Nylon Powder Research Articles

Hypersensitivity pneumonia from the past to the future

HP is an inflammatory and/or fibrotic disease affecting the lung parenchyma and small airways. Exploring the historical context of HP helps to understand how significant changes in risk factors over time have influenced its development. More than 300 etiologic agents have been identified as the cause of the disease. Bacteria, fungi, animal proteins, plant proteins, low molecular weight chemicals, and metals have been identified as inciting agents. Many inciting agents have been associated with HP since its recognition in 1700. New exposures continue to be suspected as causative factors in the development of HP. As occupational and unsalaried avocational practices evolve, give rise to an ever-expanding list of HP-inducing risk factors, including three-dimensional printers (thought to be due to nylon powder used in its manufacture), contaminated home continuous positive airway pressure machines and dental products (methyl acrylates affecting dental technicians).

Epoxy filled with nylon powder—An approach to reduce void formation via fused particle method

AbstractIn the quest for superior materials, especially in industrial applications demanding strength, stiffness, low density, and cost‐efficiency, composite materials have emerged as game changers. Combining a polymer matrix with reinforcement materials, they hold great promise. However, the challenge of particle agglomeration looms large, especially at high loadings. Particle agglomeration disrupts filler distribution and gives rise to voids in polymer composites. This study investigates the fusion behavior of agglomerated Nylon particles and their influence on Nylon/epoxy composites. Using epoxy resin and Nylon SP301, a micron‐sized Nylon 12 powder with a 185°C melting point, composites were prepared at 3%, 9%, and 15% Nylon loading. After curing, these composites underwent controlled heating at 185, 195, and 205°C, with a fusion of 20–100 min. At 185°C, particles initially remain separate, forming slight clumps after 20 min and increasingly sticking together at 60 and 100 min. Shifting to 195°C, particles begin consolidating into a solid mass even after 20 min. The introduction of Nylon decreases composite density compared to pure epoxy, and density changes vary with fusion time, exhibiting complete fusion, partial fusion, and shrinkage‐induced gap formation. Differential scanning calorimetry analysis reveals evolving glass transition temperatures (Tg) influenced by the fusion process, with longer fusion times yielding higher Tg and greater heat capacity.

Powder flowability characterisation at preheating temperature in additive manufacturing

ABSTRACT The powder spreading process is usually performed at preheating temperature in powder-bed-based additive manufacturing (AM). Thus, the powder flowability characterisation at preheating temperature is important for powder spreading processes. However, devices for traditional powder flowability characterising methods are mainly designed for specific conditions at room temperature and cannot consider the effect of temperature on powder flowability. In this work, an experimental platform with a heated rotating drum was set up and a high-speed camera was used to record powder avalanche processes in a heated rotating drum for the powder flowability characterisation at preheating temperature. Nylon and stainless steel powder flowability at different temperatures was assessed by the statistical analysis of avalanche angle, avalanche time, arithmetic mean deviation and surface linearity of powder surface profile. Four parameters provide a good characterisation of powder flowability. The results can provide guidance for the powder flowability characterisation method at preheating temperature in AM.

Recycling PA12 powder from laser powder bed fusion through producing filament for fused deposition modelling

The laser-powder bed fusion (L-PBF) process presents advantages over other polymer additive manufacturing processes in terms of part strength and high production rate possible with the technology. The high cost and limited re-use of nylon powder used in the process however limit the large-scale adoption of the technology in industry. This paper investigated the re-use of PA12 powder that is no longer suitable for the L-PBF process through producing filament for the fused deposition modelling (FDM) process. Results from the study showed that parts with good mechanical strength and reasonable dimensional accuracy can be produced using FDM.

Absorption of millimeter- and micrometer-sized droplets on nylon powder

Absorption of droplet by the powder media is a ubiquitous phenomenon in many natural and engineering processes, in which the diameter of droplets ranges from tens of micrometers (μm) to a few millimeters (mm) depending on the specific condition. In this study, we investigate the absorption process following the impact of the droplet with radii varying from mm- to μm-scale on nylon powder substrate. The fluid properties are varied by mixing the deionized water with isopropyl alcohol at different volume ratios. A syringe pipette tip is used to generate droplets of diameter ranging from 2.08 to 2.30 mm, whereas a drop-on-demand inkjet device is used to dispense droplets of diameter ranging from 88 to 140 μm. The absorption process of the single droplet is captured by a high-speed imaging system. We find that for mm- and μm-droplets, there exists different critical surface tension below which the imbibition into the nylon powder can occur. With the proposed nondimensionalization process, the scattered data of dimensionless absorbed volume V and dimensionless time τ for different fluids generally collapse into a power law relation V ~ τα, where the exponent α for mm-sized and μm-sized droplets is 0.856 and 0.518, respectively. The experimental data of μm droplets generally agree with the prediction of the Washburn equation and diffusion-type equation for the unidirectional capillary flow, i.e., V ~ τ0.5. However, the results of mm-droplets favor more the prediction of the 3D radial flow (i.e., a hemispherically advancing infiltration front inside the powder), V ~ τ.

Modeling and numerical research on powder paving process of nylon powder in selective laser sintering

Modeling and numerical research on powder paving process of nylon powder in selective laser sintering

Optimasi Inventori Material Bubuk Nylon pada Proses Coating dengan Pendekatan Probabilistik

<p><em>This research aims to optimize the supply of raw material for nylon powder for the manufacturing industry. The problem was found in the nylon powder warehouse which was out of stock so that it had to be replaced with plastic raw materials to keep the production process running. The change of raw material from nylon powder to plasco was done because the company did not make an emergency order for nylon powder. This is due to the high cost of emergency orders. The use of plasco powder makes the company accept a sizeable return of goods. Therefore it is necessary to do a good inventory management to overcome the out of stock. The method used to solve this problem is the probabilistic P back order model. Demand in the previous period was normally distributed. The results of processing with the P back order model produce a service level of 99.95%. It is hoped that the company will not experience out of stock again. In addition, a savings of 4.50% were obtained from the total costs incurred by the company. Inventory policy obtained using the P back order model with an order time of (T) 0.358 or for 130 days a new order will be made, and the total inventory cost is Rp.418,363,268 / year with a service level of 99.995%.</em></p>

Investigation of the Effects of Roller Spreading Parameters on Powder Bed Quality in Selective Laser Sintering.

Powder spreading is one of crucial steps in selective laser sintering (SLS), which controls the quality of the powder bed and affects the quality of the printed parts. It is not advisable to use empirical methods or trial-and-error methods that consume lots of manpower and material resources to match the powder property parameters and powder laying process parameters. In this paper, powder spreading in realistic SLS settings was simulated using a discrete element method (DEM) to investigate the effects of the powder’s physical properties and operating conditions on the bed quality, characterized by the density characteristics, density uniformity, and flatness of the powder layer. A regression model of the powdering quality was established based on the response surface methodology (RSM). The relationship between the proposed powdering quality index and the research variables was well expressed. An improved multi-objective optimization algorithm of the non-dominated sorting genetic algorithm II (NSGA-II) was used to optimize the powder laying quality of nylon powder in the SLS process. We provided different optimization schemes according to the different process requirements. The reliability of the multi-objective optimization results for powdering quality was verified via experiments.

RESEARCH ON THE EFFECTS OF ROLLER-SPREADING PARAMETERS FOR NYLON POWDER SPREADABILITY IN ADDITIVE MANUFACTURING

The powder spreading process is one of the key processes in the powder-bed-based additive manufacturing (AM) technology. The roller-spreading parameters include the powder spreading layer thickness H, roller’s diameter D, roller’s rotational speed ω and translational velocity V, which have a major impact on the powder spreadability in AM processes. In this paper, the nylon powder was taken as the research object, and the discrete element method (DEM) was deployed to simulate the nylon powder spreading process by a roller. The three powder spreadability indicators including the deposition fraction, percent coverage and deposition rate were established. The central composite design (CCD) model was used to generate 30 groups of simulation cases. The regression models of three powder spreadability indicators were fitted by the response surface method (RSM). The analysis of variance was used to prove the accuracy and predicting effectiveness of regression models. In addition, the effect of process parameters on powder spreadability indicators was analyzed in detail. The results showed that the powder spreading layer thickness H was a leading influencing factor. The roller’s translational velocity V was a less important influencing factor. The roller’s diameter D and rotational speed ω had a slight influence on powder spreadability indicators. Both the H and D with V were determined as the main interactive factors on powder spreadability indicators. The three powder spreadability indicators were taken as the optimization goal, and the multi-objective optimization of roller-spreading parameters was carried out by the expectation method. The predicted optimal combination of powder spreading parameters and powder spreadability indicators were obtained. Moreover, the optimal results were verified through the experiments. The results showed that the predicted results of powder spreadability indicators were in good agreement with experimental results. The research results in this paper can provide guidance for the optimization of roller-spreading parameters in AM.

Comparison of roller-spreading and blade-spreading processes in powder-bed additive manufacturing by DEM simulations

The roller-spreading and blade-spreading are main powder spreading methods in powder-bed additive manufacturing. The discrete element method was introduced to simulate nylon powder spreading by both roller and blade spreaders. The two spreading processes were compared from several aspects including particle flow behavior, particle contact forces, forces exerted on spreaders, particle segregation and powder layer density. It is found that powder spreading methods mainly affect the movement trajectory of particles, particle contact forces and forces exerted on spreaders. Complicated dispersion and circulation movement of particles occur inside the powder pile by roller-spreading, while particles have relatively weak dispersion by the blade-spreading. The normal force applied to the roller introduces a compacting effect on the powder pile and creates strong force chains that distribute uniformly in the powder pile. Therefore, the powder bed with higher density can be obtained by roller-spreading in thicker powder layer due to the compacting effect. The blade spreader sustains tangential force mainly, so the blade-spreading process limits its application to thicker powder layer. As the powder layer thickness increases, the roller-spreading is more sensitive to segregation index than that of the blade-spreading. The comprehensive comparison of two spreading processes provides criteria for selecting spreading methods.

Sifat Mekanis pada Kompon Karet Alam Variasi Campuran Serbuk Ban Bekas untuk Aplikasi Bantalan Mesin

Rubber is a good material used for engine mounting because it has good elastic and damping properties. To obtain good mechanical and damping properties, fillers can be added such as carbon black, nylon powder and silica. In this study used used tire crumb as filler material. With the method of adding used tire powder 0 phr, 6 phr, 12 phr, 18 phr sequentially on natural rubber compound A, B, C, and D. Rubber compounds made in this process are tested to determine the mechanical properties and Dumping vibrations. Tests carried out namely, strength and elongation at break, hardness, tearing strength, flex crack resistance and dumping vibration ( ability to reduce acceleration of vibration propagation ). The test results show a decrease in the strength of 21.7 N / mm², 20.9 N / mm², 20.3N / mm², 20.5 N / mm², and also at the elongation at break test with an average of 430%, 415%, 423%, 425%. Sequentially on A, B, C and D vulcanizates. Trends of hardness test chart to increase 61 Shore A, 63 Shore A, 64 Shore A and 65 Shore A, while the tear strength also shows an increase and decrease with an average yield of 12.5 N / mm², 12.6 N / mm², 11.3 N / mm², 13.3 N / mm² on A, B, C and D vulcanizates.

Study on traces left on a mechanical lock picked by a 3D printed key in toolmarks examination

The three-dimensional (3D) printed key is a key that can be manufactured from its virtual model by means of a 3D printer. This research focuses on the picking feasibilities and traces that can be observed and exploited from a forensic point of view after the picking of such type of keys.In this paper, 40 printed keys were manufactured using three different polymer materials (white resin, white nylon powder and black ABS). All the experiments were carried out under controlled conditions to allow the collections of data and traces produced by the picking. Of the 40 prints, only 38 picked the locks and the total picking ratio was 95 percent, meaning that a 3D printed key using polymer materials can be used to pick a lock. Elements of lock – pins and keyways – appeared to carry polymer materials (flakes or pieces) transferred from the prints during picking process. Additional, characteristic marks of a 3D printed key on the surface of pins was identical to those of an original key, but not similar to those of other picking tools. Indeed, this method could not create more marks on the bits of an original key while striations were left by the picking method using a duplicated key. Besides, FT-IR was a useful method of analyzing the type of polymer material used.When receiving original keys and a lock suspected to be picked in a crime scene, the toolmark examiners can quickly determine whether or not the lock was picked by a 3D printed key based on the examination results of these traces.

Discrete Element Simulation of Factors Affecting the Fluidity of Nylon Powder

Powder fluidity is one of the important factors affecting the smoothness of selective laser sintered parts and the mechanical properties of sintered parts. In this paper, the angle of repose (AOR) and angle of internal friction of nylon PA3200 powder were measured by a powder comprehensive tester and a direct shear tester to evaluate the flow properties of the powder particles. Based on the discrete element method (DEM), the rolling resistance contact model and the van der Waals force model were used to describe the interaction forces between the powder particles. The rolling resistance coefficient and friction coefficient within the contact model were calibrated by the results of the AOR experiments. Based on the orthogonal experimental method, the particle size and particle size distribution (PSD) (such as uniform distribution and Gaussian distribution) were selected as the influencing factors, and the effect of particle size and PSD on the fluidity of nylon PA3200 powder was studied by numerical simulation. The results show that the PSD has a stronger influence on the AOR than particle size, and the fluidity of uniform distribution is better than that of the Gaussian distribution.

Photoprintable nanowire–polymer blends synthesized by dynamic emulsion polycondensation

ABSTRACTIn this article, we report a photoprintable nanocomposite synthesized at room temperature in less than 10 s by aggressive mixing of two monomer solutions. Polycondensation occurs in the dispersed phase of the dynamic emulsion, microdroplets, in which the nanofillers are suspended. Hence, the synthesized composite microparticles have a high dispersion and high loading of nanofillers. Specifically, silver nanowire (AgNW)–nylon 66 blends with various Ag weight fractions are synthesized and studied. The poly(vinyl pyrrolidone) (PVP)‐functionalized AgNWs (by polyol synthesis) are singly dispersed and tethered to the nylon matrix by PVP with a slight depression of the glass‐transition temperature. The Ag–nylon powder melts under low‐intensity visible continuous wave laser radiation; this allows convenient photoprinting of the nanocomposite structures. Photoprinting is demonstrated at a radiation intensity of 0.3 kW/cm2 (405 nm laser) and a scan rate of 5 mm/s for a 1.49 wt % Ag content. This enhanced photothermal characteristic of the nanocomposite, which allows printing at low radiation intensities, is attributed to the efficient coupling of light to the AgNW plasmon modes and the high dispersion of nanowires in the polymer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47670.

Digital interlooping: 3D printing of weft-knitted textile-based tubular structures using selective laser sintering of nylon powder

ABSTRACTThis paper discusses the materialisation of 3D printed textile-based tubular forms that make use of knit’s primary structures. The 3D printed forms explore both single-face and double-face weft knit structures at various sizes. 3D printing is a form of digital additive manufacturing whereby the building up of layers of material creates objects. The selective laser sintering process (SLS) uses a laser beam to sinter powdered material to create objects. This paper builds upon previous research into 3D printed textile-based structures exploring the use of SLS of Nylon powder to create flexible weft knitted structures. The results show the potential to print flexible, tubular textile-based structures at various scales that exhibit the properties of traditional knitted textile structures along with the mechanical properties of the material used to print with. The conclusion highlights the potential future development and application of such pieces within apparel-related industries.

Design and development of a lightweight SLS 3D printer with a controlled heating mechanism: Part A

Selective laser sintering (SLS) is one of the hot topics in the manufacturing research community. The SLS printers developed by the researchers have shown a great potential, however, it needs a lot of improvements to be considered for commercial usage. Here, we report an improved design of the SLS printer with a unique heating mechanism to ensure enhanced mechanical properties of the final part. These improvements came in the form of enhanced heating mechanism for the printer once the reverse engineering concepts were put together to come up with an innovative yet scalable design. The design included two axes movement of the laser via computer numerical control (CNC) router as opposed to traditional complex controlled reflecting mirrors. Complete models were developed regarding the laser power, motor torque and determining the specific layer height for layer by layer sintering based on the nylon powder as the raw material. Static structural analysis was carried out on the printer to identify the material to be used for required strength. Complete electrical control of the printer was developed using Raspberry Pi which was coded via python to control the motors of each axis in the printer. Successful testing of the electronic and control system of the proposed SLS printer is also illustrated in this work.

Adaptive monitoring of multimodal data

Abstract Multimodal process data that include several subpopulations appear frequently in many complex applications due to process heterogeneity. Different from the most existing control charts that are only applicable to unimodal data, a new adaptive monitoring method is proposed in this paper for multimodal data from heterogeneous processes. Specifically, a Gaussian mixture model is first employed for data modeling. Considering the number of subpopulations that may change in Phase II, a penalized likelihood function is devised to infer the true number of subpopulations by shrinking any insignificant or redundant Gaussian components. Our proposed control chart, is thus not only sensitive to process changes in subpopulation parameters, but also adaptive to changes in the number of subpopulations. A diagnostic procedure is also followed to classify the changes in multimodal data. The superiority of our chart is fully demonstrated through numerical Monte Carlo simulations and a real industrial example in the production process of a 3D printing nylon powder material.

A polymer colloidal technique for enhancing bending properties of carbon fiber-reinforced thermoplastics using nylon modifier

To enhance the bending properties of carbon fiber-reinforced thermoplastics (CFRTPs) by improving their interfacial properties, a new colloidal technique has been developed in this work. First, colloidal polymer containing the main components of thermoplastic nylon resin was synthesized from nylon powder and surfactants or through emulsion polymerization and then subsequently adsorbed on the surface of carbon fibers by electrodeposition. The strength of the surface adhesion between the modified carbon fibers and nylon was estimated by measuring their interfacial shear strength (ISS) via fragmentation testing. The obtained results revealed that both the ISS and impregnation ratio of nylon depended on the amount and composition of the adsorbed particles. Furthermore, the relationship between the interfacial and bending properties of CFRTP was clarified. The data by three-point bending tests showed that the contribution of the impregnation ratio of nylon to the enhancement of the bending strength of CFRTP was much larger than that of ISS.

Understanding and improving optical coherence tomography imaging depth in selective laser sintering nylon 12 parts and powder

Optical coherence tomography (OCT) has shown promise as a process sensor in selective laser sintering (SLS) due to its ability to yield depth-resolved data not attainable with conventional sensors. However, OCT images of nylon 12 powder and nylon 12 components fabricated via SLS contain artifacts that have not been previously investigated in the literature. A better understanding of light interactions with SLS powder and components is foundational for further research expanding the utility of OCT imaging in SLS and other additive manufacturing (AM) sensing applications. Specifically, in this work, nylon powder and sintered parts were imaged in air and in an index matching liquid. Subsequent image analysis revealed the cause of “signal-tail” OCT image artifacts to be a combination of both inter and intraparticle multiple-scattering and reflections. Then, the OCT imaging depth of nylon 12 powder and the contrast-to-noise ratio of a sintered part were improved through the use of an index matching liquid. Finally, polymer crystals were identified as the main source of intraparticle scattering in nylon 12 powder. Implications of these results on future research utilizing OCT in SLS are also given.

Mechanical Properties of 3D Isotropic Anti‐Tetrachiral Metastructure

Chiral metastructures consisting of ring (polygonal or cubic) nodes and elastic bending ligaments exhibit excellent design flexibility for compliant structures. In this paper, based on rigid cubic node rotation and the kinematic geometrical relations of a three‐dimensional (3D) isotropic anti‐tetrachiral structure, an analytical expression for the modulus of the 3D isotropic anti‐tetrachiral structure is derived from strain energy analysis. The nylon powder Selected Laser Sintering (SLS) additive manufacturing technique is employed for fabricating two types of 3D isotropic anti‐tetrachiral specimens with different geometrical parameters; then comparison between experiments, finite element analysis (FEA), and theoretical studies is performed for verifying the analytical formula. The mechanical properties of 3D isotropic anti‐tetrachiral structures can be tuned with two independent dimensionless geometrical parameters. The proposed 3D anti‐tetrachiral structures can be employed for designing advanced structures against impact damages, realizing flexibility of industrial components, and optimizing the vibration attenuation abilities of engineering structures.