Ergonomic Design of Small Containers Using the Quality Function Deployment (QFD)

7/27/2019 Ergonomic Design of Small Containers Using the Quality Function Deployment (QFD)

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Ergonomic design of small containers using theQuality Function Deployment (QFD)

V. Guedez*, P. Mondelo**, A. Hernand ez**, L. Mosqu era**.

*Departamento de Tecnología y DiseñoUniversidad de los Andes (ULA)

Facultad de Ingeniería Avenida Tulio Febres Cordero

Mérida- Venezuela+34-934011758

[email protected]

**Departamento de Organización de EmpresasUniversidad Politécnica de Cataluña (UPC)

Avenida Diagonal 647, piso 108028 Barcelona-Spain

[email protected]; [email protected]; [email protected]

Abstract:

The aim of this paper is to improve the ergonomic design of containers that will be used inflexible manufacturing systems (FMS).Manny times, the flexible manufacturing system needs to produce few pieces and very differentbetween them . In this case FMS can not work totally automatic, then it needs persons to loadand unload the main machine. In this case it is necesary to improve the interface between themachine and the persons.

The QFD method is very helpfull to analyse the customers desires and to generate highquality and competitive ergonomic products and processes.It is posible to link the desires with solutions along an ergonomics projet to get the desiredergonomic design.

1.Introduction

The concept of Quality Function Deployment (QFD), was introduced in Japan by Yoji Akao in1966. It was not translated into English until 1994 (Mizuno and Akao, 1994).According to Akao(1990), QFD "is a method for developing a design quality aimed at satisfying the consumer andthen translating the consumer's demand into design targets and major quality assurance pointsto be used throughout the production phase." As a very important side benefit, Akao (1990)points out that, when appropriately applied, QFD has demonstrated the reduction of

development time by one-half to one-third. QFD is a very important piece to improvement thequality and ergonomics requirements (Streckfuss 2000).

A quality characteristic is measurable as an atrtibute by which one can measure whether acustomer is getting the demanded quality ( Dean E. B. 2000). Quality characteristics are definedthrough the brainstorming of the group that are involved in the projet.

2. How work the quality function deployment (QFD)

The QFD method, needs a developing matrix to show how the method works. It is very helpfulwhen the parameter number is very high and the design and ergonomics performances aredifferent. The matrix contains entries for user’s requirements and design parameters. The list of client requirements, receives the name of “What`s”. Not all requirements are equally importan t.User requirements have numerical values indicating the importance of a certain requirement. Ituses a scale between 1 and 5 to prioritise the importance of the requirements. The following

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matrix show the fourteen most important requirements, for containers that will be used in flexiblemanufacturing (Table 1).

User Requirements What`s

1 Durable and robust grip 4

2 Must be a small container 5

3 Can be used equally well with the right and the left hand 4

4 Container is light to carry 5

5 Container can be used with gloves 4

6 Wheel lock mechanism is easy to use 3

7 Container does not cause any pinching, stubbing, cutting hazards 3

8 Good visibility over the container 3

9 Durable lock mechanism for wheels 3

10 Container is easy to maintain 2

11 Good appearance 3

12 Material needs to be resistant 3

13 Good environmental resistance 2

14 Must be palletizable (stack up) 4

The next matrix which the QFD contains is the „How‟ matrix. This is the solution, how it ispossible to answer the what`s matrix. It is very frequent that each what needs an specific how,in some cases it is necessary to develop a quality function to assure that all objectives arealmost covered.(Zaïdi 1993).The following matrix shows the “how‟s” for ergonomics design of containers (Table 2).

Performarces, solutions, ( How )

Antropom. Biomecanics Fiability

Dimentional Postural analisys Lifting analisys Machine performarces

Container adjustable

DimensionPerson/Machine

Linevelocity

Equipmentand tools in

surroundings

piecesweightmorethan3 kg

repetitiveload ( 3min or less).

HandInterface

Visualpossibility

designmaterial

selection

Handpoweredcontainer

The next matrix is the correlation between the whats and How’s-list. In this matrix it is

necessary to prioritise with the following sign-scale: Strong positive + 9 () , positive +3 (),

lightly positive 1( ), empty box 0.



The next matrix is the customers analysis field, it show the requirement impacts in the right sideof diagram. These results show which are the most important requirements.In the down side of the matrix, it shows the technical analysis field with the results about thedifficulties to obtain the how‟s . (Table 3)

Table 3: Flexible and ergonomic design of small conteiner using QFD

3. Flexible design of small containers



The studied alternatives to design ergonomics containers are oriented principally to improve thequality of the work from the human point of view, but also considers to cover with success theprocesses of building and it’s production system to assure the competivity of the product. Thefundamental principles that should guide the improvement of the processes were summarisedby Ishiwata Junichi (2000) in the following way.

1- 1- Delete processes if possible2- 2- Simplify them3- 3- Combine them4- 4- Change their sequence

Also remember the four aims of the improvements:

1- 1- Do the work easier and more ergonomic2- 2- Improve the product or service (improve of the quality)3- 3- Work in less time (reduce periods)4- 4- Reduce costs

The aportations of this paper allows the elimination of processes related to feeding andunload of pieces in FMS(flexible manufacturing system). In the cases in which the number of pieces to build is very low and variated , is necessary to use a small container to carrythe pieces. The obtained improvements have speciall impacts to work easier and moreergonomically, although improve of the other three items listed above.

The use of a container oriented to manipulate a family of pieces determined by humancapacities and limited by the geometrics of the machine. It also has advantages from aprocessing point of view because it can be designed with a low weight, volume and better possibility of transport.

In the new filosofies of flexible production is very important that the containers are small andeasy to carry, but it is better not to use them, but they are needed when the size of the lot is

small and the pieces are variated.

Harmon & Peterson (1994) present the advantages of the reduction of the size of thecontainer due to the reduction of pieces in the line production and the waste of time andunnecessary movement. “The use of small containers placed at the height of the machine,increase their use and reduce the fatigue of the worker”.

4. Evaluation of ergonomic small containers

In order to obtain values about the importance of user requirements, an interview involvingvoluntary subjects was conducted.

The group contained 30 persons that used the containers and worked around the FMS.Twenty persons were male and ten was female; this was the group which worked togheter infour manufacturing flexible cells to produce metallic hydraulic cylinders.

First the tables were filled with the anthropometric data to compare the persons’ dimensionswith the container and machine dimensions (Guédez 1999).

Then, each person was asked to use each container loaded, as on every day use, and after thesubjects answer a questionnaire ( Haapalainen, Kivistö- Rahnasto ,Mattila 2000).It is necessary to interview each person separately, each person was asked which was the bestcontainer tried. The subjects had to answer to a given statement, on preliminary user requirements indicating which was the best container .The answer was indicated on a 5 pointscale (Table 4)



Prototype C : Inclined and Flexible Container

Table 4: Container evaluation for users

Container Model Evaluation

A. Horizontal and rigid 1

B. Inclined and rigid 3

C. Inclined and flexible 5

The users and technicians found that the adjustable container are the best solution. Thisprototype C is more flexible and ergonomic than prototypes B and A.

5. Discussion

The QFD for container shows that the most important target for the production workers isrequirement number 2: “must be a small a container”. The flexibility is the most importantrequirement for the customer.The next requirement is “durable and robust grip”. This shows that safety is very important for expert workers in FMS production.Ranking third in order of importance is the requirement “ container is light to carry” and “can beused equally well with the right and the left hand”. It show that the ergonomic requirements inflexible production are very important.Then comes the requirement “must be palletizable ( stack up)” and “ mate rial need to beresistant”; these are design parameter very useful to help with load manipulation, security and

to prevent musculoeskeletical disorders.The next graphic shows the ranking of the remaining items.



6. Conclusions

Container C is the best option for the users, as shown by this QFD featuring ergonomicrequirements.The QFD is useful for container design in a flexible manufacturing systems and shows that the

users want a safe small container, with wheels in order to be easily carried and with palletpossibilities.

The QFD enables to know which are the most important requirements for the users and whichneed to be included in the final product.

References

[1] Akao, Y., ed. (1990). Quality Function Deployment : Integrating customer requirements intoproduct design. Productivity Press, Cambridge MA

[2] E.B. Dean. Quality Function Deployment From the perspective of of competitive advantage ,published in Internet, address http:// mijuno.larc.nasa.gov/dfc/qfd.html

[3] E.B. Dean. Quality Function Deployment for Large System, published in Internet, address

http:// mijuno.larc.nasa.gov/dfc/qfd.html

[4] Haapalainen, M; Kivistö- Rahnasto J and Mattila M. 1999-2000. “Ergonomic design of non- powered hand tools: An application of quality function deployment (QFD)” . OccupationalErgonomics 2 (3) 1999-2000 179-189. IOS Press. Tampere. Finland

[5] Harmon & Peterson (1994). “ Reinventar la Fábrica ( Reinventing the Factory )” . AndersenConsulting. Editorial Limusa, Noriega Editores. México.



[6] Huge y Anderson .(1988). “ Paradigma de la Excelencia en Fabricación” . Dow Jones-Irwin.Gráficas Dehon. Madrid. España

[7] Ishiwata J.( 2000). “Productividad a través del Análisis de Procesos”.Productivity Press.Pórtland, Oregon. TGP Hoshin. Madrid. España

[8] Mizuno, S. and Y. Akao, ed. (1994). “QFD: The Customer-Driven Approach to Quality Planning and Development ,” Asian Productivity Organization, Tokyo, Japan, available fromQuality Resources, One Water Street, White Plains NY.

[9] Guédez T, V (1999). “QFD for FMS”. Centro CIM-UPC. Barcelona. Spain

[10] Guédez T, V (2000 ).“QFD: Análisis y Propuestas de Mejor as en Centros de torneado y Mecanizado”. Centro CIM-UPC. Barcelona. Spain

[12] Streckfuss, G. ( 2000). What ist Quality Function Deployment (QFD)?.Published in Internet,address http://www.qfd-id.de/qfdwasis.html

[13] Zaïdi A. (1993). “QFD”. Ediciones Díaz de Santos. Madrid. España

http://www.qfd-id.de/qfdwasis.html




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Ergonomic Design of Small Containers Using the Quality Function Deployment (QFD)