Manufacturing Technology

SACMA Group has introduced a new warm forming production line, which it says reaffirms its position as the market specialist for headers and threaders for special materials.

Initially the hot forging process was the first, and for many years the only, process applied to form shaped metal pieces. In the second half of the last century, pushed by the needs of mass production, the cold forming process became widespread, initially to produce bolts and screws and after also special parts – solid and hollow. The warm forming process stays in the middle of the cold and hot processes, but is closer to cold forming to ensure precision/accuracy of the tools and machinery.

The main difference among processes are the temperature of the material to be formed. For cold forming, all the materials start the deformation from room temperature. At hot, the steel blanks are heated in the range from 950°C up to 1,250°C. For warm forming, the operating temperature is lower and doesn’t exceed 900°C for steels. The total energy spent to perform the warm forming process is less than hot forging and quite similar to cold forming, because the heating energy is compensated by the lower amount of deformation energy. However, the tools are generally more durable for cold forming, less for hot forging and in the middle for warm forming. 

By warm forming it is possible to produce more difficult parts than cold forming and also the range of suitable materials is much wider. Despite the interesting features of the warm forming process, the development is still quite limited for different reasons – such as dedicated machinery, specific lubricants, as well as effective coatings.  

A common question when approaching the warm forming process is about 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 warm forming process is not so interesting, because these are typical materials for cold forming. High carbon and alloy steels require temperatures in the range of 600°C – 700°C.

Austenitic stainless steels are heated to 200°C – 300°C to form solid parts and up to 500°C to produce hollow parts by backward extrusion. Lastly, the typical materials used in the aerospace industry, such as titanium alloys and nickel superalloys, need temperatures from 500°C to 850°C – depending on the quality of material and shape of the part.

The key point for warm forming machinery is to handle the temperature without affecting reliability and precision. For high temperatures the technology becomes more complex and exclusive. When the products don’t require important pre-heating, the machine could be more simple and less expensive.

It’s because of the ‘right equipment for each demand’ focus that SACMA is now presenting the ultimate WF headers product line. The line is suitable for a range of wire diameters from 4mm to 25mm and of temperatures from room to 900°C. The 5 and 6 die headers WF are size 2 – wire max 10.5mm, size 3 – max 15mm, size 4 – max 20mm and size 5 – max 25mm.

For size 2 and 3, there are different models defined by the maximum reachable temperature: WF300, WF500 and WF900. For sizes 4 and 5 there is only one warm forming version covering all the field up to 900°C.

Ingramatic introduces new warm forming rollers

To complete the SACMA warm former line, Ingramatic has also introduced new warm forming rollers. Combining the heavy-duty design and the features of the revolutionary I-Thread, the warm WF rollers provide a significant increase in thread quality, productivity, and efficiency, by rolling all shapes of bolts, screws, studs, and parts, made of materials difficult to be rolled by cold forming. 

Features of the new line include new feeding rails allowing the installation of the induction coil with an exclusive design; a generator from 12kW to 30kW; high frequency inverter box; optical pyrometer; chiller; and a coolant system to thermoregulate the stationary die holder and the feeding rails.

A system of cadencers manage the parts out the exit of the induction coil to ensure the parts are delivered to the starter unit at the right temperature. During the production, to manage the quality and the repeatability of the part dimensions, the pyrometer and the load monitor check each part and reject the non-conforming parts automatically without stopping the machine and the heating unit.

For a complete changeover, Ingramatic says only 30 minutes is necessary and for a changeover consisting only on the part length, 10 minutes is enough. This makes the rollers very competitive for the aerospace market where the production quantity is very low. This is possible because the WF rollers are part of the I-Thread machine design, the revolutionary line of thread rolling machines emphasised by a quick set-up with all adjustments fully motorised, as well as the rigidness of the WF rollers – the one piece iron casting bed frame includes the reaction block designed to counter the stresses caused by thread rolling special materials and profiles.

The rollers are also user-friendly with an I-Panel touch screen to control all warm forming functions integrated in a page dedicated to the WF unit and constant control is possible  thanks to the main page showing the real temperature and the kW necessary to warm the parts. Flexibility also features with the WF rollers, with the single starter unit driven by servomotor. The bigger machines also feature the servomotor for die match adjustment with load monitor control and hydraulic clamping of the drive unit.

Simple to use for operators, the WF roller also features an electronic handwheel that can be used for all machine adjustments – die match, rail position and starter unit – eliminating the use of hand tools.

With this new WF line, SACMA Group completes its whole range of machines and is now able to provide the right equipment for each individual demand of a variety of industries – including the aerospace market. 

www.sacmagroup.com