Metal Injection Molding (MIM)


Metal Injection Molding (MIM)

In recent years, diverse processing technologies and methods, such as machining, precision (lost-wax) casting, die casting, press sintering, are being selected and adopted for the forming of metal parts to meet functional and cost requirements. METAMOLD, a metal injection molding (MIM) process, developed as a new 5th generation processing technology in addition to these processing technologies based on our long cultivated metallurgy technology, enables the production of very complex shaped parts similar to plastic products or die cast products, but with savings in resources and energy.

*METAMOLD is a registered trademark of NPR for its Metal injection molding (MIM) parts.



Metal powder and binder (wax + resins, etc.) are kneaded together uniformly.


The mixture is pelletized for better moldability.

3.Injection molding
Injection molding

Injection molding is done to produce formed items, similar to plastic products.

The mold will shrink about 10% to 20% after sintering. A mold will be created slightly larger in dimensions than the actual product, taking shrinkage into consideration.
4.Binder removal (degreasing furnace)
Binder removal (degreasing furnace)

The product is heated to remove the binder.

5.Sintering (continuous sintering furnace)
Sintering (continuous sintering furnace)

By sintering, a high density sintered product with relative density of 95% or higher is obtained.

6.Inspection / Shipment

Apply post processing (heat treatment, plating, etc.) as required, and pack and ship after inspection.

Features of METAMOLD

1.Costs reduced by forming of complex shaped items integrally.

METAMOLD has enabled the mass production of complex shaped products, similar to plastic and die cast products, from various metals. By enabling integral forming, it has enabled the manufacture of complex shaped parts for all fields at low cost.

Example of conversion to METAMOLD

2.Enables highly flexible design focused on design and functionality

Shapes made possible by METAMOLD

3.Excellent properties, such as high density and high strength promised

METAMOLD enables the manufacture of sintered items with a relative density of 95% or higher by using very fine metal powder. It has excellent mechanical properties, corrosion resistance and magnetic characteristics, and can provide a maximum surface roughness of around 6S after sintering.

Structural comparison of METAMOLD and conventional powder metallurgical products

It has excellent mechanical properties for its high density, with vacancies that are spherical and independent.
Powder metallurgical products
Powder metallurgical products
It has poor mechanical properties from its low density, with irregular vacancies existing along the grain boundary.
4.Shows superb dimensional accuracy

Internal stress and powder packing density are uniform because they are formed by introducing metal powder into the metal die cavity using binders. As a result, isotropic contraction occurs and high-accuracy dimension (±0.5% or less) can be obtained.

5.Diverse processing possible

Diverse processing to respond to complicating client needs, such as tapping, mechanical processing like various grinding, quenching and tempering, vacuum heat-treatment, plating, and lubricant processing, is possible.

Material characteristics and applications

Material Material quality Characteristics Applications
Low alloy steel Fe-Ni-C High strength, high toughness Automobiles, sewing machines, guns
Fe-Cr-C High strength, friction resistance Power tools, hydraulic machinery, musical instruments
SNCM,SCM Shock resistance Keys, automobiles
Stainless steel SUS316L Corrosion resistance Fishing goods, OA equipment, timepieces
SUS630 High strength, corrosion resistance OA equipment, medical parts
SUS410L Electromagnetic characteristics Electromagnetic parts, valves
SUS444 Electromagnetic characteristics Electromagnetic parts, valves
SUS440 high strength Time pieces, medical parts
SUS262 Allergy resistance, high strength Timepieces, hair dressing
SUS420J High strength, corrosion resistance Pneumatic machinery
SUS440C friction resistance,corrosion resistance Spinning machines, blades
Titanium Pure Ti, Ti alloy Corrosion resistance, light weight Timepieces, hair dressing
Other Super invar Low thermal expansion AV equipment
Kovar Thermal expansion close to glass Measuring equipment
Cemented carbide High hardness, high corrosion resistance Keys, timepieces
Heavy alloy High specific gravity Weight

Mechanical properties


Material quality

Tensile strength (MPa)

Elongation (%)

Hardness, etc.

Low alloy steel

Fe-Ni-C 1000-1800 2 - 10 HRC 30-50
Fe-Cr-C 1000-1800 1 - 7 HRC 30-60
SNCM 1120 3

Surface hardness Hv

 650 - 700
Stainless steel SUS316L 530 40
SUS630 1300 10

Post aging process HRC42

SUS410L 380 45
SUS444 450 35
SUSXM27 570 25
SUS420J 1000 8 HRC ≥40
SUS440C HRC ≥50
Titanium Pure Ti 555 15 Hv 150-240
Ti alloy 780 5 Hv 260
Other Kovar 540 30
Cemented carbide Hv 1600-1800
Heavy alloy

Specific gravity 18

Design points

Nominal dimensions (mm)

General tolerance(±mm) Special tolerance(±mm)

Dimensional tolerance

≤10 0.10 0.03
10<L≤20 0.15 0.10
20<L≤30 0.20 0.15
30<L≤50 0.30 0.20
50<L 0.5% 0.4%


General tolerance(±') Special tolerance(±')
0.5' 0.3'

Surface roughness

Rmax <12S

About 6S

Injector mark

0.05 - 0.1mm

Parting line

0.05 - 0.1mm

*The values vary depending on material and shape.