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Newsletter "SEI NEWS" 2012

Home > Company Information > SEI WORLD > Back number > Vol.417

[Newsletter "SEI NEWS" Vol.417]

Sumitube and Irrax Sleeve, products made with irradiation technology

In the early 1960s, Sumitomo Electric began development of new materials and products made with irradiation technology. Sumitomo Electric Fine Polymer Inc. now produces irradiated products such as Sumitube and Irrax Sleeve.

Sumitube and Irrax Sleeve, products made with irradiation technology

■Sumitube and Irrax Sleeve, products made with irradiation technology Product Data
Start of production 1964
Production bases Japan (Osaka), U.S., Germany, China, Taiwan

What is irradiation?

In general, when plastics are exposed to electron beams (i.e. electrons accelerated by high voltage in a vacuum), the individual molecules comprising the material begin to interconnect in a reaction called cross-linking. This results in improved shape-memory effects and high resistance to heat, oil and chemical treatment.

Since building the first industrial electron irradiation device in Japan in 1964, Sumitomo Electric has been developing and marketing products based on its proprietary plastic irradiation technology.

What are irradiated products used for?

Sumitube is a heat-shrinkable tube made by taking advantage of the shape-memory effect resulting from electron irradiation.
Heat-shrinkable means that the tube can be shrunk in the radial direction by applying heat. Sumitube is used in electric appliances and electronic devices as well as automobile and aerospace instruments for protection of electric cable, wiring harness and insulators.

Irrax Sleeve is a heat-shrinkable tube with larger dimensions. Waterproof and climate resistant to a high degree, it is widely used for preventing corrosion of outdoor cables and pipes.

■Interview with engineers in charge

Yasutaka Emoto
Irradiated Products Engineering Dept. Sumitomo Electric Fine Polymer, Inc.

Toshiyuki Shiozaki
Manufacturing Dept. Sumitomo Electric Fine Polymer, Inc.

What do you think satisfies customers?

The main appeal of our irradiated product services lies in our extensive product lineup and development teams that enable us to rapidly respond to a wide range of customers’ needs. To take a familiar example from our routine work, we’ve had customers who were experiencing trouble with rats chewing away at residential electric wiring. In response, we developed a unique tube incorporating a rat-repelling substance. Technological expectation are rising due to a recent increase in customers in the automobile and aerospace industries, but we will take advantage of the experience we’ve accumulated to this day to conceive new applications and develop new fields.

Tell us about products you’ve developed recently.

We developed a dual-wall tube with meltable adhesive to be used in waterproofing harness joints for motor vehicles. We also developed and marketed a special heat-shrinkage machine called the SumiShrinker that utilizes a belt conveyance system to provide this dual-wall tube with shrinkage properties. In this manner, we’ve gone beyond leaving heat-shrinkage processing to the customer and have prepared a system where we can make suggestions and provide support in terms of shrinkable tubes and shrinkage conditions that suit the electrical wiring used for harnesses.

What’s difficult in making irradiated products?

Sumitube and Irrax Sleeve are made through three basic processes: extrusion, irradiation and expansion. Among these, the expanding process is the most characteristic. First, the tube that was molded through extrusion is irradiated to facilitate cross-linking. Then in the expanding process, the tube is expanded in the radial direction to enlarge its diameter. Expanding long tubes continuously to the required product specification is comparable to controlling the expansion of a long and thin balloon several hundred meters in length and is very difficult. We need to carefully manage various manufacturing parameters in this process and this necessitates the implementation of a lot of technological knowhow concerning equipment and methods.

・Sumitube, Irrax and SumiShrinker are trademarks or registered trademarks of Sumitomo Electric Industries, Ltd.

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