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SAMPLE

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G Codes

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G85, G86, G87, G88, G89 = Boring cycles. Function & imput will vary depending on the machine mfgr. Variations include.... Feed in, feed out. Feed in, dwell, feed out. Feed in, dwell, spindle stop, rapid out. Feed in, dwell, spindle stop, move insert from wall, rapid out.

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Exercise

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Exercise

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Exercise

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for aast 3   How to produce a part program and manufacture a component

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The Milling Calculator is designed to support engineers, programmers and machinists when working with milling tools. This includes machining calculations and cost calculations.

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Turning

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How to calculate RPM for HSS drills and Carbide tools for a Lathe

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turning

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Sandvik Coromant - manufacturing tools & machining solutions

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Daewoo Puma 280LM 3 Axis CNC Lathe New 2007

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Uploaded by Apex Auctions on 2011-01-17.

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fast rapid speed --up to 35M/min professional slant bed cnc lathe machine manufacturer in China

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Q Hunt | You Will Discover All That Pertains To Life By Reading

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Measuring Systems for Slide Displacement

The different types of measuring devices used in CNC system are:

(1) Transducers. (2) Optical Gratings. (3) Pneumatic. (4) Hydraulic System.

Transducers

Transducers. A transducer is a device which converts one form of energy (the input) into another form of energy (the output) such that the output is known function of the input. To monitor the position of the slides, the following two types of transducers are used. Positional transducers on NC machines accept signals related to slide movement and give a corresponding output-usually in an electrical code, e.g. voltage. These can be either analog or digital type. There are two types of positional transducers:

(a) Linear Transducers. A linear transducer determines the displacement directly from the movement of the slide along its linear axis. The linear transducers should be positioned at the following positions:

Near to the sliding surface and lead screw

In an accessible position for maintenance purposes.

(b) Rotary Transducer. A rotary transducer is connected to a rotating member of the slide-displacement system, e.g. the lead screws. It should be located at the following positions:

At the driving end of lead screw

On the nut if a fixed screw and rotating nut system is used

All transducers used for measuring slide displacement will need to possess two characteristics in common. They must operate over a long range of movement, and they must register the table position within fine limits of accuracy.

To satisfy these two somewhat conflicting requirements, many systems adopt a three-stage process of measurement, combining coarse, medium and fine transducers in one system. This arrangement also helps to overcome another difficulty experienced with rotary transducers, i.e. in a rotary device one cycle is similar to the next and this cyclic repetition may result in identical signals occurring each revolution, thus producing ambiguous readings. Provision must be made in the system, e.g. with coarse/medium/ fine transducers, to prevent occurrence of this ambiguity. These transducers may be either Analog or Digital type.

Optical Gratings

Optical Gratings. Linear optical gratings consist of a glass (or reflective metal) strip marked with fine, closely spaced parallel lines. When monitoring the displacements of a machine slide, two gratings are used - a short index grating enclosed in the reading head, and the scale grating covering the full extent of the slide movement.

The lines of the index grating are inclined at a slight angle to the lines of the scale grating, and the interference effect at the intersections of these two sets of line causes the well known moiré-fringe pattern. When the machine slide moves, one grating is displaced relative to the other and the dark interference fringes travel across the width of the grating.

The interference effect is used in monitoring slide displacement by means of the arrangement shown in Figure " Optical Arrangements" below. With reference to the transparent gratings, a collimated beam of light is passed through the index and scale gratings and is received by four photocells. When the machine slide is moved, the interference fringes are displaced across the gratings at right angles to the direction of slide movement, and each photocell is de-energized in turn. The pulses generated in this way are counted to determine the amount of slide displacement.

The following numerical example should make the principle clear. Assume two gratings both of 100 lines/mm, i.e. pitch of the lines is 0.01 mm, and that four photocells are spaced across the gratings. If the gratings are so inclined that one fringe passes across the grating for a slide displacement of 0.01 mm, i.e. one pitch of the lines, and then the four photocells will each pick up a pulse in this amount of movement, hence one pulse will represent 0.01/4=0.0025 mm of slide movement.

Pneumatic

Pneumatic System . As different from hydraulic fluid, air medium (or other gases in special situations) is used in pneumatic control systems. Air medium has the advantage of being non-inflammable and having almost negligible viscosity compared to the high viscosity of hydraulic fluids, which also varies considerably with temperature causing a marked effect on the performance of control systems.

On the other hand, the high incompressibility of a hydraulic fluid causes the force wave to travel faster and therefore the hydraulic system have a shorter response time, while in pneumatic system there is a considerable amount of compressibility flow so that such system are characterized by longer time delays. Pneumatic systems find considerable application in the process control field. These are sometimes used in guided missiles and aircraft system.

Hydraulic System

Hydraulic System. Hydraulically operated components are frequently used in hydraulic feedback system and in combined electromechanical hydraulic systems. In these elements, power is transmitted through the action of fluid flow under pressure. The fluid used is relatively incompressible such as petroleum- base oils or certain non-inflammable synthetic fluids.

The main advantage of the hydraulic system lies in the hydraulic motor which can be made much smaller in physical size than an electric motor for the same power output. In addition to this, hydraulic components are rapidly acting and more rugged compared to the corresponding electrical components. On the other hand, hydraulic system have the inherent problems of leak and of sealing them against foreign particles, operating noise and the tendency to become sluggish at low temperature because of increased viscosity of the fluid. Furthermore hydraulic lines are not as flexible as electric cables.

Common hydraulic control applications are power steering and brakes in automobiles, the steering mechanism of large ships, the control of large machine tools, etc.

The hydraulic output devices used in control system are generally of two types, these are as follows:

Those intended to produce rotary motion are known as hydraulic motors.

Those whose output is translational are known as hydraulic linear actuators.

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Different types of measuring devices used in CNC system

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The different types of measuring devices used in CNC system are: (1) Transducers. (2) Optical Gratings. (3) Pneumatic. (4) Hydraulic System. Transducers Transducers . A transducer is a device which converts one form of energy (the input) into another form of energy (the output) such that the output is known function of the input.

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On CNC equipment, transducers are used to record actual machine motion for feedback to the controller, improving accuracy and preventing error. July 21, 2006

Question
Can anyone explain the operation and use of rotary and linear transducers in CNC control systems?

Forum Responses
(CNC Forum)
From contributor M:
In CNC applications, a transducer measures physical motion, then converts that measurement to an electrical input/output. There are different applications of this technology, but the prevalent one is using the transducer in a closed loop environment. This insures that the actual movement of the CNC machine as commanded by the control, then encoded to the motor for that particular axis is, in effect, actually occurring. If the system was not closed loop and had no means to verify movement, potential problems that could occur would be:

1.) CNC control sends signal to encoder to count the revolutions of the axial motor and sends signal to the axial motor telling it to revolve, resulting in linear axial movement across the machine.

2.) The machine momentarily strikes a rigid portion of the machine or fixturing on the machine, momentarily causing the machine to physically pause its linear movement.

3.) Because the motor is designed to "clutch slip" in this case to prevent damage to the motor itself, the motor shaft at the encoder end keeps revolving and the encoder keeps counting.

4.) At the end of its movement the control thinks the correct revolutions of the motor have been executed, therefore assuming the axis has moved linearly correctly also. However, the actual linear physical movement is inaccurate because of the physical pause which occurred.

If a transducer of some type were added to this scenario, now all of a sudden a signal is sent back to the control verifying that the actual physical movement the control thought had occurred, in fact has not. An error would be generated within the control to prevent further movement until the condition is corrected.

From contributor C:
Talk to me about following errors. What are they and can I adjust my AC servos to get a better result?

From contributor M:
Following error is basically the result of the condition we discussed above. The main method of correcting or minimizing it, within servo driven closed loop systems, is adjustment of the servo/servo amplifiers. This process is commonly called "tuning." The process and technique can vary dramatically depending on machine manufacturer and servo/servo amplifier manufacturer. You will have to consult both of the above to get the specific process for your configuration.
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On CNC equipment, transducers are used to record actual machine motion for feedback to the controller, improving accuracy and preventing error. July 21, 2006 Question Can anyone explain the operation and use of rotary and linear transducers in CNC control systems? Forum Responses (CNC Forum) From contributor M: In CNC applications, a transducer measures physical motion, then converts that measurement to an electrical input/output.

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G Codes

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CNC G-Code and M-Code Reference List for CNC Mills

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Handy g-code reference list for Fanuc and other CNC Milling Machines and VMC's with examples.

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LJ Create LMS - Course - ENG1_ Engineering (BTEC Level 3) - CNC and the Basics of Programming (Investigation)

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Unit 26 Applications of Computer Numerical Control in Engineering Task 1

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for aast 3   How to produce a part program and manufacture a component

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P3

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Questions

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EXERCISE

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Power Point P3