Neri Volpato

The influence of support base on FDM accuracy in Z

Purpose – The aim of this work is to study the influence of the quality (surface profile) of the support base on dimensional accuracy in the Z-axis in fused deposition modeling (FDM). Design/methodology/approach – The surface profile of a support base produced using a standard (default) FDM configuration is analyzed experimentally, and two new deposition configurations are proposed. Some parts are built using these approaches, and the influence of the profile on Z accuracy is investigated. The parts are examined using a contact method and measured using a caliper. Findings – The surface profile of the support base has a direct influence on FDM part accuracy in Z. The results show that the accuracy in the Z dimension of an FDM prototype can be increased by improving the surface quality of the support base. In cases where accuracy is paramount, this can be achieved by better planning (tuning) of the support strategy. Originality/value – A significant component of the Z error in FDM has been identified and s...

Development of new rapid prototyping process

Purpose – The purpose of this paper is to identify the key elements of a new rapid prototyping process, which involves layer‐by‐layer deposition of liquid‐state material and at the same time using an ultraviolet line source to cure the deposited material. This paper reports studies about the behaviour of filaments, deposition accuracy, filaments interaction and functional feasibility of system. Additionally, the author describes the process which has been proposed, the equipment that has been used for these studies and the material which was developed in this application.Design/methodology/approach – The research has been separated into three study areas in accordance with their goals. In the first, both the behaviour of filament and deposition accuracy was studied. The design of the experiment is described with focus on four response factors (bead width, filament quality, deposition accuracy and deposition continuity) along with function of three control factors (deposition height, deposition velocity an...

An optimal algorithm for 3D triangle mesh slicing

Abstract We describe an algorithm for slicing an unstructured triangular mesh model by a series of parallel planes. We prove that the algorithm is asymptotically optimal: its time complexity is O ( n log k + k + m ) for irregularly spaced slicing planes, where n is the number of triangles, k is the number of slicing planes, and m is the number of triangle–plane intersections segments. The time complexity reduces to O ( n + k + m ) if the planes are uniformly spaced or the triangles of the mesh are given in the proper order. We also describe an asymptotically optimal linear time algorithm for constructing a set of polygons from the unsorted lists of line segments produced by the slicing step. The proposed algorithms are compared both theoretically and experimentally against known methods in the literature.

Development and Evaluation of Low-Cost Custom Splint for Spastic Hand by Additive Manufacturing

Spastic hand is a health condition that may decrease the functional capabilities of an individual. In such cases it may be indicated orthosis as a therapeutic resource. Such devices can be manufactured by digital processes, helping to mitigate many problems encountered in traditional orthotic processes and could increase user participation in product development. In this context this paper presents the development of a custom orthosis produced by Additive Manufacturing with a focus on low-cost solutions. The orthosis resulting from this development was evaluated by the user, the family and therapists using a Semantic Differential tool. This evaluation has shown that user participation in the development of the formal and aesthetic solutions can increase engagement in device usage, collaborating with the therapeutic process.

Slide design and manufacturing issues in prototype tooling

When a prototype tool for injection molding has to deal with undercut features, the difficulty involved in manufacturing the tooling increases considerably as slides must be used. However, the use of slides in prototype tooling has not been extensively explored. Various design and manufacturing issues, mainly related to the geometry, accuracy and extraction of slides, may prevent these working satisfactorily in a multi-piece mold. In this work, the main types of undercuts are analyzed and some issues related to the design and manufacture of slides for prototype tooling are discussed. A study is carried out to understand a specific issue related to peripheral milling accuracy, and a fit procedure is proposed to overcome this. Polymeric inserts for a test part were manufactured following the proposed design and manufacturing recommendations and fit procedure. The mold was used to produce polypropylene prototypes in an industrial injection molding machine. The results showed that similar design and manufacturing concepts can be applied to different types of undercuts. Extraction of the slide worked satisfactorily, and ejector pins were not required. Finally, the proposed solution to ensure computer numerical control machining produced an adequate slide fit proved successful and significantly reduced post-processing time.