Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 UDK - UDC 005.6 Pregledni znanstveni članek - Preview scientific paper (1.02) Izboljšanje kakovosti - krog PDCA v primerjavi z DMAIC in DFSS Quality Improvement - PDCA Cycle vs. DMAIC and DFSS Mirko Sokovič1 - Duško Pavletič2 ('Fakulteta za strojništvo, Ljubljana; 2Tehnična fakulteta na Rijeki, Hrvaška) Za doseganje stalnih izboljšav kakovosti vsaka organizacija potrebuje ustrezno izbiro orodij in tehnik Osnovne zahteve za uspeh v teh prizadevanjih so popolno razumevanje tako orodij in tehnik kakor tudi postopka, v katerem naj bi bili uporabljeni. Prispevek prinaša pregled in področja uporabe kroga PDCA, Šest Sigma in tehnik DFSS za stalno izboljšanje kakovosti izdelkov, postopkov in storitev. Krog PDCA je enostaven za razumevanje zasnove stalnih izboljšav kakovosti, Šest Sigma metodologija DMAIC je sistematičen pristop k vodenju projekta na osnovi dejstev, metoda DFSS pa je sistematični pristop k načrtovanju izdelka ali postopka, ki vključuje vse funkcije organizacije. © 2007 Strojniški vestnik. Vse pravice pridržane. (Ključne besede: kakvost izdelkov, izboljšanje kakovosti, krog PDCA , DMAIC metoda, Šest Sigma, DFSS) To achieve continuous quality improvements every organization needs to use an appropriate selection of tools and techniques. The fundamental requirements for success are a clear understanding, both of the tools and techniques as well as the process by which they should be applied. In this paper we provide an overview and the fields of application of the PDCA, Six Sigma and DFSS techniques for the continuous quality improvement of products, processes and services. The PDCA cycle is a simple-to-understand concept of continuous quality improvement; the Six Sigma DMAIC methodology is a systematic and fact-based project-management approach; while DFSS methodology is a systematic approach to product or process design that includes all organization functions. © 2007 Journal of Mechanical Engineering. All rights reserved. (Keywords: product quality, quality improvement, PDCA cycle, DMAIC, Six Sigma, DFSS) 0 UVOD 0 INTRODUCTION Metodologija uvajanja upravljanja kakovosti in programa stalnega izboljšanja kakovosti je lahko različna. Program bo imel verjetno različno ime ali oznako, npr. TQM (Celovito obvladovanje kakovosti), Šest Sigma, BPR (Re-inženiring poslovnega postopka) ali proizvodna odličnost. Ne glede na metodologijo ali ime programa stalnih izboljšav bo vsaka organizacija verjetno potrebovala izbiro orodij in tehnik v svojem postopku izvajanja. Večina izmed teh orodij in tehnik je preprosta za razumevanje in bo lahko uporabna za večino ljudi v podjetju (npr. PDCA- ali Demingov krog). Vendar pa je nekaj tehnik na tem področju bolj zapletenih (Šest Sigma, Vitka Sigma ali načrtovanje za Šest Sigma - DFSS). Specialisti za reševanje specifičnih problemov uporabljajo prav te napredne tehnike. Zelo The methodology for implementing quality management and programmes for continuous quality improvement can be varied. The programme is likely to have a different name or label, such as TQM (Total Quality Management), Six Sigma, BPR (Business Process Reengineering) or Operational Excellence. Regardless of the methodology or the name of the continuous improvement programmes, each organization will certainly need to use a selection of tools and techniques in its implementation process. Most of these tools and techniques are simple to understand and can be used by a large number of people in the company, e.g., the PDCA cycle or Deming’s circle. However, some techniques in this area are more complex, e.g., Six Sigma, Lean Sigma, and Design for Six Sigma. Specialists for specific problem-solving applications use these advanced techniques. It is very important that tools and techniques should be 369 Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 pomembno je, da so orodja in tehnike izbrani od ustrezne skupine ter pravilno uporabljeni v ustreznem postopku. Osnovni pogoji za uspeh pri tej nalogi so popolno razumevanje samih orodij in tehnik ter postopka, v katerem bi lahko bili ti uporabljeni. Namen tega prispevka je seznaniti bralca z značilnostmi orodja PDCA in tehnik Šest Sigma in DFSS, ki jih je mogoče uporabiti za izboljšanje kakovosti izdelkov, postopkov in storitev. 1 KROG PDCA 1.1 Definicija V osrednjem postopku se rezultati dejavnosti primerjajo s ciljem ali nastavitveno točko. Razlika med obema vrednostma se potem vzame za popravne ukrepe, če ta razlika postaja prevelika. Ponavljajoča se in nepretrgana narava stalnih izboljšav sledi tej običajni definiciji upravljanja in je predstavljena s PDCA-krogom (načrtuj-naredi-preveri-ukrepaj) [l]. Pogosto se tudi omenja kot Demingov krog, imenovan po W.E. Demingu. Naslednja mogoča inačica PDCA je PDSA (načrtuj-naredi-študiraj-ukrepaj) [2]. 1.2 Uporaba Uporaba Kroga PDCA se je pokazala bolj učinkovita kot uporaba postopka “naredi prav prvič". Uporaba Kroga PDCA pomeni nenehno iskanje učinkovitejših metod izboljšanja. PDCA je učinkovit na obeh področjih: pri opravljanju dela in vodenju programa. Omogoča dva tipa popravnih ukrepov - začasne in trajne. Začasni ukrep se doseže kot rezultat praktične obravnave in poprave napake. Po drugi strani pa trajni popravni ukrep sestoji iz raziskave in odprave glavnega vzroka - cilj je vzdrževanje tako izboljšanega postopka. Vidiki kroga PDCA, ki so uporabljeni za njegove notranje postopke zagotavljanja kakovosti: o Kaj bomo poskusili izpolniti? o Kako bomo vedeli, da je sprememba izboljšanje? o Katere spremembe lahko naredimo za izboljšanje? Slika 1 podrobno prikazuje krog PDCA ([3] in [4]). 370 selected for the appropriate team and applied correctly to the appropriate process. The fundamental requirements for success in this task are a clear understanding, both of the tools and techniques themselves and the process by which they can be applied. The purpose of this paper is to introduce the reader to the characteristics of the PDCA tool and Six Sigma and DFSS techniques, which are possible to use for the quality improvement of products, processes and services. 1 THE PDCA CYCLE 1.1 Definition In a central process, the actual results of an action are compared with a target or a set point. The difference between the two is then mentioned and corrective measures are adopted if the disparity becomes large. The repeated and continuous nature of continuous improvement follows this usual definition of control and is represented by the PDCA (Plan-Do-Check-Act) cycle [1]. This is also referred to as the Deming circle, named after W. E. Deming. Another variation of PDCA is PDSA (Plan, Do, Study, Act) [2]. 1.2 Application The application of the PDCA cycle has been found more effective than adopting “the right first time” approach. Using the PDCA cycle means continuously looking for better methods of improvement. The PDCA cycle is effective in both doing a job and managing a programme. The PDCA cycle enables two types of corrective action – temporary and permanent. The temporary action is aimed at results by practically tackling and fixing the problem. The permanent corrective action, on the other hand, consists of investigation and eliminating the root causes and thus targets the sustainability of the improved process. The aspects of the PDCA cycle were applied to internal quality-assurance procedures: o What are we trying to accomplish? o How will we know that a change is an improvement? o What changes can we make to improve? Figure 1 shows the PDCA cycle in detail ([3] and [4]). Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 Ukrepaj / Act Upravljanje neskladnosti / Managing Nonconformity Izboljševanje / Improvement Certifikat ISO 9001 / ISO 9001 Certification Kulturni in organizacijski vidiki / Cultural and Organizational Aspects Celovito obvladovanje kakvosti / Total Quality Management Sistem upravljanja z okoljem / Environmental Management Systems Povezovanje sistema upravljanja / Management System Integration Načrtuj / Plan • Zamisel kakovosti in cilji / The Quality Concept and Objectives • Upoštevaj predpise / Statutory Considerations • Funkcija in varnost izdelka / Product Liability and Product Safety • Usposabljanje za kakovost / Training for Quality • Nadzor načrtovanja / The Control of Design Preveri / Check Uvod v statistiko / An Introduction to Statistics Kontrolne karte / Control Charts Pregled, kontrola / Inspection Funkcionalno preizkušanje / Functional Testing Oprema za kontrolo in merjenje / Inspection and Measurement Equipment Meroslovje / Metrology Presoja kakovosti in pregledi / Quality Audits and Reviews Stroški povezani s kakovostjo in varnostjo / Quality- and Safety-related Costs Primerjanje z najboljšimi / Benchmarking Naredi / Do • Nabava / Procurement • Dobava ravno ob pravem času / Just-in-Time Supplies • Zmogljivost procesa / Process Capability • Zanesljivost izdelka / Product Reliability • Strega materiala / Materials Handling • Servisiranje / Servicing • Kakovost storitev / Service Quality • Dokumentacija in zapisi / Documentations and Records • Nadziranje sprememb / Controlling Changes • Standardi, standardizacija, skladnost, harmonizacija / Standards, Standardization, Conformity and Compatibility Sl. 1. Krog PDCA Fig. 1. PDCA cycle -Z^ Načrtuj . Plan I \«\ü SI. 2. Napredni krog PDCA [5] Fig. 2. Advanced PDCA cycle [5] V fazi naredi je mogoče vključiti manjši Krog PDCA (slika 2), dokler se problemi pri izvajanju ne razrešijo [5]. PDCA je več kakor samo orodje; je zasnova stalnega izboljšanja postopkov (si. 3), ki je vgrajena v kulturo organizacije (podjetja). Najpomembnejši vidik PDCA leži v fazi ukrepaj po izpolnitvi projekta, ko celotni krog ponovno zaženemo za naslednje izboljšanje. Krog PDCA prav tako lahko uporabimo znotraj zasnove Kaizen (si. 4). V tem primeru govorimo o SDCA (standardiziraj, naredi, preveri, ukrepaj) in krogih PDCA [6]. Q SI. 3. Krog PDCA v procesu stalnih izboljšav Fig. 3. PDCA cycle in continuous improvement process In the Do stage or implementation stage it is possible to involve a mini-PDCA cycle (Fig. 2) until the issues of implementation are resolved [5]. The PDCA cycle is more than just a tool; it is a concept of continuous improvement processes (Fig. 3) embedded in the organization’s culture. The most important aspect of PDCA lies in the “act” stage after the completion of a project when the cycle starts again for the further improvement. The PDCA cycle is also possible to use within the Kaizen concept, Figure 4. In this case we are talking about the SDCA-PDCA cycle [6]. Izboljšanje kakovosti - Quality Improvement 371 Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 c d7 PDCA - načrtuj, naredi, preveri, ukrepaj SDCA - standardiziraj, naredi, preveri, ukrepaj Čas / Time SI. 4. Krogi SDCA - PDCA za izboljševanje kakovosti v zasnovi Kaizen Fig. 4. SDCA-PDCA cycles for quality improvement in the Kaizen concept PDCA DMAIC (Six Sigma) DMADV (DFSS) Načrtuj Plan Naredi Do Preveri Check Ukrepaj Act j\ Definiraj Define Meri Measure Analiziraj Analyse Izboljšaj Improve Nadzoruj Control Definiraj Define Meri Measure Analiziraj Analyse Načrtuj Design Verifi ciraj Ve r ify Doba trajanja projekta Project life cycle Definiraj Define Organiziraj Organize Izvedi Implement Zaključi ' Closure SI. 5. Krog PDCA nasproti DMAIC (Šest Sigma), DMADV (DFSS) in Dobi trajanja projekta (PLC) Fig. 5. The PDCA cycle vs. DMAIC (Six Sigma), DMADV (DFSS) and the Product Life-Cycle (PLC) Medtem ko se Demingov Krog PDCA na veliko uporablja v razvoju in pri razširjanju politike kakovosti, sta DMAIC (Šest Sigma) in DMADV (DFSS) dodali natančnost dobi trajanja projekta (PLC) pri uvajanju in sklenitvi Šest Sigma projektov. Slika 5 kaže zvezo med PDCA-krogom, DMAIC, DMADV in tipično dobo trajanja projekta (PLC) ([1] in [2]). While Deming’s PDCA cycle has been extensively used in the development and deployment of quality policies, DMAIC (Six Sigma) and DMADV (DFSS) have added the rigour of a project life-cycle (PLC) to the implementation and close-out of Six Sigma projects. Figure 5 shows the relationship between the PDCA cycle, DMAIC, DMADV and a typical project life-cycle ([1] and [2]). 2 DMAIC 2 DMAIC 2.1 Definicija 2.1 Definition DMAIC izkorišča zasnovo s podatki upravljane dobe trajanja Šest Sigma projektov za izboljšanje postopka in je bistven del programa Šest Sigma v podjetju. DMAIC je kratica za pet medsebojno povezanih faz: definiraj, meri, analiziraj, izboljšaj in krmili (nadziraj). Preproste definicije posameznih faz so [1]: DMAIC (Define, Measure, Analyse, Improve, and Control) refers to a data-driven life-cycle approach to Six Sigma projects for improving processes; it is an essential part of a company’s Six Sigma programme. DMAIC is an acronym for five interconnected phases: define, measure, analyse, improve and control. The simplified definitions of each phase are [1]: 372 Sokovič M. - Pavletič D. Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 o Definiraj pravi projekt z razpoznavo, prednostjo in izbiro. o Meri ključne značilke postopka, pomembnost parametrov in njihovo izvajanje. o Analiziraj postopek z določevanjem ključnih vzrokov in določb postopka. o Izboljšaj postopek z njegovim spreminjanjem in optimiranjem izvajanja. o Krmili postopek pri trajnostnih ciljih. Define by identifying, prioritizing and selecting the right project, Measure key process characteristic, the scope of parameters and their performances, Analyse by identifying key causes and process determinants, Improve by changing the process and optimizing performance, Control by sustaining the gain. 2.2 Uporaba Orodji Šest Sigma in Proizvodna odličnost se uporabljata najbolj pogosto znotraj okvira DMAIC, ki pa je integralni del pobude Šest Sigma. DMAIC se tudi uporablja za oblikovanje “zaprtih postopkov” za nadzor projekta. Merila za posamezne faze so definirana, in če so ti pri posamezni fazi projekta doseženi, se lahko začne izvajanje naslednje faze, kakor to prikazuje slika 6 ([l] in [7]). 2.2 Application The tools of Six Sigma and operational excellence are most often applied within the framework of DMAIC. As such, DMAIC is an integral part of a Six Sigma initiative. DMAIC also used to create a “gated process” for project control. The criteria for a particular phase are defined and the project is reviewed, and if the criteria are met then the next phase starts, Figure 6, according to ([1] and [7]). Naslednji projekt Next project Definiraj/Define - Zakaj je projekt potreben? Why is the project necessary? - Kaj je namen tega projekta? What is the scope of this project? - Kateri so kvantificirani cilji? What are the quantified objections? - Kdo je kupec? Who is the customer? Nadziraj/Control - Ali nadziram tveganja, cilj, urnik in stroške? Have I controlled risks, scope, schedule and costs? - Ali delam zaključno poročilo? Have I made a close-out report? - Ali zagotavljam raven dobre prakese? Have I ensured the leverage of best practice? Izmeri/Measure - Katere so ključne matrike tega projekta? What are the key metrics for this project? - Ali lahko merim te matrike? Can I measure these metrics? - Ali lahko uporabim te matrike? Can I use these metrics? - Kaj je poslovni primer? What is the business case? Izboljšaj/lmprove - Kaj so ključne naloge za uvajanje sprememb? What are the key tasks to implement changes? - Ali spremembe dajejo rezultate? Are the changes producing results? - Ali vključujem projekt v program? Have I embedded the project in the programe? Analiziraj/Analyse - Ali lahko prepoznam odstopanja tekočega postopka? Can I identfy the gaps in the curent process? - Kaj so vzroki? What are the causes? - Kaj so njegovi viri in ovire? What are he resources and obstacles? SI. 6. Krog DMAIC kot osnova metodologije Šest Sigma Fig. 6. The DMAIC cycle as a methodology for Six Sigma Izboljšanje kakovosti - Quality Improvement 373 Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 Kot povzetek pri uporabi tehnike DMAIC lahko zapišemo: če ne morete definirati vašega postopka, ga tudi ne morete meriti. To tudi pomeni, če ne morete opisati podatkov ne boste sposobni upehati DMAIC v vaše razvojne dejavnosti. Zaradi tega ne morete izboljšati ali vzdrževati kakovosti ([8] in [9]). DMAIC je, kakor je že bilo omenjeno, sestavni del Šest Sigem. Je sistematičen in temelji na dejstvih ter zagotavlja strogi okvir za projektno vodenje, usmerjeno na rezultate. Metodologija naj bi se pojavila kot linearna in izrecno definirana, toda treba je opozoriti, da se najboljše rezultate z DMAIC doseže, če je postopek prilagodljiv, prav tako izločanje slabih korakov. Dober je kot iterativni postopek, če je potrebno, še posebej, ko so člani skupine še začetniki na področju uporabe orodij in tehnik. 3 DFSS 3.1 Definicija DFSS (Načrtovanje za Šest Sigem) je sistematičen in Strukturiran postopek načrtovanja novega izdelka ali postopka, ki se osredotoči na “preprečevanje problema”. To opravi z namenom doseči ali preseči vse potrebe kupca ter CTQ (kritične značilke kakovosti) kot izhodne zahteve, ko se izdelek izdela prvič. Osrednji cilj DFSS je “oblikovati stvari pravilno prvič". Sistem sestoji iz vrste orodij za zbiranje potreb, inženirstva in statističnih metod, ki se uporabljajo med razvojem izdelka. DFSS zahteva natančno uporabo orodij in najboljših praks za izpolnjevanje zahtev kupca in prinaša finančne koristi pri zadovoljevanju zahtev kupca [10]. Temeljna značilka DFSS je preverjanje, ki jo razlikuje od Šest Sigem. Zagovorniki priporočajo DFSS bolj kot celovit pristop re-inženiringa in manj kot tehniko dopolnilno k Šest Sigmam. 3.2 Uporaba Primarna uporaba DFSS kot tehnike je v stopnji načrtovanja in razvoja izdelka, postopka ali storitve. Načrtovanje novega izdelka ali postopka z uporabo postopka DFSS ne nadomešča sedanjih inženirskih metod, niti ne olaj ša organizaciji potrebo po skrbnem pregledovanju odličnosti v inženiringu in razvoju izdelka. To daje še dodatno vrednost pri razvoju izdelka. Pomaga v postopku inoviranja, 374 As a summary of the application of the DMAIC technique, if you cannot define your process you cannot measure it. This means if you cannot express the data you are not able to utilize DMAIC in your development actions. Therefore, you cannot improve and sustain the quality ([8] and [9]). DMAIC is an integral part of Six Sigma. It is systematic and fact based and provides a rigorous framework of results-oriented project management. The methodology may appear to be linear and explicitly defined, but it should be noted that the best results from DMAIC are achieved when the process is flexible, thus eliminating unproductive steps. An iterative approach may be necessary as well, especially when the team members are new to the tools and techniques. 3 DFSS 3.1 Definition DFSS (Design for Six Sigma) is a systematic and structured approach to new products or processes design that focuses on “problem prevention”. This is done with the aim of meeting or exceeding all the needs of the customer and the CTQ (critical to quality) output requirements when the product is first released. The major objective of DFSS is to “design things right the first time”. The system consists of the set of tools, needs-gathering, engineering and statistical methods to be used during the product’s development. DFSS requires the rigorous use of tools and best practices to fulfil customer requirements and brings financial benefits by satisfying customer requirements [10]. One fundamental characteristic of DFSS is the verification, which differentiates it from Six Sigma. The proponents of DFSS are promoting it as a holistic approach to re-engineering rather than a technique to complement Six Sigma. 3.2 Application The primary application of DFSS as a technique is in the design and development stage of a product, process or service. Designing new products or processes using DFSS approach does not replace current engineering methods, nor does it relieve an organization of the need to peruse excellence in engineering and product development. It adds another dimension to product development. It helps in the Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 razvijanja, optimiranja in prenosa nove tehnologije v program načrtovanja izdelka. Omogoča tudi zaporedje poddejavnosti zasnove razvoja, načrtovanja, optimiranja in ovrednotenja novega izdelka pred njegovim uvajanjem na zahteven trg ([11] in [12]). DFSS metodologija prinaša kakovostne in merljive rezultate pri obvladovanju kritičnih parametrov v nasprotju od tipične vrste zahtev za izdelek, ki temelji na glasu kupca (VOC). DFSS je primerna znotraj zamisli ključnega poslovnega postopka, a to je razvoj izdelka; zajema številna orodja in najboljše prakse, ki jih lahko selektivno razvija skozi faze postopka razvoja izdelka. Posebnost DFSS je v integraciji treh ključnih taktičnih elementov za dosego zahtevanih poslovnih ciljev - nizkih stroškov, visoke kakovosti in krajših časov v razvojnem krogu izdelka [10]: o Jasen in prilagodljiv postopek razvoja izdelka. o Uravnotežena zbirka orodij za razvoj in načrtovanje ter dobrih praks. o Disciplinirana uporaba metod vodenja projektov. DFSS se izogiba štetju napak in mest, na katerih se inženirski tim osredotoči na merjenje dejanskih delovanj. Dobljeni temeljni model se lahko preigra, analizira in ovrednoti statistično skozi simulacije Monte Carlo in načrtovanje poizkusov (DoE). Napake in časi zastoja niso poglavitne metrike pri DFSS. DFSS uporablja zvezne spremenljivke, ki vodijo kazalnike nevarnosti za napake in poškodbe, meri in optimira kritične delovne odgovore ob določenih vzrokih za variiacije v proizvodnji, dostavi in uporabi okolja. Preprečevati je treba probleme -ne čakati, da se ti pojavijo in se potem odzivati na njih. Osnovni razlog za izvajanje DFSS je finančni. To ustvarja vrednost delničarjem, ki temelji na dobavni vrednosti za kupca na trgu. DFSS pomaga izpolniti zahteve poslovanja z izpolnjevanjem glasu kupca. Najbolj pogosto omenjena metodologija za uvajanje DFSS v prakso sta DMADV (definiraj, meri, analiziraj, načrtuj in overi) in IDOV (identificiraj, načrtuj, optimiraj in validiraj). DMADV je pogosto opisana kot naslednja stopnja DMAIC (Šest Sigem) in tako lahko vodi k rodovnemu postopku [1]. Z namenom da bi poudarili določene značilke DFSS, smo vzeli postopek IDOV, da bi ponazorili osnovne korake postopka (si. 7) [2]. Zagovorniki DFSS verjamejo, da bodo v nekaj naslednjih letih izkušnje naraščale, DFSS pa bo process on inventing, developing, optimizing and transferring new technology into product design program. It also enables sub-sequent conceptual development, design, optimization and verification of new products prior to launch into their respective market ([11] and [12]). DFSS methodology delivers qualitative and quantitative results by managing critical parameters against the clear set of product requirements based on Voice of customer (VOC). Design for Six Sigma fits within the context of the key business process, namely the product development process; encompasses many tools and best practices that can be selectively deployed during the phases of a product development process. Specifically, DFSS integrates three major tactical elements to help attain the ubiquitous business goals of low cost, high quality and rapid cycle-time from product development [10]: o A clear and flexible product development process. o A balanced portfolio of development and design tools and best practices. o Disciplined use of project management methods. DFSS avoids counting failures and places the engineering team’s focus on measuring real functions. The resulting fundamental model can be exercised, analyzed and verified statistically through Monte Carlo simulations and the sequential design of experiment (DoE). Defects and time-to-failure are not the main metrics of DFSS. DFSS uses continuous variables that are leading indicators of impending defects and failures to measure and optimize critical functional responses against assignable causes of variation in the production, delivery and use environment. We need to prevent the problems – not wait until they occur and then react to them. The reason for using DFSS is ultimately financial. It generates shareholder value based on delivering customer value in the marketplace. DFSS helps fulfil the voice of the business by fulfilling the voice of the customer. Most frequently reported methodologies for putting DFSS into practice are DMADV (Define, Measure, Analyze, Design and Verify) and IDOV (Identify, Design, Optimise and Validate). DMADV is often described as the next stage of DMAIC (Six Sigma) and thus may lead to a generic approach [1]. In order to emphasize the distinctive characteristic of DFSS we have adapted IDOV to show the basic steps of the process, Figure 7 [2]. The proponents of DFSS believe that within the next few years, as experience grows, DFSS will Izboljšanje kakovosti - Quality Improvement 375 Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 SI. 7. Zveza med DMADV (DFSS) in običajnim DMAIC (Šest Sigem) - dodan je tudi novi postopek IDOV [2] Fig. 7. The relationship between DMADV (DFSS) and classical DMAIC (Six Sigma) - a new approach IDOV is also added [2] uporabljena pri načrtovanju v podjetjih z enakim zaupanjem kakor v standarde ISO (ISO 9001, ISO 14001, ISO/TS 16949 in ISO OHSAS 18001). DFSS je dolgotrajen in drag postopek, ki terja obsežne vire. Zato naj bi bil skrbno uporabljen samo na nekaj bistvenih projektih in še posebej usmerjen k razvoju novih izdelkov. Ne začenjajte projektov DFSS brez kupcev, vključevanja prodaje, zavezanosti vrhovnega vodstva in ustrezne skupine, po možnosti usposobljene za Šest Sigem. DFSS je močna tehnika in njena moč naj bi bila primerno uporabljena. be used in design houses with the same familiarity as the ISO standards (ISO 9001, ISO 14001, ISO/TS 16949, and ISO OHSAS 18001). DFSS is a longer-term, resource-hungry process and it is expensive. Therefore, it should be deployed with care and on just a few vital projects, and specifically targeted towards the development of new products. Do not start a DFSS project without the customer, sales involvement, top-management commitment and a team, preferably one with Six Sigma training. DFSS is a powerful technique and its power should not be abused. 4 SKLEPNE UGOTOVITVE 4 CONCLUSIONS Metodologija uvajanja nenehnih izboljšav kakovosti se lahko razlikuje v različnih organizacijah. Ne glede na metodologijo in program nenehnih izboljšav vsaka organizacija potrebuje izbiro orodij in tehnik kakovosti v svojem postopku izvajanja izboljšav. Pomembno je to, da so orodja in tehnike izbrane za ustrezno skupino in da se pravilno uporabljajo v ustreznem postopku. PDCA (Demingov) krog je več kakor le orodje kakovosti. PDCA je zasnova postopka nenehnih izboljšav, vgrajen v kulturo The methodology for implementing continuous quality improvement can be varied in different organizations. Regardless of the methodology of the continuous-improvement programmes, each organization needs to use a selection of quality tools and techniques in their implementation process. It is vital that the tools and techniques are selected for the appropriate team and applied correctly to the appropriate process. The PDCA cycle (Deming’s circle) is more than just a quality tool. The PDCA cycle is a concept of 376 Sokovič M. - Pavletič D. Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 organizacije. Je preprost za razumevanje in naj bi continuous-improvement processes embedded in the ga uporabljala širša skupina ljudi v podjetju (tudi organization’s culture. It is simple to understand and skozi standard ISO 9001:2000). Najpomembnejši should be used by a large number of people in the vidik PDCA leži v stopnji “ukrepaj” po izpolnitvi company (also throughout standard ISO 9001:2000). projekta, ko krog ponovno zavrtimo za nadaljnje The most important aspect of PDCA lies in the “act” izboljšanje. stage after the completion of a project when the cycle Metodologija DMAIC (kot sestavni del Šest starts again for the further improvement. Sigem) je sistematična in temelji na dejstvih; The methodology DMAIC (an integral part of zagotavlja natančen okvir za „na rezultate” Six Sigma) is systematic and fact based and provides usmerjeno vodenje projekta. Pripomniti je treba, da a rigorous framework of results-oriented project man-so najboljše rezultate z DMAIC dosegli pri agement. It should be noted that the best results from prilagodljivih postopkih in izločanju slabih korakov. DMAIC are achieved when the process is flexible, Kot ponovitveni postopek je primeren zlasti, ko so thus eliminating unproductive steps. An iterative člani skupine še začetniki na področju uporabe approach may be necessary as well, especially when orodij in tehnik. the team members are new to the tools and techniques. Metodologija DFSS je sistematičen in DFSS methodology is a systematic and discipliniran postopek načrtovanja izdelka ali disciplined approach to product or process design, postopka, vključujoč vse funkcije organizacije od including all organizational functions from the early samega začetka, z namenom oblikovati stvari beginning, with the objective to design things right pravilno že prvič. Glas kupca (VOC) in Razvoj from the first time. Voice of the customer (VOC), to funkcije kakovosti (QFD) sta orodji za razpoznavo gather customer requirements, and Quality Function zahtev kupca, prevajanje le-teh v tehnične zahteve deployment (QFD) are tools to identify customer reza načrtovanje izdelka in njihovo uvrstitev glede na quirements, translate them into the product’s techni-pomembnost za izpolnitev temeljnih zahtev kupca. cal design requirements and prioritize them according Ne začenjajte projektov DFSS brez kupcev, to weighted importance to meet customers’ basic vključevanja prodaje, zavezanosti vrhovnega requirements. Do not start a DFSS project without the vodstva in ustrezne skupine, po možnosti customer, sales involvement, top-management usposobljene za Šest Sigem. DFSS je izjemno močna commitment and a team, preferably one with Six Sigma tehnika in njena moč naj ne bi bila zlorabljena. Vendar training. DFSS is a powerful technique and its power prav tako ne smemo pozabiti: DFSS je dolgotrajen in should not be abused, and do not forget: DFSS is a drag postopek, ki zahteva obsežne vire. Iz teh longer-term, resource-hungry process and it is very razlogov naj bi bil skrbno uporabljen samo na nekaj expensive. For this reason it should be deployed with bistvenih projektih in še to usmerjen predvsem k care and on just a few vital projects, and specifically razvoju novih izdelkov. targeted towards the development of new products. 5 LITERATURA 5 REFERENCES [1] Basu, R. (2004) Implementing quality - a practical guide to tools and techniques, Thomson Learning, London. [2] Sokovič, M. (2006) PDCA cycle vs. DMAIC and DFSS, Proceedings of the International Conference ICQME 2006, 13. - 15. September 2006, Miločer, Montenegro. [3] Seaver, M. (2003) Gower handbook of quality management, Third Edition, Gower Publishing Ltd, England. [4] Sokovič, M., et al. (2005) Quality management - Seminar, Educational material, Faculty of Mechanical Engineering, Ljubljana, Slovenia (in Slovene). [5] Kondo, Y. (1995) Companywide quality control, 3A Corporation, Tokyo. [6] Lesjak, M. and J. Kusar (2006) Optimisation of working place, Diploma thesis, Faculty of Mechanical Engineering, Ljubljana, Slovenia (in Slovene). [7] Breyfogle III, F W., et al. (2001) Managing Six Sigma, John Wiley & Sons, Inc., New York. Izboljšanje kakovosti - Quality Improvement 371 Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378 [8] Pavletič, D. and M. Sokovič (2002) Six Sigma - a complex quality initiative, J. of Mech. Eng, Vol. 48 (2002) 3, pp. 158-168. [9] Pavletič, D., Fakin, S. and Sokovič M. (2004) Six Sigma in process design,/. of Mech. Eng., Vol. 50 (2004), Nr. 3, pp. 157-167. [10] Mesec, A. (2005) Designing new products using DFSS, Proceedings of the 7th Conference IAT ‘05, 21.- 22. April 2005, Bled, Slovenia. [11] Crevelin, C. M., et al. (2003) Design for Six Sigma in technology and product development, Prentice Hall PTR, London. [12] Yang, K., et al. (2003) Design for Six Sigma - a roadmap for product development, Mc Graw Hill, London. Naslova avtorjev: Authors’ Addresses: prof. dr. Mirko Sokovič Prof. Dr. Mirko Sokovič Univerza v Ljubljani University of Ljubljana Fakulteta za strojništvo Faculty of Mechanical Engineering Aškerčeva 6 Aškerčeva 6 1000 Ljubljana SI-1000 Ljubljana, Slovenia mirko.sokovic@fs.uni-lj.si mirko.sokovic@fs.uni-lj.si doc. dr. Duško Pavletič Doc. Dr. Duško Pavletič Univerza v Rijeki University of Rijeka Tehnična fakulteta Faculty of Engineering Vukovarska 58 Vukovarska 58 HR-51000 Rijeka, Hrvaška HR-51000 Rijeka, Croatia duskop@riteh.hr duskop@riteh.hr Prejeto: 6.2.2007 Received: Sprejeto: Accepted: Odprto za diskusij 25.4.2007 Open for discussio 378 Sokovič M. - Pavletič D.