China
Africa
Explore chapters and articles related to this topic
Use of Conventional Manufacturing Techniques for Materials
Published in T. S. Srivatsan, T. S. Sudarshan, K. Manigandan, Manufacturing Techniques for Materials, 2018
T. S. Srivatsan, K. Manigandan, T. S. Sudarshan
The use of an expendable pattern confers a unique advantage on the investment casting process in that the pattern is removed from the mold without any disturbance to the mold. This obviates the need for having a taper in the pattern, thereby enhancing dimensional accuracy over depth of the mold since it is unnecessary to split the mold once molding has been completed. Undercut sections, requiring additional process techniques such as (1) core assembly in sand casting and (2) using a permanent pattern and movable inserts in permanent mold or die casting, are a regular feature of the investment mold. The design capability of an investment casting will be determined by the foundry characteristics of the metal chosen rather than the molding technique used. This necessitates the need to adhere to basic design criteria to achieve both soundness and quality in the component.
Chemical Machining (CHM)
Published in Gary F. Benedict, Nontraditional Manufacturing Processes, 2017
The amount of undercut that occurs in a particular application is a function of many factors including the depth of cut, the type and strength of the etchant, and the workpiece material. Because compensation for undercut must be made during selective masking to ensure the proper final size of details, it is important to be able to quantify the undercut for particular combinations of process variables. This relationship is known as the etch factor and is defined as the undercut/depth of cut ratio. Etch Factor = UndercutDepth of Cut
Effect of Manufacturing Processes on Design
Published in Mahmoud M. Farag, Materials and Process Selection for Engineering Design, 2020
Undercuts are undesirable features in molded parts as they cause difficulties in ejection from the mold. Examples of external and internal undercuts are shown in Figure 7.6d. Some parts with minor undercuts may be flexible enough to be stripped from the mold without damage. Many thermoplastics can tolerate about 10% strain during ejection from the mold.
An integrated design methodology for components produced by laser powder bed fusion (L-PBF) process
Published in Virtual and Physical Prototyping, 2018
Alessandro Salmi, Flaviana Calignano, Manuela Galati, Eleonora Atzeni
The fact that layer-based production processes do not require tooling has led to the assumption that these technologies are free from the rules that govern manufacturing design, such as those pertaining to draft angles and undercuts. The great freedom of design of AM has renewed interest in topology optimisation (TO) techniques (Leary et al.2014). TO methods are able to solve a material distribution problem within a defined design space, given a particular load and boundary condition, and one or more objectives (stiffness, displacements, eigenvalues, etc.). Optimal design is essentially very complex and intricate, but the limits of conventional processes are overcome with AM manufacturing, and parts very close to the best design can be produced (Zegard and Paulino 2016). However, like all traditional processes, AM suffers from part and process considerations of its own which can affect its success. In spite of the capability and constraints of AM, the designs that result from topology optimisation may not be the most suitable solutions for the manufacturing technique. Major or minor modifications of the designs sometimes have to be introduced by the designer in order to satisfy the requirements of the chosen technology. A suitable approach to the design of components that is able to fully exploit the clear benefits of AM technology and which can be produced easily and economically is the design for AM (Atzeni et al.2010b). This approach supports designer with guidelines and strategies in order to develop new components or to improve existing ones: the design guidelines depend on the process type and on the process/material relationship.
Formation of resistance of welded seams against forming of hot cracks when welding is performed with an increased speed
Published in Welding International, 2021
B. V. Sitnikov, V. P. Marshuba
In order to reduce the power of the plasma stream flowing round the crater cavity and avoid undercuts in high-speed welding, the arc is turned with the ‘angle forward’ in the direction of welding (Author’s Cert. USSR No. 721,267, 1980). Investigations showed that the action of the CMF of the direct current flowing along a contact conductor on the arc and the weld metal of the pool leads to turning of the arc with the ‘angle forward’, movement of liquid metal into the head part of the weld pool and weld formation without undercuts in welding at a speed above 80 m/h, but has practically no effect on the resistance of the weld seams to the formation and development of hot cracks.
Concept and simulation of an alternative design for an orthopaedic shoulder implant
Published in Journal of Medical Engineering & Technology, 2022
The most suitable materials for the implant are grade 5 Ti–6Al–4V for the platform components, CoCrMo for the glenosphere/head and XLPE for the cup. These are recommended based on a comprehensive search using defined criteria for each component. A draft analysis and undercut analysis indicates that the design is suitable for additive manufacturing and requires a post-processing operation to process the undercuts. Although both types of radiation sterilisation can be used, it is recommended that E-beam sterilisation is used as it has a shorter dwell time and is less damaging to the polymer components recommended for the design.