Abstract: The metal injection molding process was applied to produce Ti-6Al-7Nb alloys using 3
types of mixed powders. The first is a mixture of Ti and Al-Nb pre-alloyed powders, the second is a
mixture of Ti, Ti-Al alloy and Nb powders, and the third is a mixture of elemental powders of Ti,
Al and Nb. The sintered compacts using the first and second powders showed higher density and
mechanical properties than the compacts using the third powder which showed many large pores
formed due to the dissolution of Al particles during the sintering steps. Eventually, the compacts
using a mixture of Ti+Al-Nb or Ti+Ti-Al+Nb powders showed tensile strength of above 800MPa
and elongation of above 10%, which are similar to the properties of wrought materials.
Abstract: Gas surface treatment is considered to be especially effective for Titanium because of its
high reactivity. In this study, we investigated the gas nitriding mechanism in titanium sintered parts
produced by metal powder injection molding (MIM) process. In MIM process, gas nitriding can be
surface-treated subsequently after debinding and sintering process. Then, the microstructure and
nitrogen content of sintered MIM parts are considered to be greatly influenced by not only nitriding
conditions but also sintered conditions. In this study, the effects of sintering time on microstructure
such as nitrided layer thickness and hardness was investigated. Focus was given to the effects of
specimen size on nitriding process, because the size of micro metal injection molding (μ-MIM)
product is so small and the specific surface of that product is so large that the mechanical and
functional properties can be subject to change by nitriding.
Abstract: The MIM technology is an alternative process for fabricating near net shape components
that usually uses gas atomised powders with small size (< 20 μm) and spherical shape. In this work,
the possibility of changing partially or totally spherical powder by an irregular and/or coarse one that
is cheaper than the former was investigated.
Different bronze 90/10 components were fabricated by mixing three different types of powder: gas
atomised spherical powder (usual MIM powder < 22 μm) and two water atomised irregular powders
(size < 35 μm and < 140 μm). The blends were made by using only two types of powder in each
mixture with the following volume proportions (100/0, 67/33, 33/67, 0/100).
The influence of the particle size and shape on the powder packing density and sintering stage was
analyzed through the apparent density of the powder blends, as well as, densification, hardness and
porosity of the sintered parts.
The addition of irregular and/or coarse powder was found to affect the moulding process, although
good densifications and hardnesses were obtained in the sintering step. Therefore it could be a
promising way to diminish production costs in this technology.
Abstract: The production method of micro sacrificial plastic mold insert metal injection molding,
namely μ-SPiMIM process has been proposed to solve specific problems involving the
miniaturization of MIM. The sacrificial plastic mold (SP-mold) with fine structures was prepared by
injection-molding polymethylmethacrylate (PMMA) into Ni-electroform, which is a typical LIGA
(Lithographie-Galvanoformung-Abformung) process. Stainless steel 316L feedstock was injectionmolded
into the SP-mold which had micro structures with multi-pillars. The green compact was
demolded as one component with the SP-mold, which was decomposed along with binder
constituent of feedstock in debinding process. This study focused on the effects of metal particle
size and processing conditions on the shrinkage, transcription and surface roughness of sintered
parts, which were evaluated by SEM (Scanning Electron Microscope) observation.
Abstract: To overcome the lack of micro manufacturing processes suitable for medium and large
scale production as well as to process high resistive materials a special variant of micro injection
molding is currently under development: micro powder injection molding (MicroPIM), which
already enables the manufacturing of finest detailed components with structure sizes down to a few
ten micrometer. In order to expand the scope of application of MicroPIM, tests are being conducted
with pure tungsten powders or tungsten alloy powders. As further improvement, micro twocomponent
injection molding allows, for example, the fabrication of micro components consisting
of two ceramic materials with different physical properties.
Abstract: Mo2FeB2 boride base cermets produced by a novel sintering technique, called reaction
boronizing sintering through a liquid phase, have excellent mechanical properties and wear and
corrosion-resistances. Hence, the cermets are applied to the injection molding die-casting machine
parts and so on.
Metal injection molding (MIM) is a suitable processing route for the mass production of
complex shaped and high performance components. In general, it is difficult for the liquid phase
sintered materials to be applied to the injection molding process because significant shrinkage and
deformation occur during sintering.
In this study, the MIM process was applied in the production of Mo2FeB2 boride base cermets
parts. We investigated that the effect of deoxidization and sintering temperature on mechanical
properties and deformation of the cermets. As a result, deoxidization temperature of 1323K and
sintering temperature of 1518K were suitable. The MIM products of the cermets showed allowable
dimensional accuracy and the same mechanical properties as the press-sintered.
Abstract: This study aims to investigate the effects of hybrid micro/nano powders in a micro metal
injection molding (μ-MIM) process. A novel type of mixing-injection molding machine was used to
produce tiny specimens (<1mm in size) with high trial efficiency using a small amount of feedstock
(<0.05cm3 in volume). Small dumbbell specimens were produced using various feedstocks prepared
by changing binder content and fraction of nano-scale Cu powder (130nm in particle size). The
effects of adding the fraction of nano-scale Cu powder on the melt viscosity of the feedstock,
microstructure, density and tensile strength of sintered parts were discussed.
Abstract: The kneading process and formulations of feedstock obviously affect the quality of MIM
products. In the present work, the rheological behaviour of the composite MIM feedstock, metal
matrix (Cu) with few additions of ceramic powders (Al2O3), was measured by a selfdesigned/
manufactured simple capillary rheometer. Experimental results show that the distribution
between powders and binder is more uniformly when blending time increased. Though high powder
loading will increase the feedstock viscosity, the fluidity reveals relatively stable through the load
curves of extrusion. Besides, the temperature-dependence of viscosity of the feedstock
approximately follows an Arrehnius equation. Basing on Taguchi’s method, the kneading
optimization conditions and the rheological model of the feedstock were established, respectively.
Abstract: Two atomized alloy powders, those chemical compositions are Al-10Si-5Fe-1Zr and Al-
10Si-5Fe-4Cu-2Mg-1Zr, were pre-compacted by cold pressing with 350MPa and subsequently hot
forged at temperatures ranging from 653K to 845K and at an initial strain rate of 10-2/s in order to
produce bulk cylindrical type alloys with the diameter of 10 mm. The addition of Cu and Mg into
the present alloy causes a decrease in the eutectic reaction temperature of Al-10Si-5Fe-1Zr alloy
from 841K to 786K and results in a decrease of flow stress at the given forging temperature. TEM
observation revealed that in addition to Al-Fe based intermetallics, Al2Cu and Al2CuMg
intermetallics appeared to display the alloying effect additionally. The volume fraction of
intermetallic dispersiods increased by the addition of Cu and Mg. Compressive strength of the
present alloys was closely related to the volume fraction of intermetallic dispersoids.
Abstract: In present work, manufacturing technologies of micro parts by micro forging and
pressing were studied using strain softening phenomenon in nano grained Al-1.5mass%Mg alloy.
During compressive test at 300, the Al alloy showed stain softening phenomenon by grain
boundary sliding regardless of strain rate. Micro spur gear with ten teeth (height of 200 μm and
pitch of 250 μm) was fabricated with sound shape by micro forging. During micro forging, increase
of applied stress induced by friction between material and die surface was effectively compensated
by decrease of stress by strain softening behavior and as a result, flow stress increased only about
50 MPa more than that in compressive test. However, in micro pressing, flow of material did not
occurred sufficiently to fill die and the resultant shape of gear was very poor.