Laser processing for reducing core loss of grain oriented silicon steel

Iuchi, Tohru; Yamaguchi, S.; Ichiyama, Tadashi; Nakamura, Masashi; Ishimoto, Takahiro; Kuroki, Katsuro

doi:10.1063/1.330828

Cited by 110 publications

(18 citation statements)

References 5 publications

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“…While all these techniques improve the core loss reduction, laser scribing invented by NSC in 1982 is the most attractive because of its efficiency, ease of implementation, non-contact nature, and relative lack of damage to the surface coating [51]. Many electrical steel manufacturers have already implemented laser scribing in their production line.…”

Section: Magnetic Domain Refinementmentioning

confidence: 98%

Developments in the production of grain-oriented electrical steel

Xia

Kang

Wang

2008

Journal of Magnetism and Magnetic Materials

162

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Section: Magnetic Domain Refinementmentioning

confidence: 98%

Developments in the production of grain-oriented electrical steel

Xia

Kang

Wang

2008

Journal of Magnetism and Magnetic Materials

162

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“…In the first method, thin films of MgO are coated on a grain-oriented SiFe surface and appropriate tension is applied in a longitudinal direction. In the second method, magnetic domains are controlled by stress induced in an MgO-coated SiFe surface in a transverse direction [11,12]. The laser scribing method also generates stress on the SiFe surface and magnetic domains are also refined by this stress [9].…”

Section: Resultsmentioning

confidence: 99%

Investigation of core loss characteristics of 3% SiFe using the laser scribing method

Ahn¹,

Kim²,

Kim³

et al. 2004

Physica Status Solidi (b)

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The core loss of 3% SiFe is strongly dependent on silicon content, impurities, permeability, and domain structure of the SiFe. Domain refining has proved to be a very good method for the reduction of core loss in high-permeability grain-oriented SiFe, and laser scribing is well known as an effective and industrially important method of domain refinement. In this work, magnetic domain refinement was carried out using a pulsed and Q-switched Nd : YAG laser, and the core losses were measured and analysed to find the optimal parameters of the laser treatment. The laser beam was focused with a spot size of 0.2 mm and pulse energy of 15 -30 mJ and the lines were scribed with a period of ~5 mm. The core loss was improved by up to 18% in 3% SiFe using this method, and the loss was relatively insensitive to the optical energy of the Q-switched pulse. 1 Introduction In the field of metal processing lasers have been very useful tools for the processing or heat treatment of many materials, such as silicon, ceramics, magnetic materials, and thin films. Among these applications, laser scribing, in particular, has been paid a lot of attention as a very powerful method for improving the electrical characteristics of silicon steel (SiFe) [1 -5]. SiFe is used as an important material for motors and transformer cores. Since 65% of electrical energy is consumed by motors, SiFe can be said to be one of the main factors in electrical energy consumption. The efficiency of a motor is known to be about 86% [6] and most energy loss is caused by heat radiation (I 2 R) and core loss. It is expected that the efficiency of a motor can be increased to 93% by reducing the core loss, which will, in turn, contribute greatly to energy savings.In this work we try to decrease the core loss by directing a laser beam on the surface of SiFe. Generally, laser processing of materials has many advantages over mechanical methods: easy automation of the process, no frictional wear of processing tools, and it is free from pollution caused by direct contact of mechanical tools with materials. Also, no mechanical damage occurs when handling hard and fragile materials like SiFe, silicon, and ceramics. If we use a laser in pulsed mode, the laser pulse energy and corresponding heat transfer can be localized to a very small region. Therefore the distortion and shrink of the target object caused by heat can be avoided [7,8].Laser scribing, in particular, is expected to enhance the quality of processing substantially because it provides much higher controllability and reproducibility than the conventional method where stress is

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“…A reduction of Bloch wall distances in grain-oriented iron silicon steels can be reached by the introduction of surface defects mostly arranged perpendicular to the axis of easy magnetization by several techniques such as scratching, spark ablation, electron or ion beam scribing, chemical etching, or the well-known laser scribing [4][5][6][7][8]. The induced surface defects usually lead to an increase of hysteresis loss while dynamic losses are decreased.…”

Section: Introductionmentioning

confidence: 98%