Mechanics of CNC 110

Transcription

1 Mechanics of CNC 110 Welcome to the Tooling University. This course is designed to be used in conjunction with the online version of this class. The online version can be found at We offer high quality web -based e -learning that focuses on today's industrial manufacturing training needs. We deliver superior training content over the Internet using text, photos, video, audio, and illustrations. Our courses contain "roll -up -your -sleeves" content that offers real -world solutions on subjects such as Metal Cutting, Workholding, Materials, and CNC with much more to follow. Today's businesses face the challenge of maintaining a trained workforce. Companies must locate apprenticeship programs, cover travel and lodging expenses, and disrupt operations to cover training needs. Our web -based training offers low -cost, all -access courses and services to maximize your training initiatives. Class Outline

2 Class Outline Objectives CNC for Modern Manufacturing Movement of CNC Machines CNC Coordinates The Axes and Origin Plus and Minus Directions Rotational Axes Machine Control Unit Point-to-Point Positioning System Continuous Path System Open-Loop Systems Closed-Loop Systems Servomechanisms Feedback Devices Input Methods Control and Operation Features Summary Lesson: 1/17 Objectives l Describe how CNC machines have impacted modern manufacturing. l Identify machine components that move during CNC machining. l Explain the role of axes in the Cartesian coordinate system. l Identify axes on a CNC machine. l Identify positive and negative movement along machine axes. l Identify rotational axes. l Describe the role of the machine control unit. l Define point-to-point positioning. l Define continuous path movement. l Define open-loop system. l Define closed-loop system. l Describe the role of servomechanisms. l Distinguish between different feedback devices. l Describe various input methods. l Describe different control and operation features available to the CNC machine. Figure 1. The three axes of a milling machine intersect at right angles.

3 Lesson: 1/17 Objectives l Describe how CNC machines have impacted modern manufacturing. l Identify machine components that move during CNC machining. l Explain the role of axes in the Cartesian coordinate system. l Identify axes on a CNC machine. l Identify positive and negative movement along machine axes. l Identify rotational axes. l Describe the role of the machine control unit. l Define point-to-point positioning. l Define continuous path movement. l Define open-loop system. l Define closed-loop system. l Describe the role of servomechanisms. l Distinguish between different feedback devices. l Describe various input methods. l Describe different control and operation features available to the CNC machine. Figure 1. The three axes of a milling machine intersect at right angles. Figure 2. Special feedback devices in a closedloop system send signals back to the control system to verify instructions. Lesson: 2/17 CNC for Modern Manufacturing Over the past four generations, the shop floor has experienced a computer revolution. Computer technology has led to the development of computer numerical control (CNC) machines. Though CNC machines, like the one in Figure 1, are very costly, they have solved numerous manufacturing problems. CNC machines are very efficient, accurate, and productive. They help companies make high-quality parts in small to medium lot sizes. CNC machines are also able to change over from one part to another in a very short amount of time. This makes it economically to run small lot sizes of parts. Copyright 2015 Tooling U, LLC. Allfeasible Rights Reserved. To understand how CNC machines work, you must understand which components move and how

4 Lesson: 2/17 CNC for Modern Manufacturing Over the past four generations, the shop floor has experienced a computer revolution. Computer technology has led to the development of computer numerical control (CNC) machines. Though CNC machines, like the one in Figure 1, are very costly, they have solved numerous manufacturing problems. CNC machines are very efficient, accurate, and productive. They help companies make high-quality parts in small to medium lot sizes. CNC machines are also able to change over from one part to another in a very short amount of time. This makes it economically feasible to run small lot sizes of parts. To understand how CNC machines work, you must understand which components move and how they move. Taken at once, all the complex elements of motion can confuse anyone. You will examine each of these elements one at a time to see how they all fit together. Figure 1. Though more expensive than traditional machines, CNC machines have solved many manufacturing problems. Lesson: 3/17 Movement of CNC Machines CNC machines require an understanding of motion and position for both the machine and the workpiece. With CNC lathes, like the one in Figure 1, the part rotates about a centerline while a cutting tool, attached to the slide, moves against it. With CNC milling machines, like the one in Figure 2, the part is fixed to a worktable, and this table moves while the cutting tool rotates into the workpiece. A motor moves the table of a CNC mill and the slides of a CNC lathe. These motors drive rotating ballscrews, as shown in Figure 3. The speed at which the ballscrew spins determines how fast the table or slide moves from one point to the next. The number of turns the ballscrew makes determines the distance the worktable or slide travels. The success of these systems depends on how well these intricate moves between the machine and part are controlled and carried out. Figure 1. The CNC lathe rotates a part while a tool cuts it.

5 Lesson: 3/17 Movement of CNC Machines CNC machines require an understanding of motion and position for both the machine and the workpiece. With CNC lathes, like the one in Figure 1, the part rotates about a centerline while a cutting tool, attached to the slide, moves against it. With CNC milling machines, like the one in Figure 2, the part is fixed to a worktable, and this table moves while the cutting tool rotates into the workpiece. A motor moves the table of a CNC mill and the slides of a CNC lathe. These motors drive rotating ballscrews, as shown in Figure 3. The speed at which the ballscrew spins determines how fast the table or slide moves from one point to the next. The number of turns the ballscrew makes determines the distance the worktable or slide travels. The success of these systems depends on how well these intricate moves between the machine and part are controlled and carried out. Figure 1. The CNC lathe rotates a part while a tool cuts it. Figure 2. On the CNC mill, a workpiece is attached to a moveable worktable. Figure 3. A plastic model next to an actual ballscrew. The ballscrew moves CNC machine components. (Courtesy of Wedin International, Inc.)

6 Lesson: 4/17 CNC Coordinates All the positions and motions of a CNC machine are understood in terms of numbers. Numbers describe the shape of the workpiece, the movement of the tool, the depth and speed of the cut, etc. How exactly are numbers used in this way? The common system used to describe location is called the Cartesian coordinate system, also called a rectangular coordinate system. The Cartesian system defines the location of a single point in three-dimensional space using three axes, as shown in Figure 1. These axes are called the X-axis, Y-axis, and Z-axis, and each one indicates a particular direction. An axis is a straight line. In the Cartesian system, the X-, Y-, and Z-axes meet at right angles. In other words, they join together like the corners of a box, as shown in Figure 2. Figure 1. The X-, Y-, and Z-axes define the location of a single point in three-dimensional space. Figure 2. The axes intersect each other at right angles. Lesson: 5/17 The Axes and Origin An effective way to picture the three Cartesian axes is by learning the right-hand rule. Turn your right palm up, and then extend only the thumb and forefinger. This forms an "L." With the middle finger pointing up to the ceiling, as in Figure 1, the thumb is the X-axis, the forefinger is the Yaxis, and the elevated is the Z-axis. Copyright 2015 Toolingcenter U, LLC.finger All Rights Reserved. The Z-axis, frequently depicted as a vertical line, always corresponds to the spindle of the machine tool. The drawing of a milling machine in Figure 2 shows these three axes. On some

7 Lesson: 5/17 The Axes and Origin An effective way to picture the three Cartesian axes is by learning the right-hand rule. Turn your right palm up, and then extend only the thumb and forefinger. This forms an "L." With the middle finger pointing up to the ceiling, as in Figure 1, the thumb is the X-axis, the forefinger is the Yaxis, and the elevated center finger is the Z-axis. The Z-axis, frequently depicted as a vertical line, always corresponds to the spindle of the machine tool. The drawing of a milling machine in Figure 2 shows these three axes. On some machines where the tool is mounted horizontally, such as in Figure 3, the Z-axis would actually be horizontal. The point where all three axes meet is called the origin. This occurs roughly in the palm of your hand, or on the corner of the box. Within this Cartesian system, any specific location can be described by its place along the three axes and the distance from the origin. Figure 1. The right-hand rule is an effective way to remember the three Cartesian axes. Figure 2. The Z-axis of a milling machine corresponds to the spindle and is frequently vertical. Figure 3. The Z-axis of a horizontal milling machine is parallel to the shop floor.

8 Lesson: 6/17 Plus and Minus Directions As you learned earlier, each axis line contains a range of numbers. The origin, or the center of the axis line, is always zero. Numbers are then counted as they move away from the center on each side of the axis. One direction is positive ( +), and the other is negative ( -). Measurements taken to the right side of the origin along the X-axis are generally considered positive, or +x, while measurements to the left of the origin along the X-axis are minus, or x, as shown in Figure 1. The plus and minus directions work the same way for the Y- and Z-axes as well. Figure 2 shows the box corner. The positive direction of the Y-axis points away, and the positive direction of the Z-axis points upward. Figure 1. The X-, Y-, and Z-axes have both positive and negative directions. Figure 2. The positive direction of the Y-axis points away, and the positive direction of the Z-axis points upward. Lesson: 7/17 Rotational Axes In addition to the movements on the X-, Y-, and Z- linear axes, tools and workpieces can also move along rotational axes. These rotational axes describe how a part tilts or spins around a single point. The three rotational axes are the A-axis, B-axis, and C-axis, as shown in Figure 1. Each rotational axis corresponds to one of the linear axes. Rotational can a workpiece that is turned to expose different areas of its Copyright movement 2015 Tooling U, describe LLC. All Rights Reserved. surface for machining. Rotational movement can also describe the angle of the cutting tool. If you have ever done any woodworking, you can certainly appreciate being able to cut at different angles.

9 Lesson: 7/17 Rotational Axes In addition to the movements on the X-, Y-, and Z- linear axes, tools and workpieces can also move along rotational axes. These rotational axes describe how a part tilts or spins around a single point. The three rotational axes are the A-axis, B-axis, and C-axis, as shown in Figure 1. Each rotational axis corresponds to one of the linear axes. Rotational movement can describe a workpiece that is turned to expose different areas of its surface for machining. Rotational movement can also describe the angle of the cutting tool. If you have ever done any woodworking, you can certainly appreciate being able to cut at different angles. Sophisticated CNC machines can move a tool along two or more axes, either linear or rotational, at once. This movement is called contouring. Contour movements can produce curves, circles, and even cones, like those shapes in Figure 2. However, very few CNC systems factor all six axes at once during their operations, and many only address two or three axes at the same time. Figure 1. Each rotational axis corresponds to one of the linear axes. Figure 2. CNC machines create contours by moving a tool along two or more axes at once. Lesson: 8/17 Machine Control Unit Numbers describe the position and motion of the tool and the workpiece. The numbers and formulas that develop can be quite complex. CNC machines have a machine control unit (MCU) that interprets the numerical information and guides the movement of the machine. The information comes to the CNC machine in the form of a part program. CNC machines require a combination of hardware and software to perform operations. The hardware is the physical equipment, which is shown in Figure 1. The software is the list of instructions, formulas, and operations, as shown in Figure 2. If you bake a cake, the "hardware" is the bowl, the spoon, the oven, etc. The "software" is the directions use for mixing baking. You act as the MCU that performs the operations. Copyright you 2015 Tooling U, LLC.and All Rights Reserved.

10 Lesson: 8/17 Machine Control Unit Numbers describe the position and motion of the tool and the workpiece. The numbers and formulas that develop can be quite complex. CNC machines have a machine control unit (MCU) that interprets the numerical information and guides the movement of the machine. The information comes to the CNC machine in the form of a part program. CNC machines require a combination of hardware and software to perform operations. The hardware is the physical equipment, which is shown in Figure 1. The software is the list of instructions, formulas, and operations, as shown in Figure 2. If you bake a cake, the "hardware" is the bowl, the spoon, the oven, etc. The "software" is the directions you use for mixing and baking. You act as the MCU that performs the operations. Figure 1. This indexing machine component and the cutting tools loaded in it are part of the hardware. Figure 2. This screen shows the software, or list of instructions, that is used to make a part. Lesson: 9/17 Point-to-Point Positioning System There are two main types of control systems used with CNC machines: point-to-point positioning (PTP) and continuous path systems. Both of these systems are used to guide the tool as it moves from one position to the next. With a PTP system, like the press in Figure 1, the machine guides the cutting tool from one predetermined location to the next. Figure 2 shows a typical PTP product. Cutting only takes place at each end position. No cutting takes place during the move.

11 Lesson: 9/17 Point-to-Point Positioning System There are two main types of control systems used with CNC machines: point-to-point positioning (PTP) and continuous path systems. Both of these systems are used to guide the tool as it moves from one position to the next. With a PTP system, like the press in Figure 1, the machine guides the cutting tool from one predetermined location to the next. Figure 2 shows a typical PTP product. Cutting only takes place at each end position. No cutting takes place during the move. Automated drills and punch presses are two types of machines most frequently directed by PTP systems. In the case of a drill, the machine would move to a position, drill a hole, move to a new location, drill a new hole, and so on. Figure 1. The punch press uses a PTP positioning system. Figure 2. The holes on this part are the result of a PTP process. Lesson: 10/17 Continuous Path System Unlike PTP systems, a continuous path system allows the tool to cut the workpiece during movement. This lets the machine, like the one in Figure 1, cut curved paths, circles, cones, and other contour shapes that require more than one direction, as shown in Figure 2. Continuous path systems are more expensive than PTP systems, but they can perform a greater number of operations. Machining centers and turning centers are the most common continuous path CNC machines. In fact, almost every modern machining center and turning center is equipped with a continuous path system. Figure 1. A CNC milling machine travels along a continuous path.

12 Lesson: 10/17 Continuous Path System Unlike PTP systems, a continuous path system allows the tool to cut the workpiece during movement. This lets the machine, like the one in Figure 1, cut curved paths, circles, cones, and other contour shapes that require more than one direction, as shown in Figure 2. Continuous path systems are more expensive than PTP systems, but they can perform a greater number of operations. Machining centers and turning centers are the most common continuous path CNC machines. In fact, almost every modern machining center and turning center is equipped with a continuous path system. Figure 1. A CNC milling machine travels along a continuous path. Figure 2. A portion of this part was created with a continuous path. Lesson: 11/17 Open-Loop Systems You just learned that control systems are grouped according to the number of axes they can control at once. Another way to distinguish control systems is by whether they provide feedback or not. Closed-loop systems provide feedback, but open-loop systems do not. In an open-loop system, the control system sends a signal to a motor, which then turns a number of times to move either the tool or the worktable. Figure 1 illustrates the path of the signal in an open-loop system. The machine measures the location of the workpiece by the number of turns that the motor makes. Once the process is underway, no modifications are made. Most PTP machines are open loop. An open-loop system is similar to following driving directions on a sheet of paper. You can write down directions for someone, but once they drive off, you cannot be sure that they have made all the right turns and reached the desired location.

13 Lesson: 11/17 Open-Loop Systems You just learned that control systems are grouped according to the number of axes they can control at once. Another way to distinguish control systems is by whether they provide feedback or not. Closed-loop systems provide feedback, but open-loop systems do not. In an open-loop system, the control system sends a signal to a motor, which then turns a number of times to move either the tool or the worktable. Figure 1 illustrates the path of the signal in an open-loop system. The machine measures the location of the workpiece by the number of turns that the motor makes. Once the process is underway, no modifications are made. Most PTP machines are open loop. An open-loop system is similar to following driving directions on a sheet of paper. You can write down directions for someone, but once they drive off, you cannot be sure that they have made all the right turns and reached the desired location. Figure 1. In an open-loop system, the control system sends a signal to a motor, which then rotates a number of times in order to move either the tool or the worktable. Lesson: 12/17 Closed-Loop Systems Closed-loop systems are more accurate than open-loop systems because they have devices that provide feedback. Feedback devices verify that the signals sent out from the control system were actually performed. Most continuous path machines are closed-loop systems. Just like the open-loop system, the closed-loop system sends a signal to a motor, which then moves either the tool or the worktable. But unlike the open-loop system, special feedback devices send signals back to the control system to verify that the instruction was accurately performed. Figure 1 illustrates the path of the signal in the closed-loop system. If there is a slight error of position, the control system then corrects it during the process. Using the idea of driving directions once again, a closed-loop system is similar to equipping a friend with a cellular phone or a global positioning system (GPS) so that he or she can verify the directions as they are being followed. Figure 1. Unlike the open-loop system, special feedback devices in the closed -loop system send signals back to the control system in order to verify that the instructions were accurately performed.

14 Lesson: 12/17 Closed-Loop Systems Closed-loop systems are more accurate than open-loop systems because they have devices that provide feedback. Feedback devices verify that the signals sent out from the control system were actually performed. Most continuous path machines are closed-loop systems. Just like the open-loop system, the closed-loop system sends a signal to a motor, which then moves either the tool or the worktable. But unlike the open-loop system, special feedback devices send signals back to the control system to verify that the instruction was accurately performed. Figure 1 illustrates the path of the signal in the closed-loop system. If there is a slight error of position, the control system then corrects it during the process. Using the idea of driving directions once again, a closed-loop system is similar to equipping a friend with a cellular phone or a global positioning system (GPS) so that he or she can verify the directions as they are being followed. Figure 1. Unlike the open-loop system, special feedback devices in the closed -loop system send signals back to the control system in order to verify that the instructions were accurately performed. Lesson: 13/17 Servomechanisms Servomechanisms, or servos, are the devices in a CNC machine that control the exact, proper axis positioning for the tool and the workpiece. Figure 1 shows a servo on a machine. They consist of an electronic control unit and a motor. Each axis has its own motor. They are used in closedloop systems. Servomechanisms are categorized by the type of motor used in the system. The most common servomechanisms include the following: l l l l Stepper motor servos generate pulses to drive steps, or motion, of the ballscrew. It is usually electric. DC servos use direct current for power. AC servos use an alternating current for power. The AC servo provides better reliability and performance for less power consumption. Hydraulic servos use hydraulics to deliver power to the motor. All of these servomechanisms can produce highly accurate dimensions. Figure 1. CNC servos are the devices in a CNC machine that control the exact, proper axis positioning for the tool and the workpiece.

15 Lesson: 13/17 Servomechanisms Servomechanisms, or servos, are the devices in a CNC machine that control the exact, proper axis positioning for the tool and the workpiece. Figure 1 shows a servo on a machine. They consist of an electronic control unit and a motor. Each axis has its own motor. They are used in closedloop systems. Servomechanisms are categorized by the type of motor used in the system. The most common servomechanisms include the following: l l l l Stepper motor servos generate pulses to drive steps, or motion, of the ballscrew. It is usually electric. DC servos use direct current for power. AC servos use an alternating current for power. The AC servo provides better reliability and performance for less power consumption. Hydraulic servos use hydraulics to deliver power to the motor. All of these servomechanisms can produce highly accurate dimensions. Figure 1. CNC servos are the devices in a CNC machine that control the exact, proper axis positioning for the tool and the workpiece. Figure 3. Servos control the motion that enables parts with very accurate dimensions. Lesson: 14/17 Feedback Devices In a closed-loop system, servomechanisms work together with feedback devices to accurately position tools and workpieces. Each axis has its own motor and feedback devices. As shown in Figure 1, the feedback device returns a signal to the controller to report a speed or position. The controller will then adjust the motor motion based on this feedback. Feedback can happen several ways. An optical encoder uses light signals to track the position of the tool or worktable. The feedback sent to the controller converts information about ballscrew rotation into distance traveled. The rotary resolver works somewhat like the optical encoder. Instead of light, it sends an

16 Lesson: 14/17 Feedback Devices In a closed-loop system, servomechanisms work together with feedback devices to accurately position tools and workpieces. Each axis has its own motor and feedback devices. As shown in Figure 1, the feedback device returns a signal to the controller to report a speed or position. The controller will then adjust the motor motion based on this feedback. Feedback can happen several ways. An optical encoder uses light signals to track the position of the tool or worktable. The feedback sent to the controller converts information about ballscrew rotation into distance traveled. The rotary resolver works somewhat like the optical encoder. Instead of light, it sends an electronic signal to the controller. The signal conveys information about ballscrew rotations. A linear scale conveys position or distance information based on the size of an electric current created between two points. Since the scale is installed in the worktable, it is a more direct measurement of position than the optical encoder or rotary resolver. Regardless of the device used, the controller compares feedback information to the program and makes necessary adjustments. Figure 2 shows a feedback device on a CNC machine. Figure 1. The feedback device returns a signal to the controller to report a speed or position. Figure 2. Feedback devices enable the controller to evaluate feedback information and make necessary adjustments. Lesson: 15/17 Input Methods CNC controls may receive instructions, or part programs, in several ways. Older machines may use one-inch wide paper tapes or mylar tapes whose holes communicate the program through tape readers, like the one in Figure 1. Even these older machines can be converted to accommodate more modern input methods, such as floppy drives. Most CNC machines accept either EIA or ASCII input. These types of input are standards defined in the information exchange and industries. Nearly every CNC machine today comes with Copyright 2015 Tooling U, LLC. Allcomputer Rights Reserved. a RS232 port. The RS232, sometimes called the EIA-232, defines how a computer communicates with other devices using certain cables.

17 Lesson: 15/17 Input Methods CNC controls may receive instructions, or part programs, in several ways. Older machines may use one-inch wide paper tapes or mylar tapes whose holes communicate the program through tape readers, like the one in Figure 1. Even these older machines can be converted to accommodate more modern input methods, such as floppy drives. Most CNC machines accept either EIA or ASCII input. These types of input are standards defined in the information exchange and computer industries. Nearly every CNC machine today comes with a RS232 port. The RS232, sometimes called the EIA-232, defines how a computer communicates with other devices using certain cables. ASCII (pronounced "askee") text is basically unpolished text. ASCII is easily read by nearly every computer, regardless of age. Computer information besides CNC programs is still commonly exchanged in ASCII format. Figure 1. Tape readers convey program information from tapes to the control of an NC machine. Lesson: 16/17 Control and Operation Features The CNC control reads programs that direct part and tool movement. The progress of the operation is displayed on the CNC control panel like the one in Figure 1. To aid in programming, canned cycles are available for common operations such as drilling holes. Usually, before production of a part begins, the programmer performs a dry run of the proposed program. This allows the programmer to evaluate the tool path without a workpiece. The program can also be verified on the computer screen. CNC controls also offer operators the opportunity to manually override or input information such as feed rate and spindle speed. Optional stops are written into the program to suspend the machining operation temporarily. These control features do not change the program. Instead, it allows for occasional human intervention when necessary for inspection or other reasons. Today s CNC machines may be networked, or linked together. This means programs may be transferred to the CNC control from a central location in an office around the corner or around the world. Figure 1. A CNC control panel displays the progress of a machining operation.

18 Lesson: 16/17 Control and Operation Features The CNC control reads programs that direct part and tool movement. The progress of the operation is displayed on the CNC control panel like the one in Figure 1. To aid in programming, canned cycles are available for common operations such as drilling holes. Usually, before production of a part begins, the programmer performs a dry run of the proposed program. This allows the programmer to evaluate the tool path without a workpiece. The program can also be verified on the computer screen. CNC controls also offer operators the opportunity to manually override or input information such as feed rate and spindle speed. Optional stops are written into the program to suspend the machining operation temporarily. These control features do not change the program. Instead, it allows for occasional human intervention when necessary for inspection or other reasons. Today s CNC machines may be networked, or linked together. This means programs may be transferred to the CNC control from a central location in an office around the corner or around the world. Figure 1. A CNC control panel displays the progress of a machining operation. Lesson: 17/17 Summary Computers have revolutionized manufacturing processes. Today s CNC machines are both highly efficient and versatile. CNC machines rely on a system of numbers in order to calculate the motion and position of parts. The basic system used to describe motion is the Cartesian coordinate system. This system contains three linear axes (X-, Y-, and Z-axes) that are used to describe the position of a tool or worktable. The A-, B-, and C-axes describe rotational movement on the X-, Y-, and Z- axes, respectively. Figure 1 shows these axes. A machine control unit (MCU) controls and guides the movements of the machine s parts. Point-topoint positioning moves to the end position before the tool begins to cut, but continuous path systems can move a tool along two or more axes at once and also cut during the movement. Open-loop systems direct tool movement without feedback. In a closed-loop system, servomechanisms move the tool or the worktable, and feedback sensors send a return signal to report the actual position. CNC machines that use a variety of tools to perform multiple operations are called machining centers. Figure 1. Each rotational axis corresponds to one of the linear axes.

19 Lesson: 17/17 Summary Computers have revolutionized manufacturing processes. Today s CNC machines are both highly efficient and versatile. CNC machines rely on a system of numbers in order to calculate the motion and position of parts. The basic system used to describe motion is the Cartesian coordinate system. This system contains three linear axes (X-, Y-, and Z-axes) that are used to describe the position of a tool or worktable. The A-, B-, and C-axes describe rotational movement on the X-, Y-, and Z- axes, respectively. Figure 1 shows these axes. A machine control unit (MCU) controls and guides the movements of the machine s parts. Point-topoint positioning moves to the end position before the tool begins to cut, but continuous path systems can move a tool along two or more axes at once and also cut during the movement. Open-loop systems direct tool movement without feedback. In a closed-loop system, servomechanisms move the tool or the worktable, and feedback sensors send a return signal to report the actual position. CNC machines that use a variety of tools to perform multiple operations are called machining centers. Figure 1. Each rotational axis corresponds to one of the linear axes. Figure 2. A plastic model next to an actual ballscrew. The ballscrew moves CNC machine components. (Courtesy of Wedin International, Inc.) Figure 3. Servos control the motion that enables parts with very accurate dimensions.

20 enables parts with very accurate dimensions. Class Vocabulary Term Definition A-Axis AC Servo ASCII A rotational axis describing motion around the X-axis. A type of servomechanism that is more reliable and less energy consuming than the DC servo. American Standard Code for Information Interchange. It is a standard for information exchange. Axes An imaginary line that passes through the center of an object. Axes are used to measure the distances of objects in the Cartesian coordinate system. Ballscrew A long, threaded device that rotates to move the worktable of a CNC machine. The ballscrew is powered by a motor. B-Axis Canned Cycle Cartesian Coordinate System C-Axis Closed-Loop System CNC Lathe CNC Milling Machine Computer Numerical Control Continuous Path Contouring Control System Cutting Tool DC Servo Drill Dry Run EIA A rotational axis describing motion around the Y-axis. A predetermined machining sequence used to simplify programming. The numerical system that describes the location of an object by numerically expressing its distance from a fixed position along three linear axes. A rotational axis describing motion around the Z-axis. A control system that provides feedback to the controller. A lathe that is controlled by a computer running programs driven by numerical data. A milling machine that is controlled by a computer running programs driven by numerical data. The use of a computer with numerical instructions and program codes to carry out various machining operations. A type of control system where cutting can take place as the tool moves from one position to the next. Tool movement along two or more axes at the same time. A method of tool and part movement in CNC machining. Point-to-point and continuous path are the two main control systems. A device made of hard, tough material that is used to remove metal by creating chips. A common type of servomechanism. A machining tool used to penetrate the surface of a workpiece and make a round hole. A trial run of the part program without any parts or cutting fluids. Electronics Industry Association. It publishes Recommended Standards (RS) for transmitting data between devices. Feed Rate The rate at which the cutting tool and the workpiece move in relation to one another. Feedback A return signal that confirms the position of the tool or worktable. Feedback Device Floppy Drive Hardware A device that sends information back to the controller in the closed-loop system. A device that reads magnetic data from a floppy disc. The physical components of a CNC machine. to the horizon, like a table top. Copyright 2015 ToolingHorizontally U, LLC. All RightsParallel Reserved. Hydraulic Servo A type of servomechanism that is driven by fluids.

21 Class Vocabulary Term Definition A-Axis AC Servo ASCII A rotational axis describing motion around the X-axis. A type of servomechanism that is more reliable and less energy consuming than the DC servo. American Standard Code for Information Interchange. It is a standard for information exchange. Axes An imaginary line that passes through the center of an object. Axes are used to measure the distances of objects in the Cartesian coordinate system. Ballscrew A long, threaded device that rotates to move the worktable of a CNC machine. The ballscrew is powered by a motor. B-Axis Canned Cycle Cartesian Coordinate System C-Axis Closed-Loop System CNC Lathe CNC Milling Machine Computer Numerical Control Continuous Path Contouring Control System Cutting Tool DC Servo Drill Dry Run EIA A rotational axis describing motion around the Y-axis. A predetermined machining sequence used to simplify programming. The numerical system that describes the location of an object by numerically expressing its distance from a fixed position along three linear axes. A rotational axis describing motion around the Z-axis. A control system that provides feedback to the controller. A lathe that is controlled by a computer running programs driven by numerical data. A milling machine that is controlled by a computer running programs driven by numerical data. The use of a computer with numerical instructions and program codes to carry out various machining operations. A type of control system where cutting can take place as the tool moves from one position to the next. Tool movement along two or more axes at the same time. A method of tool and part movement in CNC machining. Point-to-point and continuous path are the two main control systems. A device made of hard, tough material that is used to remove metal by creating chips. A common type of servomechanism. A machining tool used to penetrate the surface of a workpiece and make a round hole. A trial run of the part program without any parts or cutting fluids. Electronics Industry Association. It publishes Recommended Standards (RS) for transmitting data between devices. Feed Rate The rate at which the cutting tool and the workpiece move in relation to one another. Feedback A return signal that confirms the position of the tool or worktable. Feedback Device Floppy Drive Hardware Horizontally A device that sends information back to the controller in the closed-loop system. A device that reads magnetic data from a floppy disc. The physical components of a CNC machine. Parallel to the horizon, like a table top. Hydraulic Servo A type of servomechanism that is driven by fluids.

22 Horizontally Hydraulic Servo Parallel to the horizon, like a table top. A type of servomechanism that is driven by fluids. Linear Axes The axes that describe movement along a straight line. Linear Scale A device that relies on the size of an electrical current to convey the position or distance on a CNC machine. A linear scale is one of the most accurate feedback devices. Lot Machine Control Unit Machining Center Mylar Tape Open-Loop System Optical Encoder Origin Paper Tape Part Program Point-To-Point Positioning Punch Presses Rectangular Coordinate System A group of similar parts created during the use of a particular tooling setup. A small, powerful computer that controls and operates a CNC machine. A sophisticated CNC machine that can perform multiple machining operations at the same location with a variety of tools. A thin, yet strong polyester film that was used to transmit programs to numerically controlled machines. A control system that does not provide feedback to the controller. A type of feedback sensor that records light reflections and converts the reflections into feedback signals. The fixed, central point in the Cartesian coordinate system. The origin has a numerical value of zero. A way of transmitting programs to numerically controlled machines. This is a somewhat older method. The instructions for the CNC machine about how to create a part. A type of control system where no cutting takes place during the movement of the tool from one position to the next. A machine that uses force to either cut or form a workpiece. Another name for the Cartesian coordinate system. Right-Hand Rule A quick reference that shows the X-, Y-, and Z-axes. A person displays his or her right hand, and the first three fingers from the right each represent the X-, Y-, and Z-axis in order. Rotary Resolver A device that sends signals back to the CNC controller to indicate position or speed. Rotational Axes The axes that describe turning or spinning movement. RS232 Servomechanism Signal Slide Software Spindle Speed Stepper Motor Servo Turning Center Vertical Line A standard that defines a computer's serial port and interaction with other devices. A special motor used in CNC machines that moves with precision. A message sent electronically. The part that moves and holds a tool. The coded instructions, formulas, and operations that structure the actions of a computer. The rate that the cutting tool or workpiece moves at the point of contact. A servomechanism that generates steps to move the tool and the worktable. A sophisticated CNC machine that specializes in turning, boring, drilling, and threading operations, all at the same location. A line that travels up and down. Workpiece A part that is being worked on. It may be subject to cutting, welding, forming, or other operations. Worktable The table that supports a workpiece during a manufacturing operation. X-Axis The linear axis that represents motions and positions to the left or right of the operator. Y-Axis The linear axis that represents motions and positions both toward and away from the operator. Z-Axis The linear axis that represents motions and positions both up and down. The Z-axis is always parallel to the main cutting device.

23 Y-Axis The linear axis that represents motions and positions both toward and away from the operator. Z-Axis The linear axis that represents motions and positions both up and down. The Z-axis is always parallel to the main cutting device.