Digital Manufacturing Process Chain for One-Off Replacement Parts: A Precision Casting Case Study

Abstract

The need to manufacture a copy of a mechanical part typically arises when a single replacement part is necessary and is out of stock or out of production altogether. For parts with intricate details and associated accuracy requirements, investment casting may be preferred to machining, for size and detail reasons, or 3D printing, for material reasons. This work applies the digital manufacturing paradigm to one-off vacuum-aided rapid investment casting focusing on the process chain rather than on engineering issues. 3D laser scanning, digital model construction by surface fitting, casting model making by exploiting additive manufacturing, material investigation using scanning electron microscopy, casting simulation exploring process parameter scenarios, as well as the corresponding implementation on a vacuum casting machine are the pertinent interlinked steps and techniques. The added value of this work is that for each process link the important steps and the potential pitfalls are analyzed in detail using as an example a cylinder liner from a model car engine. Quality of the result was quite acceptable, the main benefit of the streamlined approach being that “right-first-time” parts can be achieved.

Keywords

• investment casting
• one-off manufacturing
• 3D scanning
• surface reconstruction
• casting simulation
• additive manufacturing
• digital manufacturing
• process chain