Effects of process parameters on dimensional precision and tensile strength of wax patterns for investment casting by selective laser sintering

Abstract

Turbine blades, produced by the directional solidifi cation (DS) process, often require high dimensional accuracy and excellent mechanical properties. A critical step in their production is the fabrication of wax patterns. However, the traditional manufacturing process has many disadvantages, such as long-term production, low material utilization rate, and the high cost of producing a complex-shaped wax pattern. Selective laser sintering (SLS) is one of the most extensively used additive manufacturing techniques that substantially shortens the production cycle. In this study, SLS was adopted to fabricate the wax pattern instead of the traditional manufacturing process. The orthogonal experiment method was carried out to investigate the effects of laser power, scanning speed, scanning space, and layer thickness on the dimensional precision and morphologies of the SLS parts. The SLS parts showed a minimum dimensional deviation when laser power, scanning speed, scanning space, and layer thickness were 10 W, 3000 mm•s-1, 0.18 mm, and 0.25 mm, respectively. In addition, the tensile strength and fracture morphologies were closely associated with the laser volumetric energy density (VED). The tensile strength reached a maximum when the VED was 0.0762 J•mm-3, with an evident brittle fracture morphology. The wax pattern manufactured in this way meets the accuracy and strength requirements for investment casting. This research offers a novel path for the production of wax patterns for complex-shaped turbine blades by SLS.

Keywords

• polystyrene
• additive manufacturing
• SLS
• investment casting
• orthogonal experiment