Slicing Issues in CAD Translation to STL in Rapid Prototyping (original) (raw)
Related papers
Some Slicing Issues in Rapid Prototyping
2011
Rapid prototyping (RP) processes such as fused deposition modeling (FDM) and stereolithography (SL) are being widely used in the industry with great potential for direct digital manufacturing of functional parts. In the RP process, surface finish and build time are important and are affected due to improper selection of slice thickness. It is evident that there is a strong relation between the slicing and tessellation process for which more scientific efforts are necessary to develop methods for creating more efficient STL files. The aim of this study is to show the effect of slicing on the surface finish, layering error and build time of a prototype. Furthermore, this study shows how tolerance and slice thickness are related in creating more efficient STL files. In this regard, three objects were modeled for generation of STL files. Each object’s STL file was sliced with different slice thickness values. Screenshots approach was used to show the slicing effect on layering error. Th...
An Enhanced Slicing Algorithm Using Nearest Distance Analysis For Layer Manufacturing
2009
Although the STL (stereo lithography) file format is widely used as a de facto industry standard in the rapid prototyping industry due to its simplicity and ability to tessellation of almost all surfaces, but there are always some defects and shortcoming in their usage, which many of them are difficult to correct manually. In processing the complex models, size of the file and its defects grow extremely, therefore, correcting STL files become difficult. In this paper through optimizing the exiting algorithms, size of the files and memory usage of computers to process them will be reduced. In spite of type and extent of the errors in STL files, the tail-to-head searching method and analysis of the nearest distance between tails and heads techniques were used. As a result STL models sliced rapidly, and fully closed contours produced effectively and errorless.
Free-form thick layer object manufacturing technology for large-sized physical models
Automation in Construction, 2002
Large-sized free-form objects of different materials are widely used in various industrial applications. Currently, layered rapid prototyping technologies are not suitable for the fabrication of this kind of objects, due to the necessity of a large number of layers and the limitations in size. This paper reports a novel approach of layered manufacturing that is more appropriate for the fabrication of these large objects. A method of thick-layered object manufacturing is presented, which is based on a higher order approximation of the shape and application of a flexible curved cutting tool.
Some STL File Generation Issues in Rapid Prototyping
laccei.org, 2007
The stereolithography (STL) file format was introduced by 3D Systems and has become the de facto industry standard. However, this is not an ideal format due to the existence of some inherent problems. Due to the nonrobustness of commercial CAD systems, the choice of tolerance is a major issue when saving STL files. These tolerances will affect the file size, the number of triangular facets and the number of STL file errors. The primary focus of this paper is to outline the relationship between tolerance and these issues in the conversion of CAD models to STL files. To meet the aim of this study, the file size and the number of triangular facets were recorded after STL file generation while the number of file errors was obtained after scanning. Some interesting relationships were noticed and are documented. It is noted that the number of errors decreases with increasing tolerance and that in general there are more errors in the ASCII file format than in the binary equivalent. This paper is intended to provide to the practitioner an idea of how the different factors mentioned are affected by tolerance and allow them to choose the best values based on the findings.
Effect of Direct Slicing on Precision Additive Manufacturing
IFAC-PapersOnLine
An intelligent process planning for additive manufacturing (AM) is proposed in a paper presented at IFAC-IMS 2019 1. An important aspect of the intelligent process planning is to directly slice CAD models to generate paths for AM machines. In this paper an experimental approach is carried out to investigate the improvements in the results of fabrication using direct slicing approach. In the proposed process, a CAD model is directly sliced and layer contours are extracted from the ideal surface. The curvature based parametrization using a multi-step method is implemented for finding the position of layers. The dimensional errors are investigated first by comparing the errors generated during the tessellation process with the ideal surfaces. Then the results of printing using paths generated from STL files and the ideal surface defined in an IGES file are compared. The results show considerable improvements in surface continuity and dimensional accuracy of the parts fabricated form the direct slicing approach.
Determination of optimal build direction in rapid prototyping with variable slicing
International Journal of Advanced Manufacturing Technology - INT J ADV MANUF TECHNOL, 2006
Several important factors must be taken into consideration in order to maximize the efficiency of rapid prototyping (RP) processes. The ability to select the optimal orientation of the build direction is one of the most critical factors in using RP processes, since it affects part quality, build time, and part cost. This study aims to determine the optimal build-up direction when a part is built with the variable layer thickness for different RP systems. The average weighted surface roughness (AWSR) that is generated from the stair stepping effect, the build time, and the part cost using the variable layer thickness are all considered in the process. Using the multi-attribute decision-making method, the best orientation is determined among the orientation candidates chosen from the convex hull of a model. The validity of the algorithm is illustrated by an example. The algorithm can help RP users select the best build-up direction of the part and create an efficient process planning.
Simplified Production of Large Prototypes using Visible Slicing
2005
Rapid Prototyping (RP) is a totally automatic generative manufacturing technique based on a “divide-and-conquer” strategy called ‘slicing’. Simple slicing used on 2.5-axis kinematics of the existing RP machines is responsible for the staircase error. Although thinner slices will have less error, the slice thickness has practical limits. Visible Slicing overcomes these limitations. A few visible slices exactly represent the object. Each visible slice can be realized using a 3axis kinematics machine from two opposite directions. Visible slicing is implemented on Segmented Object Manufacturing (SOM) machine under development. SOM can produce soft large prototypes faster and cheaper with accuracy comparable to that of CNC machining.
Slicing procedures for layered manufacturing techniques
Computer-Aided Design, 1994
The 1980s witnessed the emergence of new manufacturing technologies that build parts layer by layer. These layered-manufacturing techniques can significantly reduce the design-to-product leadtimes. The paper overviews several procedures for generating the layers from a cad ...
International Journal of Scientific Research in Science, Engineering and Technology, 2020
Tooling is one of the most important elements in the manufacturing process. To achieve the high quality requirements, moulds are traditionally made by CNC-machining, electro-discharge machining or conventional technologies. The term Rapid Prototyping (RP) refers to a group of technologies that can automatically construct physical model from Computer Aided Design data. Rapid Prototyping allows them to be made quicker and less expensively. The Rapid Prototyping techniques involves basic five step process like, Create a 3D CAD model of the required design, Convert the CAD model to STL format, Slice the STL file, Construct the model Layer by Layer and finally Clean and finish the model. Rapid Prototyping is widely used in fabrication of intricate parts of automotive, aerospace, medical and consumer products industries. Also especially moulds are made from RP model from Rapid Tooling. In this paper, a case study of manufacturing of engine head is taken. In contrast to construction of models by machining, based on the removal of material until the required form is achieved, RP model is made by adding material layer by layer until the whole part will be completed.