The forming process of sand mold 3D printing technology is composed of a coating process, a printing process, and post-processing. In each forming process, the influences of the forming device and process parameters affect forming quality. The state of sand particles affects the flowability and accumulation of sand particles, significantly impacting the quality of sand layers [
6]. The thickness of a sand layer is related to the accuracy of a 3D-printed sand mold. When a sand layer is thicker, the stepping effect of a 3D-printed sand mold is more significant. When a sand layer is thinner, the influences of the sand particle state and coating process parameters on its quality are more significant. In general, the thickness of a sand layer should be three times the diameter of sand particles [
7]. Parteli and Pöschel [
8] analyzed the processes of pushing and extruding powder particles during the movement of a spreading roller. The uniformity and smoothness of the surface of a powder layer during the coating process were analyzed. A functional curve that relates surface roughness to the movement speed of the spreading roller was established. The bulk density of the sand layer directly affects the density of the final sand mold, which considerably influences the mechanical and casting properties of the mold [
9]. The amount of adhesive used significantly affects the strength and precision of a printed sand mold. When the adhesive dose is higher, the strength of the sand mold is greater. The accuracy of a printed sand mold initially increases and then decreases with an increase in adhesive dose [
10]. This phenomenon is related to the penetration of the adhesive into the sand layers [
11]. The scanning printing mode of the 3D printing processes and the layered manufacturing concept make sand molds anisotropic. Research has shown that the bending strength of a sand mold along the scanning direction is approximately 10% higher than that perpendicular to the scanning direction [
12]. In addition, the strength of a sand mold along the layer thickness direction is relatively low. Ma et al. [
13] systematically studied penetration error analysis and compensation technology in sand mold 3D printing processes and proposed a penetration error compensation method based on a standard triangle language model. Current sand mold 3D printing technology requires post-processing, which primarily aims to accelerate the curing speed of adhesives and increase the strength of sand molds. Post-processing methods include visible light exposure, heating, and pressurization [
14]. Nyembwe et al. [
15] conducted a comparative test between post-processed and untreated sand molds. Post-processing temperature was 110 °C and heating time was 2 h. They found that post-processing can effectively improve the mechanical properties (e.g., tensile strength, bending strength, and surface hardness) of sand molds. When the adhesive content of a sand mold is higher, the improvement of its mechanical properties due to post-processing is more significant. However, post-processing slightly reduces the surface quality of sand molds. Mitra et al. [
16] studied the effects of different post-processing temperatures and heating times on the mechanical properties, ablation, and gas permeability of printed sand molds. Various studies have shown that excessive post-processing temperatures significantly reduce the mechanical strength of sand molds. When heating temperature is approximately 100 °C and heating time is within the range of 0–5 h, the mechanical properties of printed sand molds improve. However, the ablation amount of a sand mold increases continuously as heating time increases. Sand mold 3D printing technology exhibits strong flexibility in manufacturing. Hawaldar and Zhang [
17] compared the traditional sand manufacturing and sand mold 3D printing manufacturing processes. Sand mold 3D printing technology demonstrates evident advantages in production efficiency, material saving, and casting cleaning. Sama et al. [
18] changed the simple design of traditional runners and adopted a complex runner design with better filling effect to make the filling of liquid metal smooth and effectively prevent casting defects. Deng et al. [
19–
21] of Tsinghua University used sand mold 3D printing technology to achieve considerable systematic research in the manufacture of sand patterns with hollow structures.