Inductive billet heating

For induction billet heating, EltaTech offers billetXpresstechnology, an innovative induction system for extrusion processes. The new system with improved coil design and a new concept for energy supply using direct inverter technology has been developed to achieve higher energy efficiency and increased performance as well as significant cost and space savings.

Advantages of induction billet heating

Induction heating of billets offers many advantages compared to conventional heating systems. The main advantages are process reliability, high throughput and, in particular, the ability to create a conical temperature profile (also known as a "taper"). EltaTech offers a new process for induction billet heating that significantly reduces investment costs and the space required. Furthermore, the billetXpress billet heater opens up new possibilities for process control thanks to freely adjustable frequency selection.

Two different processes are used for induction billet heating, depending on the application.

Induction heating using the single block method

For aluminum and aluminum alloys as well as sensitive materials, the single-block method is predominantly used. The induction billet heaters of this type operate in the mains to medium frequency range and are equipped with multi-layer coils, which are divided into several independently operating heating zones. The individually controlled power in the heating zones allows a linear or conical temperature profile to be generated, whereby a targeted material flow can be set during the pressing process. To prevent unwanted surface damage, the billetXpressblock heating systems are equipped with a particularly gentle loading system.

Induction block heaters using the push-through method

In order to achieve a high throughput with a small footprint, the push-through method is used in induction block heaters. The new billetXpresstechnology is based on the combination of a highly efficient induction coil and innovative direct inverter technology. With this concept, the blocks are fed into the coil individually using a pusher, while a part heated to the target temperature is pushed out at the same time. Intelligent process control also enables continuous production with blocks of different lengths without the need for retooling.

Optimum temperature distribution as a result of billetxpress technology for induction billet heating

Advantages of direct inverter technology for induction billet heating

Converters with resonant circuits are usually used to supply power to induction systems. With this converter technology, it is necessary to compensate for the reactive current component using resonant circuit capacitors. Reactive current compensation accounts for a not inconsiderable proportion of the investment costs, which is in the order of around 10% - 15% of the total system value. Regular maintenance work and, if necessary, the replacement of the associated wear-prone system components and the additional large amount of space required are further disadvantages.

The innovative concept of the billetXpressbillet heater therefore relies on state-of-the-art direct inverter technology, which no longer requires power factor correction. This results in considerable cost and space savings.

The digital control of the modern direct inverter technology enables infinitely variable adjustment of the operating frequency. This achieves optimum efficiency. In addition, this enables a high degree of flexibility in the production process under different process conditions (e.g. different materials or workpiece dimensions). A low operating frequency below the mains frequency is particularly advantageous for large block diameters and materials with poor thermal conductivity.

This allows a greater penetration depth of the electromagnetic field to be achieved, which significantly reduces the heating time. Furthermore, the optimized heating rate and increase in throughput leads to an increase in overall efficiency, which was verified by means of energy measurements.

Intelligent process control for billet heating

For both types of production (single block and pusher process), the integrated PLC control ensures a continuous flow of material to the downstream press. In addition, the new billetXpress technology offers the option of interrupting the production flow (e.g. for inspection or changeover work on the press) without having to restart the heating process. Intelligent temperature management of the PLC control system keeps the blocks in the oven section at the right temperature. It is therefore no longer necessary to empty the furnace section and restart it after an interruption in production. All process values (parameters + current measured values) are displayed and monitored for quality assurance purposes. Trend curves are displayed visually. In addition, all process-relevant information is archived and can be forwarded to higher-level systems for quality assurance and process documentation if required.