PRIMAs Process Information Maps

Each PRIMA is divided into seven categories, as listed and defined below, covering the characteristics and capabilities of the process  

A key feature of the PRIMAs is the inclusion of process capability charts for the majority of the manufacturing processes. Tolerances tend to be dependent on the overall dimension of the component characteristic, and the relationship is specific and largely nonlinear. The charts have been developed to provide a simple means of understanding the influence of dimension on tolerance capabUity. The regions of the charts are divided by two contours. The region bounded by these two contours represents a spectrum of tolerance-dimension combinations where Cpt 1.33 is achievable. Below this region, tolerance-dimension combinations are likely to require special control or secondary processing if Cpk= 1.33 is to be realized. 

In the preparation of the process capabiUty charts it has been assumed that the geometry is well suited to the process and that all operational requirements are satisfied. Where the material under consideration is not mentioned on the charts, care should be taken. Any adverse effects due to this or geometrically driven component variation should be taken into consideration. For more information the reader is referred to reference (1.32). The data used in the charts has been compiled from contacts in industry and from published work. Although attempts have been made to standardize the data as far as possible, difficulties were faced in this connection, since it was not always easy to obtain a consensus view. Consequently, as many as twenty different data sources have been used in the compilation of the individual process capability charts to provide an understanding of the general tolerance capability range offered by each manufacturing process. 

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In the development of the assembly variability risks analysis, expert knowledge, data found in many engineering references and information drawn from the CSC DFA/MA practitioner s manual (CSC Manufacturing, 1995) were collated and issues related to variability converged on. Much of the knowledge for the additional assembly variability risks analysis was reviewed from the fabrication and joining data sheets called PRocess Information MAps (PRIMAs) as given in Swift and Booker (1997). 

To provide for the first point, a set of so-called manufacturing PRocess Information MAps (PRIMAs) have been developed. In a standard format for each process, the PRIMAs present knowledge and data on areas including material suitability, design considerations, quality issues, economics and process fundamentals and process variants. The information includes... 

The work is presented in three main parts. Part I addresses the background to the problem and puts process selection and costing into the context of modern product introduction processes and the application of techniques in design for manufacture. Part II presents the manufacturing process information maps (PRIMAs) and their selection. Part III is concerned with methods and data for costing design solutions. 

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