State-of-the-Art Tailored Blank Facility Introduced at SSC Kyushu
- Acceleration of Steel Sheet Supply System Aimed at Reducing Vehicle Body Weight -

Sumitomo Metal Industries, Ltd. (Sumitomo Metals) recently introduced a state-of-the-art tailored welded blank facility at SSC Kyushu Co., Ltd. (location: Fukuoka; hereinafter KSSC), a coil center based in the Kyushu region that Sumitomo Metals operates in cooperation with Kanpoh Steel Co., Ltd, Sumitomo Corporation, and Sumikin Bussan Corporation. The facility entered operation on October 1.

Tailored welded blanks (TWB)( *1) are a technology used to manufacture automobile parts by welding steel sheets with varied thickness and strength and then by forming into a part by only one blanking. Compared to the conventional method, the TWB technology enables to achieve both vehicle collision safety and the reduction of body weight, and contributes to auto makers' development of environmentally friendly vehicles.

The TWB facility that recently entered operation at KSSC is a state-of-the-art fiber laser system. As a result, there are now six TWB supply bases operated by Sumitomo Metals and Sumitomo Corporation, which represents the largest TWB supply capacity in Japan.

1. Sumitomo Metals' TWB technology
Sumitomo Metals has a long tradition of research into welding technologies. With regard to TWB technology as well, Sumitomo Metals was the first company in Japan to start joint research on CO2 laser welding(*2) with Toyota Motor Corporation from around 1980. At its Corporate Research & Development Laboratories, as well, Sumitomo Metals initiated research by introducing mash seam welding, plasma welding, and various kinds of laser welding machines. In 2000, Sumikin Plant, Ltd., a group company, started manufacturing and selling TWB production equipment, and so far it has supplied 15 machines to 11 companies.

Sumitomo Metals also developed an evaluation method based on micro tension and fatigue testing of parts in the vicinity of weld zones, and then established computer aided engineering (CAE)(*3) of welded joints by using the acquired data. Based on this process, the Company provides customers with technical information such as the combination of materials that suit TWB products and optimal welding locations. In such ways, Sumitomo Metals has built a comprehensive organization related to TWB that covers from the stage of customers' product design to material selection, the proposal of welding conditions, the provision of mass production equipment, the establishment of quality in its operation (welding and pressing). the sale of materials, to the provision of solutions.

2. KSSC's state-of-the-art TWB equipment
Previously, the Sumitomo Metals Group's TWB facilities that had been introduced in Japan mainly comprised YAG laser welding systems, but the Company has now introduced its first fiber laser welding machine (oscillator: output of 4 kW, manufactured by IPG Photonics Corporation; production equipment: Sumikin Plant, Ltd.). The fiber laser welding machine is the latest type of laser welding machine that causes lasers to oscillate from optical fibers. As Sumitomo Metals introduced a fiber laser welding machine with the highest output in Japan (10 kW) at the Kashima Steel Works No. 2 Steel Sheet Plant in September 2007, the Company has built up expertise concerning actual equipment. Based on this expertise, Sumitomo Metals introduced a TWB facility for fiber laser welding with the aim of ensuring the stability of performance and quality in tandem with low running costs.

KSSC's TWB materials are supplied to Toyota Motor Kyushu Inc. after pressing and assembly at Toyotetsu Fukuoka Co., Ltd., a major customer.

3. Sumitomo Metals' and Sumitomo Corporation's TWB supply system
In the steel sheet business, Sumitomo Metals has established coil centers at various locations in Japan and overseas, in cooperation with Sumitomo Corporation, and worked to ensure carefully tailored delivery services with the aim of being rated number one by customers. As TWB technology enables different types of steel sheets, such as high-tensile steel and ordinary steel, to be combined on a customized basis in terms of optimal materials and optimal locations, it fulfills demands for a reduction in the body weight of vehicles and greater collision safety for automobiles, the largest source of demand for the steel sheet.

Sumitomo Metals and Sumitomo Corporation have deployed blanking equipment and TWB facilities at coil centers in major regions of Japan. At present, there are six domestic locations, including KSSC, in the country. In the Kyushu region, after introducing a facility at Summit Steel Oita Co., Ltd., which began producing TWB components in June 2008, Sumitomo Metals has now introduced a facility at KSSC as well. The Company has newly built a mass production system for TWB components in the Kyushu region for supply to Toyota Motor Kyushu Inc. and other manufacturers.

Profile of KSSC

  

*1: Tailored Welded Blank
Tailored welded blanks (TWB) are a technology used to manufacture automobile parts by welding steel sheets with varied thickness and strength and then by forming into a part by only one blanking. This compares with the conventional method which enables to make pieces with uniform thickness and strength only. The new technology is used to manufacture parts such as pillars and inner door panels which requires durability against collisions with reduction of weight.

*2: Laser welding
Laser welding is a form of welding that entails transmitting a laser beam with a heat source that is condensed and has high energy density and heating the weld zone with the use of this light energy. There are various forms of laser welding such as CO2 laser welding, YAG laser welding, and fiber laser welding, depending on the type of laser light source. (YAG is an abbreviation from Yttrium, Aluminum, and Garnet.) Laser welding is distinguished by the fact that 1) it has a low quantity of heat input, as it is possible to heat only the necessary parts; 2) it is high speed and can obtain a very deep depth of fusion; 3) welding heat impact is very low; and 4) it causes little weld distortion.

*3: Computer Aided Engineering
This is a technology that supports the design of products, and so forth, through simulations utilizing a computer. It is also called numerical analysis, and is one of the elemental technologies that are the greatest strengths of Sumitomo Metals.

<SSC Kyushu (Fukuoka)’s TWB facility that uses the latest type of laser welding machines>

<Domestic TWB product supply system of Sumitomo Metals and Sumitomo Corporation>