A modular testbed for mechanized spreading of powder layers for additive manufacturing

Abstract

Powder bed additive manufacturing (AM) processes, including binder jetting (BJAM) and powder bed fusion (PBF), can manufacture complex three-dimensional components from a variety of materials. A fundamental understanding of the spreading of thin powder layers is essential to develop robust process parameters for powder bed AM and to assess the influence of powder feedstock characteristics on the subsequent process outcomes. Toward meeting these needs, this work presents the design, fabrication, and qualification of a testbed for modular, mechanized, multi-layer powder spreading. The testbed is designed to replicate the operating conditions of commercial AM equipment, yet features full control over motion parameters including the translation and rotation of a roller spreading tool and precision motion of a feed piston and the build platform. The powder spreading mechanism is interchangeable and therefore can be customized, including the capability for dispensing of fine, cohesive powders using a vibrating hopper. Validation of the resolution and accuracy of the machine and its subsystems, as well as the spreading of exemplary layers from a range of powder sizes typical of BJAM and PBF processes, are described. The precision engineered testbed can therefore enable the optimization of powder spreading parameters for AM and correlation to build process parameters in future work, as well as exploration of spreading of specialized powders for AM and other techniques.

A laboratory-scale binder jet additive manufacturing testbed for process exploration and material development

“…The BJAM testbed fits on a tabletop (500 mm x 500 mm x 400 mm) and is the combination of a powder spreading testbed (previously fabricated and described by Oropeza et al [74]) and an inkjet printing testbed, which are mechanically and electrically integrated to enable programmed binder jetting. Figure 2 shows the CAD model and fabricated apparatus, as well as images taken during a binder jetting experiment.…”

“…The testbed was designed according to the target specifications listed in Table 1, and is suited for processing custom powder feedstocks (e.g., polymer, metal and ceramic powders) and binder compositions (e.g., polymer, nanoparticle suspensions, metal salt solutions). The following are the major modules of the machine, including a summary of the modules for powder spreading testbed (denoted by * below) described by Oropeza et al [74]:…”

“…Here we detail the inkjet module which consists of an inkjet dispenser mounted on single-axis linear motion systems stacked in an X-Y configuration. The module is kinematically mounted on top of the powder spreading testbed; the modules and validation of the powder spreading apparatus have been previously presented in detail [74], and therefore are not described further in this paper.…”

A Novel Apparatus for the Simulation of Powder Spreading Procedures in Powder-Bed-Based Additive Manufacturing Processes: Design, Calibration, and Case Study

“…Such configurations can be used for the bi-directional spreading of powders to enhance the process productivity. The use of such systems with cohesive powders can be problematic, since vibrations generated by the scraper movement tend to pack powder in the tank, thereby hindering its flow into the hopper [14][15][16][17][18].…”

“…Furthermore, a series of advanced and highly automated testers were presented in [17,51,52]. Oropeza et al [17] proposed a testing system containing two motorized platforms for controlled powder supply and spreading, a modular powder spreading mechanism capable of using different spreading tools (e.g., motorized roller, stiff or flexible scraper, hopper), and an imaging system overhanging the powder bed. This testing system was designed to study the impact of a spreading mechanism and the layer thickness on the powder bed uniformity.…”