Influence of droplet velocity, spacing, and inter-arrival time on line formation and saturation in binder jet additive manufacturing
Influence of droplet velocity, spacing, and inter-arrival time on line formation and saturation in binder jet additive manufacturing
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DOI：
10.1016/j.addma.2020.101711
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发表时间：
2021-01-01
影响因子：
11
通讯作者：
Crane, Nathan B.
中科院分区：
文献类型：
--
作者：
Colton, Trenton;Crane, Nathan B.
粘合剂喷射（BJ）是一种低成本的增材制造（AM）工艺，它使用喷墨技术选择性地将颗粒粘合在粉末床中。BJ不仅依赖于控制粘结剂在表面上的位置，而且还依赖于其在粉末床中的吸收。这是一个复杂的过程，其中皮升大小的液滴以1-10 m/s的速度撞击粉末床。然而，诸如液滴速度、尺寸、间距和到达间隔时间的打印参数对饱和度（填充有粘合剂的孔隙空间的分数）和线形成（液滴合并以形成线）的影响是未知的。利用液滴基元和毛细管压力的简单测量来预测饱和度水平的先前尝试假定液滴/粉末相互作用由静态平衡主导并且忽略打印参数的影响。本研究分析了这些参数的影响，有效的饱和度和条件的线形成时，打印单线到粉末床的各种材料（316不锈钢，420不锈钢，和氧化铝）和不同的颗粒尺寸（d（50）=10-47 μ m）。结果表明，增加液滴速度或液滴间距会降低有效饱和度，而液滴间距、速度和到达间隔时间会影响线的形成。在恒定的打印速度，成功的行打印的条件被示出为是一个功能的液滴间距和平方根的液滴到达间隔时间类似于渗透到多孔介质中的Washburn模型。研究结果对最大化BJ中小特征的构建速率和提高小特征的质量具有重要意义。
Binder Jetting (BJ) is a low-cost Additive Manufacturing (AM) process that uses inkjet technology to selectively bind particles in a powder bed. BJ relies on the ability to control, not only the placement of binder on the surface but also its imbibition into the powder bed. This is a complex process in which picoliter-sized droplets impact powder beds at velocities of 1-10 m/s. However, the effects of printing parameters such as droplet velocity, size, spacing, and inter-arrival time on saturation level (fraction of pore space filled with binder) and line formation (merging of droplets to form a line) are unknown. Prior attempts to predict saturation levels with simple measurements of droplet primitives and capillary pressure assume that droplet/powder interactions are dominated by static equilibrium and neglect the impact of printing parameters. This study analyzes the influence of these parameters on the effective saturation level and conditions for line formation when printing single lines into powder beds of varied materials (316 stainless steel, 420 stainless steel, and alumina) and varied particle size (d(50)=10-47 mu m). Results show that increasing droplet velocity or droplet spacing decreases effective saturation while droplet spacing, velocity, and inter-arrival time affect line formation. At constant printing velocity, the conditions for successful line printing are shown to be a function of droplet spacing and square root of the droplet inter-arrival time analogous to the Washburn model for infiltration into a porous media. The results have implications to maximizing build rates and improving quality of small features in BJ.