03 Production Automation

Production Automation TechnologiesHenry C. CoTechnology and Operations Management, California Polytechnic and State University

Evolution of Production Technology

YearCasting Deformation Joining Machining Ceramics Plastics 4000 B.C. Stone, clay molds Bending, forging (Au, Ag, Cu) Riveting Stone, emery, corundum, garnet, flint Earthenware Wood, natural fiber 2500 BCLost wax (bronze) Shearing, sheet forming Soldering, brazing Drilling, sawing Glass beads, potter's wheel 1000 BCHot forging (iron), wire- drawing (?) Forge welding, gluingIron sawsGlass pressing, glazing 0. A.D.Coining (brass), forging (steel) Turning (wood), filing Glass blowing 1000 Wire drawing Stoneware, porcelain (China) 1400 Sand casting, cast iron Water hammer Sandpaper Majolica, crystal glass 1600 Permanent mold Tinplate can, rolling (Pb) Wheel lathe (wood) 1800 Flasks Deep drawing, rolling, (steel), extrusion (Pb) Boring, turning, screw cuttingPlate glass; porcelain (Germany) 1850 Centrifugal, molding machine Steam hammer, tinplate rolling Shaping, milling, copying lathe Window glass from slit cylinder Vulcanization

YearCasting Deformation Joining Machining Ceramics Plastics 1875 Rail rolling, continuous rolling Turret lathe, universal mill, vitrified wheel Celluloid, rubber extrusion, molding 1900 Tube rolling, extrusion (Cu) Oxyacetylene, arc welding, electrical resistance weldingGeared lathe, automatic screw machine, hobbing, high-speed steel, synthetic SiC, Al2O3 Automatic bottle making 1920 Die casting W wire (from powder) Coated electrode Bakelite, PVC casting, cold molding, injection molding1940 Lost wax for engineering parts, resin-bonded sandExtrusion (steel) Submerged arc Acrylics, PMMA, P.E., nylon, synthetic rubber, transfer molding, foaming 1950 Ceramic mold, modular iron, semi-conductors Cold extrusion (steel) TIG welding, MIG welding, electroslag EDM ABS, silicones, fluorocarbons, polyurethane 1960 Plasma arc Manufactured diamond Float-glass Acetals, polycarbonate, polypropylene

Production Automation Technologies (Henry C. Co)*

Production Automation Technologies (Henry C. Co)

Production Automation Technologies (Henry C. Co)*Computer managed numerical control (NC) is a generic term that encompasses.Computer numerical control (CNC),Direct numerical control (DNC), and.Industrial robots.Computer managed numerical control, integrated with an automated material handling and storage system, form the building blocks of the flexible manufacturing system (FMS).


Numerical Control (NC)

Production Automation Technologies (Henry C. Co)*Numerical control (NC) is a form of flexible (programmable) automation in which the process is controlled by numbers, letters, and symbols. The electronic industries association (EIA) defined NC as A system in which actions are controlled by the direct insertion of numerical data at some point. The system must automatically interpret at least some portion of this data.


Production Automation Technologies (Henry C. Co)*Basic ComponentsAn NC system consists of the machine tools, the part-program, and the machine control unit (MCU).


Production Automation Technologies (Henry C. Co)*Machine ToolsThe machine tools perform the useful work.A machine tool consists of.A worktable,One or more spindles, motors and controls,Cutting tools,Work fixtures, and.Other auxiliary equipment needed in the machining operation.


Production Automation Technologies (Henry C. Co)*The drive units are either powered by stepping motors (for open-loop control), servomotors (for close-loop control), pneumatic drives, or hydraulic drives.


Production Automation Technologies (Henry C. Co)*The Part-program

The part-program is a collection of all data required to produce the part. It is arranged in the form of blocks of information.Each block contains the numerical data required for processing a segment of the work piece.


Production Automation Technologies (Henry C. Co)*The Machine Control UnitThe machine control unit consists of the data processing unit (DPU) and the control loop unit (CLU). The DPU decodes the information contained in the part-program, process it, and provides instructions to the CLU. The CLU operates the drives attached to the machine leadscrews and feedback signals on the actual position and velocity of each one of the axes. The drive units are actuated by voltage pulses.


Production Automation Technologies (Henry C. Co)*The Machine Control UnitThe number of pulses transmitted to each axis is equal to the required incremental motion, and the frequency of these pulses represent the axial velocity. Each incremental motion is called a basic length unit (BLU). One pulse is equivalent to 1 BLU. The BLU represents the resolution of the NC machine tool.


Types of NC Systems

Production Automation Technologies (Henry C. Co)*Point-to-point (PTP) NCThe cutting tool is moved relative to the work piece (i.E., Either the cutting tool moves, or the work piece moves) until the cutting tool is at a numerically defined position and then the motion is paused. The cutting tool then performs an operation. When the operation is completed, the cutting tool moves relative to the work piece until the next point is reached, and the cycle is repeated. The simplest example of a PTP NC machine tool is the NC drilling machine.


Production Automation Technologies (Henry C. Co)*Straight-cut NCStraight-cut system are capable of moving the cutting tool parallel to one of the major axes (X-Y-Z) at a controlled rate suitable for machining. It is appropriate for performing milling operations to fabricate work pieces of rectangular configurations. Straight-cut NC systems can also perform PTP operations.


Production Automation Technologies (Henry C. Co)*Contouring NCIn contouring (continuous path) operations, the tool is cutting while the axes of motion are moving. The axes can be moved simultaneously, at different velocity. The path of the cutter is continuously controlled to generate the desired geometry of the work piece.


Computer-assisted NC Programming

Production Automation Technologies (Henry C. Co)*The computer interprets the instructions in the program into computer-usable form.The computer performs the necessary geometry and trigonometry calculations required to generate the part surface.The part-programmer specifies the part outline as the tool path. Since the tool path is at the periphery of the cutter that machining actually takes place, it must be offset by the radius of the cutter.


Production Automation Technologies (Henry C. Co)*The cutter offset computations in contour part-programming are performed by the computer.Part-programming languages are general-purpose languages. Since NC machine tool systems have different features and capabilities, the computer must take the general instructions and make them specific to a particular machine tool system. This function is called post processing.


Production Automation Technologies (Henry C. Co)*After converting all instructions into a detailed set of machine tool motion commands, the computer controls a tape punch device to prepare the tape for the specific NC machine.Graphic proofing techniques provide a visual representation of the cutting tool path.


Production Automation Technologies (Henry C. Co)*This representation may be a simple two-dimensional plot of the cutter path or a dynamic display of tool motion using computer generated animation. If necessary, part-programs are also verified on the NC station using substitute materials such as light metals, plastics, foams, wood, laminates, and other castable low cost materials used for NC proofing.


Computer Numerical Control (CNC)

Production Automation Technologies (Henry C. Co)*The EIA definition of computer numerical control (CNC).A numerical control system wherein a dedicated, stored program computer is used to perform some or all of the basic numerical control functions in accordance with control programs stored in the read-write memory of the computer.

The CNC uses a dedicated microprocessor to perform the MCU functions.


Production Automation Technologies (Henry C. Co)*CNC supports programming features not available in conventional NC systems:Subroutine macros which can be stored in memory and called by the part-program to execute frequently-used cutting sequence. Inch-metric conversions, sophisticated interpolation functions (such as cubic interpolation) can be easily accomplished in CNC. Absolute or incremental positioning (the coordinate systems used in locating the tool relative to the work piece) as well as PTP or contouring mode can be selected.


Production Automation Technologies (Henry C. Co)*The part-program can be edited (correction or optimization of tool path, speeds, and feeds) at the machine site during tape tryout. Tool and fixture offsets can be computed and stored. Tool path can be verified using graphic display.Diagnostics are available to assist maintenance and repair.


Direct Numerical Control (DNC)

Production Automation Technologies (Henry C. Co)*The EIA definition of DNC.A system connecting a set of numerically controlled machines to a common memory for part program or machine program storage with provision for on-demand distribution of data to machines.In DNC, several NC machines are directly controlled by a computer, eliminating substantial hardware from the individual controller of each machine tool. The part-program is downloaded to the machines directly (thus omitting the tape reader) from the computer memory.


Industrial Robots

Production Automation Technologies (Henry C. Co)*A programmable device equipped with a tool that can move along several directions.

Stand-Alone Operation: once a program is entered, the robot can function with or without further human intervention.


Production Automation Technologies (Henry C. Co)*The ManipulatorThe manipulator is the equivalent of the machine tool in CNC. It consists of a series of segments, jointed or sliding relative to one another, that performs the work such as grasping and/or moving objects. The manipulator is composed of the main frame (the arm of the robot), and the wrist. The tools, called the end-effectors, are attached to the wrist. The end-effectors perform a prescribed task ordinarily done by the human worker.


Production Automation Technologies (Henry C. Co)*The Main FrameStructurally, the robot can be classified according to the coordinate system of the main frame. The types of coordinate systems are:Cartesian coordinate manipulator, which consists of three linear axes,Cylindrical coordinate manipulator, which consists of two linear axes and one rotary axis,Spherical coordinate manipulator which consists of one linear and two rotary axes,Articulated or jointed robots which consists of three rotary axes, and Gantry robotSCARA robot.


Production Automation Technologies (Henry C. Co)*Cartesian Robot


Production Automation Technologies (Henry C. Co)*Cylindrical Robot


Production Automation Technologies (Henry C. Co)*Spherical Robot


Production Automation Technologies (Henry C. Co)*Articulated (Jointed) Robot


Production Automation Technologies (Henry C. Co)*Gantry Robot


Production Automation Technologies (Henry C. Co)*SCARA RobotMachine Tools


Production Automation Technologies (Henry C. Co)*The WristThe end-effectors is connected to the main frame of the robot through the wrist. The wrist has three rotary axes -- roll, bend (pitch), and swivel (yaw). The end-effectors. Attached to the wrist is the end-effectors. The end-effectors is the robot's hand. The most common end-effectors is the gripper, which is a device by which a robot may grasp and hold external objects. Other standard end-effectors include welding torch, magnetic vacuum, gun mounts for spray painting or coating operations, hydraulic toggle, and custom made tools.


Production Automation Technologies (Henry C. Co)*Resolution,Accuracy,RepeatabilityResolution is the smallest increment of distance that can be read and acted upon by an automatic control system of a robot. The unit of measure is the basic resolution unit (BRU). The accuracy of an industrial robot is the ability of the robot to make a motion with an end point as specified by a program. The closeness of agreement of repeated position movement under the same conditions to the same location is called the repeatability of the robot.


Production Automation Technologies (Henry C. Co)*ProgrammingAn industrial robot can be programmed using theManual teaching method, Lead-through method, or aProgramming language.


Production Automation Technologies (Henry C. Co)*Applications Perhaps the most extensive applications of industrial robots are in jobs involving repetitive tasks. Industrial robots installed to-date are in Material handling (about 40%),Painting and arc welding (45%),Inspection, assembly and Other operations (15%).


Production Automation Technologies (Henry C. Co)*Operations that require precise positioning control. For example, in spray painting where severe articulation is required.Use of industrial robots in sand blasting is on the rise not only because of the abrasive environment, but the severe articulation requirements of the process.


Production Automation Technologies (Henry C. Co)*In areas where hazardous working conditions exist and/or where heavy parts are involved. For example, in unloading of die casting machines, the workplace is dirty and hot (molten metal); in spot welding operations, the welding guns are heavy and the work cycles rigorous; and in investment casting, the environment is abrasive and of the loads heavy. Industrial robots are also replacing the human operator in corrosive environment, such as handling of dangerous chemicals.


Production Automation Technologies (Henry C. Co)*Hazards, operator tasks, inspection, quality, part presentation, part weight, product variation, product runs, frequency of changeover, process variables, process equipment, floor space, and cycle time, are some of the variable that must be examined in justifying the use of industrial robots. However, industrial robots should not be treated simply as an emulation of human work. More importantly, the justification process should reflect an accurate implementation of corporate manufacturing plans for competitive advantage and productivity improvement.


03 Production Automation

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