07 sisprod - fms

Model VariationsModel Variations

Single model caseSingle model case –– One product or model is One product or model is produced that is identical from one unit to the nextproduced that is identical from one unit to the next

Batch model caseBatch model case –– Different products or models Different products or models produced in batchesproduced in batchesproduced in batchesproduced in batches

(Requires changeover between models)(Requires changeover between models)

Mixed model caseMixed model case –– Different products or models Different products or models produced on same line or equipment with no produced on same line or equipment with no changeovers between modelschangeovers between models

Requirements for Unattended OperationRequirements for Unattended Operationfor Single and Batch Model Casesfor Single and Batch Model Cases

oo Programmed work cycleProgrammed work cycle

oo Parts storage subsystemParts storage subsystem

oo Automatic transfer of workAutomatic transfer of work--pieces between pieces between storage subsystem and production machinestorage subsystem and production machine

oo Periodic attention of workerPeriodic attention of worker

Requirements for Unattended OperationRequirements for Unattended Operationfor Single and Batch Model Casesfor Single and Batch Model Cases

oo Resupply and removal of workResupply and removal of work--pieces, tool pieces, tool changes, minor repairs, maintenancechanges, minor repairs, maintenancechanges, minor repairs, maintenancechanges, minor repairs, maintenance

oo BuiltBuilt--in safeguards to protect the system itself in safeguards to protect the system itself and the work units processed by the systemand the work units processed by the system

Requirements for Mixed Model CaseRequirements for Mixed Model Case ––Flexible Manufacturing Systems (FMS)Flexible Manufacturing Systems (FMS)

Identification of different modelsIdentification of different modelsoo No problem for human workersNo problem for human workers

oo For automated system, some means of For automated system, some means of product identification is requiredproduct identification is required

Requirements for Mixed Model CaseRequirements for Mixed Model Case ––Flexible Manufacturing Systems (FMS)Flexible Manufacturing Systems (FMS)

Quick changeover of operating instructionsQuick changeover of operating instructions

oo For automated system, change part programFor automated system, change part program

Quick changeover of physical setupQuick changeover of physical setup

oo Change tooling and fixtures in very short timeChange tooling and fixtures in very short time

o Presently, the plant either (1) produces parts in batches, or (2) uses manned GT cells and management wants to automate

FMS technology can be applied inFMS technology can be applied insituations similar to those for cellularsituations similar to those for cellularmanufacturing:manufacturing:

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

HighHigh StandStand--alonealone

CNC machinesCNC machines

MediumMediumFlexible Flexible

manufacturing manufacturing systemssystems

Transfer Transfer LowLow Transfer Transfer lineslines

LowLow MediumMedium HighHigh

Production VolumeProduction Volume

Application characteristics of flexible manufacturing systems.

Differences between implementing aDifferences between implementing amanually operated machine cell and amanually operated machine cell and aflexible manufacturing system are:flexible manufacturing system are:

The FMS requires a significantly greater capital The FMS requires a significantly greater capital investment because new equipment is being investment because new equipment is being investment because new equipment is being investment because new equipment is being installed rather than existing equipment being installed rather than existing equipment being rearrangedrearranged

The FMS is technologically more sophisticated for The FMS is technologically more sophisticated for the human resources who must make it workthe human resources who must make it work

Benefits that can be expected from a FMSBenefits that can be expected from a FMSinclude:include:

Increased machine Increased machine utilisationutilisation

Fewer machines requiredFewer machines required

Reduction in factory floor space requiredReduction in factory floor space required

Greater responsiveness to change.Greater responsiveness to change.

Benefits contBenefits cont……

oo Reduced inventory requirementsReduced inventory requirements

oo Lower manufacturing lead timesLower manufacturing lead timesoo Lower manufacturing lead timesLower manufacturing lead times

oo Reduced direct Reduced direct labourlabour requirements and higher requirements and higher labourlabour productivityproductivity

oo Opportunity for unattended production Opportunity for unattended production

What is a FMS?What is a FMS?

A A flexible manufacturing systemflexible manufacturing system is a highly is a highly automated GT machine cell, consisting of a group of automated GT machine cell, consisting of a group of processing workstations, interconnected by an processing workstations, interconnected by an automated material handling and storage system, automated material handling and storage system, and controlled by a distributed computer system. and controlled by a distributed computer system.

FMS is called FMS is called flexibleflexible because it is capable of because it is capable of FMS is called FMS is called flexibleflexible because it is capable of because it is capable of processing a variety of different part styles processing a variety of different part styles simultaneously at the various workstations, and the simultaneously at the various workstations, and the mix of part styles and quantities of production can be mix of part styles and quantities of production can be adjusted in response to changing demand patterns. adjusted in response to changing demand patterns.

A FMS relies on the principles of group technology. No manufacturing system can be completely flexible.

There are limits to the range of parts or products that can be made in a FMS.

A FMS is designed to produce parts (or products) within a defined range of styles, sizes, and processes.within a defined range of styles, sizes, and processes.

In 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 flexible automated manufacturing systemautomated manufacturing system. .

The word “automated”“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”“flexible” would distinguish it from other manufacturing systems that are highly automated but not flexible, such as a conventional transfer line.

Automated Manufacturing CellAutomated Manufacturing Cell

Machine Tool

Parts Carousel

Machine Work table

Parts CarouselRobot

1. Part variety test. Can the system process different

To qualify as being flexible, a manufacturingTo qualify as being flexible, a manufacturingsystem should satisfy several criteria.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?

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 introduced into the existing product mix with relative ease?

o Can machine different part configurations in a mix rather than in batches;

o Permits changes in production schedule and part

A robotic work cell satisfies the criteria if it:A robotic work cell satisfies the criteria if it:

o Permits changes in production schedule and part mix;

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

Cont….Cont….

to the other machine; and

o Allows development of new parts to be written off-line and then downloaded to the system for execution.

Manufacturing flexibility:Manufacturing flexibility:Flexibility Flexibility

typetype DefinitionDefinition Dependant on..Dependant on..

Machine Machine flexibilityflexibility

Capability to adapt a given Capability to adapt a given machine (workstation) in machine (workstation) in the system to a wide the system to a wide range of production range of production operations and part styles. operations and part styles. The greater the range of The greater the range of

Setup or changeover time.Setup or changeover time.

Ease of machine reprogramming Ease of machine reprogramming (ease with which part programs (ease with which part programs can be downloaded to can be downloaded to machines).machines).

The greater the range of The greater the range of operations and part styles, operations and part styles, the greater the machine the greater the machine flexibility.flexibility.

machines).machines).

Tool storage capacity of Tool storage capacity of machines.machines.

Skill and versatility of workers in Skill and versatility of workers in the system.the system.

Production Production flexibilityflexibility

The range or universe of The range or universe of part styles that can be part styles that can be produced on the system.produced on the system.

Machine flexibility of individual Machine flexibility of individual stations.stations.

Range of machine flexibilities of Range of machine flexibilities of all stations in the system.all stations in the system.

Mix Mix flexibilityflexibility

Ability to change the product Ability to change the product mix while maintaining the mix while maintaining the same total production same total production quantity; that is, producing quantity; that is, producing the same parts only in the same parts only in different proportions.different proportions.

Similarity of parts in the mix.Similarity of parts in the mix.

Relative work content times of Relative work content times of parts producedparts produced

Machine FlexibilityMachine Flexibility

Product Product flexibility flexibility

Ease with which design Ease with which design changes can be changes can be accommodated. Ease with accommodated. Ease with which new products can be which new products can be

How closely the new part How closely the new part design matches the existing design matches the existing part family.part family.

OffOff--line part program line part program which new products can be which new products can be introduced.introduced.

OffOff--line part program line part program preparation.preparation.

Machine flexibilityMachine flexibility

Routing Routing flexibilityflexibility

Capacity to produce parts Capacity to produce parts through alternative station through alternative station sequences in response to sequences in response to equipm’t breakdowns, tool equipm’t breakdowns, tool failures, and other failures, and other interruptions at individual interruptions at individual stations.stations.

Similarity of parts in the mixSimilarity of parts in the mix

Similarity of workstationsSimilarity of workstations

Duplication of workstationsDuplication of workstations

CrossCross--training of manual training of manual workers.workers.

Common tooling.Common tooling.

Volume Volume flexibilityflexibility

Ability to economically Ability to economically produce parts in high and produce parts in high and low total quantities of low total quantities of production, given the fixed production, given the fixed investment in the system.investment in the system.

Level of manual labour Level of manual labour performing production.performing production.

Amount invested in capital Amount invested in capital equipment.equipment.

Expansion Expansion flexibilityflexibility

Ease with which the Ease with which the system can be expanded to system can be expanded to increase total production increase total production quantities.quantities.

Expense of adding Expense of adding workstations.workstations.

Ease with which layout can be Ease with which layout can be expanded.expanded.expanded.expanded.

Type of part handling system Type of part handling system used.used.

Ease with which properly Ease with which properly trained workers can be added.trained workers can be added.

FMSs’ can be distinguished according to theFMSs’ can be distinguished according to thenumber of machines.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.

Differences between FMC and FMSDifferences between FMC and FMS

Number of machines: a FMC has two or three Number of machines: a FMC has two or three machines, while a FMS has four or more.machines, while a FMS has four or more.

FMS generally includes nonFMS generally includes non--processing processing workstations that support production but do not workstations that support production but do not workstations that support production but do not workstations that support production but do not directly participate in it (e.g., part/pallet washing directly participate in it (e.g., part/pallet washing stations, coordinate measuring machines)stations, coordinate measuring machines)

Computer control system of a FMS is generally Computer control system of a FMS is generally larger and more sophisticated, often including larger and more sophisticated, often including functions not always found in a cell, such as functions not always found in a cell, such as diagnostics and tool monitoring. diagnostics and tool monitoring.

Flexibility criteria applied to the 3 types ofFlexibility criteria applied to the 3 types ofmanufacturing cells and systems.manufacturing cells and systems.

System typeSystem type Part varietyPart varietySchedule Schedule changechange Error recoveryError recovery

New New partpart

Single Single machine cell machine cell (SMC)(SMC)

Yes, but processing Yes, but processing sequential, not sequential, not simultaneoussimultaneous

YesYes Limited recovery Limited recovery due to only one due to only one machinemachine

YesYes

Flexible mfg Flexible mfg cell (FMC)cell (FMC)

Yes, simultaneous Yes, simultaneous production of production of different partsdifferent parts

YesYes Error recovery Error recovery limited by fewer limited by fewer machines than machines than FMSFMS

YesYes

Flexible mfg Flexible mfg system system (FMS)(FMS)

Yes, simultaneous Yes, simultaneous production of production of different partsdifferent parts

YesYes Machine Machine redundancy redundancy minimises effect minimises effect of machine of machine breakdownsbreakdowns

YesYes

Another classification of FMS is by its levelAnother classification of FMS is by its levelof flexibility: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 Part family is likely to be based on product commonality rather than geometric similarity.commonality rather than geometric similarity.

made on the system is known in advance.

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 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”)

Random Order FMSRandom Order FMS

More appropriate when the part family is large, More appropriate when the part family is large, substantial variations in part configurations, new substantial variations in part configurations, new part designs introduced into the system and part designs introduced into the system and engineering changes in parts currently produced, engineering changes in parts currently produced, and production schedule is subject to change.and production schedule is subject to change.and production schedule is subject to change.and production schedule is subject to change.

More flexible than the dedicated FMS. More flexible than the dedicated FMS.

General purpose machines to deal with the General purpose machines to deal with the variations in productvariations in product

More sophisticated computer control system is More sophisticated computer control system is required.required.

Flexibility criteria applied to dedicated FMSFlexibility criteria applied to dedicated FMSand randomand random--order FMSorder FMS

System System typetype

Part varietyPart variety Schedule Schedule changechange

Error Error recoveryrecovery

New partNew part

Dedicated Dedicated FMSFMS

Limited. All parts Limited. All parts known in known in

Limited Limited changes can changes can

Limited by Limited by sequential sequential

New part New part introduction introduction FMSFMS known in known in

advance.advance.changes can changes can be tolerated.be tolerated.

sequential sequential processes.processes.

introduction introduction is difficult.is difficult.

RandomRandom--order order FMSFMS

Substantial part Substantial part variations variations possible.possible.

Frequent Frequent and and significant significant changes changes possible.possible.

Machine Machine redundancy redundancy minimizes minimizes effect of effect of machine machine breakdownsbreakdowns

System System designed for designed for new part new part introductionsintroductions

Basic Components of a FMS:Basic Components of a FMS:

WorkstationsWorkstations

Material handling and storage systemMaterial handling and storage system

Computer control systemComputer control system

People are required to manage and operate People are required to manage and operate the system.the system.

WorkstationsWorkstations

Load/Unload StationsLoad/Unload Stations -- Physical interface: FMS and Physical interface: FMS and factory.factory.

Machining StationsMachining Stations -- Most common is the Most common is the CNC CNC machining centremachining centre..

Other Processing StationsOther Processing Stations –– sheetsheet--metal fabrication, metal fabrication, Other Processing StationsOther Processing Stations –– sheetsheet--metal fabrication, metal fabrication, forging. forging.

AssemblyAssembly -- Industrial robots, component placement Industrial robots, component placement machines.machines.

Other Stations and EquipmentOther Stations and Equipment --inspection stations, inspection stations, cleaning stations, central coolant delivery and chip cleaning stations, central coolant delivery and chip removal systems.removal systems.

Material Handling and Storage SystemMaterial Handling and Storage System

Functions of the Handling SystemFunctions of the Handling System

oo Random, independent movement of Random, independent movement of workpiecesworkpiecesbetween stations.between stations.

oo Handle a variety of Handle a variety of workpieceworkpiece configurations.configurations.

Temporary storage.Temporary storage.oo Temporary storage.Temporary storage.

oo Convenient access for loading and unloading Convenient access for loading and unloading workpiecesworkpieces..

oo Compatible with computer controlCompatible with computer control..

FMS Layout ConfigurationsFMS Layout Configurations

oo InIn--line layoutline layout

oo Loop layoutLoop layout

Ladder layoutLadder layoutoo Ladder layoutLadder layout

oo Open field layoutOpen field layout

oo RobotRobot--centered cellcentered cell

FLEXIBLE MANUFACTURINGFLEXIBLE MANUFACTURINGSYSTEMS (FMS)SYSTEMS (FMS)SYSTEMS (FMS)SYSTEMS (FMS)

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.

Flexbile Manufacturing SystemsFlexbile Manufacturing Systems

Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.

© 2009 Leicester College

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07 sisprod - fms

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