Stress relief with workpiece control. Better suited to small lot production

Shikoku Heat Treatment Co., Ltd.

Company website

Head Office

1-2-45 Sawazu-cho, Niihama, Ehime 792-0862

Saijo Plant

473 Minatokitashinchi, Saijo, Ehime 793-0046

TEL (0897) 55-6187 FAX (0897) 55-1501

Certified products and technology
Metal heat treatment technology for stress relief in plate working products
Shikoku Heat Treatment Co., Ltd. 1

Shikoku Heat Treatment operates three types of heat treatment furnaces – large, medium and small – for various types of metal heat treatment including quenching and tempering, annealing and stress relief of large workpieces, as well as sandblasting and base coat paint processing. Founded in 1974, Shikoku Heat Treatment first began operations with the installation of a furnace 5 m wide, 10 m long and 4 m high, one of the largest furnaces operated by heat treatment specialists in the Chugoku and Shikoku regions. The Sumitomo Group has been the company's main client since being founded, and today orders are received from customers in the Chugoku, Shikoku and Kyushu regions for products including chemical plant tanks, press frame stands and other welded structures.

Shikoku Heat Treatment Co., Ltd. 2

Temperature control is an essential technology for heat treatment. To control temperatures, Shikoku Heat Treatment uses atmospheric control for monitoring temperatures inside quenching furnaces, and workpiece control during stress relief by attaching thermocouples to workpieces. Precise monitoring of the level of temperature increases in workpieces is essential, especially during stress relief for improving machining accuracy and limiting age degradation. The large furnace that is currently in operation suits workpieces up to 15 m long, and during workpiece control the temperature is normally monitored in three locations over a 15 m span. Measurements can be taken in up to six or nine locations if required by customers. Shikoku Heat Treatment also applies its own methods and expertise for determining locations to attach thermocouples, and this gives the company its competitive edge. With this level of monitoring precision, temperatures in the furnace during stress relief is controlled with the range of 625ºC ±20ºC.

Shikoku Heat Treatment Co., Ltd. 3

Today, business is equally balanced between work requests for steel material quenching from steel material retailers, and orders for stress relief of plate working products received from steelworks. Plant Manager Norimitsu Tokuno explains: "The normal process involves quenching after rough machining, however quenching is increasingly being done with raw materials." He says that the number of customers is decreasing, and the overall amount of heat treatment work has also become less. In light of such conditions, the aging small furnace was upgraded in November 2017 to better prepare for small lot production.

Shikoku Heat Treatment Co., Ltd. 4

The company's large furnace is suited to stress relief work, while the medium furnace is mainly used for quenching and other processes. When costs are taken into consideration, operating the medium furnace is difficult unless there are a sufficient number of workpieces that can be treated together. There are times when jobs might be on hold for around a week until a sufficient number of workpieces becomes available. The new small furnace is 2.2 m wide, 2.5 m long and 1.2 m high. Quenching and tempering processes are automated, and the quickest turnaround can be the day after a job is received, which makes delivery times 3 to 4 days faster. Fuel use is more efficient with a high-precision, high-efficiency burner, which has cut down on fuel costs.

While the majority of orders involve a single large workpiece, Plant Manager Tokuno says the company wants to take on mass-production jobs in the future. The company is also looking at covering surface treatment methods such as high-frequency carburizing and quenching, to keep orders in Shikoku that would otherwise be sent to Hiroshima or Osaka. There are around just five heat treatment businesses operating in Shikoku, and the types of jobs they cover are also limited. The aim is to increase the types of treatment services available and expand sales by marketing themselves as 'local' companies. Company staff are encouraged to acquire the certification for the relevant skills, with financial aid provided to cover any costs required to do so. In this way, Shikoku Heat Treatment helps staff to remain motivated and boost their skills, as well as increasing the company's competitive edge.

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