Programmable Logic Controller (plc)
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This document provides an overview of material requirements planning (MRP). It defines MRP as a computer-based inventory management system that helps production managers schedule dependent demand items based on final product demand. The document outlines the key steps in MRP, including determining gross requirements, net requirements, and release times for items. It also lists some common benefits of MRP systems such as improved inventory planning and reduced inventory levels without compromising customer service.
Programmable Logic Controller (plc)
- 1. Subject – Computer Aided Manufacturing Topic - Programmable Logic Controller (PLC) Presented By :- Dhruv Shah
- 2. Introduction of PLC This training introduces the basic hardware and software components of a Programmable Controller (PLC). It details the architecture and basic instruction set common to all PLC’s. Basic programming techniques and logic designs are covered. This training describes the operating features of the PLC, the advantages of the PLC over hard-wired control systems, practical applications, troubleshooting and maintenance of PLC’s.
- 3. 3 Objectives At the end of the training the participants should be able to: Describe the major components of a common PLC. Interpret PLC specifications. Apply troubleshooting techniques. Convert conventional relay logic to a PLC language. Operate and program a PLC for a given application.
- 4. PLC Contents History of Programmable Controllers Relay Ladder Logic Central Processing Unit Input/Output System Programming and Peripheral Devices Programming Concepts Applications Troubleshooting and Maintenance
- 5. PLC Origin Developed to replace relays in the late 1960s Costs dropped and became popular by 1980s Now used in many industrial designs
- 6. History of PLC The Hydramatic Division of the General Motors Corporation specified the design criteria for the first programmable controller in 1968 To eliminate the high costs associated with inflexible, relay- controlled systems.
- 7. History of PLC • The controller had to be designed in modular form, so that sub- assemblies could be removed easily for replacement or repair. • The control system needed the capability to pass data collection to a central system. • The system had to be reusable. • The method used to program the controller had to be simple, so that it could be easily understood by plant personnel.
- 8. Programmable Controller Development 1968 Programmable concept developed 1969 Hardware CPU controller, with logic instructions, 1 K of memory and 128 I/O points 1974 Use of several (multi) processors within a PLC - timers and counters; arithmetic operations; 12 K of memory and 1024 I/O points 1976 Remote input/output systems introduced 1977 Microprocessors - based PLC introduced
- 9. Programmable Controller Development 1980 Intelligent I/O modules developed Enhanced communications facilities Enhanced software features (e.g. documentation) Use of personal microcomputers as programming aids 1983 Low - cost small PLC’s introduced 1985 Networking of all levels of PLC, computer and machine using SCADA software.
- 10. Programmable Logic Controllers ( Definition according to NEMA standard ICS3-1978) A digitally operating electronic apparatus which uses a programming memory for the internal storage of instructions for implementing specific functions such as logic, sequencing, timing, counting and arithmetic to control through digital or analog modules, various types of machines or process.
- 11. Leading Brands Of PLC AMERICAN 1. Allen Bradley 2. Gould Modicon 3. Texas Instruments 4. General Electric 5. Westinghouse 6. Cutter Hammer 7. Square D EUROPEAN 1. Siemens 2. Klockner & Mouller 3. Festo 4. Telemechanique
- 12. Leading Brands Of PLC JAPANESE 1. Toshiba 2. Omron 3. Fanuc 4. Mitsubishi
- 13. PLC Size 1. SMALL - it covers units with up to 128 I/O’s and memories up to 2 Kbytes. - these PLC’s are capable of providing simple to advance levels or machine controls. 2. MEDIUM - have up to 2048 I/O’s and memories up 3. LARGE - the most sophisticated units of the PLC family. They have up to 8192 I/O’s and memories up to 750 Kbytes. - can control individual production processes or entire plant.
- 14. Major Components of a Common PLC PROCESSOR POWER SUPPLY I M N O P D U U T L E O M U O T D P U U L T E PROGRAMMING DEVICE From SENSORS Pushbuttons, contacts, limit switches, etc. To OUTPUT Solenoids, contactors, alarms etc.
- 15. Major Components of a Common PLC POWER SUPPLY Provides the voltage needed to run the primary PLC components I/O MODULES Provides signal conversion and isolation between the internal logic- level signals inside the PLC and the field’s high level signal.
- 16. Major Components of a Common PLC PROCESSOR Provides intelligence to command and govern the activities of the entire PLC systems. PROGRAMMING DEVICE used to enter the desired program that will determine the sequence of operation and control of process equipment or driven machine.
- 17. Areas of Application Manufacturing / Machining Food / Beverage Metals Power Mining Petrochemical / Chemical
- 18. Advantages of PLCs • Less wiring. • Wiring between devices and relay contacts are done in the PLC program. • Easier and faster to make changes. • Trouble shooting aids make programming easier and reduce downtime. • Reliable components make these likely to operate for years before failure.
- 19. Material requirements planning (MRP) is a computer-based inventory management system designed to assist production managers in scheduling and placing orders for items of dependent demand. Dependent demand items are components of finished goods—such as raw materials, component parts, and subassemblies—for which the amount of inventory needed depends on the level of production of the final product.
- 20. MRP is a material planning methodology developed in the 1970's making use of computer technology. The main features of MRP are the creation of material requirements via exploding the bills of material, and time-phasing of requirements using posted average lead times. MRP II was developed as the second generation of MRP and it features the closed loop system: production planning drives the master schedule which drives the material plan which is the input to the capacity plan. Feedback loops provide input to the upper levels as a reiterative process.
- 21. The goal of the MRP or Material Requirements Planning document is to supply information that will enable the company to have enough inventory on hand to fulfill demand, (and no more) available only when needed, (and no sooner) at a quality level that meets specification, (but does not have to exceed it) and at the lowest price. A good MRP or Material Requirements Planning program can provide the basic needs of keeping inventory levels low and fulfilling customer expectations for on time delivery.
- 22. There are two important questions to ask here. How much of an item is needed? When is an item needed to complete a specified number of units, in a specified period of time? The MRP process involves the following steps: Determine the gross requirements for a particular item Determine the net requirements and when orders will be released for fabrication or subassembly Net Requirements = Total Requirements – Available Inventory Net Requirements = (Gross Requirements + Allocations) – (On Hand) + Scheduled Receipts
- 23. Multiple planning cycles Concurrent MRP planning views Optionally driven by selected glovia G2 Master Production Scheduling cycle Computer-planned orders Generate purchase requisitions Generate purchase orders Contract purchase order releases for suppliers Work orders optionally generated Repetitive schedules created from MRP-planned orders MRP planning by work center MRP transfers for supply & demands across locations
- 24. Material Requirements Planning solution includes modules for inventory management, product definition and costing, master scheduling and materials requirement planning, capacity planning, work order management, purchase order management, sales order management, shipping and receiving, and sales analysis. Material requirements planning software can also include a full accounting package.
- 25. The MRP is a framework for providing useful information for decision makers. The key to realizing the benefits from any MRP system is the ability of the inventory planner to use the information well. The specific benefits of MRP include the following: Increased customer service and satisfaction Improved utilization of facilities and personnel Better inventory planning and scheduling Faster response to market changes and shifts Reduced inventory levels without reduced customer service
- 26. The MRP is also a very powerful tool since it takes into consideration changes in certain assumptions especially under uncertain conditions, especially when the inputs to the MRP system change because of the following realities in the production area: Delays in scheduled receipts Changes in planned order sizes because of capacity constraints Changes in gross requirements which dictate changes in lot sizes at sub-component levels
- 27. Unavailability of raw materials for one sub-component which negates the need for a fellow subcomponent as both must be ready for the parent production Utilization of same parts at different levels indicating the need to restructure the bill of materials and Presence of price discounts or some other features which makes it advisable to purchase more than the anticipated need