Case-Based Reasoning (CBR) has been successfully applied to many fields especially in the design domain. Poor assembly part design increases the cost, raises the manufacturing complexity and reduces the product quality. However, little research has been devoted to predict the potential design problems in the early design stage. The objective of this paper is to integrate the indexes of assemblability and manufacturability into adaptive phase in CBR to avoid inexperienced mistakes. Early experimental results indicate that quantitative feedback of these indexes can guide novices to depict a good assembly part design, let experienced designers confirm their experience judgments and finally impart the experience to novices through CBR methodology.

Product designers address the costs of assembly during the design process. Design process can be more efficient if assembly issues could be addressed early in its design process. Doing this requires the ability to assess assemblability among others. Assemblability refers to the ease of assembling the final product from its parts. Assemblability evaluation is applied by product designers for quantitatively estimating the degree of difficulty of the assembly. This helps in identifying areas of improvement, so as to reduce process time and production costs. This work focuses on assessing assemblability in a manual assembly and its importance in the earlier phases of design. Literature contains various methods for assessing assemblability (e.g. Boothroyd-Dewhurst method, the DFA house, Sturges DFA calculator and Sony DFA method). These methods are typically rule-based and their use requires insight and knowledge on the part of the designer. Further, the designer has to interpret and apply them differently in each specific and unique case. Literature also contains methods for ergonomic assessment of manual work and its link with assemblability. Both observation based ergonomic assessment such as RULA, REBA, VIDAR, LUBA and OWAS and instrumentation based ergonomic assessment using electro-goniometer and accelerometer are the techniques reviewed in this thesis for their suitability in assembly assessment. The most recent trend in the area is automation of the evaluation process. This thesis proposes an approach to automated assessment of assemblability using electromagnetic trackers. In spite of advances in industrial automation, manual assembly tasks continue to be an important feature of many industrial operations. The method proposed in the thesis is for the assessment of assemblability of manual assembly that combines both time and postural analysis. The tool used for the static analysis is called Rapid Upper Limb Assessment (RULA); for dynamic analysis a new method of time analysis is proposed that is based on the ratio of time spent in fine and gross motions carried out in an assembly process. The difficulty of assembly of a series of manual assembly tasks are carried out in a laboratory setting. Then by correlating this assessment with the feedback on the difficulty of these assembly task obtained from the subjects who carried out these tasks. The remaining work carried out as a part of this thesis is focussed on automating the process of carrying out the above assessment in an automated manner. Suitability of electromagnetic trackers as a means for automated capture of data necessary for executing the proposed assessment method is studied. Electromagnetic trackers have been used to capture postural data for various limbs of the assembly operators. Data from the limbs are then analysed to identify, to which limb movement signifies which sources of difficulty (i.e. reach, visibility, etc.) in assembly; for example reach difficulty is indicated by torso movement. Finally, the thesis proposes as a part of the future work in possible improvement of the assessment method. Also, its application using a virtual reality (VR) platform assesses in ascertaining ease or difficulties in assembly and many.

Many conflicting issues exist between product design and manufacturing department. In the early design stage, designers often do not have enough expertise to successfully address all these issues. This results in a product design with a low level of assemblability and manufacturability. Hence, an intelligent decision support system is needed for early design stages to improve a design. This paper proposed a web-based intelligent decision support system, CBR-DFMA, connecting with a case base, database and knowledge base. Early experimental results indicate that potential design problems can be detected in advance, design expertise can be effectively disseminated and effective training is offered to designer by employing this system.

The need to work with Design for Automatic Assembly (DFAA) has been widely recognizedin the literature. However, the implementation of DFAA is not clearly defined. Therefore, thepurpose of this master thesis is to investigate and contribute with knowledge of how DFAAshould be implemented into an organization, such as Company Y.Several interviews have been conducted to establish a current state analysis, to receive anunderstanding of the current problems at Company Y and how to address them. Abenchmarking study was conducted, where the three companies Ericsson, Company X andScania were interviewed. All three companies have successfully implemented DFA and wereinterviewed with the purpose to obtaining their best practices. The study also included an earlyimplementation of DFAA, where a software based DFA2-method created by Eskilander (2001)was tested on a current product and a new developed design concept at Company Y. Based onthis a recommended workflow of the evaluation could be attained.Based on the empirical gatherings several recommendations of how DFAA should beimplemented into the organization could be made. The study highlights that DFAA should beapplied as early as possible in the product development process. The DFA2-method should beutilized at product level to facilitate concept selection and at part level to make theproducts/modules suited for automatic assembly, before the design is “locked” and before aphysical prototype is created. The departments that should be working with DFAA includesindividuals from production, design quality and purchasing. However, once DFA becomesrooted in the company, more functions in the company’s supply chain will become affected.This means that more functions might need to be included in the work of DFAA. Finally, thestudy includes a decision model, in which the decisions are based on the measurable valuesreceived from the DFA2-method. / Behovet av att arbeta med Design for Automatic Assembly (DFAA) har uppmärksammat ilitteraturen. Däremot har implementeringen av DFAA inte blivit tydligt definierat. Syftet meddetta examensarbete blir således att undersöka och bidra med kunskap om hur DFAA skaimplementeras i en organisation, så som Företag Y.Flera intervjuer har genomförts för att upprätta en nuvarandeanalys för att få förståelse för derådande problemen hos Company Y och hur dessa ska hanteras. En benchmarkingstudiegenomfördes, där de tre företagen Ericsson, Company X och Scania intervjuades. Alla treföretagen har framgångsrikt implementerat DFA och har intervjuats med syftet att erhålla derasbästa praxis. Studien innefattar även en tidig implementering av DFAA, där enmjukvarubaserad DFA2-metod skapad av Eskilander (2001), har testats på en aktuell produktoch ett nytt utvecklat koncept på Company Y. Baserat på detta kunde ett rekommenderatarbetsflöde av utvärderingen presenteras.Baserat på empiriska studien kunde flera rekommendationer gällande hur DFAA skaimplementeras i en organisation skapas. Studien belyser att DFAA bör tillämpas så tidigt sommöjligt i produktutvecklingsprocessen. DFA2-metoden bör utnyttjas på produktnivå för attunderlätta konceptvalet och på komponentnivå för att göra produkterna/modulerna lämpade förautomatisk montering, detta innan designen är "låst" och innan en fysisk prototyp harkonstruerats. Avdelningar som ska arbeta med DFAA inkluderar produktion, designkvalitet ochinköp. När DFA blir rotad i företaget kommer dock fler funktioner i företagets supply chain attpåverkas. Det innebär att fler funktioner kan behöva inkluderas med arbetet kring DFAA.Slutligen så inkluderar studien en beslutsmodell relaterat till DFAA. Besluten baseras på demätbara värden från DFA2-metoden.