3D printing materializes physical objects through sequentially depositing thin layers. The layer-by-layer stacking involves controlling 3D printing parameters (e.g., fan speed, nozzle temperature, printing bed temperature, and filament extrusion rate) to ensure conformity to a CAD (Computer-aided Design) model. Attackers target the parameters during a printing process to sabotage the printing object. This paper presents four new sabotage attacks on the fused filament fabrication (FFF)-based 3D printing process: 1) cavity through filament-kinetics, 2) density variation through filament state, 3) density variation through filament speed, and 4) dynamic-thermal manipulation. These attacks produce an insignificant attack footprint on a finished printed object by targeting localized regions or using small changes in temperature profile, making them hard to detect. Specifically, the first three attacks manipulate filament-kinetics to change the print density or create a cavity in a small localized region, while the fourth attack makes slight changes to the nozzle temperature to manipulate thermal stress in a printing object without creating any visual deformation. Mechanical (tensile and three-point bending) tests carried out on the objects under attack demonstrate that these attacks with insignificant attack footprints can still change the physical properties (e.g., stress and strain) of the printed objects.

3D 打印通过顺序沉积薄层来实现物理对象。逐层堆叠涉及控制 3D 打印参数（例如，风扇速度、喷嘴温度、打印床温度和长丝挤出速率）以确保符合 CAD（计算机辅助设计）模型。攻击者在打印过程中以参数为目标，以破坏打印对象。本文介绍了对基于熔丝制造 (FFF) 的 3D 打印工艺的四种新的破坏攻击：1）通过丝动力学的腔，2）通过丝状态的密度变化，3）通过丝速度的密度变化，以及 4）动态-热操纵。这些攻击通过针对局部区域或使用温度分布的微小变化对完成的打印对象产生微不足道的攻击足迹，使它们难以被发现。具体来说，前三个攻击操纵灯丝动力学来改变打印密度或在一个小的局部区域创建一个空腔，而第四个攻击对喷嘴温度进行轻微的改变，以在不产生任何视觉变形的情况下操纵打印对象中的热应力。在受到攻击的物体上进行的机械（拉伸和三点弯曲）测试表明，这些攻击痕迹微不足道的攻击仍然可以改变打印物体的物理特性（例如，应力和应变）。而第四次攻击对喷嘴温度进行轻微改变，以在不产生任何视觉变形的情况下操纵打印对象中的热应力。在受到攻击的物体上进行的机械（拉伸和三点弯曲）测试表明，这些攻击痕迹微不足道的攻击仍然可以改变打印物体的物理特性（例如，应力和应变）。而第四次攻击对喷嘴温度进行轻微改变，以在不产生任何视觉变形的情况下操纵打印对象中的热应力。在受到攻击的物体上进行的机械（拉伸和三点弯曲）测试表明，这些攻击痕迹微不足道的攻击仍然可以改变打印物体的物理特性（例如，应力和应变）。