End Milling Tool Selection 230

Transcription

1 End Miing Too Seection 230 Cass Outine Objectives What Is End Miing? End Mis Seecting an End Mi Extended Length End Mis End Mi Diameter Radia Width of Cut Spinde Capacity and Avaiabe Machine Power Rake Ange Tangentia Force Heix Ange Hand Hand of Cut and Hand of Fute Heix Combinations Heix Ange and Resuting Forces Futes Seecting Futes Reief Anges Radia Reief Configurations Cutting Edge Configurations End Mi Shank Styes Spinde Mounting Adaptation Summary Copyright 2009 Tooing U, LLC. A Rights Reserved. Lesson: 1/22

2 Cass Outine Objectives What Is End Miing? End Mis Seecting an End Mi Extended Length End Mis End Mi Diameter Radia Width of Cut Spinde Capacity and Avaiabe Machine Power Rake Ange Tangentia Force Heix Ange Hand Hand of Cut and Hand of Fute Heix Combinations Heix Ange and Resuting Forces Futes Seecting Futes Reief Anges Radia Reief Configurations Cutting Edge Configurations End Mi Shank Styes Spinde Mounting Adaptation Summary Lesson: 1/22 Objectives Identify common types of end miing processes. Describe end miing cutters. Describe variabes that affect the end mi seection process. Describe the function of extended ength end mis. Describe how the end mi diameter affects the end miing process. Describe how radia width of cut affects the end miing process. Describe how spinde capacity and avaiabe machine power affect end miing capabiities. Describe how rake ange affects the end miing process. Identify the types of cutting forces that occur during the end miing process. Describe how heix ange affects the end miing process. Describe how hand of cut and hand of fute heix combinations affect the end miing process. Describe how axia rake affects the end miing process. Describe how heix ange affects the end miing process. Describe how the number of futes affect the end miing process. Describe important considerations for seecting futes on end miing centers. Describe how reief anges affect the end miing process. Describe common radia reief configurations for end mis. Describe the most common cutting edge configurations. Describe end mi shank styes. Describe common types of spinde mounting adaptation for end mis. Copyright 2009 Tooing U, LLC. A Rights Reserved. Figure 1. End mis can be singe-or doube-ended and are manufactured in soid HSS, soid carbide, and in soid cermet. Figure 2. The axia rake ange provides greater design fexibiity than radia rake.

3 Lesson: 1/22 Objectives Identify common types of end miing processes. Describe end miing cutters. Describe variabes that affect the end mi seection process. Describe the function of extended ength end mis. Describe how the end mi diameter affects the end miing process. Describe how radia width of cut affects the end miing process. Describe how spinde capacity and avaiabe machine power affect end miing capabiities. Describe how rake ange affects the end miing process. Identify the types of cutting forces that occur during the end miing process. Describe how heix ange affects the end miing process. Describe how hand of cut and hand of fute heix combinations affect the end miing process. Describe how axia rake affects the end miing process. Describe how heix ange affects the end miing process. Describe how the number of futes affect the end miing process. Describe important considerations for seecting futes on end miing centers. Describe how reief anges affect the end miing process. Describe common radia reief configurations for end mis. Describe the most common cutting edge configurations. Describe end mi shank styes. Describe common types of spinde mounting adaptation for end mis. Figure 1. End mis can be singe-or doube-ended and are manufactured in soid HSS, soid carbide, and in soid cermet. Figure 2. The axia rake ange provides greater design fexibiity than radia rake. Lesson: 2/22 What Is End Miing? End miing is the process of machining workpiece surfaces that are predominanty parae to the machine spinde. The primary end miing processes are shown in Figures 1, 2, and 3 and incude side miing, sot miing, and sab miing. This aows end miing to be used for machining the sides and ends of workpieces. In particuar, sot miing typicay uses end miing cutters to perform many additiona operations. End mis are versatie cutting toos that are capabe of performing numerous meta cutting operations in addition to the primary end miing processes. Some of these end miing processes are isted in Figure 4. This cass expains the process of end miing as we as other meta cutting processes that use end miing cutters on machining centers. You wi aso earn about the variabes for seecting the proper too geometry for various end miing appications. Figure 1. During side miing, the surface of the workpiece is parae to the machine spinde. Copyright 2009 Tooing U, LLC. A Rights Reserved.

4 Lesson: 2/22 What Is End Miing? End miing is the process of machining workpiece surfaces that are predominanty parae to the machine spinde. The primary end miing processes are shown in Figures 1, 2, and 3 and incude side miing, sot miing, and sab miing. This aows end miing to be used for machining the sides and ends of workpieces. In particuar, sot miing typicay uses end miing cutters to perform many additiona operations. End mis are versatie cutting toos that are capabe of performing numerous meta cutting operations in addition to the primary end miing processes. Some of these end miing processes are isted in Figure 4. This cass expains the process of end miing as we as other meta cutting processes that use end miing cutters on machining centers. You wi aso earn about the variabes for seecting the proper too geometry for various end miing appications. Figure 1. During side miing, the surface of the workpiece is parae to the machine spinde. Figure 2. During sot miing, the end mi produces a narrow channe or groove. Figure 3. During sab miing, the mi rotates on an axis parae to the workpiece. Figure 4. End miing processes. Copyright 2009 Tooing U, LLC. A Rights Reserved.

5 Lesson: 3/22 End Mis Figure 1 shows exampes of end mis. End mis can be singe- or doube-ended and are manufactured in numerous materias, incuding soid HSS, soid carbide, and soid cermet. The design can be brazed construction, inserted bade, or with indexabe inserts. Each configuration is designed and manufactured with a wide range of cutting geometry, heix anges, number of futes, and mounting adaptations. End mis are very versatie but are aso the east rigid and potentiay the most chaenging of a miing cutters due to the reationship between the cutting too diameter and its ength. Aso, the process of end miing directs the feed forces across the radius, which is the weakest section of the too. End mis function as cantievered beams and are subject to defection under oad. You can think of an end mi as a bar rigidy supported at one end with the feed forces directed across the radius at the opposite end that cause defection, as shown in Figure 2. Figure 3 ists the characteristics of defection for end mis. The ratios show that a reduction in ength or an increase in diameter greaty increases the rigidity of the end mi. Increased processing speeed of modern CNC contros used on machining centers, mi/turn machines, and athes with ive spindes has ed to increased use of end mis as a means of increasing productivity and reducing manufacturing costs. End mis are often the most extensivey used too, accounting for neary 50% of the tota toos in the too carriage of modern machining centers. Pus, new manufacturing methods, such as trochoida miing, make the use of end mis one of the greatest potentia growth areas in meta cutting. Figure 1. End mis can be singe- or doube-ended and are manufactured as soid, brazed, or indexabe-insert toos. Figure 2. To avoid excess defection, aways seect the shortest end mi capabe of making the desired cut. Figure 3. Certain key factors determine the degree of an end mi's defection. Lesson: 4/22 Seecting an End Mi Seecting the proper end mi requires more attention to detai than many other meta cutting processes. This is because end mis function as side cutting toos with greater axia depth of cut and onger too projection. End mis aso require reativey sma diameters. These variabes dictate the geometry designed into the cutter as we as the proper seection and appication of that geometry. If you are famiiar with end mi geometry and its impact on cutter performance, it wi make the seection process easier. Copyright 2009 Tooing U, LLC. A Rights Reserved. To choose an end mi, you must seect both a cutter ength and a diameter. There are many variabes invoved with seecting ength and diameter. To seect cutter ength, you must consider the three variabes shown in Figure 1: the overa ength, Figure 1. Overa ength, fute ength, and cutting ength

6 Lesson: 3/22 End Mis Figure 1 shows exampes of end mis. End mis can be singe- or doube-ended and are manufactured in numerous materias, incuding soid HSS, soid carbide, and soid cermet. The design can be brazed construction, inserted bade, or with indexabe inserts. Each configuration is designed and manufactured with a wide range of cutting geometry, heix anges, number of futes, and mounting adaptations. End mis are very versatie but are aso the east rigid and potentiay the most chaenging of a miing cutters due to the reationship between the cutting too diameter and its ength. Aso, the process of end miing directs the feed forces across the radius, which is the weakest section of the too. End mis function as cantievered beams and are subject to defection under oad. You can think of an end mi as a bar rigidy supported at one end with the feed forces directed across the radius at the opposite end that cause defection, as shown in Figure 2. Figure 3 ists the characteristics of defection for end mis. The ratios show that a reduction in ength or an increase in diameter greaty increases the rigidity of the end mi. Increased processing speeed of modern CNC contros used on machining centers, mi/turn machines, and athes with ive spindes has ed to increased use of end mis as a means of increasing productivity and reducing manufacturing costs. End mis are often the most extensivey used too, accounting for neary 50% of the tota toos in the too carriage of modern machining centers. Pus, new manufacturing methods, such as trochoida miing, make the use of end mis one of the greatest potentia growth areas in meta cutting. Figure 1. End mis can be singe- or doube-ended and are manufactured as soid, brazed, or indexabe-insert toos. Figure 2. To avoid excess defection, aways seect the shortest end mi capabe of making the desired cut. Figure 3. Certain key factors determine the degree of an end mi's defection. Lesson: 4/22 Seecting an End Mi Seecting the proper end mi requires more attention to detai than many other meta cutting processes. This is because end mis function as side cutting toos with greater axia depth of cut and onger too projection. End mis aso require reativey sma diameters. These variabes dictate the geometry designed into the cutter as we as the proper seection and appication of that geometry. If you are famiiar with end mi geometry and its impact on cutter performance, it wi make the seection process easier. To choose an end mi, you must seect both a cutter ength and a diameter. There Copyright 2009 Tooing U, LLC. A Rights Reserved. are many variabes invoved with seecting ength and diameter. To seect cutter ength, you must consider the three variabes shown in Figure 1: the overa ength, fute ength, and cutting ength. Typicay, the workpiece characteristics dictate the Figure 1. Overa ength, fute ength, and cutting ength must be considered for seecting cutter ength.

7 Lesson: 4/22 Seecting an End Mi Seecting the proper end mi requires more attention to detai than many other meta cutting processes. This is because end mis function as side cutting toos with greater axia depth of cut and onger too projection. End mis aso require reativey sma diameters. These variabes dictate the geometry designed into the cutter as we as the proper seection and appication of that geometry. If you are famiiar with end mi geometry and its impact on cutter performance, it wi make the seection process easier. To choose an end mi, you must seect both a cutter ength and a diameter. There are many variabes invoved with seecting ength and diameter. To seect cutter ength, you must consider the three variabes shown in Figure 1: the overa ength, fute ength, and cutting ength. Typicay, the workpiece characteristics dictate the required ength of the end mi. Figure 1. Overa ength, fute ength, and cutting ength must be considered for seecting cutter ength. Workpiece characteristics typicay fa into two categories. The ength of the surface to be cut estabishes the minimum ength of the cutting edges of the mi. Because an end mi is a side cutting too designed to cut a surface that is parae to the axis of the spinde, the tota ength of the cutting edge must be greater than the ength of the surface to be cut. In Figure 2, the distance from the spinde to the bottom of the workpiece surface to be cut estabishes the overa ength of the end mi. Many workpieces require the too to reach into cavities or housings to cut the desired surface. The ength of cut may be shaow, even though the tota reach may be much onger. Figure 2. The distance from the spinde to the bottom of the workpiece surface to be cut estabishes the overa ength of the end mi. Lesson: 5/22 Extended Length End Mis Certain appications, such as air-frame parts, die and mod parts, and many castings and housings require miing cutters to reach significanty onger distances for machining the required surface. These appications are typicay performed with extended ength end mis, which have extraordinariy ong fute engths. Figure 1 shows exampes of these toos. Extended ength end mis pace extraordinary force across the diameter of the cutter. As a resut, they are made from very tough materias such as HSS or the tougher grades of carbide. The use of these tough materias reduces the wear characteristics as we as too ife. Extended reach end mis are designed with a short fute ength and a reduced shank to aow ony the cutting edge to contact the workpiece. This combination increases the rigidity of the end mi whie controing the maximum axia depth of cut. Recent deveopments in end mi design have provided an aternative to extended ength end mis. The shrink-fit end mi aows manufacturers the fexibiity of designing and buiding the cutter with the optimum cutting edge materia and shank type. The cutting edge materia provides improved wear characteristics based on the workpiece materia. The shank is designed and buit separatey, providing improved strength without sacrificing too ife. As you can see in Figure 2, an aoy stee coar is used to shrink fit the cutter and shank together, providing an end mi with idea wear characteristics and shank toughness. Copyright 2009 Tooing U, LLC. A Rights Reserved. Lesson: 6/22 End Mi Diameter Figure 1. Extended ength end mis are used when the too must reach onger distances. Figure 2. Shrink-fit end mis are designed with optimum cutting edge materia and shank type.

8 Lesson: 5/22 Extended Length End Mis Certain appications, such as air-frame parts, die and mod parts, and many castings and housings require miing cutters to reach significanty onger distances for machining the required surface. These appications are typicay performed with extended ength end mis, which have extraordinariy ong fute engths. Figure 1 shows exampes of these toos. Extended ength end mis pace extraordinary force across the diameter of the cutter. As a resut, they are made from very tough materias such as HSS or the tougher grades of carbide. The use of these tough materias reduces the wear characteristics as we as too ife. Extended reach end mis are designed with a short fute ength and a reduced shank to aow ony the cutting edge to contact the workpiece. This combination increases the rigidity of the end mi whie controing the maximum axia depth of cut. Recent deveopments in end mi design have provided an aternative to extended ength end mis. The shrink-fit end mi aows manufacturers the fexibiity of designing and buiding the cutter with the optimum cutting edge materia and shank type. The cutting edge materia provides improved wear characteristics based on the workpiece materia. The shank is designed and buit separatey, providing improved strength without sacrificing too ife. As you can see in Figure 2, an aoy stee coar is used to shrink fit the cutter and shank together, providing an end mi with idea wear characteristics and shank toughness. Figure 1. Extended ength end mis are used when the too must reach onger distances. Figure 2. Shrink-fit end mis are designed with optimum cutting edge materia and shank type. Lesson: 6/22 End Mi Diameter When seecting an end mi diameter, there are two primary diameters you must choose: the diameter of the cut and the diameter of the shank. Figure 1 iustrates these two diameters. The cutting diameter of an end mi is the maximum width that the cutter wi machine and is measured at the outer cutting edge points. The cutting diameter is aso caed the effective diameter. The cutting diameter is a critica dimension in cutter seection based on the workpiece configuration. When seecting a cutting diameter, you must consider rigidity, the radia width of the surface to be cut, cutter ength, spinde capacity, and avaiabe machine power. The second consideration is the shank diameter. The rigidity of an end mi increases in proportion to its shank diameter by the 4th power. The rigidity of an end mi decreases in proportion to its overa ength and its ength of cut by the 3rd power. For exampe, a 2 in. diameter end mi is 16 times more rigid than a 1 in. diameter end mi. A 4 in. ength of cut is 1/8 times as rigid as a 2 in. ength of cut. Figure 1. You must choose the diameter of the cut and the diameter of the shank when seecting an end mi diameter. Lesson: 7/22 Radia Width of Cut When considering the radia width of cut, remember that the idea end mi diameter shoud provide an effective negative entry ange between the cutter and the workpiece. As you can see in Figure 1, the entry ange is estabished through the combination of the cutter diameter and the positioning of the cutter in reation to the workpiece. Positioning the cutter so that the first point of contact is on the eading side of the cutter s centerine estabishes a negative entry ange. Positioning the cutter so that the first point of contact is on the traiing side of centerine estabishes a positive entry ange. Figures 2 and 3 compare negative and positive entry anges. The cutting edge is exposed to compressive forces with negative entry and transverse rupture forces with positive entry. The compressive strength of cutting edge materias is as much as three times greater than their transverse rupture strength. Negative entry aows the seection of more wear-resistant cutting edge materias. Positive entry requires tougher, more chip-resistant cutting edge materias. An optimum negative entry ange is obtained when approximatey 25% of the cutter diameter overhangs the workpiece on the entry side of rotation. An end mi's effective cutter diameter, where possibe, shoud be approximatey 1½ times width of cut.reserved. Copyright the 2009desired Tooingradia U, LLC. A Rights The idea end mi diameter provides an effective entry ange. However, end miing invoves side cutting with a reativey shaow radia width of cut, which compicates the Figure 1. Entry ange is estabished through the combination of the cutter diameter and the positioning of the cutter in reation to the workpiece.

9 Lesson: 6/22 End Mi Diameter When seecting an end mi diameter, there are two primary diameters you must choose: the diameter of the cut and the diameter of the shank. Figure 1 iustrates these two diameters. The cutting diameter of an end mi is the maximum width that the cutter wi machine and is measured at the outer cutting edge points. The cutting diameter is aso caed the effective diameter. The cutting diameter is a critica dimension in cutter seection based on the workpiece configuration. When seecting a cutting diameter, you must consider rigidity, the radia width of the surface to be cut, cutter ength, spinde capacity, and avaiabe machine power. The second consideration is the shank diameter. The rigidity of an end mi increases in proportion to its shank diameter by the 4th power. The rigidity of an end mi decreases in proportion to its overa ength and its ength of cut by the 3rd power. For exampe, a 2 in. diameter end mi is 16 times more rigid than a 1 in. diameter end mi. A 4 in. ength of cut is 1/8 times as rigid as a 2 in. ength of cut. Figure 1. You must choose the diameter of the cut and the diameter of the shank when seecting an end mi diameter. Lesson: 7/22 Radia Width of Cut When considering the radia width of cut, remember that the idea end mi diameter shoud provide an effective negative entry ange between the cutter and the workpiece. As you can see in Figure 1, the entry ange is estabished through the combination of the cutter diameter and the positioning of the cutter in reation to the workpiece. Positioning the cutter so that the first point of contact is on the eading side of the cutter s centerine estabishes a negative entry ange. Positioning the cutter so that the first point of contact is on the traiing side of centerine estabishes a positive entry ange. Figures 2 and 3 compare negative and positive entry anges. The cutting edge is exposed to compressive forces with negative entry and transverse rupture forces with positive entry. The compressive strength of cutting edge materias is as much as three times greater than their transverse rupture strength. Negative entry aows the seection of more wear-resistant cutting edge materias. Positive entry requires tougher, more chip-resistant cutting edge materias. An optimum negative entry ange is obtained when approximatey 25% of the cutter diameter overhangs the workpiece on the entry side of rotation. An end mi's effective cutter diameter, where possibe, shoud be approximatey 1½ times the desired radia width of cut. The idea end mi diameter provides an effective entry ange. However, end miing invoves side cutting with a reativey shaow radia width of cut, which compicates the diameter seection process. The combination of a shaow radia width of cut, suggesting a sma cutter diameter, and a ong cutter ength in reation to the diameter, makes foowing the entry ange recommendation difficut. Figure 1. Entry ange is estabished through the combination of the cutter diameter and the positioning of the cutter in reation to the workpiece. Figure 2. Negative entry aows the seection of more wear resistant cutting edge materias. Copyright 2009 Tooing U, LLC. A Rights Reserved.

10 Lesson: 7/22 Radia Width of Cut When considering the radia width of cut, remember that the idea end mi diameter shoud provide an effective negative entry ange between the cutter and the workpiece. As you can see in Figure 1, the entry ange is estabished through the combination of the cutter diameter and the positioning of the cutter in reation to the workpiece. Positioning the cutter so that the first point of contact is on the eading side of the cutter s centerine estabishes a negative entry ange. Positioning the cutter so that the first point of contact is on the traiing side of centerine estabishes a positive entry ange. Figures 2 and 3 compare negative and positive entry anges. The cutting edge is exposed to compressive forces with negative entry and transverse rupture forces with positive entry. The compressive strength of cutting edge materias is as much as three times greater than their transverse rupture strength. Negative entry aows the seection of more wear-resistant cutting edge materias. Positive entry requires tougher, more chip-resistant cutting edge materias. An optimum negative entry ange is obtained when approximatey 25% of the cutter diameter overhangs the workpiece on the entry side of rotation. An end mi's effective cutter diameter, where possibe, shoud be approximatey 1½ times the desired radia width of cut. The idea end mi diameter provides an effective entry ange. However, end miing invoves side cutting with a reativey shaow radia width of cut, which compicates the diameter seection process. The combination of a shaow radia width of cut, suggesting a sma cutter diameter, and a ong cutter ength in reation to the diameter, makes foowing the entry ange recommendation difficut. Figure 1. Entry ange is estabished through the combination of the cutter diameter and the positioning of the cutter in reation to the workpiece. Figure 2. Negative entry aows the seection of more wear resistant cutting edge materias. Figure 3. Positive entry requires tougher, more chipresistant cutting edge materias. Lesson: 8/22 Spinde Capacity and Avaiabe Machine Power Figure 1 ists variabes to consider for seecting cutter diameter. Spinde capacity and avaiabe machine power are important to cutter diameter seection. Spinde size and cutter mounting estabish the potentia rigidity and spinde capacity. You must maintain a reationship between spinde diameter and end mi diameter to minimize torsiona defection. Smaer spindes require smaer end mi diameters. In order to reduce rotationa mass, spinde size is often decreased in Copyright 2009 Tooing U, LLC. A Rights Reserved. machining centers designed for high spinde speeds. This reduces the spinde capacity for end mi diameters. In appications with wide workpieces, a cutter diameter shoud be seected that best matches the spinde capacity, and mutipe passes shoud be taken if necessary.

11 Lesson: 8/22 Spinde Capacity and Avaiabe Machine Power Figure 1 ists variabes to consider for seecting cutter diameter. Spinde capacity and avaiabe machine power are important to cutter diameter seection. Spinde size and cutter mounting estabish the potentia rigidity and spinde capacity. You must maintain a reationship between spinde diameter and end mi diameter to minimize torsiona defection. Smaer spindes require smaer end mi diameters. In order to reduce rotationa mass, spinde size is often decreased in machining centers designed for high spinde speeds. This reduces the spinde capacity for end mi diameters. In appications with wide workpieces, a cutter diameter shoud be seected that best matches the spinde capacity, and mutipe passes shoud be taken if necessary. The diameter, the number of futes, and the heix ange estabish the maximum number of cutting edges that can be in the cut at any given time. A greater number of cutting edges, or futes, in the cut at any given time smoothes out the cut but aso increases tota power consumption. As the cubic inches of meta removed increases, power consumption aso increases. Likewise, the number of cutting edges in the cut aso increases power consumption. Limited horsepower machines often require you to imit the end mi diameter, and potentiay the heix ange, to adjust for the number of cutting edges in the cut. Figure 1. Seecting the cutter diameter is specific to your appication. Lesson: 9/22 Rake Ange The rake ange is the incination of the top surface of the cutting edge, or the surface that makes contact with the chip. This is true for a cutting toos, incuding end mis. Rake ange contros tangentia forces, the strength of the cutting edge, and initia direction of chip fow. The rake ange is measured in two panes, which yieds an axia rake ange and radia rake ange, shown in Figure 1. The rake can be positive, neutra, or negative in both the axia and radia panes. Though the cutting edge is aways positioned on centerine, the rake positions the face of the cutting edge on the centerine (neutra), ahead of centerine (negative), or behind centerine (positive). You can visuaize radia rake on an end mi by drawing a ine from one cutting edge, through the centerine, to another cutting edge. Because soid end mis require a web or core, they tend to form a neutra or sighty negative radia rake. You can make radia rake in soid end mis more positive by grinding a concave surface, or hook, in the face of the cutting edge. A concave radia rake surface does reduce tangentia cutting forces, but by a imited amount. The thickness of the cutting edge, pus the ocation of the foowing cutting edge, imits the amount of space avaiabe for radia rake modification. However, these modifications to the radia rake face of mutipe fute end mis can resut in ineffective chip fow patterns. Many manufacturers minimize the positive radia rake on the cutting edge's face at the end of the end mi to direct chip fow away from the center of the cutter. Figure 1. The rake ange is measured in two panes, which yieds an axia rake ange and radia rake ange. The axia rake of soid end mis is formed by the heix ange, which is measured from the axis of the end mi to the eading edge of the fute. Like the radia rake, the axia rake can be neutra, positive, or negative, as shown in Figure 2. Standard axia rake anges, or heix anges, range from 0 to 60 degrees. Figure 2. The heix ange can be neutra, positive, or negative. Lesson: 10/22 Tangentia Force There are three forces acting on the cutting too during end miing: tangentia forces, radia and axia shown in Figure 1. Tangentia forces, which Copyright 2009 forces, Tooing U, LLC. A forces, Rights Reserved. act on the rake face of the cutting edge, are the argest of the three forces. Tangentia forces act in the direction of cutting veocity as resistance to rotation. Tangentia forces account for approximatey 70% of the tota force generated during

12 Lesson: 9/22 Rake Ange The rake ange is the incination of the top surface of the cutting edge, or the surface that makes contact with the chip. This is true for a cutting toos, incuding end mis. Rake ange contros tangentia forces, the strength of the cutting edge, and initia direction of chip fow. The rake ange is measured in two panes, which yieds an axia rake ange and radia rake ange, shown in Figure 1. The rake can be positive, neutra, or negative in both the axia and radia panes. Though the cutting edge is aways positioned on centerine, the rake positions the face of the cutting edge on the centerine (neutra), ahead of centerine (negative), or behind centerine (positive). You can visuaize radia rake on an end mi by drawing a ine from one cutting edge, through the centerine, to another cutting edge. Because soid end mis require a web or core, they tend to form a neutra or sighty negative radia rake. You can make radia rake in soid end mis more positive by grinding a concave surface, or hook, in the face of the cutting edge. A concave radia rake surface does reduce tangentia cutting forces, but by a imited amount. The thickness of the cutting edge, pus the ocation of the foowing cutting edge, imits the amount of space avaiabe for radia rake modification. However, these modifications to the radia rake face of mutipe fute end mis can resut in ineffective chip fow patterns. Many manufacturers minimize the positive radia rake on the cutting edge's face at the end of the end mi to direct chip fow away from the center of the cutter. Figure 1. The rake ange is measured in two panes, which yieds an axia rake ange and radia rake ange. The axia rake of soid end mis is formed by the heix ange, which is measured from the axis of the end mi to the eading edge of the fute. Like the radia rake, the axia rake can be neutra, positive, or negative, as shown in Figure 2. Standard axia rake anges, or heix anges, range from 0 to 60 degrees. Figure 2. The heix ange can be neutra, positive, or negative. Lesson: 10/22 Tangentia Force There are three forces acting on the cutting too during end miing: tangentia forces, radia forces, and axia forces, shown in Figure 1. Tangentia forces, which act on the rake face of the cutting edge, are the argest of the three forces. Tangentia forces act in the direction of cutting veocity as resistance to rotation. Tangentia forces account for approximatey 70% of the tota force generated during the cut. They are controed primariy by the combined rake anges, or true rake ange (TRA) of the end mi. Both axia and radia rake have simiar infuence on tangentia cutting forces. The axia rake ange, in the form of the heix ange, provides greater design fexibiity than radia rake. Radia rake is restricted by the fute form, the number of futes, and required reief anges. Radia forces are the resut of resistance to tabe movement and are directed across the diameter of the too. These forces account for 20% of the tota forces during the cut. Axia forces are directed off the heix ange of an end mi in much the same manner as forces are directed off the ead ange of a turning too. The resut is a puing force on end mis with a positive heix ange and a pushing force on end mis with a negative heix ange. Axia forces account for 10% of the tota cutting forces. Lesson: 11/22 Heix Ange Copyright 2009 Tooing U, LLC. A Rights Reserved. Some end mis are designed with straight cutting edges that are parae to the cutter's axis. However, most end mis are designed with the cutting edges at an ange to the Figure 1. Tangentia forces are a resistance to rotation, radia forces are feed forces, and axia forces are the effect of the heix ange.

13 Lesson: 10/22 Tangentia Force There are three forces acting on the cutting too during end miing: tangentia forces, radia forces, and axia forces, shown in Figure 1. Tangentia forces, which act on the rake face of the cutting edge, are the argest of the three forces. Tangentia forces act in the direction of cutting veocity as resistance to rotation. Tangentia forces account for approximatey 70% of the tota force generated during the cut. They are controed primariy by the combined rake anges, or true rake ange (TRA) of the end mi. Both axia and radia rake have simiar infuence on tangentia cutting forces. The axia rake ange, in the form of the heix ange, provides greater design fexibiity than radia rake. Radia rake is restricted by the fute form, the number of futes, and required reief anges. Radia forces are the resut of resistance to tabe movement and are directed across the diameter of the too. These forces account for 20% of the tota forces during the cut. Figure 1. Tangentia forces are a resistance to rotation, radia forces are feed forces, and axia forces are the effect of the heix ange. Axia forces are directed off the heix ange of an end mi in much the same manner as forces are directed off the ead ange of a turning too. The resut is a puing force on end mis with a positive heix ange and a pushing force on end mis with a negative heix ange. Axia forces account for 10% of the tota cutting forces. Lesson: 11/22 Heix Ange Some end mis are designed with straight cutting edges that are parae to the cutter's axis. However, most end mis are designed with the cutting edges at an ange to the cutter axis. The resuting heix ange forms both the axia rake and functions as a ead ange. The heix ange affects tangentia cutting forces, the direction of axia forces, and chip thickness. Figure 1 shows cutting toos with increasing heix anges. A heix forms when a point on the cutting edge moves aong the axis of the cutter body at a uniform rate for each rotation of the cutter. As iustrated in Figure 2, you can think of the heix as a triange. The vertica ine represents one fu revoution of the cutter, the horizonta ine represents the axia movement per revoution, and the hypotenuse represents the heix. The ange formed by the ead with the heix is caed the heix ange. Increasing the heix ange on an end mi increases the axia advance per revoution in reation to the circumference of the cutter and produces chip thinning. Chip thinning eases the oad on the cutter as it enters and exits the workpiece. Undeformed chip thickness can be cacuated by dividing the advance per revoution by the ength of the hypotenuse. As you can see in Figure 3, increasing the heix ange aso reduces the tangentia cutting forces per cutting edge and thins the chip, but it can aso increase the number of cutting edges in the cut, which resuts in an increase in the tota power consumption. Figure 1. Heix ange affects tangentia cutting forces, the direction of axia forces, and chip thickness. Figure 2. The heix can be compared to a triange. Copyright 2009 Tooing U, LLC. A Rights Reserved.

14 Lesson: 11/22 Heix Ange Some end mis are designed with straight cutting edges that are parae to the cutter's axis. However, most end mis are designed with the cutting edges at an ange to the cutter axis. The resuting heix ange forms both the axia rake and functions as a ead ange. The heix ange affects tangentia cutting forces, the direction of axia forces, and chip thickness. Figure 1 shows cutting toos with increasing heix anges. A heix forms when a point on the cutting edge moves aong the axis of the cutter body at a uniform rate for each rotation of the cutter. As iustrated in Figure 2, you can think of the heix as a triange. The vertica ine represents one fu revoution of the cutter, the horizonta ine represents the axia movement per revoution, and the hypotenuse represents the heix. The ange formed by the ead with the heix is caed the heix ange. Increasing the heix ange on an end mi increases the axia advance per revoution in reation to the circumference of the cutter and produces chip thinning. Chip thinning eases the oad on the cutter as it enters and exits the workpiece. Undeformed chip thickness can be cacuated by dividing the advance per revoution by the ength of the hypotenuse. As you can see in Figure 3, increasing the heix ange aso reduces the tangentia cutting forces per cutting edge and thins the chip, but it can aso increase the number of cutting edges in the cut, which resuts in an increase in the tota power consumption. Figure 1. Heix ange affects tangentia cutting forces, the direction of axia forces, and chip thickness. Figure 2. The heix can be compared to a triange. Figure 3. Increasing the heix ange increases the number of cutting edges, but aso increases power consumption. Lesson: 12/22 Hand The hand of rotation or hand of cut may be either right-hand or eft-hand. Figure 1 compares right-handed and eft-handed cutters. A right-handed end miing cutter, when it is viewed facing spinde of a horizonta miing machine, revoves countercockwise as it cuts. A eft-handed end miing cutter, when it is viewed Copyright 2009 Tooing U, LLC. A Rights Reserved. facing the spinde of a horizonta miing machine, revoves cockwise as it cuts. The hand of fute heix is used to describe end mis with a fute heix. The futes on

15 Lesson: 12/22 Hand The hand of rotation or hand of cut may be either right-hand or eft-hand. Figure 1 compares right-handed and eft-handed cutters. A right-handed end miing cutter, when it is viewed facing spinde of a horizonta miing machine, revoves countercockwise as it cuts. A eft-handed end miing cutter, when it is viewed facing the spinde of a horizonta miing machine, revoves cockwise as it cuts. The hand of fute heix is used to describe end mis with a fute heix. The futes on a right-hand fute heix cutter twist away from the observer in a cockwise direction when viewed from either end of the cutter. The futes on a eft -hand fute heix cutter twist away from the observer in a countercockwise direction when viewed from either end of the cutter. End mis are designed with neutra, positive, and negative axia rakes in the form of neutra or straight futes, right-hand, and eft-hand heix anges. Many manufacturers offer end mis with matching hand rotation and heix ange as we as opposing hand rotation and heix ange. Matching hand rotation and heix ange cutters feature righthand rotation and right-hand heix or eft-hand rotation and eft-hand heix. Opposing hand rotation and heix ange cutters have right-hand rotation with eft-hand heix or eft-hand rotation and right-hand heix. Figure 1. When viewed from the end, a right-handed end mi revoves countercockwise as it cuts. A eft-handed end mi revoves cockwise as it cuts. Lesson: 13/22 Hand of Cut and Hand of Fute Heix Combinations Choosing between matching hand rotation and heix ange cutters or opposing hand rotation and heix ange cutters depends on the appication. Each combination comes with a set of seection variabes based on the cutting action that makes the cutter more or ess suitabe for specific appications. These seection variabes are isted in Figure 1. Figure 2 shows exampes of cutters with matching hand and heix. Cutters with matching hand and heix provide positive axia rake, which reduces tangentia forces. They aso direct the axia force forward. This can pu the cutter out of the spinde in the same manner that a screw thread transfers motion. End mis with matching hand and heix aso provide a ift to the chips, directing them up and out of the cut. Matching hand and heix cutters are recommended for sotting operations as we as operations where both the end and side of the cutter are engaged. Figure 3 shows cutters with opposing hand and heix. Cutters with opposing hand and heix provide negative axia rake, which increases tangentia forces. They aso tend to force the cutter toward the spinde in the same manner that a screw thread transfers motion. This action increases stabiity and reduces or eiminates too movement in the hoder. Opposing hand and heix cutters direct the chips forward aong the axis. They are recommended for sab miing operations but are not recommended for operations where the end of the cutter is engaged in the cut. Based on the number of futes, end mis with straight futes experience abrupt changes in the cutting oad as each cutting edge enters and exits the workpiece at reguar intervas. The shock resuting from this abrupt change in oad is transferred to the machine too as vibration and appears on the workpiece as chatter. Cutting edges designed on a heix distribute the oad of entry and exit onto mutipe cutting edges. The greater the heix ange, the greater the potentia number of cutting edges engaged at once. Increasing the number of cutting edges engaged in the workpiece aso increases the meta remova rate, resuting in an increase in the tota power consumed. Increasing the heix ange resuts in more cutting edges engaged in the workpiece and aso increases the tota axia force, which can resut in movement of the cutter in the hoder. Figure 1. Each hand of rotation and heix combination is suited for specific appications. Copyright 2009 Tooing U, LLC. A Rights Reserved. Figure 2. Cutters with matching hand and heix

16 Lesson: 13/22 Hand of Cut and Hand of Fute Heix Combinations Choosing between matching hand rotation and heix ange cutters or opposing hand rotation and heix ange cutters depends on the appication. Each combination comes with a set of seection variabes based on the cutting action that makes the cutter more or ess suitabe for specific appications. These seection variabes are isted in Figure 1. Figure 2 shows exampes of cutters with matching hand and heix. Cutters with matching hand and heix provide positive axia rake, which reduces tangentia forces. They aso direct the axia force forward. This can pu the cutter out of the spinde in the same manner that a screw thread transfers motion. End mis with matching hand and heix aso provide a ift to the chips, directing them up and out of the cut. Matching hand and heix cutters are recommended for sotting operations as we as operations where both the end and side of the cutter are engaged. Figure 3 shows cutters with opposing hand and heix. Cutters with opposing hand and heix provide negative axia rake, which increases tangentia forces. They aso tend to force the cutter toward the spinde in the same manner that a screw thread transfers motion. This action increases stabiity and reduces or eiminates too movement in the hoder. Opposing hand and heix cutters direct the chips forward aong the axis. They are recommended for sab miing operations but are not recommended for operations where the end of the cutter is engaged in the cut. Based on the number of futes, end mis with straight futes experience abrupt changes in the cutting oad as each cutting edge enters and exits the workpiece at reguar intervas. The shock resuting from this abrupt change in oad is transferred to the machine too as vibration and appears on the workpiece as chatter. Cutting edges designed on a heix distribute the oad of entry and exit onto mutipe cutting edges. The greater the heix ange, the greater the potentia number of cutting edges engaged at once. Increasing the number of cutting edges engaged in the workpiece aso increases the meta remova rate, resuting in an increase in the tota power consumed. Increasing the heix ange resuts in more cutting edges engaged in the workpiece and aso increases the tota axia force, which can resut in movement of the cutter in the hoder. Figure 1. Each hand of rotation and heix combination is suited for specific appications. Figure 2. Cutters with matching hand and heix provide positive axia rake, which reduces tangentia forces. Figure 3. Cutters with opposing hand and heix provide negative axia rake, which increases tangentia forces. Copyright 2009 Tooing U, LLC. A Rights Reserved. Lesson: 14/22 Heix Ange and Resuting Forces

17 Lesson: 14/22 Heix Ange and Resuting Forces Three forces act on heica end mis. Tangentia forces act on the cutting edge by resisting rotation, radia forces resut in side defection, and axia forces act in either direction aong the end mi's axia centerine. Straight-futed end mis generate minima axia force. Increasing the number of cutting edges engaged in the workpiece aso increases the meta remova rate, resuting in an increase in the tota power consumed. Increasing the heix ange resuts in more cutting edges engaged in the workpiece and aso increases the tota axia force, which can resut in the cutter moving in the hoder. On most soid end mis, the heix ange forms the axia rake, which can be neutra, positive, or negative. Axia rake tends to be the primary design feature used to contro tangentia cutting forces. Tangentia cutting forces generated by the end mi account for neary 70% of the tota power consumption. Power consumption can be reduced by using end mis with higher positive axia rake anges. As the heix ange increases, the axia rake ange becomes more positive on matching rotation and heix cutters, which reduces the tangentia cutting forces per cutting edge. End mis with sine wave cutting edges have varying axia rake, athough the heix may be positive or negative. Figure 2 shows an end mi with a sine wave cutting edge. The varying rake ange cutter is effective in breaking up harmonic vibrations. Figure 1. As heix ange increases, axia rake becomes more positive. As the number of cutting edges engaged increases, power consumption increases. Figure 2. Sine wave cutting edge end mis have varying axia rake athough the heix ange may be positive or negative. Lesson: 15/22 Futes The number of futes on an end mi is a major too seection factor and determines the too's capacity for rigidity, meta remova rate, surface finish, and size contro. Rigidity is controed by the cross section of the cutter's core diameter. Figure 1 iustrates how increasing the number of futes affects end miing. The number of futes directy impacts the core diameter. Less futes resut in a smaer core and reduced rigidity, whie more futes resut in a arger core and increased rigidity. Chip space is aso a factor of the number of futes. Less futes resut in greater chip space, whie more futes resut in ess chip space. End mis with increased chip space are preferabe for miing ductie materias. End mis with fewer futes permit more efficient chip fow than end mis with a greater number of futes. However, for operations that invove very narrow workpiece cross sections, end mis with a greater number of futes aow mutipe edges to remain in the cut. This resuts in a reduction of cutter and workpiece vibration. The formua in Figure 2 can be used to determine the number of cutting edges that an end mi shoud have to maintain the desired number of cutting edges in the cut. If more than two teeth are desired in the cut, you can find the number of teeth that the cutter shoud have by dividing the resut of the formua by 2 and then mutipying that resut by the desired number of teeth in the cut. Copyright 2009 Tooing U, LLC. A Rights Reserved. Figure 1. As the number of futes increase, rigidity increases and chip space decreases. Figure 2. This formua determines the number of cutting edges that an end mi shoud have to maintain the desired number of cutting edges in the cut.

18 Lesson: 15/22 Futes The number of futes on an end mi is a major too seection factor and determines the too's capacity for rigidity, meta remova rate, surface finish, and size contro. Rigidity is controed by the cross section of the cutter's core diameter. Figure 1 iustrates how increasing the number of futes affects end miing. The number of futes directy impacts the core diameter. Less futes resut in a smaer core and reduced rigidity, whie more futes resut in a arger core and increased rigidity. Chip space is aso a factor of the number of futes. Less futes resut in greater chip space, whie more futes resut in ess chip space. End mis with increased chip space are preferabe for miing ductie materias. End mis with fewer futes permit more efficient chip fow than end mis with a greater number of futes. However, for operations that invove very narrow workpiece cross sections, end mis with a greater number of futes aow mutipe edges to remain in the cut. This resuts in a reduction of cutter and workpiece vibration. The formua in Figure 2 can be used to determine the number of cutting edges that an end mi shoud have to maintain the desired number of cutting edges in the cut. If more than two teeth are desired in the cut, you can find the number of teeth that the cutter shoud have by dividing the resut of the formua by 2 and then mutipying that resut by the desired number of teeth in the cut. Figure 1. As the number of futes increase, rigidity increases and chip space decreases. Figure 2. This formua determines the number of cutting edges that an end mi shoud have to maintain the desired number of cutting edges in the cut. Lesson: 16/22 Seecting Futes Seecting the number of futes requires carefu consideration of your specific appication. Figure 1 ists the characteristics for end mis with varying numbers of futes. Roughing cuts typicay yied higher chip oads and higher meta remova rates, requiring increased chip space. Two- and three-fute end mis have the greatest chip space and are therefore recommended for heavy cuts. End mis with arger numbers of futes tend to be used for ess rigorous appications with ighter chip oads. For exampe, four- to eight-fute end mis are typicay recommended for finishing operations, especiay with higher heix anges. In addition, hard workpiece materias, high temperature aoys, and other highy abrasive materias typicay require a greater number of futes to increase too ife. In sotting, radia forces cause end mis to defect, resuting in cuts that tend to taper from the start of the cut to the end of the sot. Two -fute end mis have cutting edges 180 apart. This aows each cutting edge to enter and eave the cut on each revoution independent of each other. As each cutting edge rotates into the cut, radia forces cause defection, which is then reieved when the cutting edge rotates out of the cut, as Figure 2 iustrates. This sequentia oading and unoading of the cutter aows the cutter to return to axia straightness twice on each revoution, which resuts in a more accurate sot. Figure 1. Seecting the number of futes on an end mi depends upon the specific appication. Copyright 2009 Tooing U, LLC. A Rights Reserved.