Highest performance with low-pressure pouring

ABP Induction has developed an adapted system for the special processes of low-pressure pouring. The OCN furnace system is so far the only system for the low-pressure pouring of steel castings that has proven itself in industrial practice in continuous operation. This process has long been established for aluminum, with a recycled material content of less than 50 per cent of the weight of the component, compared with 100 per cent for gravity pouring. The capacities this yields in the area of melting result in valuable savings and additional sales potential for the foundries.

The use of materials in particular is interesting with respect to lightweight construction in the automotive sector: Although composite materials such as CFRP and lightweight materials such as aluminum or magnesium have outstanding lightweight construction potential, both materials also have numerous drawbacks in comparison with steel. As it is possible to produce steel through low-pressure pouring in a way that is load-bearing and has thinner walls, the material can bring about a significant advantage: It is easy to handle in common and globally available final assembly processes and also for repairs. It is therefore worthwhile to take a closer look at steel processing in low-pressure pouring processes.

The environmental factor also plays a role: The reduced rates of recycled and scrap material reduce the energy required per kilogram of good castings by up to 50 percent. In addition, the lower quantities of liquid material and the lower temperatures mean that less molding material is required, which is also a major driver of energy consumption and costs.

Differences to the common gravity pouring process

In the conventional pouring process, gravity is used to fill the mold with melt. The mold itself has openings at the top so that the air in the mold can escape during filling. Basically, it is possible to pour the melt directly into the mold, but different gating systems can also be used. And: A distinction can be made between descending mold filling and ascending mold filling.

In the case of the ascending mold filling, the melt flows from above into the space to be filled. One drawback: With this procedure it is not possible to regulate the speed and influence the filling section.

This is the significant difference to low-pressure pouring. Here, the casting mold is filled with melt through a riser pipe using pneumatic pressure applied against gravity. The casting mold “stands”, so to speak, on the riser pipe, which is immersed in the melt. Important in operation: It must be ensured that the entire furnace system is sealed pressure-tight.

100 SECONDS ABP: Markus Hagedorn about low-pressure pouring

What are the next steps? The internal pressure of the furnace can be increased with a valve. This causes the melt to rise up the riser pipe against gravity. Once the mold has been filled with melt, it must be ensured that gravity has no effect on the filled melt. In the process, the pressure in the furnace is therefore maintained until the melt has solidified in the transition from the gate to the mold. The challenge here in turn is that the melt in the riser pipe should remain liquid, as it flows back into the crucible after pressure equalization. There are numerous approaches that have proven themselves in practice to ensure that the melt in the riser pipe can flow off again. Methods of heat insulation or heating the riser pipe are possible. In contrast to manual pouring processes in steel casting, pouring is fully automated. The temperature and level process parameters in the riser tube are always kept at a constant level. Thus, the reproducibility of the pouring process is fully ensured and thus maintains the quality standard.

The OCN furnace system from ABP Induction

To enable the low-pressure pouring process to be used in steel pouring, ABP Induction has developed the OCN furnace. The furnace system with modern IGBT converter technology is designed for steel, iron and non-ferrous castings. The application for producing bronze and copper components is also possible with the above-mentioned benefits.

Components with a thickness of up to 0.8 millimeters have been realized in low-pressure pouring. In practice, the average has currently settled at 1.5 to 2 millimeters for components with a length of up to 1.2 meters. Thanks to the ABP pressure control, corresponding casting molds can be completely filled within a few seconds, without the risk of blowholes or pores if the process is properly controlled.

Low-pressure pouring thus enables complex and weight-optimized geometries to an extent similar to that of precision pouring. In contrast, there are the significantly lower manufacturing costs of components with low-pressure pouring, as well as the possibility of producing thin-walled components in almost any size.

The OCN low-pressure pouring furnace is designed on the basis of the Teapot principle. This offers considerable benefits in operation: First, we have the buffering capacity. The possibility of depositing residual slag in the furnace vessel and slag-free pouring without the risk of freezing have also proven successful in practical applications. Another feature resulting in positive feedback from practical experience: The crucible inductor allows the OCN to be quickly and fully emptied, e.g. for an alloy change. Moreover, the furnace has a modular design so that the individual elements can be replaced easily and quickly at the end of their refractory life and the system is highly available.

Further information:
Markus Hagedorn, ABP Induction Systems GmbH
Sales Manager Liquid Metals
Phone: +49 231 997 2295
Cell: +49 175 5538500

Industry 4.0-capable thanks to DICU3

Absolutely nothing works in an ABP thyristor melting plant without the „Digital Inverter Control Unit“. If that’s not working, neither is the plant. A new version of the inverter control electronics, called DICU for short at ABP Induction, is now available. DICU2 becomes DICU3.

DICU2 has a long history: Developed in the early 90s, DICU2 was a real leap forward in terms of innovation: It replaced old analog controls from the 70s and 80s from 1991 onwards. The customer‘s systems were converted gradually step by step – to the first digital control system for systems of this type. At that time, this meant a significant simplification of work, both during commissioning and actual operation by the customer, as well as during servicing and maintenance.

From 1991 to the present day is a very long time. ABP components are known to be particularly reliable and durable, but the availability of spare parts has started to become an issue: The controller contains components that are no longer available on the market today. Consequently, ABP can only guarantee the usual full service by repairing or replacing the DICU2 and its components until the end of March 2020. Beyond this period, ABP can no longer offer the supply of spare parts or repairs. Service cases are then to be considered depending on hardware availability. Settings and parameter changes are still possible by ABP engineers, but when it comes to hardware, we are at the end of the DICU2‘s life cycle.

For this reason, ABP started early with the development of the DICU3. Since 2016, engineers have been working on the all-new development, since 2017 the DICU3 has been installed in new plants, and since 2018 it has also been available for modernization. ABP highly recommends that customers plan to modernize the plant, just to ensure plant availability. In addition, the DICU3 naturally also offers significant advantages over its predecessor model, which is getting on in years. Some of the things ABP mentions are the technological leap the new processor technology is making and the potential that the new remote maintenance system offers: The DICU3 is M2M-ready, so that error analysis via Remote Service is possible. This makes the customer‘s systems Industry 4.0-capable.

The DICU3 offers high operational reliability. Thanks to fast and improved controls, customers will be encountering fewer downtimes of the melting plant. Construction-related differences in replacement transformers would be compensated electronically, critical situations in the converter would be corrected more quickly and semiconductors protected from damage. Basically, the customers have three options: they could ignore the announced discontinuation of the DICU2 – which would however lead to a complete system failure should the control unit be damaged again. Of course, they could now also procure a replacement DICU2 and set it aside in the event of damage – but they must also be aware of the fact that this is only a temporary solution.

ABP therefore recommends only the third way – budgeting the acquisition of a new DICU3. Depending on the number of thyristor melting plants, a step-by-step conversion is of course also an option: Spreading this process over several years ensures continuous operation and is easy on the budget. ABP points out that the delivery time is about 12 weeks if one system fails.

Speaking of downtimes: Downtimes are reduced to a minimum even during the conversion phase. „The conversion time is short – and of course it can be scheduled so that it does not take place during regular operation. ABP generally schedules the long weekends for such cases – with the actual rebuild on the weekend and production monitoring by ABP experts on Monday. Why is this so fast? Thanks to a conversion kit that ABP developed with a gateway solution, the DICU3 is Plug&Play-capable for modernization – independent of the PLC of the plant control system.

With the DICU3, ABP wants to ensure that customers can use their melting plant economically and reliably for as long as possible: And to ensure production stability, ABP recommends that customers consider upgrading to the new DICU3 now.

For more informatiom:
Johann Konjer, ABP Induction Systems GmbH

Service Sales Engineer Modernization
Phone: +49 231 997 2739
Cell:     +49 171 7548129