Metal Injection Molding Process Research Articles

The effect of printing parameters on the properties of 17-4 PH stainless steel fabricated by material extrusion additive manufacturing

The 17-4PH stainless steel filament was characterised and utilised to study the effect of printing parameters, i.e. printing temperature, layer thickness, infill pattern and extrusion multiplier on the physical properties. The as-printed and as-sintered internal structures were analysed. The results showed that the as-printed density increases with increasing printing temperature and extrusion multiplier and decreasing layer thickness. The use of the line infill pattern also provided slightly higher as-printed density than the concentric infill pattern due to the low fraction of void between deposited paths. After sintering, the trace of these voids can be observed together with smaller-size residual pores from the spaces between powders, which is the nature of the pressureless sintering process. The microstructure of the as-sintered specimens was similar to the typical microstructure of the 17-4PH alloy fabricated by metal injection moulding process, which contains delta ferrite, martensite and Si-rich phases. In additions, the internal void generated during debinding and sintering results in unexpectedly low tensile properties and results in the difference in tensile properties between the concentric and line infill patterns.

Surface modification and enhanced wear performance through severe shot peening treatment in 316L stainless steel manufactured by metal injection moulding

This study investigates the micro-to nanostructural evolution, hardness, and linear reciprocating wear resistance, using Al2O3 ball as a counterpart of 316L stainless steel fabricated by the metal injection moulding (MIM) process, with and without severe shot peening treatment (SSP). SSP treatment led to a slight increase in Ra but a decrease in Rz and the formation of nanocrystalline surface, α′-martensite and mechanical twin. The subsurface hardness increased significantly. Surprisingly, the coefficient of friction remained constant (0.37–0.56) and depended solely on the testing load, despite alterations in surface roughness and subsurface microstructure due to SSP treatment. Furthermore, wear resistance notably improved under 10 N and 20 N loads, attributed to the surface modification by SSP treatment, but showed no significant difference at 30 N. The wear mechanisms, including abrasive, adhesive wear, and oxidative wear, remained similar, with adhesive and oxidative wear dominating at lower testing loads (10–20 N). However, with a testing load of 30 N, the strengthening effect of SSP treatment was surpassed, leading to the dominance of severe adhesive and oxidative wear. Consequently, the wear resistance exhibited insignificant differences between specimens before and after SSP treatment.

Development of a Rapid Tool for Metal Injection Molding Using Aluminum-Filled Epoxy Resins.

Metal injection molding (MIM) is a near net-shape manufacturing process combining conventional plastic injection molding and powder metallurgy. Two kinds of injections molds for MIM were developed using conventional mold steel and aluminum (Al)-filled epoxy resins in this study. The characteristics of the mold made by rapid tooling technology (RTT) were evaluated and compared with that of the fabricated conventional machining method through the MIM process. It was found that the service life of the injection mold fabricated by Al-filled epoxy resin is about 1300 molding cycles with the average surface roughness of 158 nm. The mold service life of the injection mold fabricated by Al-filled epoxy resin is about 1.3% that of the conventional mold steel. The reduction in manufacturing cost of an injection mold made by Al-filled epoxy resin is about 30.4% compared with that of the fabricated conventional mold steel. The saving in manufacturing time of an injection mold made by RTT is about 30.3% compared with that of the fabricated conventional machining method.

In vitro evaluation of cytotoxicity and genotoxicity of porous nickel titanium dental implants produced by metal injection molding technique.

Porous NiTi (pNiTi) is a promising biomaterial for functional long-term implantation that has been produced using various manufacturing techniques and tested for biocompatibility. pNiTi produced using a more recent technology of Metal Injection Molding (MIM) has shown better physical and mechanical properties than those produced by earlier manufacturing methods, but its biocompatibility has yet to be determined. Hence, extracts from pNiTi dental implants produced by MIM were tested for cytotoxicity and genotoxicity in this work. Its toxicity was evaluated at the cellular and in vitro levels using elution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Short-term testing revealed that pNiTi extract was cytocompatible with L-929 fibroblast and V79-4 lung cells, with no cell lysis or reactivity observed, respectively (USP grade 0). Following exposure to varied extract concentrations, good cell viability was observed where the lowest concentration showed the highest optical density (OD) and cell viability (2.968 ± 0.117 and 94%, respectively), and the highest concentration had the least OD and cell viability (2.251 ± 0.054 and 71%, respectively). pNiTi extracts demonstrated genocompatibility in two independent assays: mutagenic potential using a bacterial reverse mutation test and a clastogenic effect on chromosomes using the micronucleus test. Similar to the negative control reactions, there was no significant increase in revertant colonies following exposure to 100% pNiTi extract with and without metabolic activation (p = .00). No DNA clastogenic activity was caused by pNiTi at varied extract concentrations as compared to the negative control when tested with and without metabolic activation (p = .00). As a result, both cytotoxic and genotoxic investigations have confirmed that pNiTi dental implants utilizing the MIM process are cytocompatible and genocompatible in the short term, according to the International Standard, ISO 10993 - Parts 3, 5, and 33.

PENGGUNAAN MATERIAL 316L UNTUK GREEN-PART TEST PIECE DENGAN TEKNIK METAL INJECTION MOLDING

Material 316L is one type of iron with excellence corrosion resistant and was used in many industries. 316L is used as feed stock material for Green-part test piece which is a product of the Metal Injection Molding (MIM) process. The study showed, the manufacture of green part made from standard 316L material has been carried out. Green part is a product made by injection mold stage from MIM process. The stages of research carried out refer to the Metal Injection Molding process with the standard references that included three stages carried out which are the preparation of feedstock, mold design, and mold testing with the injection process by testing material and by the 316L feedstock. The purpose of this study is to analyze the green part test piece that was made with 316L material in MIM process with a specific measurement and the quality of the end product using tensile test. Results of this study indicate that the right parameters was achieved to produce shapes that match the targeted geometry of the 316L feed stock material. The tensile strength test show reading of 110Mpa but when compared with other studies, the value was still under standard.

Recent Advances in Processing of Titanium and Titanium Alloys through Metal Injection Molding for Biomedical Applications: 2013-2022.

Metal injection molding (MIM) is one of the most widely used manufacturing processes worldwide as it is a cost-effective way of producing a variety of dental and orthopedic implants, surgical instruments, and other important biomedical products. Titanium (Ti) and Ti alloys are popular modern metallic materials that have revamped the biomedical sector as they have superior biocompatibility, excellent corrosion resistance, and high static and fatigue strength. This paper systematically reviews the MIM process parameters that extant studies have used to produce Ti and Ti alloy components between 2013 and 2022 for the medical industry. Moreover, the effect of sintering temperature on the mechanical properties of the MIM-processed sintered components has been reviewed and discussed. It is concluded that by appropriately selecting and implementing the processing parameters at different stages of the MIM process, defect-free Ti and Ti alloy-based biomedical components can be produced. Therefore, this present study could greatly benefit future studies that examine using MIM to develop products for biomedical applications.

Effect of Temperature, Holding Time, and Addition of Sn on Density on Metal Injection Molding Sintering Process

Metal injection molding (MIM) is a metal forming technique that combines powder metallurgy with plastic injection molding. MIM is very efficient in manufacturing small and complex products in large quantities. The MIM process has four steps: mixing, debinding, injection molding, and sintering. This research was conducted to determine the effect of variations in Sn addition, temperature, and holding time on the density of Al-PP products after the sintering process. Density is mass per volume so to find out the volume of Al-PP products, the use of a 3D scanner was attempted along with the EinScan application and a mesh mixer. The Taguchi method was used for data processing to determine the influence of variations in Sn addition, temperature, and holding time on density. The calculation of the percentage contribution showed that variations in Sn addition, temperature, and holding time affected density by 47%, 21%, and 3%. Also, 2% Sn addition yielded a reasonably good microstructure formation compared to without Sn addition and 1% Sn addition, where many voids remained in the specimen (the more significant the voids, the lower the density).

Fe-Cr-Si and Fe-Cr-Si-Mo Soft Magnetic Alloys Produced by MIM Process

In recent years, metal injection molding (MIM) has been adopted as a manufacturing method for solenoid valves which are parts of electronic fuel injectors, and PB permalloy parts have been commercialized. However, Ni, a constituent element of PB permalloy, is an expensive material, making it difficult to produce fuel injector parts at low cost. To solve this problem, the use of inexpensive Fe-Cr alloys has been considered. However, its properties are insufficient as a material for solenoid valves, which require improved magnetic properties, reduced core loss, and improved corrosion resistance, and these requirements have been increasing year by year. As a solution to this problem, we studied magnetic and material properties of Fe-Cr-Si and Fe-Cr-Si-Mo alloys produced by MIM process. These results revealed that magnetic properties were improved by reducing the amount of Cr, and that corrosion resistance was improved by adding Mo even if the amount of Cr was reduced. In this review, we describe the magnetic and material properties of Fe-Cr-Si and Fe-Cr-Si-Mo alloys produced by MIM process.

Mechanical Properties and Deformation Behavior of Metal Injection Molded Products with Cellulose Nanofiber

Metal Injection Molding (MIM) process is suitable for fabricating small and complex shaped metal parts with high production volume. In this study, in order to improve the MIM process, cellulose nanofibers (CNF) were focused. There are problems such as deformation during debinding and sintering due to the addition of a large amount of binder. On the other hand, the strength of the green compact decreased with decreasing binder contents. In this study, cellulose nanofibers were added with a binder during mixing in order to improve the handling of green compacts, and decrease the deformation during debinding and sintering. The effects of CNF contents on the mechanical properties were investigated. It was clarified that CNF is effective in improving the handleability of the debound compacts and suppressing deformation during sintering.

Fabrication of Equiatomic CoCrFeMnNi High-Entropy Alloy by Metal Injection Molding Process Using Coarse-Sized Powders

Fabrication of Equiatomic CoCrFeMnNi High-Entropy Alloy by Metal Injection Molding Process Using Coarse-Sized Powders

Metal Injection Molding of Low Alloy Steel by Using a Palm Stearin/HDPE Binder System

Metal injection molding (MIM) is a proven technology for fabricating complex geometry and low-cost components. The binder system formulation and powder loading are the key parameters affecting the final properties of the manufactured parts in this process. This study investigates the influence of palm stearin (PS) content in a PS/High-Density Polyethylene (HDPE) binder system for three powder loadings of 60, 65, and 70 Vol.%. The manufactured feedstocks are characterized using scanning electron micrograph (SEM), thermo gravimetric analysis (TGA), and differential scanning calorimeter (DSC), rheological and mechanical tests. The results show that PS enhances mechanical properties at increased powder loading. In addition, residual carbon following changing the PS percentages has a significant role in determining the final characteristics of parts. Findings demonstrated that PS could drastically alter the rheological behavior, a crucial criterion for optimizing the feedstock formulation in the MIM process.

Integrated Numerical Simulations and Experimental Measurements for the Sintering Process of Injection-Molded Ti-6Al-4V Alloy.

Metal injection molding (MIM) is an advanced manufacturing technology that enables the mass production of high-performance and complex materials, such as the Ti-6Al-4V alloy. The determination of the size change and deformation of the Ti-6Al-4V alloy after the sintering process is challenging and critical for quality control. The numerical simulation could be a fast and cost-effective way to predict size change and deformation, given the large degrees of freedom for the sintering process. Herein, a finite element method based on the thermal-elastic-viscoplastic macroscopic model is developed to predict the shrinkage, deformation, relative density, and crack of injection-molded Ti-6Al-4V after sintering, using the Simufact software. Excellent agreements between experimental measurements and numerical simulations of the size and deformation are demonstrated (within a 3% error), confirming the accuracy of the numerical model. This approach can serve as a guideline for the mold design and sintering optimization of the MIM process.

A Review on Material Extrusion Additive Manufacturing of Metal and How It Compares with Metal Injection Moulding

Material extrusion additive manufacturing of metal (metal MEX), which is one of the 3D printing processes, has gained more interests because of its simplicity and economics. Metal MEX process is similar to the conventional metal injection moulding (MIM) process, consisting of feedstock preparation of metal powder and polymer binders, layer-by-layer 3D printing (metal MEX) or injection (MIM) to create green parts, debinding to remove the binders and sintering to create the consolidated metallic parts. Due to the recent rapid development of metal MEX, it is important to review current research work on this topic to further understand the critical process parameters and the related physical and mechanical properties of metal MEX parts relevant to further studies and real applications. In this review, the available literature is systematically summarised and concluded in terms of feedstock, printing, debinding and sintering. The processing-related physical and mechanical properties, i.e., solid loading vs. dimensional shrinkage maps, sintering temperature vs. relative sintered density maps, stress vs. elongation maps for the three main alloys (316L stainless steel, 17-4PH stainless steel and Ti-6Al-4V), are also discussed and compared with well-established MIM properties and MIM international standards to assess the current stage of metal MEX development.

Eff ect of Injection Moulding Sequences on Mechanical Properties of Two-material Metal Injection Moulding

Two-Material Metal Injection Moulding (2M-MIM) process was developed for a component that requires different properties of materials. The materials used in this study were SCM 415, Fe-2Ni and 316L stainless steel (316L SS). The tensile test specimens were injected into 2M-MIM of SCM 415-Fe-2Ni and SCM 415-316L SS. In addition, each alloy was fabricated by MIM as reference samples. The 2M-MIM processes were injected with two different injection moulding sequences, which are “sequential injection” and “simultaneous injection”. The injection process of “sequential injection” specimens is to fi ll a half of the mould with the fi rst alloy and then inject the second half of the mould with the second alloy. The “simultaneous injection” specimens utilised the co-nozzle and co-injected both alloys simultaneously from each end of tensile specimen. The weld line positions of both injection moulding sequences were controlled in the middle at the gauge length. After injection, all specimens were sintered at 1325°C for 2 hrs. The shrinkage of each single-material specimen is 12.20 ± 0.64%, 14.90 ± 1.95% and 13.84 ± 0.24% for SCM 415, Fe-2Ni and 316L SS respectively. The ultimate tensile strength of SCM 415, Fe-2Ni and 316L SS are 549.62 ± 7.87 MPa, 474.08 ± 8.1 MPa and 351.44 ± 0.42 MPa respectively and the elongation is 9.68 ± 0.71%, 23.05 ± 2.64% and 51.33 ± 3.76% respectively. For 2M-MIM, the mechanical properties of the “sequential injection” specimens are more superior than the “simultaneous injection” specimens. This is due to the difference of weld line interface of 2M-MIM. The interface of sample was investigated by SEM and OM. Cracks were observed at the weld line of SCM – Fe-2Ni using “simultaneous injection” and the sharp crack was observed near the edge of specimen all specimens. The ultimate tensile strength of SCM 415-Fe-2Ni specimens and SCM 415-316L SS specimens are 374.42 ± 13.80 MPa and 403.35 ± 31 MPa respectively for “sequential injection” and 223.87 ± 31.98 MPa and 193.75 ± 15.41 MPa respectively for “simultaneous injection”. EDS results across the weld line of SCM 415-Fe-2Ni “sequential injection” specimen show that nickel diffused from Fe-2Ni to SCM 415 while chromium diffused from SCM 415 to Fe-2Ni.

MIMプロセスによって作製した高硬度Fe-Cr-Si系軟磁性材料の磁気特性および機械的性質

An electronic fuel injection system of automobiles have been commercialized at the end of 1960’s, they have been adopted as environmental measures for many automobiles and motorcycles. In recent years, metal injection molding (MIM) has been adopted as a process for manufacturing a solenoid valve which is a component of an electronic fuel injector, and PB permalloy components have been commercialized. However, Ni, an element of PB permalloy, is expensive material, making it difficult to produce the fuel injector component at a low cost. As a solution to this problem, we studied the magnetic and material properties of Fe-Cr-Si and Fe-Cr-Si-Mo alloys by MIM process. These results revealed that the magnetic and mechanical properties were improved by reducing Cr content, and the corrosion resistance were improved by adding Mo even if the amount of Cr reduced. On the other hand, we found that the hardness of these alloys increased by adding Si and Mo. In this study, Fe-Cr-Si alloy specimens containing Si and Mo to increase hardness are manufactured by MIM process, and we investigated the magnetic and mechanical properties. These results revealed that Fe-12Cr-4.5Si-2Mo alloy is a material with excellent magnetic and mechanical properties.

Studi Pengembangan Komponen Implan Paduan Ti6Al4V untuk Aplikasi Biomedis dengan Proses Metal Injection Molding

Titanium alloy Ti6Al4V is a material that has a combination of mechanical properties required for implants such as good ductility, high corrosion resistance and good biocompatibility, so it is widely used as a material for biomedical implant applications. One method that is currently widely used to produce Ti6Al4V implants is by using the metal injection molding (MIM) process. The MIM process is widely used because it can produce parts more effectively, and low-cost production. One of the important factors in the MIM process is the powder loading of metal powders and the binder system used as feedstock material. So, it is necessary to conduct further studies and in-depth literature review related to this matter. Literature search using the ScienceDirect, a digital database and limited to year 2011-2020. The results of the study show that both the binder and powder loading systems have an influence on the mechanical properties of the injection product, the results are evident that the viscosity of the feedstock decreases with the increase in the shear rate.

Effect of thermal debinding and sintering parameters on the mechanical properties of 4605 MIM compact using the RSM

ABSTRACT In metal injection moulding (MIM) process, improper debinding or sintering process is mainly responsible for forming defects in final parts. In this study, the effects of thermal debinding and sintering parameters on the physical and mechanical properties of low alloy steel parts produced by the MIM process are investigated. For this reason, the design of experiments was done using the central composite design (CCD) method with parameters of 3–7 °C/min for heating rate, 1–3 h for sintering time, and 1200–1300 °C for temperature. The density, strength, hardness, and elongation of the sintered parts were measured for each experiment. The results showed that among the process variables, the heating rate has the most significant effect on the properties mentioned above. Also, the impact of sintering temperature showed to be more significant than the sintering time. Finally, it was observed that with the increase in the thermal debinding rate from 3 to 7 °C/min, the relative density decreased by 3%, and elongation decreased from 10 to 4%. As for the strength, there is an optimum point of heating rate after which, with the increase of heating rate (from 5 to 7 °C/min), the strength decreases significantly by 70 MPa.

Investigating the Effect of Stearic Acid on the Mechanical, Rheological, and Microstructural Properties of AISI 4605 Feedstock for Metal Injection Molding Process

Investigating the Effect of Stearic Acid on the Mechanical, Rheological, and Microstructural Properties of AISI 4605 Feedstock for Metal Injection Molding Process

Effects of Sintering Variables on the Physical and Mechanical Properties of Metal Injection Molding Molded 17-4 PH Stainless Steel

Metal injection molding (MIM) is a near net shape manufacturing technique for producing small, complex, precision parts in mass production. MIM process is manufacturing method that combines traditional shape-making capability of plastic injection molding and the materials flexibility of powder metallurgy. The process consists of the following four steps: mixing of metal powder and binder, injection molding to shape the component, debinding to remove the binder in the component, sintering to consolidate the debound parts. In this research, the physical and mechanical properties of metal injection molded 17-4 PH stainless steel were investigated with the variation of sintering temperatures (1300 °C - 1360 °C) and atmosphere conditions (argon and vacuum conditions). The relative density, microstructure, distortion, and hardness are measured and analyzed in this study. The results show that highest relative density of 87%, relative homogeneous shrinkage and high hardness are achieved by sintering at 1360 °C for 1.5 hours and argon atmosphere. At the same sintering temperature and time, sintering in vacuum shows lower relative density (81%) than that in argon condition due to pores growth. The pore growths were not observed in the argon atmosphere. It can be concluded that sintering stages more rapidly under vacuum condition. The hardness measurements result also showed that high hardness is obtained by high density parts. The optimum average hardness obtained in this study is 239 HV. However, the hardness properties results are still lower than 280 HV according to MPIF Standard 35 for MIM parts.

Additive manufacturing of 316L stainless-steel structures using fused filament fabrication technology: mechanical and geometric properties

Purpose Fused filament fabrication (FFF) technique using metal filled filaments in combination with debinding and sintering steps can be a cost-effective alternative for laser-based powder bed fusion processes. The mechanical behaviour of FFF-metal materials is highly dependent on the processing parameters, filament quality and adjusted post-processing steps. In addition, the microstructural material properties and geometric characteristics are inherent to the manufacturing process. The purpose of this study is to characterize the mechanical and geometric performance of three-dimensional (3-D) printed FFF 316 L metal components manufactured by a low-cost desktop 3-D printer. The debinding and sintering processes are carried out using the BASF catalytic debinding process in combination with the BASF 316LX Ultrafuse filament. Special attention is paid on the effects of build orientation and printing strategy of the FFF-based technology on the tensile and geometric performance of the 3-D printed 316 L metal specimens. Design/methodology/approach This study uses a toolset of experimental analysis techniques [metallography and scanning electron microcope (SEM)] to characterize the effect of microstructure and defects on the material properties under tensile testing. Shrinkage and the resulting porosity of the 3-D printed 316 L stainless steel sintered samples are also analysed. The deformation behaviour is investigated for three different build orientations. The tensile test curves are further correlated with the damage surface using SEM images and metallographic sections to present grain deformation during the loading progress. Mechanical properties are directly compared to other works in the field and similar additive manufacturing (AM) and Metal Injection Moulding (MIM) manufacturing alternatives from the literature. Findings It has been shown that the effect of build orientation was of particular significance on the mechanical and geometric performance of FFF-metal 3-D printed samples. In particular, Flat and On-edge samples showed an average increase in tensile performance of 21.7% for the tensile strength, 65.1% for the tensile stiffness and 118.3% for maximum elongation at fracture compared to the Upright samples. Furthermore, it has been able to manufacture near-dense 316 L austenitic stainless steel components using FFF. These properties are comparable to those obtained by other metal conventional processes such as MIM process. Originality/value 316L austenitic stainless steel components using FFF technology with a porosity lower than 2% were successfully manufactured. The presented study provides more information regarding the dependence of the mechanical, microstructural and geometric properties of FFF 316 L components on the build orientation and printing strategy.