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Flexible Manufacturing Systems V2 090310


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Flexible Manufacturing Systems - An overview of the basic concepts, types of system and design parameters.

Published in: Education, Business

Flexible Manufacturing Systems V2 090310

  1. 1. FLEXIBLE MANUFACTURING SYSTEMS (FMS) Author: Leicester College Date created: Date revised: 2009 Abstract: The use of flexible manufacturing systems in production is rapidly increasing. The rationale for the use and some of the main design parameters are investigated. The different types and configurations are identified with major design factors being discussed. © Leicester College 2009. This work is licensed under a Creative Commons Attribution 2.0 License. Flexbile Manufacturing Systems
  2. 2.  Model Variations Contents  Requirements for Unattended Operation for Single and Batch...  Requirements for Mixed Model Case – Flexible Manufacturing...  Differences between implementing a manually operated mach...  Benefits that can be expected from a FMS include:  What is a FMS?  Automated Manufacturing Cell  Manufacturing flexibility:  Differences between FMC and FMS  Another classification of FMS is by its level of flexibil...  Random Order FMS  Flexibility criteria applied to dedicated FMS and random-...  Basic Components of a FMS:  Workstations  Material Handling and Storage System  FMS Layout Configurations  Credits These files support the Edexcel HN unit – Design for Manufacture (NQF L4) File Name Unit Outcome Key Words Design 1.1, 1.2,1.4 Overview, Cost, quality, reliability, assembly, guidelines forassembly FMS 2.2 Models, work cycles, volume, machine utilisation, automation, flexible, systems Geometric 3.1,3.2 Geometric, tolerance, system, symbols, orientation, BS, Tolerancing ISO, location, runout, datum Industrial Robots 2.2,2.3 Robot, industrial, robot arm, Cartesian, polar, cylindrical, jointed arm Jigs and Fixtures 2.1,2.3 Efficiency, production, jigs, fixtures, tooling, production, For further information regarding unit outcomes go to HN/ Engineering / Specifications
  3. 3. Model Variations  Single model case – One product or model is produced that is identical from one unit to the next  Batch model case – Different products or models produced in batches (Requires changeover between models) Mixed model case – Different products or models produced on same line or equipment with no changeovers between models
  4. 4. Requirements for Unattended Operation for Single and Batch Model Cases o Programmed work cycle o Parts storage subsystem o Automatic transfer of workpieces between storage subsystem and production machine o Periodic attention of worker
  5. 5. Requirements for Unattended Operation for Single and Batch Model Cases o Resupply and removal of workpieces, tool changes, minor repairs, maintenance o Built-in safeguards to protect the system itself and the work units processed by the system
  6. 6. Requirements for Mixed Model Case – Flexible Manufacturing Systems (FMS)  Identification of different models o No problem for human workers o For automated system, some means of product identification is required
  7. 7. Requirements for Mixed Model Case – Flexible Manufacturing Systems (FMS)  Quick changeover of operating instructions o For automated system, change part program  Quick changeover of physical setup o Change tooling and fixtures in very short time
  8. 8. FMS technology can be applied in situations similar to those for cellular manufacturing: o Presently, the plant either (1) produces parts in batches, or (2) uses manned GT cells and management wants to automate o It must be possible to group a portion of the parts made in the plant into part families, whose similarities permit them to be processed on the machines in the flexible manufacturing system o The parts or products made by the facility are in the mid- volume, mid-variety production range. The appropriate production volume range is 5000 to 75,000 parts per year
  9. 9. Stand-alone High CNC machines Flexible Medium manufacturing systems Transfer Low lines Low Medium High Production Volume Application characteristics of flexible manufacturing systems.
  10. 10. Differences between implementing a manually operated machine cell and a flexible manufacturing system are:  The FMS requires a significantly greater capital investment because new equipment is being installed rather than existing equipment being rearranged  The FMS is technologically more sophisticated for the human resources who must make it work
  11. 11. Benefits that can be expected from a FMS include:  Increased machine utilisation  Fewer machines required  Reduction in factory floor space required  Greater responsiveness to change.
  12. 12. Benefits cont… o Reduced inventory requirements o Lower manufacturing lead times o Reduced direct labour requirements and higher labour productivity o Opportunity for unattended production
  13. 13. What is a FMS?  A flexible manufacturing system is a highly automated GT machine cell, consisting of a group of processing workstations, interconnected by an automated material handling and storage system, and controlled by a distributed computer system.  FMS is called flexible because it is capable of processing a variety of different part styles simultaneously at the various workstations, and the mix of part styles and quantities of production can be adjusted in response to changing demand patterns.
  14. 14. oA FMS relies on the principles of group technology. No manufacturing system can be completely flexible. o There are limits to the range of parts or products that can be made in a FMS. oA FMS is designed to produce parts (or products) within a defined range of styles, sizes, and processes. oIn other words, it is capable of producing a single part family or a limited range of part families. A more appropriate term for FMS would be flexible automated manufacturing system.
  15. 15. The word “automated” would distinguish this technology from other manufacturing systems that are flexible but not automated, such as a manned GT machine cell. The word “flexible” would distinguish it from other manufacturing systems that are highly automated but not flexible, such as a conventional transfer line.
  16. 16. Automated Manufacturing Cell Machine Tool Parts Carousel Robot Machine Work table
  17. 17. To qualify as being flexible, a manufacturing system should satisfy several criteria. Four reasonable tests of flexibility: 1. Part variety test. Can the system process different part styles in a non-batch mode? 2. Schedule change test. Can the system readily accept changes in production schedule: changes in either part mix or production quantities?
  18. 18. 3. Error recovery test. Can the system recover gracefully from equipment malfunctions and breakdowns, so that production is not completely disrupted? 4. New part test. Can new part designs be introduced into the existing product mix with relative ease?
  19. 19. A robotic work cell satisfies the criteria if it: o Can machine different part configurations in a mix rather than in batches; o Permits changes in production schedule and part mix;
  20. 20. Cont…. o Is capable of continuing to operate even though one machine experiences a breakdown - for example, while repairs are being made on the broken machine, its work is temporarily reassigned to the other machine; and o Allows development of new parts to be written off-line and then downloaded to the system for execution.
  21. 21. Manufacturing flexibility: Flexibility type Definition Dependant on.. Machine Capability to adapt a  Setup or changeover time. flexibility given machine  Ease of machine (workstation) in the reprogramming (ease with system to a wide which part programs can range of production be downloaded to operations and part machines). styles. The greater  Tool storage capacity of the range of machines. operations and part  Skill and versatility of styles, the greater the machine flexibility. workers in the system. Production The range or universe  Machine flexibility of flexibility
  22. 22. Mix Ability to change the product  Similarity of parts in the mix. flexibility mix while maintaining the  Relative work content times of same total production parts produced quantity; that is, producing  Machine Flexibility the same parts only in different proportions. Product Ease with which design  How closely the new part flexibility changes can be design matches the existing accommodated. Ease with part family. which new products can be  Off-line part program introduced. preparation.  Machine flexibility Routing Capacity to produce parts  Similarity of parts in the mix flexibility through alternative station  Similarity of workstations sequences in response to  Duplication of workstations equipm’t breakdowns, tool  Cross-training of manual failures, and other interruptions at individual workers. stations.  Common tooling.
  23. 23. Volume Ability to economically  Level of manual labour flexibility produce parts in high performing production. and low total quantities  Amount invested in of production, given capital equipment. the fixed investment in the system. Expansion Ease with which the  Expense of adding flexibility system can be workstations. expanded to increase  Ease with which layout total production can be expanded. quantities.  Type of part handling system used.  Ease with which properly trained workers can be added.
  24. 24. FMSs’ can be distinguished according to the number of machines. •Single machine cell - One CNC machining center combined with a parts storage system for unattended operation. •Flexible manufacturing cell - Consists of two or three processing stations plus a parts handling system connected to a load/unload station. •Flexible manufacturing system - Four or more processing workstations connected mechanically by a common parts handling system and electronically by a distributed computer system.
  25. 25. Differences between FMC and FMS  Number of machines: a FMC has two or three machines, while a FMS has four or more.  FMS generally includes non-processing workstations that support production but do not directly participate in it (e.g., part/pallet washing stations, coordinate measuring machines)  Computer control system of a FMS is generally larger and more sophisticated, often including functions not always found in a cell, such as diagnostics and tool monitoring.
  26. 26. Flexibility criteria applied to the 3 types of manufacturing cells and systems. Schedule New System type Part variety change Error recovery part Single Yes, but processing Yes Limited recovery Yes machine cell sequential, not due to only one (SMC) simultaneous machine Flexible mfg Yes, simultaneous Yes Error recovery Yes cell (FMC) production of limited by fewer different parts machines than FMS Flexible mfg Yes, simultaneous Yes Machine Yes system production of redundancy (FMS) different parts minimises effect of machine breakdowns
  27. 27. Another classification of FMS is by its level of flexibility: Dedicated FMS – Designed to produce a limited variety of part styles, and the complete universe of parts to be made on the system is known in advance.  Part family is likely to be based on product commonality rather than geometric similarity.
  28. 28. Dedicated FMS – cont… Product design is stable, so the system can be designed with a certain amount of process specialization to make the operations more efficient. • The machine sequence may be identical or nearly identical for all parts processed, and so a transfer line may be appropriate, in which the workstations possess the necessary flexibility to process the different parts in the mix (“flexible transfer line”)
  29. 29. Random Order FMS  More appropriate when the part family is large, substantial variations in part configurations, new part designs introduced into the system and engineering changes in parts currently produced, and production schedule is subject to change.  More flexible than the dedicated FMS.  General purpose machines to deal with the variations in product  More sophisticated computer control system is required.
  30. 30. Flexibility criteria applied to dedicated FMS and random-order FMS System Part variety Schedule Error New part type change recovery Dedicated Limited. All parts Limited Limited by New part FMS known in changes can sequential introduction advance. be tolerated. processes. is difficult. Random- Substantial part Frequent Machine System order variations and redundancy designed for FMS possible. significant minimizes new part changes effect of introductions possible. machine breakdowns
  31. 31. Basic Components of a FMS:  Workstations  Material handling and storage system  Computer control system  People are required to manage and operate the system.
  32. 32. Workstations  Load/Unload Stations - Physical interface: FMS and factory.  Machining Stations - Most common is the CNC machining centre.  Other Processing Stations – sheet-metal fabrication, forging.  Assembly - Industrial robots, component placement machines.  Other Stations and Equipment -inspection stations, cleaning stations, central coolant delivery and chip removal systems.
  33. 33. Material Handling and Storage System  Functions of the Handling System o Random, independent movement of workpieces between stations. o Handle a variety of workpiece configurations. o Temporary storage. o Convenient access for loading and unloading workpieces. o Compatible with computer control.
  34. 34. FMS Layout Configurations o In-line layout o Loop layout o Ladder layout o Open field layout o Robot-centered cell
  36. 36. This resource was created Leicester College and released as an open educational resource through the Open Engineering Resources project of the Higher Education Academy Engineering Subject Centre. The Open Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme. © 2009 Leicester College This work is licensed under a Creative Commons Attribution 2.0 License. The JISC logo is licensed under the terms of the Creative Commons Attribution-Non-Commercial-No Derivative Works 2.0 UK: England & Wales Licence. All reproductions must comply with the terms of that licence. The HEA logo is owned by the Higher Education Academy Limited may be freely distributed and copied for educational purposes only, provided that appropriate acknowledgement is given to the Higher Education Academy as the copyright holder and original publisher. The Leicester College name and logo is owned by the College and should not be produced without the express permission of the College. Flexbile Manufacturing Systems