A state-of-the-art digital light processing 3D printing material and process for production of investment casting sacrificial patterns

最先进的数字光处理3D打印材料和熔模铸造牺牲模型的生产工艺

• 批准号: 2116944
• 金额: --
• 依托单位: Loughborough University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2116944
• 关键词: state; art; digital; light; processing

Investment Casting (IC) is one of the oldest and most versatile methods of manufacturing near net shape metal parts. IC can deliver parts with intricate geometries, thin walls, superb surface finish, and high dimensional accuracy with an ability to manufacture most metallic materials used in different industries. However, the main shortcoming of IC method is its rather long development lead-time and high toolmaking cost. Specifically, in high-value manufacturing where fast development, low order quantities, short product life cycles, geometrical complexities, and customised designs are in highest demand, conventional investment casting method is prohibitively expensive and slow. However, additive manufacturing (AM) is set to change this shortcoming by reducing the production lead time and cost of sacrificial patterns used in IC. Patterns can be directly produced by AM techniques to entirely eliminate the need for the injection moulding tools and the injection process, which often comprise up to one-third of the product development cost and up to half of the development lead-time. These estimations are even higher for customised products such as biomedical implants.Among many AM methods, Vat Photopolymerization process in which a liquid photo-resin is selectively solidified under light illumination, is known for its low cost, excellent resolution and high scalability. Digital Light Processing (DLP) is one of the Vat Photopolymerisation techniques in which the whole cross-section of the part is light cured at once making the process faster compared to other techniques. This AM technique and its application in IC will be studied in this research.Research GapAlthough material jetting and stereolithography printing methods have been long studied in IC applications, there is currently little academic literature and limited industrial reports on using DLP systems to produce cost effective, fast and accurate IC patterns. Thus, one needs to define a methodology to develop a set of processes and materials to enable a wide use of DLP method in the casting patterns production. However, the challenges are to develop a resin mix, print process and handling/assembling procedure to offer the following: 1) minimum shrinkage during printing and post printing processes; 2) minimum residual stress during printing process to avoid deformations after printing; 3) minimum ash-content after pattern burn-out process; 4) minimum thermal expansion during burn-out process to avoid cracking and breaking IC ceramic mould; 5) best print resolution, surface finish and geometrical printability; 6)best handling and storing conditions for AM-IC patterns and best method to embed a ceramic core into an AM-IC pattern when needed. Aims and objectivesThis research aims to design, verification, and validation of a DLP system and material to achieve the highest castability, dimensional and geometrical accuracy, and cost effectiveness for IC patterns.To achieve this aim, the following objectives are defined:- To develop a methodology to better study an understand burning AM-IC patterns and thermal and gas expansion during burn-out process. It may include physical and computer-aided finite element simulation methods.- To modifying the photocurable resin material and the DLP 3D-printing process to achieve the best dimensional accuracy and geometrical printability by reducing the shrinkage and residual stress during printing and post-printing, in order to minimise/control deformation of the part during print and post-print stages. - Enhancing pattern removal process capability by introducing additives to the resin, improving resign mix materials, and adjusting the pattern removal operations, in order to prevent damage to the ceramic mould. - Develop and validate a method to best store, handle and assemble AM-IC patterns and to fit the ceramic cores inside the patterns while maintaining its dimensional accuracy and functionality.

熔模铸造（IC）是制造近净形金属零件的最古老和最通用的方法之一。IC可以提供具有复杂几何形状、薄壁、极好表面光洁度和高尺寸精度的零件，并能够制造不同行业中使用的大多数金属材料。然而，IC方法的主要缺点是其相当长的开发周期和较高的工具制造成本。具体而言，在高价值制造业中，快速开发、低订单量、短产品生命周期、几何复杂性和定制设计是最高需求，传统的熔模铸造方法非常昂贵且缓慢。然而，增材制造（AM）通过减少IC中使用的牺牲图案的生产交付时间和成本来改变这一缺点。图案可以通过AM技术直接生产，以完全消除对注塑工具和注塑工艺的需求，而注塑工具和注塑工艺通常占产品开发成本的三分之一和开发周期的一半。对于生物医学植入物等定制产品，这些估计值甚至更高。在众多AM方法中，Vat光聚合工艺以其低成本，出色的分辨率和高可扩展性而闻名，其中液体光树脂在光照下选择性固化。数字光处理（DLP）是一种还原光聚合技术，其中部件的整个横截面立即光固化，使该过程比其他技术更快。本研究将研究这种AM技术及其在IC中的应用。研究差距尽管材料喷射和立体光刻印刷方法在IC应用中已经进行了长期研究，但目前关于使用DLP系统生产具有成本效益、快速和准确的IC图案的学术文献很少，工业报告也有限。因此，需要定义一种方法来开发一组工艺和材料，以使DLP方法在铸造模型生产中得到广泛使用。然而，挑战在于开发树脂混合物、印刷工艺和处理/组装程序以提供以下：1）印刷和印刷后工艺期间的最小收缩; 2）印刷工艺期间的最小残余应力以避免印刷后的变形; 3）图案烧除工艺之后的最小灰分含量; 4）烧除工艺期间的最小热膨胀以避免破裂和破坏IC陶瓷模具; 5）最佳的印刷分辨率、表面光洁度和几何可印刷性; 6）AM-IC图案的最佳处理和储存条件以及在需要时将陶瓷芯嵌入AM-IC图案中的最佳方法。Aims and ObjectivesThis research aims to design，verification，and validation of a DLP system and material to achieve the highest castability，dimensional and geometrical accuracy，and cost effectiveness for IC patterns.To achieve this aim，following objectives are defined：- To develop a methodology to better study a understanding burning AM-IC patterns and thermal and gas expansion during burning out process.它可能包括物理和计算机辅助有限元模拟方法。修改光固化树脂材料和DLP 3D打印工艺，通过减少打印和打印后的收缩和残余应力来实现最佳的尺寸精度和几何可打印性，以最大限度地减少/控制打印和打印后阶段零件的变形。- 通过向树脂中引入添加剂、改进树脂混合材料和调整图案去除操作来提高图案去除工艺能力，以防止对陶瓷模具的损坏。- 开发并验证一种方法，以最佳方式存储、处理和组装AM-IC图案，并在保持其尺寸精度和功能性的同时将陶瓷芯安装在图案内。