Metal Powder Injection Research Articles

Influence of the Injection Process on Two-Phase Separation in Stainless-Steel Metal Powder Injection Molding

Influence of the Injection Process on Two-Phase Separation in Stainless-Steel Metal Powder Injection Molding

Enhancement of 316 L stainless steel mechanical properties through TiC particle introduction via metal powder injection molding

Abstract Metal powder injection molding (MIM) has been a popular technique in production of alloy materials. Through this technique, near-net-shape alloy products can be molded with one-step production. Stainless steel 316 L (SS 316 L) is an important material in aerospace and marine industry for its excellent material strength and resistance to corrosion. As the industry grows with upgraded techniques, the standard for next generation material strength has improved tremendously. Here we present a practical method strengthening SS 316 L via MIM technique, which might provide a pathway for exploration of high strength materials. TiC was introduced into SS 316 matrix with polyoxymethylene (POM) binder. The metallography indicates that the introduction of TiC facilitates the refinement of the 316 L grain. As the TiC content increases from 0 wt% to 3 wt%, the material properties improve significantly, including a rise in hardness from 151 HV to 301 HV, tensile strength from 689 MPa to 792 MPa, and yield strength from 221 MPa to 339 MPa. Additionally, there is a noticeable reduction in the coefficient of friction and the wear cross-section.

Surface hardening of MIM porous metals by ultrasonic vibration assisted pressing

Metal powder injection molding (MIM) has attracted attention as a cost-effective manufacturing method for serial producing complex designed micro metal parts. However, unavoidable micropores are observed in MIM parts that lead to poor bending strength, especially in small-sized products. This disadvantage is significant in the medical field. Ultrasonic vibration assisted surface hardening can be a solution. This surface strengthening method uses an ultrasonically vibrating punch to work-harden the surface, enabling localised hardening in a short time without using highly toxic chemicals or large-scale equipment. In addition, porous metals have the properties of absorbing sound and shock, which allows them to efficiently absorb the energy of ultrasonic vibrations and effectively harden the surface. In this study, we verified the effect of the ultrasonic vibration assisted surface hardening, the influence of the porous structure, and the mechanism of surface strengthening. As a specimen, MIM processed pure copper and stainless steel 316L specimens were used to compare with specimens without porous structure through investigations such as surface hardness test, electron backscatter diffraction analysis, and surface roughness measurement. After hardening, it was confirmed that the MIM specimens had an obviously increased surface hardness and a significantly reduced surface roughness compared to the specimens without porous structure. In addition, the hardening caused a increase in strain near the surface and around the pore walls inside the material. From these results, it is supposed that the pores inside the material absorbed the vibration energy and deformed slightly, and the strain on the surface increased due to the impact effect. This experiment demonstrated that ultrasonic vibration assisted surface hardening can effectively improve the surface strength and roughness of porous metals and can be used as a method that does not impair the original ductility by absorbing vibration energy through pores.

Research on intelligent analogy design method of cylindrical gear metal powder injection molding process based on knowledge-driven

Research on intelligent analogy design method of cylindrical gear metal powder injection molding process based on knowledge-driven

Research on and Application of Feature Recognition and Intelligent Retrieval Method for Multi-Component Alloy Powder Injection Molding Gear Based on Partition Templates

The forming process of multi-alloy gears by metal powder injection molding is tedious, and the current design process mainly depends on the experience of designers, which seriously affects the product development cycle and forming quality. In order to solve the problem of the gear feature expression being missing, which hinders the automatic retrieval of similar parts in the analogical design process, a feature recognition and intelligent retrieval method for a multi-alloy powder injection molding gear based on partition templates is proposed in this paper. The partition templates of the gear are defined, and gear digitization is completed by using the automatic recognition algorithm. Searching for similar gear parts in the knowledge base, designers can analogically design the forming process for new parts according to the mature process of the parts in the knowledge base. The automatic identification and intelligent retrieval system developed according to this method has been implemented in two MIM (metal injection molding) product manufacturing enterprises. Case studies and industrial applications have proved the effectiveness of the system, the efficiency of identification and retrieval has been improved by more than 97%, and the number of mold tests has been reduced by 60%.

Investigating the mechanical properties of sintered 440 C stainless steel produced by an extrusion-based 3D printer

Extrusion-based 3D printing of parts is one of the simplest, cheapest, and most widely used additive manufacturing (AM) methods. The raw materials in this process are generally filaments with a constant diameter. By equipping extrusion-based 3D printers with the barrel and screw system and removing the filament manufacturing step, a wide range of materials can be 3D printed. In this research, the parts were 3D printed using a feedstock of metal powder injection molding process and with a direct granule extruder system equipped with a barrel and screw. Then, on the printed parts, debinding, sintering, and grinding processes were performed, and finally, their tensile and impact mechanical properties were evaluated. The average tensile strength and modulus are equal to 295 MPa and 85 GPa, respectively, the average of impact resistance is equal to 12.5 J and the hardness number is equal to 118 HB. In addition, by calculating the amount of porosity in the samples, the low value of the mechanical properties of the samples was justified.

An experimental investigation of screw-based material extrusion 3D printing of metallic parts

With the introduction of additive manufacturing (AM) methods, processes with the capability of 3D printing of metal materials were noticed. In general, AM processes with the ability to 3D print metals are more complex and costly in terms of equipment than processes that 3D print other materials (polymers and ceramics). Therefore, the use of 3D printing devices with less complexity and cost, such as extrusion-based 3D printers, for metal printing has attracted the attention of researchers. In this research, an extrusion-based 3D printer, equipped with a direct granule extruder system, was used for 3D printing of the feedstock of the metal powder injection molding (MPIM) process (with 93.7 % by weight of 440 C stainless steel metal powder). The optimal parameters of printing including linear speed (10 mm/s), temperature at the beginning (140 ℃) and end of the barrel (180 ℃), chamber's temperature (60 ℃), and nozzle diameter (0.5 mm) were determined experimentally. The debinding and sintering process was performed on 3D-printed samples. The samples are brittle after the sintering process, in such a way that the failure of the samples occurs by applying a small amount of force to them. According to the scanning electron microscope (SEM) micrograph of the fracture cross-section of the sintered samples, the number of cavities and defects in the samples was negligible and the presence of residual carbon can be seen in the sintered samples. According to the results of X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDAX), the oxidation of iron and chromium elements as well as the presence of residual carbon (7.8 %), are the main factors for the incomplete sintering of the 3D printed samples.

Characterization of Mechanical Properties and Grain Size of Stainless Steel 316L via Metal Powder Injection Molding

The metal powder injection molding process is completed by mixing a metal powder and a binder, performing an injection molding and degreasing process, and then performing a sintering process for high density. The disadvantage of metal powder injection molding is that defects occurring during the process affect mechanical properties, which are worse in mechanical properties than in products manufactured by cold-rolling. In this study, the mechanical properties and microstructure of stainless steel 316L manufactured by the metal powder injection molding process were analyzed. Mechanical properties such as density, tensile strength, and fatigue life were analyzed. The density was measured using Archimedes' principle, and a relative density of 94.62% was achieved compared to the theoretical density. The tensile strength was approximately 539.42 MPa and the elongation to fracture was approximately 92%. The fatigue test was performed at 80% of maximum tensile strength and a stress ratio of R = 0.1. The fatigue life was found in 55% (297 MPa) of maximum tensile strength that achieved 106 cycles. The microstructure was observed through scanning electron microscope after etching, and as a result, the average grain size was 88.51 μm. Using electron backscatter diffraction, inverse pole figure map, image quality map, and kernel average misorientation map of the specimen were observed in three different areas which were undeformed, uniformly deformed, and deformed. Based on these results, it is expected that research is needed to apply the metal powder injection molding process to the manufacture of agricultural machinery parts with complex shapes.

Rücktitelbild Chem. Ing. Tech. 1–2/2023

Chemie Ingenieur TechnikVolume 95, Issue 1-2 p. 296-296 Back CoverFree Access Rücktitelbild Chem. Ing. Tech. 1–2/2023 First published: 19 January 2023 https://doi.org/10.1002/cite.202370108AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Study of iron particles distribution during metal powder injection in tubular reactor for combustion analysis under μg conditions. Copyright: 2022 Leibniz-Institute for Materials Engineering IWT by courtesy of Airbus Defence and Space Volume95, Issue1-2Special Issue: Prof. Dr.-Ing. Joachim Werther zum 80. Geburtstag gewidmetJanuary/February 2023Pages 296-296 RelatedInformation

Investigation of Metal Powder Injection into a Combustion Chamber by Large Eddy Simulation for Power to X Studies

AbstractThe numerical modeling and simulation of particle dispersion during the filling process of a tubular combustion chamber are presented. By means of multiphase large eddy simulations (LES) the particle distribution inside a circular diffuser‐reactor chamber is studied to analyze the two‐phase flow dynamics for metal powder combustion in a tubular reactor with flame propagation. Typical particle accumulations are found that form close to the reactor wall and also particles tend to segregate and preferentially concentrate at vortex surfaces in particle bands. Particle segregation and accumulation effects aside vortex structures are analyzed using the LES approach. The causes of particle segregation and inhomogeneities are studied and measures for its reduction by changes in the reactor design are discussed. Alterations of the diffuser geometry are adapted to minimize the central particle jet formation and the particle distribution inhomogeneities during the filling process.

Experimental Evaluation of the Feasibility and Reproducibility of a Novel Multi-step Forming Process for Cu-OFE Micro Gear Manufacturing Compared to Macro-scale Forming

The increasing miniaturization of technical systems leads to a rising demand for micro components. Miniaturized drive systems with geared micro parts or micro gears are applied in various industries. Due to the demand for high production volumes, productive and resource-efficient fabrication is of major importance. Compared to industrially applied manufacturing methods like cutting and metal powder injection, cold forming provides technological, economic and ecological potential for the mass production of micro gears. It enables high productivity and advantageous mechanical properties of the gears. In the macroscopic size range, forming processes are well established in series production of gears. However, in micro-scale, according to the current state of the art, cold forming of modules m<0.2mm is not possible due to size effects, high tool loads and handling problems. Within this contribution, a multi-stage forming process for the fabrication of micro gears with a module of m=0.1mm is introduced and compared with a conventional forming process on macro-scale with a module of m=1.0mm. The use of coil material provides potential for easy handling of the micro parts in a progressive die for the potential application in a high-speed press. In addition, the multi-stage forming achieves a grain alignment, which enhances the formation of the micro gear profile. Based on the comparison between micro- and macro-scale, the performance of the micro process is analyzed with regard to deviations of process force as well as gear quality and possible size effects are identified. The results prove the feasibility of the process chain and the achievement of equivalent part quality and reproducibility compared to macro-scale forming.

Hybrid Taguchi-Gray Relation Analysis Method for Design of Metal Powder Injection-Molded Artificial Knee Joints with Optimal Powder Concentration and Volume Shrinkage.

Artificial knee joints play a critical role in improving the quality of life of the elderly and those with knee injuries. Such knee joints are fabricated using a composite material consisting of metal alloy particles and polymer resin and are generally produced using the metal powder injection molding (MIM) process. However, if the local powder concentration of the molded product is too low, the mechanical properties and aesthetic appearance of the joint are severely degraded. Similarly, if the product undergoes excessive shrinkage following removal from the mold, the dimensional accuracy will fail to meet the design specifications. Accordingly, the present study applies a hybrid approach based on the Taguchi robust design methodology and gray relation analysis (GRA) theory to determine the optimal MIM processing conditions that simultaneously maximize the powder concentration uniformity while minimizing the volume shrinkage. The feasibility of the proposed approach is demonstrated by means of CAE (Computer Aided Engineering) mold flow simulations. The results show that while the robust Taguchi design method enables the optimal processing parameters that maximize the powder concentration uniformity and minimize the volume shrinkage to be individually determined, the hybrid Taguchi–GRA method enables both quality measures to be optimized simultaneously.

Qualitative and Quantitative Microstructural Analysis of Copper for Sintering Process Optimization in Additive Manufacturing Applications

Abstract This work will present possibilities for the characterization of copper powder green bodies and sintered copper microstructures during pressureless sintering. The introduction of new parameters to microstructural characterization based on qualitative and quantitative microstructural analysis will facilitate the systematic optimization of the sintering process. As a result of the specific evaluation of the microstructure evolution, conventional isothermal sintering could be successfully replaced by multi-step temperature profiles, thus achieving sintering densities of more than 99 % by simultaneously reducing process time. This systematic optimization of the sintering process of Cu through specific microstructural analysis may now be applied to sinter-based manufacturing technologies such as Binder Jetting and Metal Powder Injection Moulding, enabling the manufacture of complex and highly conductive Cu parts for applications in electronics.

Fracture Toughness of Hollow Glass Microsphere-Filled Iron Matrix Syntactic Foams.

In this study, iron-based metal matrix syntactic foam (MMSF) containing hollow glass microspheres as filler was investigated with respect to notch sensitivity aspects. The MMSF was produced by means of metal powder injection molding. The notch sensitivity was studied via (i) elastic-plastic fracture mechanics measurements (determination of R-curves based on three-point bending tests) and (ii) Charpy impact tests. In both cases, the samples were machined with two different (U- and V-shaped) notch geometries. The critical J-integral value was determined for both notch types, which resulted in lower fracture toughness values in the case of the V-shaped notches and thus notch sensitivity of the material. This finding can be connected to the characteristics of the deformation zone and the associated stress concentration at the tip of the machined notches. The results were confirmed by Charpy impact tests showing ~30% higher impact energy in the case of the U-shaped notch. The failure modes were investigated by means of scanning electron microscopy. In contrast to the bulk material, the MMSF showed brittle fracture behavior.

Production of Mg-Ca-Zn-Zr-Cu alloy for resorbable compression screw in bone fixation applications

ABSTRACT In this work, biodegradable Mg-Ca-Zn-Zr-Cu alloy specimens were manufactured for temporary implant (compression bone screw or interference screw) applications in the bone fixation applications. Mg-Ca-Zn-Zr-Cu alloy specimens were produced by the metal (powder) injection moulding (MIM/PIM) method. Small and complex parts can be manufactured with the metal (powder) injection moulding (MIM) technique. The metal powder mixtures were mechanically alloyed to prepare the Mg alloys. A mixture consisting of paraffin wax, polyethylene and stearic acid was used as a multi-component polymer binder. Electrochemical corrosion performance of the Mg alloy samples was investigated in the simulated body fluid solution. The experimental findings demonstrated that the electrochemical corrosion resistance of the samples was enhanced with the alloying the Mg. Biodegradation (resorption) performance of the specimens was investigated by using weight change and metal (Mg) ion release measurements. Effect of the alloying elements on the Young’s (elastic) modulus of the alloy was also studied.

Design of a transmissive optical system of a laser metal deposition three-dimensional printer with metal powder.

A transmissive optical system of a three-dimensional (3D) printer using the laser metal deposition (LMD) technique with a metal powder is proposed here, together with its design method. An f-number of the focused laser beam emitted from the optical system should be large enough for the laser beam not to be absorbed or reflected by the metal powder injection nozzle. On the other hand, owing to the Lagrange-Helmholtz relation, the f-number should be small enough to form a minute laser spot diameter for high-resolution building. A temperature rise induced by the high-power laser may cause damage or a thermal lens effect on the optical system, which can be reduced by using lenses having plano-surfaces contacting thermally with holders. A formula of the relationship of the thermal lens effect with an f-number of each lens is derived to determine the lens specifications. A formula of longitudinal spherical aberration (LSA) of these lenses is also derived, and the total LSA is shown to be able to be zero with an acceptable f-number of the focused laser beam. The prototype LMD 3D printer with 6kW laser is fabricated and shows favorable properties, such as a minimum building width of 0.3mm and a building speed of over 500cc/h.

Mold optimization design of metal powder injection product USB interface based on Mold Flow analysis

Metal powder injection molding technology (metal injection molding, the MIM) can achieve a mass in the small and medium-sized complex shape product preparation, low cost, which is of great significance in promoting the production of products and applications.In this paper, taking the USB interface parts made of 17-4ph stainless steel as an example, through scheme verification, the optimized and reasonable die structure is obtained, the 3d modeling of the parts is carried out with UG, and MoldFlow software is used for MoldFlow analysis.The design cycle is shortened and the design quality is improved.

On Ultra-compact Gear Manufactured by Micro Metal Powder Injection Molding

On Ultra-compact Gear Manufactured by Micro Metal Powder Injection Molding

Development and improvement of production process of MIM rocker arm

In this article, 17-4PH metal powder was used as raw material to study the effects of the injection position and MIM (metal powder injection molding) thermal debinding temperature on the rocker arm...

Mathematical modeling of thermal behavior for additive manufacturing with metal powder injection

A mathematical model of the processes taking place in laser melting with injection of metal powders is suggested. The model involves the self-consistent equations for the dynamics of the free surface, the temperature, the concentration of components and the melt flow velocities. The paper presents the algorithm of its numerical realization, as well as the results of test calculation of the temperature fields, the structure of the melt convective flows, the solute distribution and the geometric characteristics of the object to be formed.