Optimization of layered manufacturing process for reducing form errors with minimal support structures

• Mathematical models were developed for calculating form errors in LM parts.
• 1D error functions were designed to correlate form errors to part orientation.
• A voxel-based algorithm was designed to calculate volume of support structure.
• An optimization model was generated to simultaneously minimize form errors and support structures.
• The techniques will help to manufacture precision LM parts with reduced material utilization.

Layered manufacturing (LM) has evolved from the rapid prototyping (RP) method to a mainstream process for manufacturing high precision parts for aerospace, automotive and medical industries. LM inherits from RP several advantages including the ability to produce complex shapes, low cost and elimination of special tooling, as well as disadvantages of poor surface finish, poor dimensional accuracy, high build time and high waste. As LM is increasingly being accepted as a traditional manufacturing process, it has to consistently manufacture parts with minimal errors while keeping the material utilization to a minimum. This paper analyzes the effect of part orientation on two types of form errors, namely, cylindricity and flatness errors. An algorithm to calculate the optimal orientation for minimizing flatness and cylindricity errors is developed and tested with the help of two test cases. However, an optimal orientation for minimum form errors may result in a greater utilization of support structures which increases the material consumption in LM processes and therefore should be avoided. A voxel-based approach for calculating support structures has been developed in this paper which is then applied to minimize the volume of support structures while minimizing the cylindricity and flatness errors of the part features. This combined optimization is applied on two test parts and the results are provided.