Due to the great drawing and shrinkage forces occurring at high operating temperatures, industrial yarn spinning processes make considerable demands on the godets used. In addition to the proven "flagship", the HF®8, Barmag now offers with the HF®4/IY-400/190, HF®4/IY-400 and the HF®7/IY-400 godets - three new heated types of godets, which are designed for managing a considerably greater number of ends at low investment costs.

The HF4/IY-400 godet has been optimized for the conventional industrial yarn process with production speeds of up to 4,500 m/min. To this end, the HF®4/IY-400/190 is a variant with a smaller jacket diameter. The HF®7/IY-400 has been developed for HMLS processes with speeds of up to 7,000 m/min. The HF®8 godet can be used for speeds of up to 8,000 m/min and for high end applications.

Seven heated godets based on the HF® modular system cover the entire range of process requirements for FDY and industrial yarn. Within the family, the new godets are extensively compatible, an important advantage in terms of retrofitting and upgrading existing systems. The spectrum of jacket dimensions ranges from diameters of between 190 mm and 250 mm and lengths of up to 500 mm. Hence, Barmag is able to fulfill the broad scope of customer requirements for these processes (fig. 1).

Fig-1: Product range, heated godets

In contrast to the HF8, the reduced dimension of the godet jackets - with the HF®4/IY-400 and HF®7/IY-400 with a diameter of 220 mm, the HF®4/IY-400/190 with a diameter of 190mm and all three with a length of 400 mm - permit the implementation of more compact and more ergonomic draw units. For processes with speeds of up to 7,000 m/min, these jacket dimensions offer - in conjunction with the installed heater performance - the right prerequisites for evenly heating all threads to the required drawing temperature. At speeds of 8,000 m/min, this is only possible with the larger jacket and the greater heater performance of the HF®8-godet (fig. 2).

Fig-2: Draw unit for industrial yarn

The development of the new godets was based on the experience gained from the success of ten years that the HF® series has been in use. The core of this experience is the bearing technology, which is decisive for the series long-term, error-free use, as the large radial forces, high speeds and high temperatures represent extreme loads for the godets. The cooperation with an aerospace bearings manufacturer resulted in a state-of-the-art spindle bearing, based on the latest technology from roller bearing technique. To this end, the patented oil-lubrication system, Barolub, guarantees minimal oil consumption at low operating costs (fig. 3).

Fig-3: Bearing

Fig-4: Heater

Barmag also offers the heated HF8/IY-Power godets up to a speed of 8000m/min and 250°C jacket temperature with a maximum draw-force potential of 250 N and a maximum possible radial load capacity of 5000 N. The HFp is designed for a denier range of up to 12.400 dtex. A broad spectrum of low-wear, ceramic surfaces with varying roughnesses ensures a safe process with a high degree of efficiency. The proven high frequency, low output-loss multi-zone heating is also used. A high output of 18 KW in 4 zones offers good reserves and further scope for process optimization. In contrast to the single zone heater godets, the temperature profiles for the HF®4/IY-400/190, the HF®4/IY-400 and the HF®7/IY-400 godet are adjustable across the working length. This guarantees temperature accuracy of ±1.5 °C within the overall operating area (fig. 4).

The compact structure of the new godets is also made possible as a result of increasing the power density of the drive motor. Here, an extremely reliable water cooling system is used. In the case of a ventilator cooling system, the torques required for great drawing forces would have meant using a considerably larger motor. This principle has proven itself in the HF®8 for many years now. For TG processes, whereby the maximum value of the drawing force is not exploited, air cooling options are available (fig. 5).

Fig-5: Motor

In designing the godets, we closely, and constantly, exchanged information and experiences with our customers with regard to the requirements for simple and safe disassembly and assembly of the bearings. By reducing the number of individual parts, the bearing can now be replaced within the shortest possible time. Heater, bearings and motor are designed in such a way as to allow the godet to be assembled or disassembled without the assistance of an electrician.

The Saurer Group's worldwide service network with its many international sites ensures speedy and efficient repair and maintenance of all Barmag machines. To this end, one of the most important prerequisites is the utilization of top quality spare parts and coatings. Alternatively, the service network's extensive special tools enable technicians to carry out maintenance at the customer site.

Summary
The new oil-lubricated HF®4/IY-400/190, HF®4/IY-400 and HF®7/IY-400 godets have been developed for use in demanding industrial yarn processes. The HF®4/IY-400/190 and HF®4/IY-400 operate at speeds of up to 4,500 m/min. For HMLS processes up to 7,000 m/min, the HF®7/IY-400 replaces the proven HF®8 godet, which is used for speeds up to 8,000 m/min.

Reliability and durability are the most significant features of this new godet concept, for which cooperation with customers and years of experience in this area were decisive.