A Novel Multi-Directional Partitioning Method for Support-Free 3D Printing of Inner Runner Structural Components

Three-dimensional printing has great advantages in manufacturing parts with complex internal structures. At present, there are still significant challenges in the unsupported 3D printing of thick-walled parts with inner runners. In this paper, a partitioning method for support-free-fabricating workparts with a built-in inner runner structure is proposed and discussed in detail. With the method, partitioning planes are firstly created according to the direction changes of the inner runner, a “top to bottom” method is used for avoiding the interference of the generated planes, and thirdly the outer surface of the workpiece is considered for a second partition for the support-free purpose. A key algorithm for calculating partitioning planes for inner runner structures is also proposed and introduced in detail, including the iteration method, the calculation for intersectional profile mass centers, and the discussion of the convergence. Algorithm analysis is also performed with a simple model for assessing the influence from the defined parameters, including the proximity Φ s and the increment coefficient σ , on the iteration results as well as on the iteration process. Also, an application test is carried out on a column model with a complex inner runner structure built-in. The result from all the tests indicates that the proposed algorithm is successful in partitioning inner runner structures for support-free fabrication.