In a previous publication, we described a novel system that forms three-dimensional (3D) structures on 3D molds and two-dimensional (2D) structures on a rotating drum through proper integration of a laboratory scale meltblown unit with a small die and a six-axis robot. In this paper, we investigate the impact of take-up speed. die-to-collector distance (DCD). polymer throughput rate. and attenuating air pressure on the fiber orientation and diameter distribution of 2D structures formed by the system. We introduce a new parameter, the fiber stream approach angle, which can be precisely controlled by the robot, and discuss its impact on the meltblown structure. In the experimental range studied, fiber orientation and diameter distribution are significantly impacted by the parameters. Among these parameters. the fiber stream approach angle shows the highest effect on fiber orientation distribution.Due to their unique microstructure. meltblown nonwoven webs are characterized by lightweight, high-surface area. fine porosity, softness, and high absorbency. which make them good components for protective garments and filtration applications. Currently, the meltblowing technology is used to manufacture tiberwebs in sheet form. but it is impossible to form garments from sheets without joints and/or seams. These seams or joints represent weak links in a protective clothing system, and such links are potential hazards for users of protective clothing. This drawback has prompted us to undertake research with the objective of producing 3D molded seamless meltblown structures by developing a novel robotic fiber assembly and control system (RFACS). In an earlier paper [4], we provided the RFACS description and capabilities along with a study about controlling the basis weight uniformity of 3D molded ti.berwebs.While the main objective of RFACS 1!~ to produce 3D meltblown webs of varying curvatures. a study of the structures of 2D meltblown webs is still providing important data on structures produced by RFACS. since the webs are formed with a small die size compared to the drum (collecting surface) size. Further. manipulating the die by the robot provides precise control of the die orientation relative to the collector surface. Thus. new parameters that may control the structures and properties of meltblown fiberwebs can be studied.It is well known that the fiber diameter and orientation of nonwoven structures govern their properties. such as softness, wicking/absorption. pore shape. pore size. and filtration efficiency. In this paper. we examine the influence of process parameters on fiber orientation (represented by the orientation distribution function. ODF) and fiber diameter distribution of 2D fiberwebs produced by RFACS using a drum as a collector. We also examined a new parameter, the fiber stream approach angle. which can be precisely controlled by the robot manipulator. ExperimentalMeltblown nonwoven samples were produced from polypropylene (PP) resin with a nominal melt flow rate (MFR) of 1200 using RFACS. The processi...

A novel system is described that forms three-dimensional (3D) molded nonwoven structures through proper integration of a laboratory scale meltblown unit with a small die and a six-axis robot. The 3D fiberweb structures can be formed by deposition of fibers from the die of the meltblown unit, which is manipulated by the robot, on any desired 3D mold. The mold rotational and surface speeds can be controlled by an additional external axis. The die is connected by two flexible hoses to the melt extruder of the meltblown unit and a hot air supply system. This system directly sprays fibers onto a 3D mannequin mold to produce structures from polypropylene polymers. With varying degrees of success. several robot manipulation algorithms of fiber deposition on the mold are developed to accurately control the basis weight uniformity the fiberwebs. A rule-based control algorithm using a linear variable differential transducer to map the mold contour results in the greatest fiberweb basis weight uniformity.

A novel system that forms two-dimensional (2D) structures on a rotating drum and three-dimensional (3D) structures on 3D molds through proper integration of a laboratory scale meltblown unit with a small die and six-axis robot is briefly described. The system advantages over traditional systems are demonstrated. Parametric studies evaluating the effect of take-up speed, die-to-collector-distance (DCD), polymer throughput rate, and attenuating air pressure on the fiber orientation distribution functions (ODFs) of 2D structures formed by the system are reported. An additional new parameter termed "fiber-stream approach-angle" is introduced and its impact on the ODF of 2D structures is also reported. Under the experimental range studied, the ODFs were significantly impacted by the parameters studied. The fiber-stream approach angle showed the highest impact, among the parameter studied, on the ODF.

In previous publication, the influence of process parameters on the fiber orientation of the meltblown web was evaluated [4]. The meltblown webs were formed using Robotic Fiber Assembly and Control System (RFACS), which is described in previous publications [3,4]. In this paper, parametric studies evaluating the effect of polymer throughput rate, attenuating air pressure and temperature, and die temperature, on fiber diameter distributions of meltblown webs from polypropylene produced by RFACS are reported. Fiber diameters were determined by analyzing fabric images obtained through scanning electron microscopy (SEM). Under the specific conditions explored, the fraction of fibers of diameter smaller than 10 microns (µm) can increase by 72% with a 7.9 x 10 -2 g/min/hole (82%) reduction in throughput. A 54% increase of the same can be observed with a 2.8 bar (400%) increase in attenuating air pressure. A change of 45ºC (16 %) in air temperature is shown not to significantly affect fiber diameters produced, while an increase of 67ºC (26%) in die temperatures can result in an increase of 17% in the fraction of fibers of diameter smaller than 10µm. All fiber diameter distributions are shown to be unique to the condition evaluated as no overlap across distributions for changes in a given parameter is observed. Further fiber fraction smaller than 10 µm data is also shown to be unique to each parameter evaluated.

This paper presents an overview of research on the production of nonwoven and tailored 3D structures for protective garments (such as those worn by fire fighters) using robotics and meltblown technology. In particular, the integration of robotics and a small-scale melt-blowing unit is discussed. This paper develops the framework and general motivation for the overall study and describes in detail the novel 3D-fiber application system developed using a seven-degree of freedom system. This system will be used with control algorithms developed at the NCRC to improve uniformity of the shaped fabric structure.