EuroFasteners July 2021

Manufacturing Technology

▲ Sacma’s warm forming technology

Warm forming product lines Hot forging (HF) was the first, and for many years only, process applied to form shaped metal pieces. In the second half of the last century, pushed by the needs of mass production, cold forming (CF) became widespread, initially to produce bolts and screws, and then also for special parts, both solid and hollow. The warm forming (WF) process is positioned between cold and hot processes. less for hot forging and in the middle for warm forming. By WF it is possible to produce more difficult parts than CF, and the range of suitable materials is wider. The key point for WF machinery is to handle the temperature without affecting reliability and precision. For high temperatures, the technology becomes more complex and exclusive. When the products do not require important pre- heating, the machine can be simpler.

A common question relates to the heating temperature to be used. The goal is to define the right temperature for each material, enlarging the plastic field and the limits of deformation just enough to allow the required deformation. For low carbon steels, the WF process is not so relevant, because they are typical materials for cold forming. High carbon and alloy steels require temperatures in the range of 600-700°C. Austenitic stainless steels are heated to 200-300°C to form solid parts and up to 500°C to produce hollow parts by backward extrusion. Typical materials used in the aerospace industry, such as titanium alloys and nickel super alloys, need temperatures from 500 to 850°C.

Focusing on a target of “the right equipment for each demand”, Sacma is now presenting its WF headers product line. The range covers wire diameters from 4 to 25mm and temperatures from room to 900°C. The five and six WF die headers are size 2 (wire up to 10.5mm), size 3 (15mm), size 4 (20mm) and size 5 (25mm). For sizes 4 and 5, just one WF version covers all of the field up to 900°C. For sizes 2 and 3, different models are defined by the maximum reachable temperature: WF300, WF500 andWF900.

The main difference among the processes is, of course, the temperature of the material to be formed. In CF, all the materials start the deformation from room temperature. In HF, the steel blanks are heated in the range from 950 to 1,250°C. In WF, the operating temperature is lower, not exceeding 900°C for steels. The total energy spent to perform the WF process is less than HF and quite similar to CF, because the heating energy is compensated for by the lower amount of deformation energy. The tools are generally more durable for cold forming,

Sacma Limbiate SpA www.sacmagroup.com

Graphics bigstockphoto.com Artist Youra_P

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July 2021