MIM Process Research Articles

Corrosion behavior of 17 - 4PH steel, produced by the MIM process, sintered in different atmospheres

Corrosion behavior of 17 - 4PH steel, produced by the MIM process, sintered in different atmospheres

Effect of residual reagents on chalcopyrite losses at Mount Isa Mines copper Operation: Part II - evaluation of flotation mechanisms

Mount Isa Mines Copper Operation (MICO) is one of the largest copper producers in Australia. The concentrator has a complex circuit, which includes a pre-flotation section designed for early removal of deleterious talc, and other naturally floating gangue including carbonaceous material.The downside of early talc removal is the loss of chalcopyrite to the pre-flotation concentrate. This work investigates the role of residual collector and frother reagents on chalcopyrite losses in the MIM pre-flotation circuit, and the possibility of improving talc recoveries whilst keeping chalcopyrite loss to a minimum. In Part I of this study, it was demonstrated that talc/chalcopyrite selectivity can be improved by removing residual reagents from the MIM process water. In Part II, the mechanisms of chalcopyrite losses are evaluated to explain the results presented in Part 1. This is done through an evaluation of mineral recoveries by true flotation and entrainment. The effect of residual reagents on chalcopyrite surfaces is evaluated using statistical analysis of Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) performed on process stream samples.

Magnetic Properties and Corrosion Resistance of Fe-Cr-Si-Mo Soft Magnetic Alloys by MIM Process

Magnetic Properties and Corrosion Resistance of Fe-Cr-Si-Mo Soft Magnetic Alloys by MIM Process

MIM2021 virtual conference overview

The 2021MIM Conference and PIM Tutorial went virtual because of COVID. Traditional format was still followed, with speakers and attendance from around the world. Interesting new studies of MIM process aspects were presented, as well as further details of investigations on a wide range of both MIM and 3-D printed materials.

Characterization of 17-4 PH stainless steel metal injection molding feedstock using mixing torque data

Currently, there are many components produced by a metal injection molding process in automotive, consumer goods, medical, and electronics. Metal Injection Molding process (MIM process) consists of four stages, mixing, injection molding, debinding, and sintering. Feedstock plays critical roles in the MIM process since the feedstock’s low quality cannot be corrected later. Feedstocks, which are a mixture of powder and binder, are mixed at an elevated temperature. A feedstock should be homogeneous and has a pseudo-plastic behavior. In the MIM process, the shear rate during injection molding is usually 10 to 10 000 s-1. Within the shear rates range, a maximum viscosity for injection molding was 100 Pas at molding temperatures. In this paper, the rheological characteristic of feedstocks was analyzed using the torque rheometer. The objective of this research was to find the value of viscosity and compare to the Material Safety Data Sheet (MSDS) of the commercial feedstock by using torque mixing data. All the three feedstocks had pseudo-plastic behavior and below 100 Pas within shear rates range. Form the validation of injection molding experiment, feedstock B with solid loading 60 %, and binder system consists of 35 % PP, 64% PW, and 1 % SA showed a good flowability and moldability.

Fabrication of Granulate from a Fe – Cr – Co Alloy with Reduced Cobalt Content for Synthesizing Permanent Magnets by the MIM Process

The possibility of fabrication of granulate based on an alloy of the Fe – Cr – Co system with reduced (7 – 10%) cobalt content for synthesizing permanent magnets by the MIM process is considered. A multicomponent granulate composition (polyformaldehyde, high-pressure polyethylene, stearic acid, beeswax) of spherical powders of the Fe – Cr – Co alloy with reduced cobalt content is produced by gas sputtering (average particle diameter 4.2 μm, degree of polydispersity 0.75). The microstructure of the granulate and its granulometric composition are studied. The characteristics of the granulate (the mean diameter of the particles, their morphology and degree of polydispersity) exceed qualitatively the characteristics of the Catamold 42CrMo4 high-quality granulate produced by the BAFS Company.

Effects of Cr and Si Contents on the Magnetic Properties of Fe-Cr-Si Soft Magnetic Alloys by MIM Process

Effects of Cr and Si Contents on the Magnetic Properties of Fe-Cr-Si Soft Magnetic Alloys by MIM Process

Preparation of Ss 316l Feedstock for Metal Injection Molding (Mim) Process

The purpose of this paper is to make the homogeneous mixing of SS 316L steel powder with a multiple binder system in a custom made mixing machine by varying the process parameters like speed, Temperature and time as the homogeneity impacts on the final product in the MIM process. A homogeneous mix of metal powder and binder is essential in metal injection molding process as it affects the product quality significantly. This paper aims at design of new mixing equipment and characterization of SS 316L feed stock. A mixing machine of 2 kg capacity is designed and fabricated to prepare a homogeneous mix of SS 316l material with a multiple binder system. Mixing time, mixing speed and Temperature of Barrel are considered as process parameters. Taguchi techniques are used to optimize the process parameters .The RPM of the blade is varied from 20 to 40 in steps of 10, the temperature is varied from 200 to 240 in steps of 20 and the mixing time is varied from 20 to 40 minutes in steps of 10. The results of the experimentation reveals that mixing temperature has a profound effect on the homogeneity of the mix.

Evolution of properties of parts during MIM and sintering of recycled oxide particles

ABSTRACTMetal injection moulding (MIM) is an established process for high volume production of complex shaped metallic parts using commercially available feedstocks. The characteristics of parts after moulding, debinding, and sintering cannot be simply predictable from raw materials because the properties get altered with the process parameters and the corresponding levels of porosity during processing steps. In this study, physical properties, microstructure, and mechanical properties of the MIM parts have been characterised to understand the evolution of strength during various steps in MIM processing. Feedstocks with different binder loading show a considerable difference in physical as well as mechanical characteristics. During sintering of parts which have solid loading of grinding sludge, simultaneous in situ reduction and densification takes place, whereas only densification occurs in carbonyl iron parts. It is, therefore, possible to make complex shaped parts of different levels of porosity from downgraded shop floor metallic waste.

The Effect of Powder Loading and Binder System on the Mechanical, Rheological and Microstructural Properties of 4605 Powder in MIM Process

In this study, the effect of powder loading of 4605 low-alloy steel has been investigated on the rheological and mechanical properties of the final part manufactured by metal injection molding process. For this, two binder systems consisting of different percentages of paraffin wax (PW), polypropylene (PP), carnauba wax (CW) and stearic acid (SA) have been compounded with 55, 60 and 65 vol% of the powder. The manufactured samples were then tested for tensile, hardness, density and rheological properties. The results showed that with the increase in the powder loading, the tensile strength, hardness and density increase. It was observed that the higher percentage of the backbone polymer and surfactant resulted in higher mechanical properties of the final part. The optimum was made using the feedstock consisting of 55 wt% PW, 25 wt% PP, 15 wt% CW and 5 wt% SA along with 65 vol% of powder loading.

Transformation of orthodontics bracket geometry in metal injection molding process

Orthodontic Bracket is a complex component; Therefore, it requires manufacturing process of a high accuracy like metal injection molding. Metal injection molding consists of three main steps. At first, the feedstock which is a mixture of steel powders and polymer is injected into a mold to form the desired design. Then the molded part is unbound to remove the polymer from the part, this process results in an absence of polymer that generates porosity. Furthermore, the unbound part is sintered to densify steel particles through capillarity force, this process is also the cause of part shrinkage that leads to a geometrical change. The bracket consists of three sections namely the geometrical functions that are affected by the sintering process, they are: wing, trunk, and base. The wing section works as a hook to hold the orthodontic ring, the trunk section supports all the bracket sections, while the base section provides surface contact with orthodontic adhesive. Each section of the bracket has its specific function namely to attach object with different geometries and to withstand a certain load. The functions will not work properly if during the sintering process the geometrical changes caused by shrinkage occurs. This paper presents transformation analysis of orthodontic bracket geometric transformation in the MIM process. In the case of wing geometry, the shrinkage of the outer part of the arch is greater than that of the inner part resulting the reduction on its slope from 35,01° to 32,11°. In the case of square geometry, the corners shrink greater than the edge side so that the square getting rounded, especially the bottom surface of the bracket that the radius of convexity reduced from 43.51 mm to 19.23 mm. The effects of shrinkage due to sintering have less impact on the trunk in the middle of the bracket that is equal to 7.23% on x-axis and 4.994% on y-axis while the wings section shrink by 10.98% on x-axis and -6.637% (elongated) on y-axis. In conclusion, the changes of size and shape are different from each section, depend on the section’s geometry, the sintering tends to effect more on the outer side of geometry. The disproportion of shrinkage will result in overall shape change in the manufacturing outcome. On the wing of the bracket, there will be a thinning and a slope reducing that will increase the risk of fracture and can not refute the orthodontic rubber well. On the base, occurs the rounding that will reduce the surface contact on the adhesive that attaches the bracket to the teeth. To adapt to the geometrical change, the first design must be larger, and the part’s faces must be designed to be more concave.

Topographic Complexities and Solutions for High Density BEOL MIM Capacitors

The BEOL compatible on-chip MIM capacitors have natural topography post MIM processing. In foundry manufacturing, design-related non uniform pattern density combined with MIM processing can lead to localized topographic process weak points. These weak points add further complexity and reduce the process window available to accommodate both MIM capacitors and Cu interconnections. The related fail modes include punch-through of MIM capacitors, un-landed Cu interconnection vias, and shorted Cu lines above the MIM capacitors. These challenges and complexities are described and characterized in this paper, as well as experiments and solutions to overcome these challenges. Manufacturing capability of BEOL MIM capacitors with capacitance density >20fF/μm2, leakage current density <100nA/cm2, and breakdown voltage > 5V has been demonstrated.

MIM2017 conference report: Industry and technology continue to flourish

Highlights from the successful MIM2017 conference in Orlando, FL, include developments in master alloy powders, MIM processing, porous MIM, and medical applications. The conference also explored ways in which 3D printing and MIM have become complementary technologies.

Structure and properties of steel produced by metal injection molding

Austenite stainless steel produced by metal injection molding (MIM process) is studied, including its structure, phase composition, and mechanical properties of initial feedstock and sintered material. Prepared feedstock consists of cylindrical granules with the diameter of approximately 3.5 mm. The main feedstock material is a mixture of chrome-nickel and steel powders. Polyacetal is used as a plastic binder. Upon sintering of the feedstock, the material is synthesized with chemical composition, structure, and mechanical properties similar to those of austenite stainless steels. The material density after sintering is higher than 98% of theoretical value. It is established that, upon sintering, a phase transformation occurs: the initial ferrite phase is transformed into the austenite phase. The phase transformation is promoted by nickel contained in initial powder mixture. The microhardness of the sintered material is 1.6 GPa; the elastic modulus is 115 GPa.

Characterization of Stainless Steel 316L Feedstock for Metal Injection Molding (MIM) Using Waste Polystyrene and Palm Kernel Oil Binder System

This paper presents the homogeneity characterisation of MIM feedstock consisting Stainless steel alloy (316 L) powder mix with binder 60wt% of waste polystyrene and 40wt% palm kernel oil. It is one of a critical step that must be conducted in MIM process in order to have a feedstock that is homogeneous and moldable. Water atomised Stainless Steel powder was mixed with the newly developed binder system in a Brabender Plastograph EC rotary mixer. Several tests were performed to assess the homogeneity of the feedstock that was produced at 60 vol % powder loading . The 60 vol.% was chosen because the Critical Powder Volume Concentration (CPVC) of the Powder was found to be 64.8 vol.%. The tests conducted were feedstock density, binder burn-out, rheology and SEM morphology observation. Rheological results exhibited pseudoplastic or shear thinning flow behavior, where its viscosity decreased with increasing shear rate. The feedstock viscosity also decreased with increasing temperature and was found to be suitable for molding. From all the tests conducted, it was found that the feedstock shows good homogeneity and suitable for subsequent processes in MIM.

Supercritical Debinding of Environmentally Friendly Inconel 718 Feedstock to Metal Injection Moulding Process

In the MIM process the debinding is a long, complicated and polluting step. The supercritical fluid debinding is a new method to reduce the time of debinding, the default of the pieces and the pollution. The goal of this study is to study the behaviour of an environmentally friendly feedstock of Inconel 718. For this, a binder formulation based on polyethylene glycol, because of is water debinding properties, and bio sourced polymer was made. Polylactic acid was investigated as bio sourced polymer. The debinding is realized with supercritical CO2 as solvent. The results were compared to the traditional debinding method using water at 60°C.

New Titanium Alloy Feedstock for High Performance Metal Injection Molding Parts

Ti 6-4 and other Titanium alloys have great potential for Metal Injection Molding of high performance parts. Markets like Automotive, Aerospace, 3C and sporting goods can benefit from the low density and high strength of Titanium. A new feedstock has been developed that incorporates pre-alloyed Ti 6-4 and discrete additions that simplify MIM processing and enhance properties. Processing and sintering parameters are presented together with mechanical and metallurgical properties of completed parts.

Dependence of Hardness to the Applied Load of the 42CrMo4 Steel Manufactured by MIM Process

Dependence of Hardness to the Applied Load of the 42CrMo4 Steel Manufactured by MIM Process

金属粉末射出成形法によるパーメンジュールの磁気特性

金属粉末射出成形法によるパーメンジュールの磁気特性

Physical and Mechanical Properties of Injection Molded Co-Cr-Mo Alloy Powder for Orthopedic Applications

Cobalt-chromium alloys are commonly used for surgical implants because of their high strength, superior corrosion resistance, non-magnetic behavior, and biocompatibility. Cobalt-Chromium-Molybdenum (Co-Cr-Mo) applications include prosthetic replacements of hips. This paper presents the attempt to produce metallic implant using Co-Cr-Mo powder by MIM process, focusing on the effects of different heating rate during sintering process at 1380°C. Co-Cr-Mo powder were mixed homogeneously with palm oil and conventional binders respectively with powder loading 65 vol% and was injection molded using vertical injection molding machine with the nozzle temperature of 160°C to produce green compacts. The binders then was removed by solvent extraction process and sintered in vacuum condition at atmosphere 10-5 mbar at temperature 1380 °C with varied heating rate; 0.5°C/min, 1.0°C/min and 3.0°C/min . Results indicated that sintered density and tensile strength varied from 8.100 gcm-3 to 8.200 gcm-3 and 546.971 MPa to 798.767 MPa respectively. The mechanical properties comply with the international standard (ASTM F75).