Parting directions for mould and die design

On the basis of the condition for demouldability, two levels of visibility, complete and partial visibility, are defined. The viewing directions from which a surface is completely visible can be represented as a convex region on the unit sphere called the visibility map of the surface. Algorithms are given for dividing a given object into pockets, for which visibility and demouldability can be determined independently, for constructing visibility maps, and for selecting an optimal pair of parting directions for a mould that minimizes the number of cores. An example illustrates the algorithms.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30430/1/0000051.pd

CERAMIC CORES FOR TURBINE BLADES : A TOOLING PERSPECTIVE

Blade/vane components used in aerospace turbines are of twisted aerofoil shape, made by the process of investment casting, using Ni based super-alloy materials. These castings operate at turbine inlet temperatures (TET) close to the melting point of the alloy, in order to maximize thermal efficiency and thrust of the engine. The castings are made hollow, with intricate features such as turbulator, pin-fin, etc built-in to maximize the effect of heat transfer during forced cooling through internal passages. The hollow geometry in the castings is produced during the investment casting process by using a suitable ceramic core made from Silica or Alumina based mixes. These ceramic cores are high pressure injected by forcing the ceramic mix into dedicated molds or dies. Development of such dies is an involved process by itself, addressing issues right from ceramic mix behavior to manufacturability of the injection mould. The present paper attempts to highlight issues related to tooling development for ceramic cores used in investment cast turbine blade/vane components

Numerical optimization of gating systems for light metals sand castings

This thesis proposed an optimization technique for design of gating system parameters of a light metal casting based on the Taguchi method with multiple performance characteristics. Firstly, the casting model with a gating system was designed and exported as International Graphics Exchange Standard (IGES) models by Unigraphic NX4.0. Based on the IGES models of the casting, Finite Element (FE) Models were generated using Hypermesh software. Then, mold filling and solidification processes of the castings were simulated with the MAGMASOFT. Finally, the simulation result can be converted to numerical data according to the 3D coordinates of the FE model by MAGMALink module of MAGMASOFT . The various designs of gating systems for the casting model were generated and the simulated results indicated that gating system parameters significantly affect the quality of the castings. To obtain the optimal process parameters of the gating system, the Taguchi method including the orthogonal array, the signal to noise (S/N) ratio, and the analysis of variance (ANOVA) were used to analyze the effect of various gating designs on cavity filling and casting quality using a weighting method. The gating system parameters were optimized with evaluating criteria including filling velocity, shrinkage porosity and product yield

Designing for rapid manufacture

Thesis (M. Tech.) -- Central University of Technology, Free State, 2008As the tendency to use sol id freeform fabrication (SFF) technology for the manufacture of end use parts grew, so too did the need for a set of general guidelines that would aid designers with designs aimed specifically for rapid manufacture. Unfortunately, the revolutionary additive nature of SFF technology left certain fundamental principles of conventional design for manufacture and assembly outdated. This implied that whole chapters of theoretical work that had previously been done in this field had to be revised before it could be applied to rapid manufacturing. Furthermore, this additive nature of SFF technology seeded a series of new possibilities and new advantages that could be exploited in the manufacturing domain, and as a result drove design for rapid manufacturing principles even further apart from conventional design for manufacture and assembly philosophy. In this study the impact that rapid manufacture had on the conventional product development process and conventional design for manufacture and assembly guidelines were investigated. This investigation brought to light the inherent strengths and weaknesses of SFF, as well as the design for manufacture and assembly guidelines that became invalid, and consequently lead directly to the characterization of a set of design for rapid manufacture guidelines

Production of plastic injection moulding tools using selective laser sintering and high speed machining

Global manufacturing trend and competition challenge every industry to seek new manufacturing methods to improve their business processes and speed up the product development cycle [Conolly, 2004a and Knights, 2001]. Among the candidates, layer manufacturing (LM) technologies appear to be a potential solution [Plam, 2002, and Grimm, 2004]. Recent LM technologies have led to a demanding application for developing production tools to manufacture parts, known as rapid tooling (RT). Selective laser sintering (SLS) is one of the leading LM systems available today in RT to manufacture injection mould (core/cavity) inserts [Kruth, 1998, Chua, 1999, Dormal, 1999, and Grenda, 2005]. However, the current capabilities of the SLS in producing metal parts have not yet fulfil the requirements of the injection mould inserts, especially in dimensional accuracy and surface finish quality [Francis, 2002 and Dalgamo, 2001 a]. The aim of this research is to use indirect SLS and high speed machining (HSM) in developing production-quality plastic injection moulding (core/cavity) inserts. The idea is that the indirect SLS process is utilised to build a near-net-shape inserts, while HSM is then utilised to finish the inserts to production specifications. Benchmark studies have been carried out to characterise the capabilities of both SLS and HSM with reference to the typical requirements of injection mould inserts. Utilising the study results, new developments of the mould inserts have been implemented on three major industrial case studies. Their performances have been evaluated and measured by comparing them with its respective original inserts. Furthermore, a set of design rules has been derived from best practices of the case studies, and have been validated by developing a new design for each case studies inserts. The results have demonstrated that the indirect SLS process has a capability III manufacturing a near-net shape of the insert which requires further related finishing to achieve final production specifications. The insert performances in some case studies have indicated significant improvements in process productivity and energy consumption as well as economic benefits to using the inserts. Regarding the significant considerations in realising the design, a recommendation on further strategic design rules and manufacturing process are highlighted so that the development of the insert using the selected approach can be more effective and efficient. Moreover, a utilisation of computer analysis software and further durability trial is also highlighted in order to predict and evaluate the optimum overall performance

Resolving internal undercuts of parts in mould design.

by Li Kai Man.Thesis (M.Phil.)--Chinese University of Hong Kong, 1996.Includes bibliographical references (leaves [112]-[113]).Chapter chapter 1 --- INTRODUCTION --- p.1-1Chapter 1.1. --- Research objective --- p.1-1Chapter 1.2. --- Thesis organisation --- p.1-2Chapter chapter 2 --- BACKGROUND ON MOULD DESIGN --- p.2 1Chapter 2.1. --- Mould design process --- p.2-2Chapter 2.2. --- Basic structure of a simple two-piece mould --- p.2-4Chapter 2.3. --- Undercuts --- p.2-5Chapter 2.3.1. --- External undercut --- p.2-6Chapter 2.3.2. --- Internal undercut --- p.2-8Chapter chapter 3 --- RELATED WORKS --- p.3 1Chapter 3.1. --- Previous works --- p.3-1Chapter 3.2. --- Overview of the proposed approach --- p.3-2Chapter chapter 4 --- BACKGROUND THEORIES --- p.4 1Chapter 4.1. --- Mouldability of a part --- p.4-1Chapter 4.1.1. --- Mouldability with a simple 2-piece mould --- p.4-1Chapter 4.1.2. --- Mouldability with side core --- p.4-1Chapter 4.1.3. --- Mouldability with split core --- p.4-2Chapter 4.2. --- Solid sweep --- p.4-2Chapter 4.3. --- Application of solid sweep in mould design --- p.4-5Chapter 4.4. --- Spherical mapping and visibility mapping --- p.4-6Chapter 4.4.1. --- Spherical mapping --- p.4-6Chapter 4.4.2. --- Visibility mapping --- p.4-8Chapter chapter 5 --- DETERMINATION OF MAIN PARTING DIRECTION FOR SIMPLE 2-PIECE MOULD --- p.5 1Chapter 5.1. --- Extraction of possible main parting directions --- p.5-2Chapter 5.2. --- Main parting direction --- p.5-3Chapter 5.3. --- Ranking of main parting direction --- p.5-4Chapter 5.4. --- Calculation of projected area of a moulded part --- p.5-5Chapter 5.5. --- Creation of cavity solid --- p.5-8Chapter 5.6. --- Cleavage of cavity solid --- p.5-10Chapter 5.7. --- Undercut solid determination --- p.5-12Chapter 5.8. --- Difference in the application area of solid sweep and Visibility map --- p.5-13Chapter 5.9. --- Search strategy for parting direction of a 2-piece mould --- p.5-18Chapter chapter 6 --- DETERMINATION OF MAIN PARTING DIRECTION AND SIDE CORE --- p.6-1Chapter 6.1. --- Undercut evaluation --- p.6-2Chapter 6.2. --- Determination of main parting direction --- p.6-4Chapter 6.3. --- Determination of side core for a given main parting direction --- p.6-4Chapter 6.4. --- Search strategy for main parting direction and side core direction --- p.6-7Chapter 6.4.1. --- The search for single side core --- p.6-7Chapter 6.4.2. --- The search for multiple side cores --- p.6-9Chapter chapter 7 --- DETERMINATION OF SPLIT CORE DIRECTION --- p.7-1Chapter 7.1. --- Determination of split core direction --- p.7-1Chapter 7.2. --- Visibility check for split core --- p.7-3Chapter 7.3. --- Selection of split core --- p.7-3Chapter 7.4. --- Trajectory of split core --- p.7-5Chapter 7.4.1. --- Primary solid sweep --- p.7-5Chapter 7.4.2. --- Secondary solid sweep --- p.7-7Chapter 7.5. --- Interference check between split cores --- p.7-9Chapter 7.6. --- Search strategy for split core --- p.7-9Chapter chapter 8 --- HEURISTIC\DEPTH-FIRST SEARCH STRATEGY --- p.8-1Chapter 8.1. --- Side core determination --- p.8-1Chapter 8.2. --- Split core determination --- p.8-3Chapter chapter 9 --- EXPERIMENTAL RESULTS --- p.9-1Chapter chapter 10 --- COMPLEXITY ANALYSIS --- p.10-1Chapter 10.1. --- Determination of main parting direction and side cores --- p.10-2Chapter 10.2. --- Determination of side core directions --- p.10-5Chapter chapter 11 --- CONCLUSIONS --- p.11-1REFERENCE

Automated Core And Cavity Design System For Mould Works Using Generative Method Of Computer Aided Process Planning

In recent years, many efforts have been made for core and cavity design system to be fully automated. Three profound limitations in the previous automated core and cavity design systems are (i) the lack in parting direction flexibility, (ii) inability to detect and generate parting direction for both inner and outer undercuts and (iii) no information transfer from automated core and cavity design system to machining system. To overcome these limitations, automated core and cavity design system (ACCDS) is developed. This system acts as a component in computer aided process planning system where it takes information from any 3D CAD model and provides information to the machining system. Generative method is the basis of this system where core and cavity models are generated from scratch. The outputs from the system are (i) the generated core, cavity and side-cores with parting direction and (ii) the information of zero tool-face collision angle range of core and cavity mould pieces. By comparing ACCDS with a recent system proposed by a researcher, improvements such as better core and cavity design and the reduction of system computational time were observed. This shows that ACCDS were able to contribute in the betterment of the core and cavity design system in automatic manner

Automated Parting Methodologies for Injection Moulds

Ph.DDOCTOR OF PHILOSOPH

Internship report and study concerning the threats and opportunities posed by additive manufacturing to moulding industry

This report will make a presentation and analysis of various parts and systems used in injection moulds for plastics. This review starts by explaining the injection moulding process of injection, followed by a description of mould standard parts and a process map of mould making. The report also comprises case studies regarding hybrid manufacturing methods of subtractive and additive manufacturing processes. A study regarding opportunities and threats posed by additive manufacturing to the moulding industry is also made in order to understand the future trends of plastic part production