PoDFA is a complete solution for inclusion measurement. It identifies inclusions and provides their concentrations in the melt for each type.
The PoDFA technique consists of filtering a predetermined quantity of liquid aluminum through a very fine porosity filter disc under controlled conditions. Inclusions of the melt are concentrated at the filter surface by a factor of 10,000.
This method has been commercialized by ABB and developed by Alcan. It is a method of metal cleanliness evaluation that provides both quantitative information on the inclusion concentration and qualitative information on the nature of inclusions.
This technology is suitable for product certification and process control and development. It can also help evaluate the effect of different operating practices on metal cleanliness.
A liquid aluminum sample is obtained from any locations in the process. This sample is then poured into a PoDFA crucible and put on a small portable PoDFA sampling station. A vacuum to force the aluminum through the filter will be created by this station.
When the metal is frozen, the filter, along with the residual metal, is cut, mounted and polished before being studied under a microscope by a trained PoDFA metallographer.
The samples can be sent to ABB’s lab for metallographic analysis. ABB offers PoDFA technology transfer and analysis training, allowing users to proceed with their own analysis.
For example, PoDFA data enables the user to make a clear decision about the suitability of an individual production run for use in critical applications such as can body stock, bright trim, lithographic sheet or foil.
ABB's Reusable Crucible has been designed to better respond to the requirements of cast houses and foundries by decreasing labor time and operational costs. This innovative approach effectively enables metal manufacturers to:
- eliminate preparation time
- significantly reduce filter detachment occurrences
- reduce the cost per sample
The patented Reusable Crucible is a permanent crucible that can last for about 100 samples. A ready-to-use filter is easily installed in the crucible within just a matter of seconds before every single test. Before sampling, it is essential for the Reusable Crucible to be preheated on the Crucible Heater.
The PoDFA Sampling Station is a low-cost portable equipment that enables the PoDFA metal samples to be taken quickly and easily. Reusable crucibles are used to gather the liquid aluminum sample.
PoDFA Metallographic Analysis
The following two possibilities exist for the analysis of the PoDFA samples:
1. Send Your Samples to Our Lab:
Users can take advantage of ABB’s Metallographic Analysis Service (MAS) by sending their PoDFA samples to ABB.
Users will then receive a report with the key residue pictures and a breakdown of each inclusion type expressed in mm2/kg of aluminum. Reports are delivered in less than two weeks and all information is strictly confidential.
2- Do the Analyses Yourself:
ABB offers PoDFA technology transfer and analysis training to those who wish to carry out their own analysis. For those individuals planning to do more than just the sampling, the vast body of knowledge of Alcan can be readily transferred to their organization (PoDFA license).
It comprises of metallographic training and a CD-ROM that has a catalog of inclusions as well as methods. This vital information has been optimized for more than 30 years by Alcan on a wide range of alloys.