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Basic solutions on shape complexity evaluation of STL data

Valentan B., Brajlih T., Drstvensek I., Balic J.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 26, nr 1

73-80

EN

Purpose: Purpose of this paper is to present basic solutions on shape complexity, based on basic information of the STL data. Design/methodology/approach: Paper presents a few methods of mathematically evaluating the complexity of the shape. Methods vary from very simple based on the number of triangles in STL file, STL file size and the parts volume, to the more complex mathematical evaluation based on the basic relations of the STL data. Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic results on part complexity and can be used for further researches. Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results. Practical implications: In a rapidly developing field of manufacturing technologies choosing the optimal manufacturing procedure is a difficult and crucial decision. Usually the decision is based on experience evaluation that is fast and can be optimal. Usually, this method produces goods results, but in some cases this method can lead to cost increases and reduced economic efficiency without us even knowing that. Therefore, it is crucial, that a fast and simple solution is developed, by which the optimal way of manufacturing can be determined. Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.

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Optimizing scale factors of the PolyJet™ rapid prototyping procedure by genetic programming

Brajlih T., Drstvensek I., Kovacic M., Balic J.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 16, nr 1-2

101--106

EN

Purpose: The main purpose of our article is to represent results of our research that investigated the implementation of genetic programming methods into optimization process of the scale factor values used in PolyJet™ rapid prototyping procedures. Design/methodology/approach: The first step in our research was to test the influence of the recommended scale factor values on the dimensional accuracy of the finished parts. Then, the genetic programming was used in optimization of scale factor values regarding to the part’s properties. Finally, the optimized values were tested on another test series of parts. Findings: The optimized scale factor values yield better results in terms of accuracy than values recommended by the manufacturer. Research limitations/implications: Due to the large increase in part’s build time/cost the data range of the Z-axis dimensions of our test series was somewhat narrow, leaving the detailed study of Z-axis scale factor values for further research. Practical implications: The optimized scale factor values can be used in the RP machine software package in order to achieve higher accuracy of manufactured prototypes. Originality/value: This paper can be used as a guideline in implementation of genetic programming in optimization process of various manufacturing parameters of RP technologies. Additionally, any user of the PolyJet™ RP machine can use optimized scale factor values described in the paper.

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Evaluation of shape complexity based on STL data

Valentan B., Brajlih T., Drstvensek I., Balic J.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

293--296

EN

Purpose: Purpose of this paper is to present a part complexity, based on basic information of the STL data. Design/methodology/approach: This paper presents a few methods of evaluating the complexity of the shape, based on the parts STL data. Methods vary from very simple based on the number of triangles in STL file and the parts volume, to the more complex mathematical determination based on the relations of the basic STL data. Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic view on part complexity. Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results. Practical implications: The complexity of the shape of a part is an important factor for all manufacturing procedures. When using conventional machining, the parts complexity presents a key factor in determining the optimal way of manufacturing. Also, when using rapid tooling (for example silicon rubber moulding) the complexity of the part determines the parting plane layout and eventual tool construction (inserts, cores, etc.). Even when using certain rapid prototyping procedures, the support material consumption depends highly on the complexity of the part and together with the problem of optimal orientation and position of the part, significantly influences the manufacturing costs. At the end of the article a few test method are presented that try to determine the complexity regarding to the procedure by which the part will be manufactured. Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.