Motor Core

Basic Information


Motors are essential commodities for human’s daily life.

For example, a hybrid car as a driver. Due to tough environmental regulations, hybridization and electric vehicles are progressing globally.
The motors of this type are for driving a large device but they are manufactured in full consideration of efficiency and economy so as to be ecological and to ensure the performance of comfortable drive.

Furthermore motors are used in many places where electricity works such as personal computers, household electrical appliances, electrical equipment and robots.

Quality First


Mitsui High-tec, Inc. supplies motor cores for automotive application with more than 1.6 million sets per year with high precision interlock technology which has been cultivated for many years.
We are committed to zero defects to our customers. We have established a Quality system to achieve zero defective products and performed the best quality production output.
We have received various Supplier Awards for Quality and On-Time Delivery from customers all over the world. Using Mitsui’s fine dies enable lamination with materials its external diameters greater than 200 mm or with materials as thin as 0.3mm and produce high quality motor cores.

MAC System

MAC system, stands for “Mitsui Automatic Core assembly system” is an innovative In-Die motor cores manufacturing system which was developed by Mitsui in 1975 in order to drastically improve the productivity of Motor Cores.

Since its first release in 1978, MAC system has been highly praised by electric manufacturers world-wide. One set of punching die, peripheral devices and its controller compose a MAC system.

MAC System features stacking lamination while pressuring by hydraulic cylinder.
This back-pressure method by hydraulic cylinder enable to produce quality motor cores with large sized materials as well as thin materials.
By introducing the MAC system, the core of the large diameter motor such as large drive motors of electric vehicle can also be made with high accuracy.

View the details of MAC system controller

Upon a user’s request technical training is available to support installation and most efficient operation of MAC system.

Improvement of quality
It is possible to carry out core-turning and alternate interlocking so as to control the decrease in product quality due to the variation in material quality.


Thickness of coiled material is not uniform. Therefore, even if the difference in thickness on a piece of material sheet is slight, the total difference will be significant when several tens of material sheets are laminated.
In order to eliminate such a significant difference, a core under forming by lamination in a die is turned by 90 or 180 degrees, by which the difference produced by lamination can be minimized.Finally, the accuracy of straightness, squareness and parallelism can be increased.

Alternate interlocks

Alternate interlocks
In conventional interlocking, a gap is generated at the corner (shown by a blue arrow) due to the bend dimensions, causing an undesirable wider gap between material sheets.
In the case of alternate interlock, the cut and bend direction is alternated so as to make a space at the corner portion (shown in a red arrow), reducing the gap between material sheets.

Capable of producing various shapes

MAC system can produce cores of various shapes such as skewed, V-skewed and counter-bored as well as straight.


Motor Core Stamping

Motor Core Stamping

Mitsui High-tec provides high quality and low cost motor core products with complete global service from die design, fabrication and stamping manufacturing.

High Quality and Low Cost

High Quality and Low Cost

Proven technology accumulated since our company foundation guarantees high quality and low cost for precision stamping dies and the MAC system which was developed in-house. MAC is a system that fuses motor core layers to complete each core product inside the stamping tool as they are stamped, eliminating the need for a separate process after stamping.
Mitsui’s motor cores are used in a variety of applications from the high-precision 2.7 mm diameter micro motors of vibrators in portable phones, to the high efficiency and high output 300 mm diameter motor cores required by hybrid automobiles.

MAC System (Mitsui Automatic Core assembly system)

Global Network

Global Network

The basic concept of “Manufacture close to customer”.
Out global supply network supplies motor core stamping in Japan and in overseas production facilities in Thailand, Guangdong, Shanghai,  and Canada.
This guarantees customers a supply of motor cores of the right quantity at the right time in the right place.

Magnet Mold®

Magnet Mold®

By filling thermosetting epoxy resin, magnets are bonded inside of holes of Rotor cores.
Compared to the conventional bonding process, Magnet Mold® has higher filling rate and shorter cure time.
Applying high precise mold enable to produce high efficiency Rotor Cores at low cost.
Mitsui High-tec, Inc. holds a patent of Magnet Mold®.

Integral- Stacked Segment Core

Integral- Stacked Segment Core

The segment core is emitted from Dies with shape of one body core.
We stamp both Stator segment and Rotor cores together which improve the productivity.We also stamp integral Stacked Segment Core with in tool rotation producing high precision motor core.
Compared to previous segment core, Integral-Stacked Segment core reduce cogging torque by eliminating gap between each tooth.
Mitsui High-tec, Inc. holds a patent of the process of Integral-Stacked Segment Core.