6 Problems In Manufacturing Of Stator Cores

With the increasingly detailed division of labor in the motor manufacturing industry, a number of motor factories have taken the stator core as a purchased part or commissioned outsourcing part. Although the core has a full set of design drawings, its size, shape and material have detailed provisions, but once the core manufacturing is completed, manufacturers can only test the size, shape, appearance and other characteristics, and cannot test the material used, lamination factor and other characteristics affecting the performance of the machine such as the insulation between silicon steel laminations and core loss. Therefore, manufacturers have no choice but to exempt from inspection, resulting in large difference in core loss or even nonconforming machine.

As an important part of the motor, the core plays a vital role of magnetic conduction in the motor. The material used in the core and the quality of the core manufacturing not only affect the craftsmanship and insulation reliability of the motor insert, but also affect the excitation current, core loss, and stray loss, etc., which in turn affects the efficiency and temperature rise of the motor. Therefore, enough attention should be paid to the core manufacturing quality. Only by knowing problems in the core manufacturing process can you develop targeted inspection measures and testing methods.

Next Gator Precision will analyze the six major problems that exist in the manufacturing process of stator cores.

1. Excessive burr on the laminations

Excessive burr on the motor laminations will affect the lamination factor, increase the core loss, and even affect the reliability of the motor by piercing the insulation. The main reasons for excessive burrs include inappropriate die clearance, blunted die edge, improper matching of silicon steel material and thickness with die clearance, and inappropriate parameters of stamping equipment and process. Usually, the lamination burr should be no more than 0.04mm.

2. Uneven lamination

Uneven lamination is the most common quality problem of core manufacturing quality, which will result in nonconforming size of the core, affect the reliability and life of the insulation structure, and affect the assembly of the core and the housing, etc. The main reasons for uneven lamination are the unsuitable lamination tooling and inappropriate positioning.

3. Extensive trimming

In case of uneven lamination, many an electrical steel laminations manufacturer chooses to trim the laminations to guarantee the size of the core slot, but it will bring a large area between the silicon steel sheet connected, seriously reduce the resistance between the sheets, increase the core loss and stray loss, increase excitation current, reduce efficiency, and increase temperature rise, etc. Usually, after the core lamination is completed, a large area of trimming is not allowed, especially for armature cores.

4. High or low lamination factor

Low lamination factor will lead to increased magnetic density, increased excitation current, and increased core loss and copper loss, as well as the core vibration in the operation, damaged insulation, and increased noise. High lamination factor will also lead to reduced resistance between laminations and increased core loss. Therefore, the lamination factor is an important indicator of the stator core, that is, the lamination factor should not be too large or too small. The lamination factor is specified in the core design drawings and is usually about 0.96.
The main reasons for high or low lamination factor are improper lamination process, inappropriate process parameters, too much or too little pressure, and too large burrs, etc.

5. Poor-quality lamination material

The commonly used material for the core is silicon steel sheet. And steel plate or solid core is often used for some DC or low frequency cores (such as synchronous rotor core, DC motor core, and even asynchronous motor rotor core). What should be emphasized here is that the material quality of the silicon steel sheet of the armature core, especially high frequency armature core, seriously affects the core loss and excitation current, so the raw materials used in the core must meet the design requirements.
However, some manufacturers use poor-quality lamination materials to replace high quality ones, and even use general thin steel plate because the material quality is hard to detect for the finished core. What’s worse, some manufacturers mix ordinary steel plate in the silicon steel “out of conscience”, which will cause more serious consequences, making the core loss worse.

6. Unqualified size

The dimensions mainly include the slot size and the finished core size. Since most of the motor laminations are stamped out using the die. As long as the first lamination passes the size inspection, the size of subsequent laminations can be guaranteed by the die, so there is usually no problem of unqualified size. In addition, most of the core sizes can still be easily inspected after the core manufacturing is completed.

Choose the best laminations manufacturer

Some of the above-mentioned problems are due to poor process equipment, poor hardware conditions, and the lack of manufacturing capacity, and it is recommended not to choose the suppliers with these problems, or you should require such suppliers to rectify the problems before the deadline, and increase the investment in equipment and other hardware conditions. Some problems are due to the insufficient implementation of process discipline or unreasonable process details and process parameters, and lack of enough attention by process personnel and operating workers. These management problems are easy to be rectified by suppliers.

To avoid all kinds of problems that may exist in the stator cores, you should choose a lamination manufacturer with strength, standard management and integrity. But you may wonder how to choose the best lamination manufacturer from numerous manufacturers. So top 5 laminate sheets manufacturers are shared with you to help you make the wise buying decision.

1. AICA Laminates India
Established in November 2011, AICA Laminates India has its manufacturing facility at Rudrapur, Uttarakhand where all its products are manufactured to the most stringent international standards, and has been providing topnotch quality decorative laminates.

2. Jiangyin Gator Precision Mold Co., Ltd.
Founded in 2011, Jiangyin Gator Precision Mould Co., Ltd. is a comprehensive enterprise integrating mold manufacturing, silicon steel sheet stamping, motor assembly, production and sales. It has applied for more than 30 inventions and utility model patents, through ISO9001, and TS16949 system certification.

3. Duroply Industries
It provides a wide range of products including plywood and blackboards, decorative veneers and flushdoors.

4. Kridha Plywood and Laminates
It started with manufacturing plywood and has evolved into a state-of-the-art electrical steel laminations manufacturer with keen eye on technological advancements in the industry.

5. Century Ply
A pioneer in Borer Proof Plywood and Boiling Water Resistant and provides excellent quality products.

Post time: Aug-17-2022