Purpose: This purpose of this study was to develop a 3D printer based on powder particle. The best degreasing and sintering process of a blank body was investigated to obtain a metal product with high precision and high surface finish. This process will greatly reduce the difficulty and cost of forming a complex metal product with high application value. Design/methodology/approach: Stainless steel powder and polymer materials were mixed using a rubber mixing machine. The powders were granulated to prepare a mixed material. A powder feed 3D printer was used at low temperature (about 200°C) to print and degrease the body. A series of sintering experiments were performed to study the different sintering temperatures, and the physical and mechanical properties of the sample sintered under various conditions were compared to determine the best degreasing and sintering process. Findings: The reaction at 1,370°C was the optimal route for the metal billet degreasing. The resulting metal products had fine structure and stable performance compared with the products with traditional powder metallurgy composition. Originality/value: Most 3D printed metal powder materials rely on imports, which are expensive and increase the manufacturing cost. These drawbacks limit the application and development of metal 3D printing technology to a certain extent. The successful study of this molding method greatly reduces the difficulty and cost of forming complex metal products with high application value. This report will provide valuable guidance for sintering process and forming methods.

Mixer rotor speed is one of the important factors which effects the mixing process and mixer rotor speed of SFRC greatly. The effects of different mixer rotor speed on mixing process of SFRC have been researched by experiments. In the paper, the mixer rotor speed was changed from 50rpm to 80rpm respectively. And also the addition of short fibers was about 0phr~6phr. The experimental results indicated that SFRC had better physical and mechanical properties as mixer rotor speed was about 70rpm, and the addition of short fibers was about 3phr.

Cooling water temperature is one of the important factors, which effects the mixing process and cooling water temperature of SFRC greatly. The effects of different cooling water temperature on mixing process of SFRC have been researched by experiments. In the paper, the cooling water temperature was changed from 20°C to 50°C respectively. Also the addition of short fibers was about 0phr~6phr. The experimental results indicated that SFRC had better physical and mechanical properties as cooling water temperature was about 40°C, and the addition of short fibers was about 3phr.

In recent years, rubber composites reinforced by short fibers has been researched deeply, because of its good performances such as higher wear resistance, higher cut resistance and so on. Some research results indicated that if short fibers get orientation in rubber composites, the performances of rubber products could be promoted greatly. But how to make short fibers get orientation in rubber matrix during extrusion is still a real problem. And there are many parameters affect the short fibers orientation. So, in this paper, the effects of die structure including expansion-die and dam-expansion-die on extrusion flow field of short fiber and rubber composite material during extrusion process has been researched by Polyflow. And the FEA results about the pressure field, velocity field and the velocity vector of the rubber composites flow field indicate that, comparing with expansion-die and the dam-expansion-die, the latter one is better for the extrusion process of rubber composites and making short fibers get radial orientation in rubber matrix.

Roof bolt pressure is one of the important factors which impacts the mixing process and roof bolt pressure of SFRC greatly. The effects of different roof bolt pressure on mixing process of SFRC have been researched by experiments. In the paper, the roof bolt pressure was changed from 0.3MPa to 0.6MPa respectively. And also the addition of short fibers was about 0phr~6phr. The experimental results indicated that SFRC had better physical and mechanical properties as roof bolt pressure was about 0.6MPa, and the addition of short fibers was about 3phr.

Die structure is one of the most important factors that impacts short fibers orientation during extrusion process. As a result, the effects of two kind of die structure which is dam-die and expansion-die on flow field including pressure field, velocity field and the velocity of short fiber and rubber composite material during extrusion process has been researched by Polyflow. The FEA results about the flow field of the short fiber and rubber composite material indicate that, compared with the two kind of dam-die and expansion-die, the dam die is better for short fibers get orientation in rubber matrix during extrusion process than the expansion-die.