool, which can cause the tool to crack. However, if the material is on the soft side, the coolant can be used with a ceramic blade.
Chip control is essential because in this process, we need to heat the chips. But you also need a large enough cutting area. If the cutting area is reduced, the mass that takes heat away from the cutting area is reduced and you will start to see the effects of chemical wear, side wear and pitting wear on the blade. When you think about surface polishing, chip control really becomes a challenge. That's why you have to choose the right geometry and maintain the proper cutting parameters for the given application.
Rigidity is also important
Many people agree that the tool bar and fixture play an important role in obtaining a high quality surface finish. If the fixture is not rigid enough, it can cause vibration, which can affect the finish. It is also important to ensure that the knife holder has the shortest possible overhang to help maintain its rigidity. The workpiece and tool should be adequately supported so that there is no vibration during finishing.
One thing that a lot of people don't necessarily think about is how the blade got on the knife holder. The design of the knife holder can play an important role. An overly open clip reduces the contact area between the blade and the clip (e.g., WNMG blades), thereby bringing motion into the clip. This causes micro-vibrations, which negatively affects the surface finish.
The movement of the tool also makes it difficult to maintain dimensional tolerances of the part. The tool holder should match the dimensional tolerance of the blade and be kept in good condition. There should be no wear or deformation, as even the slightest movement can have undesirable consequences.
Use in accordance with good processing methods
The best way to produce a good surface finish is to start with the blade manufacturer and follow the manufacturer's recommendations, which would be a good start. We can make adjustments in the trial, but these suggestions are only suitable for experienced operators, so you should accumulate professional knowledge.
Selecting a blade with a positive front Angle is preferred for finishing. The positive front Angle helps produce a sharp blade to cut through the material. For the roughing stage, a negative front Angle can be recommended, as it will apply more force behind the cutting edge to remove more material, providing a better starting point for the finishing stage.
Another thing to consider here is the directional force, in the final stage you want to apply as much force as possible along the axis of the part, as this will give you the stability you need. Choosing a blade with an entry Angle close to 0° will give you more force along the axis, but you also need to increase the back backlash of the blade for a high-quality surface finish.
Tangential force is an important factor in the machining process. Tangential force, that is, axial force plus radial force, can be regarded as a constant when turning. If the operation folds increase the axial force, they reduce the effect of the radial force, which allows them to maintain better tolerances and reduce microvibrations because of reduced natural instability. This is not necessarily a consideration at the roughing and semi-finishing stages of the process.
Finally, note that the direction of the cutting tool is also important, you want to ensure that the operating force is directed into the well-supported part of the part, machining away from the support will cause vibration, which will also affect the tool life, and your surface finish will definitely be affected.