# Assessment of the Design for Manufacturing Using Fuzzy Logic
## 2 Literature Review  
Various methods of assembly support called DFX--design for X--has been developed and spread across industry methods such as QFD (quality function deployment) [4; 5; 6] used in the processes of implementing product customer requirements, FMEA (failure mode and effect analysis) [7]--related to the prediction and prevention of problems at the product design stage, DFA (design for assembly) [8; 9; 10]--e.g., design for manufacturing (DFM) regarding the shaping of the design process of components and the product itself [9; 11; 12; 13; 14; 15]. Decisions made at the product design stage have a significant impact on production costs, efficiency and quality of production.  
In the process of implementing the product, the impact of design on the cost of its implementation is very significant. The share of design costs varies around 5% of the costs of starting production of a new product but affects about 70% of the cost of the product after its implementation into production. While the rationalization activities of the production process at the production stage of the product (direct labor costs and indirect production costs often account for around 40% of the cost of the final product) affect only about 10% on the cost of production of the product [1; 14; 16]. This information is based on the US market cost structure. This means that the actions related to the changes in the production project (with relatively low costs incurred) in the right time have the greatest real impact on the production costs of the final product [1; 15; 17]. [PERSON] [15] and others [1; 7; 18] analyzed the percentage of problems that occur in companies that have not performed and DFA activity during the product design development. For example, 35.9% had problems with the assembly of individual parts of the evaluated design. DFA methods have been selected to evaluate how their effects provide the greatest impact on manufacturing cost [1; 14; 15; 19; 20]. The DFA methods described in the literature and used in manufacturing practice were aimed at serial and mass product production [8; 9; 10; 12; 15; 17; 21]. There has been described in the latest scientific studies some of new DFA methods connected with CAD/CAM systems or Life Cycle assessment, some attempts to use fuzzy logic were also done however complete fuzzy DFA method for different kinds of production hasn't been recognized in literature [18; 21; 22; 23; 24; 25] thus the proposed method also opens to small-lot and unit production.  
Considering the methods described in the literature, we chose to focus on the analysis of unit and small-series production. We also point out that a method is needed to evaluate the production process in a comprehensive way that takes care of machining, assembly and production organizations. The use of fuzzy logic is justified by the need to estimate data due to the lower availability of complex analytical tools in small businesses, development budgets and product testing are limited there and there may be no accurate data for the reasons listed above. The method developed is open and other or additional criteria may be considered according to the production conditions of the company concerned. It may also have been interesting to develop DFA methods in medical procedures and the medical industry [26; 27; 28; 29; 30]. Another area of interest is the processes of electrical and electronic components that have been rapidly developing in recent years [28; 31; 32].