Bosch Rexroth Corporation Linear Motion and Assembly ...€¦ · must seize every opportunity to increase productivity and throughput, reduce costs, increase product quality and reliability,

Bosch Rexroth CorporationCorporate Headquarters5150 Prairie Stone ParkwayHoffman Estates, IL 60192-3707Telephone (847) 645-3600Facsimile (847) 645-6201

Bosch Rexroth CorporationIndustrial Hydraulics2315 City Line RoadBethlehem, PA 18017-2131Telephone (610) 694-8300Facsimile (610) 694-8467

Bosch Rexroth CorporationElectric Drives and Controls5150 Prairie Stone ParkwayHoffman Estates, IL 60192-3707Telephone (847) 645-3600Facsimile (847) 645-6201

Bosch Rexroth CorporationPneumatics1953 Mercer RoadLexington, KY 40511-1021Telephone (859) 254-8031Facsimile (859) 281-3491

Bosch Rexroth CorporationMobile Hydraulics1700 Old Mansfield RoadWooster, OH 44691-0394Telephone (330) 263-3300Facsimile (330) 263-3333

Printed in the United States8981 500 202 2/05

IndustrialHydraulics

Electric Drivesand Controls

Linear Motion andAssembly Technologies

ServiceAutomation

MobileHydraulicsPneumatics

Bosch Rexroth CorporationLinear Motion andAssembly Technologies816 E. Third StreetBuchanan, MI 49107Telephone (269) 695-0151Facsimile (269) 695-5363www.boschrexroth-us.com

How to OptimizeYour Assembly Operations

Designing an assembly system to fit the manufacturing process

How to Optimize Your Assembly Operations

Assembly ConveyorsLinear Motion and Assembly Technologies 8981 500 202 2/05

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Bosch Rexroth Corp.2

Bosch Rexroth Corp.Linear Motion and Assembly Technologies8981 500 202 2/05 Assembly Conveyors


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0 5 10 15 20 25 30 35 40 45

New-tothe-world

MajorRevision

MinorRevision

Time to get to market in months

Type

of P

rodu

ct

2004

2004

2004

1995

1995

1995

The flexibility of your assembly operation can make the differencein your manufacturing profit

Cutting,Forming,

Machining8-30%

Assembly50-75%

Inspection4-15%

It’s tough to make a buck in manufactur-ing today. Rapid change is driving theway products are made and even theproducts themselves. Products areincreasingly complex and require moreassembly steps. But the biggestpressure comes from time, becausewhile product variations expand, productlife cycles contract (see Figure 1). Thechallenge is to get better products tomarket faster, while maintaining profitmargins and lowering manufacturingcosts. To do this, most manufacturersare staying flexible.

Today’s manufacturingoperations present bothopportunity and challenge forimprovement.

To stay ahead of the pack, manufacturersmust seize every opportunity to increaseproductivity and throughput, reducecosts, increase product quality andreliability, while managing change on analmost daily basis. Typically, the laborinvolved in producing individual compo-nents—operations such as metal cutting,forming, and machining or plasticsmolding and finishing—representsbetween 8% and 30% of total manufac-turing costs. The labor involved ininspection and testing typically repre-sents between 4% and 15%. But thelabor involved with assembly can runbetween 50% and 75% of totalmanufacturing costs (see Figure 2). Thisis clearly where the largest manufacturingcost savings can be achieved.

While assembly operations may offer thegreatest potential for increasing efficiency,they can also pose several challenges.These include:

• Reducing work-in-process (WIP)inventory (the number of piece partsand materials waiting idly for value-added assembly operations to becarried out).

• Controlling product quality: test andinspection generally take place after allassembly operations have beencompleted. Rejected assembliesneeding rework increase WIP andcancel previous value-added gains.

• Managing rapid growth: for example,when customer demand is outstrippingcurrent capacity and/or the product mixis proliferating.

Figure 1 Product Development Time Keeps Shrinking for U.S. Marketers*

Figure 2: Production LaborBiggest manufacturing efficiency gains

can come from assembly tasks

*Source: Product Development and Management Association



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While agile and lean may bethe ultimate goal for assemblyoperations, achieving that goalis seldom simple.

There are numerous variables involved indesigning the best assembly methods tomove products through a manufacturingoperation. The more complex theproduct, the more extensive the productmix—the more difficult the task. Shorterproduct life cycles also complicate thesituation. As product mix or volumeincreases, traditional material handlingmethods (i.e., the use of plywood palletsand/or roller conveyor for staging andtransferring WIP) may prove inadequateor counter-productive. Adding more ofthe same is clearly not a long-termsolution.

Additional common assembly challengesinclude:

• Numerous parts, components, and/orsubassemblies

• Assembly operations requiring precise,repeatable positioning

• Special environmental provisions suchas clean rooms, ESD (electrostaticdischarge) protection, temperaturecontrol, etc.

• Operations to accommodate modelvariations with differing lot sizes

• Products requiring up to 100%inspection

Companies successfully managing thedemands of continued, profitable growthhave recognized the need for a mecha-nized solution, i.e., conveyor systemsdesigned specifically for assemblyflexibility. Often, the best productassembly strategy requires the right mix

Old-fashioned assembly methods, like this, are both labor intensive and inefficient.

of automated and manual operations andthe ability to adjust that mix as necessary.Flexible assembly conveyors, seamlesslyintegrated into the assembly processesthey support, provide the best solutionfor today’s complex assembly conditions.



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Assembly conveyor systemsare generally classified intotwo basic types, each withdistinct characteristics:

• Synchronous conveyor systems utilizeindexed movement of parts fromstation to station, along a fixed pathand at a fixed cycle rate. Examplesinclude rotary dial machines and cam-operated, in-line machines. Shortcycle rates, standardized production,and a high level of automation arefeatures of the synchronous system.But synchronous systems also havetheir shortcomings. System through-put, for example, must be geared to theslowest operation on the assembly line.And there is no provision for cycleindependence; all parts of the produc-tion line move in “lock step.”

• Non-synchronous conveyor systemsprovide independent movement ofparts from station to station on an asneeded basis, as they become readyfor the next operation. Work can berouted independently along a flexiblepath providing the option of batchmanufacturing or custom processing allon the same line. Non-synchronoussystems can accommodate the fullrange of product sizes and weights.Moreover, there are virtually nolimitations on the number or complexityof assembly steps with non-synchro-nous systems. Manual tasks can bereadily integrated with automatedoperations because the system allowsfor varying station cycle rate. Inaddition, you can easily add buffers asneeded to balance assembly line workflow.

Conveyor systems play an increasinglyimportant role in today’s productionoperations. As production levelsincrease, for example, a company mightconsider converting from batch tosequential assembly operations orincorporating automated workstationsinto existing sequential manual lines. Thechallenge will often include the upgradeof an existing facility (retrofit) rather thancreation of an entirely new one.

Operation

A B C D

FinishedProduct

Figure 3A: Synchronous The fixed path, synchronous system does not provide for cycle independence.

Throughput depends on the slowest operation on the assembly line.

Figure 3B: Non-synchronousNon-synchronous assembly allows buffering in slower task work areas, while

maintaining continuous flow on the main production line.

Operation

FinishedProduct

A B D

C1 C2



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For increasing numbers of manufacturers,the use of non-synchronous, pallet-basedmodular conveyors is an ideal solution totheir assembly system requirements.Non-synchronous assembly conveyorstypically incorporate a continuouslymoving belt or chain with pallets andpallet components, which move with theconveyor unless held by a stop. Modularconveyor components and accessoriesease assembly and future reconfigurationor expansion as conditions warrant.

Figure 4: A typical non-synchronous, pallet-based conveyor system is made up of modular compo

Curve ModulesChange pallet direction

and maintain leading edge pallet orientation

Drive UnitPowers the belt or

chain to move pallets through the

system

Transverse Conveyor

Transfers pallets between two lines

Return UnitReturns the belt or

chain to the drive unit

Stop GatesStandard stops halt

pallet travel. Cushioned stops reduce pallet

impact force for transport of sensitive

components

Coding SystemsRead/Write pallet coding system enables proper

workpiece pallet routing to optimize manufacturing

flexibility and control

Flat-Top ChainSide-flexing flat-top chain

can be used to create serpentine, carousel, or a

combination of configurations to meet any

assembly requirement

BeltConductive for ESD

applications; polyamide belt is the most economical

transport media for general assembly requirements



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When to consider pallet-basedmodular conveyors

While some product assemblyoperations may not call for a non-synchronous, pallet-based modularconveyor system, it could be the idealsolution when:

• Multiple product models result infrequent and time-consumingproduction changeovers.

• Changes to product design andcorresponding assembly operationsare frequent.

• Product delivery lead-times areshrinking.

• Introducing automated assemblyoperations is essential to improveproductivity.

• Material flow paths must bereconfigured.

• Precision assembly tasks arerequired.

• Line balancing is a crucial element ofproduction efficiency.

• Space is at a premium.

onents

Positioning UnitProvides precise pallet

positioning for assembly operations

Lift Transfer UnitLifts and transfers the

workpiece pallet at right angles over the

conveyor section to an adjacent line

Lift Rotate Unitchanges the orientation of the workpiece pallet

by 90˚ or 180˚

Rockers and StopsDetect workpiece

pallets and also provide a stop at the end of a

Lift-Transfer Unit

Modular ConstructionUse of standard

structural components allows flexibility when

reconfiguring a system

Workpiece PalletSizes from 80 x 80 mm

to 1243 x 1243 mm

Roller ChainLow friction power and free roller chain is ideal for heavy

loads and demanding environments



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The benefits of modularitymesh with today’s assemblyenvironment.

Based on a “building block” concept,modular, non-synchronous conveyorsystems provide an unmatched level offlexibility because the conveyor compo-nents can be quickly configured toprovide required functional characteris-tics. They can be reconfigured whenproduction requirements change, andtheir availability as off-the-shelf modulescan dramatically speed project imple-mentation. System payback (ROI) isanother advantage for using non-synchronous systems. Compared toheavily automated systems, payback on aflexible assembly conveyor occurs soonerbecause:• Start-up costs are lower• There is a shorter debug time• Reuse reduces later capital investments

The flexibility of modular, non-synchro-nous, pallet-based conveyor systemsprovides a long list of benefits that meshwith today’s assembly environment.These include:

1. Phased implementation - Stand-alone assembly tasks, for example,can be moved on-line to increaseproductivity; later, manual stations canbe replaced with automated stations,as required. See Figure 5.

2. Integration of automated pro-cesses - Many factors drive the needto introduce, or increase the level ofautomated processes to the assemblyfunction. These include incorporationof new manufacturing technology,changes in product design, anincrease in product mix, the need to

Reworking stations

Automatic stations

Manual workstations

Workpiece- pallet circulation

Figure 5: Line balanceBalancing using automated/manual operations on the same assembly line.

lower unit costs, or any combinationof these. Using conveyor modules, thetask of integrating automatedprocesses such as screw driving,ultrasonic welding, or testing intowhat may have been completelymanual assembly operations canreadily be accomplished.

3. Line balance flexibility - Balancingwork load is a primary goal forassembly operations. Without theflexibility to respond effectively tochanging production requirements,the ability to maintain optimal linebalance may be seriously compro-mised. However, the line routingflexibility of modular systems allowsparallel spurs to be added forbalancing of cycle rates between slowand fast workstation tasks or therouting of reject parts off-line andreworked parts back on-line.

4. Integration of test functions - Asassembly operations become bothmore complex and efficient, test and/or inspection functions are beingincorporated as an integral part of theprocess. Retrofitting these functionsinto an existing system may poseinsurmountable obstacles unless thesystem is modular and affords theflexibility of reconfiguration.



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5. Implementation of processcontrol(s) - The ability to fit palletswith read/write devices permits eachworkpiece pallet to be uniquelyidentified. This in turn, allows thecontrol system to track the status andcontrol the movement of units throughautomated workstations and providesa way of collecting data for statisticalprocess control (SPC). Such aprocess control system allows for twoor more models of a product to beassembled on the same line andprovides for product rework asnecessary.

6. Material flow options - Material flowthrough an assembly facility can beaffected by changes in any facet ofthe assembly operations. These caninclude the replacement of manualworkstations with automated worksta-tions, a product design change thatrequires a modification to assemblyprocedures, or the introduction of newmodels. An existing modular conveyorline can easily allow material flowpatterns to be modified orreconfigured. See Figure 6.

Yesterday

Today

Tomorrow

Figure 6:Install a system that expands with your needs



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7. Reduced WIP - Reducing the level ofWIP can have a major impact onlowering assembly costs. Non-synchronous, pallet-based conveyorsystems, by their very nature, focus onkeeping work moving, not piled instacks on the production floor. Thus,a transition from batch to progressive,sequential assembly can pave the wayto reduced in-process inventoriesnecessary for Just-In-Time (JIT)manufacturing operations.

8. Improved ergonomics - There isgrowing evidence that sound ergo-nomics goes hand-in-hand withimproved productivity. The palletpositioning and orientation modulesavailable with these modular conveyorsystems are designed to reducewasted motion and fatigue of a workerby presenting the workpiece properlypositioned for the required assemblytask. Moreover, compared withalternative systems such as a rollerconveyor, these modular assemblyconveyors are basically quiet inoperation. Low ambient noise level isanother important element in theoverall ergonomic scenario.

9. Reduced footprint - The variety ofconveyor types and modules aregeared for system designs thatconserve space and accommodate awide range of production require-ments. Modular construction permitscomplete freedom in system configu-rations, including rectangular,carousel, serpentine, over/under,parallel, and in-line (see Figure 7).The ability to run multiple productmodules on a single line providesanother significant opportunity toconserve space.

10. Reusability - Like the ability toreconfigure lines, reusability is animportant consideration in anassembly system investment. Notonly do assembly operations change,but entire manufacturing facilitiesmight be moved from one site toanother. The fact that assemblyconveyor modules can be “packed upand moved” is a significant factor inreducing their life-cycle costs.

Figure 7:Modular construction allows complete freedom in system configurations

• Ideal layout for surrounding of aworkcell or robotic station

• Best layout for limited floor space

• Most self-contained system layout • Ideal for joining two production areas, orgetting around obstructions on the plant floor

For more information about optimizing as-sembly operations, write or call:

Bosch Rexroth Corporation816 East Third StreetBuchanan, MI 49107

Phone: 1-800-322-6724Fax: (269) 695-5363

• Used for point-to-point transport• Continuous circulation of pallets within asmall footprint

Rectangular Over/Under

Carousel Serpentine

Parallel In-Line



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Bosch Rexroth - The WorldBrand Leader in Flexible

Assembly Conveyor Systems

Bosch Rexroth provides the modules that make up these flexible assembly conveyorsystems. They are pre-engineered and have established an extensive track record in thefield with well-documented performance capabilities by thousands of companies worldwide.This proven performance leads to a high probability of successful system performance.Bosch Rexroth includes extensive product documentation to simplify both start-up andmaintenance operations. And when it comes to repair, the modular, standardized design ofall Rexroth components means they can be shipped quickly for replacement, resulting inminimum downtime.

System design and support is yet another benefit that Bosch Rexroth provides. Our skilledapplications engineers will work with you or your current machine-building resource toevaluate your specific needs and provide the technical support necessary to ensuresuccessful implementation. Or if you prefer, we’ll put you in touch with an experiencedsystems integrator who can help you find a turnkey solution using Bosch Rexroth compo-nents.

Why wait? Put the Bosch Rexroth advantages of improved productivity, better productquality and cost reduction to work in your manufacturing operation now.

Call 1-800-322-6724 and we’ll get you started.

Visit us on the Web: www.boschrexroth-us.com

Bosch Rexroth CorporationCorporate Headquarters5150 Prairie Stone ParkwayHoffman Estates, IL 60192-3707Telephone (847) 645-3600Facsimile (847) 645-6201

Bosch Rexroth CorporationIndustrial Hydraulics2315 City Line RoadBethlehem, PA 18017-2131Telephone (610) 694-8300Facsimile (610) 694-8467

Bosch Rexroth CorporationElectric Drives and Controls5150 Prairie Stone ParkwayHoffman Estates, IL 60192-3707Telephone (847) 645-3600Facsimile (847) 645-6201

Bosch Rexroth CorporationPneumatics1953 Mercer RoadLexington, KY 40511-1021Telephone (859) 254-8031Facsimile (859) 281-3491

Bosch Rexroth CorporationMobile Hydraulics1700 Old Mansfield RoadWooster, OH 44691-0394Telephone (330) 263-3300Facsimile (330) 263-3333

Printed in the United States8981 500 202 2/05

IndustrialHydraulics

Electric Drivesand Controls

Linear Motion andAssembly Technologies

ServiceAutomation

MobileHydraulicsPneumatics

Bosch Rexroth CorporationLinear Motion andAssembly Technologies816 E. Third StreetBuchanan, MI 49107Telephone (269) 695-0151Facsimile (269) 695-5363www.boschrexroth-us.com

How to OptimizeYour Assembly Operations

Designing an assembly system to fit the manufacturing process

Documents

Bosch Rexroth Corporation Linear Motion and Assembly ...€¦ · must seize every opportunity to increase productivity and throughput, reduce costs, increase product quality and reliability,