Livarski vestnik 57 / 2010 nr. 2
Peter Schumacher
CONTROL OF NUCLEATION PHENOMENA IN CAST ALLOYS
Adam Kowalski, Dawid Myszka, Kazimierz Głownia
THE ISSUES OF THIN-WALLED ADI CASTINGS
Gregor Podlipnik, Žiga Kuralt, Matija Jereb
INTEGRAL MASTERING THE HIGH-PRESSURE DIE CASTING PROCESS ON EXAMPLE OF COVER FOR ELECTRONICS
Peter Schumacher
Control of Nucleation Phenomena in Cast Alloys
Abstract
Nucleation phenomena are the least understood physical process during casting. Although there is some degree of control in foundries, a better understanding of the physical metallurgy may lead to improved alloy design and a reduction in processing cost. This presentation will give an overview on how nucleation and subsequent restriction of growth by solute lead to grain refinement in Al and Mg alloys and how these insights can be applied also to the inoculation of cast irons. Particular attention will be given to crystal epitaxy, particle size distribution, and free growth criterion to achieve a controlled microstructure along the metallurgical processing path.
na vrh
Adam Kowalski, Dawid Myszka, Kazimierz Głownia
The Issues of Thin-Walled Adi Castings
Povzetek
The role and significance of thin-walled castings in modern industry has been emphasized. A set of patterns to test thin-walled castings with wall cross-sections from 3 to 12 mm was designed and made. Four melts of ductile iron of similar chemical composition but inoculated with different inoculants and by different inoculating techniques were prepared. The most effective has proved to be the Barinoc inoculant made by Elkem. Mechanical properties were tested and microstructure was examined in the as-cast state as well as after normalising and austempering carried out in two cycles. After heat treatment, pearlitic cast iron and ADI were obtained. The results were compiled in respective tables and photographs of microstructures were presented. The obtained cast iron was characterised by absence of chills and a high spheroid count. The tensile strength after normalising reached the value of 600 MPa, and 950 to 1350 MPa after austempering. The developed technology of thin-walled castings manufacture enables production of such castings in different variants of the matrix structure and with different mechanical properties.
na vrh
Gregor Podlipnik, Žiga Kuralt, Matija Jereb
Integral Mastering the High-Pressure Die Casting Process on Example of Cover for Electronics
Abstract
Final product of die casting process is a die casting product. Different target groups share different views on final products. On one side, there is buyer who demands an unconditional quality of product with a price that is highly competitive on market. On the other side, there are owners with their management structure who demand profitable product. Standard approach, in use until now, was based on design and manufacturing of die tool with emphasis on die-casting rules while other process parameters are left in the background. Process of casting is defined with tool as the main parameter of the die-casting process. Other parameters are simply subordinate to the die tool. In order to achieve all the goals, the process parameters are pushed to extreme conditions. Long-term consequences usually appear both as lower product quality and high maintenance expenses of tools. Goal of this paper is to present a new approach towards mastering the die-casting process, based on work experiences. Systematic perception of problem sources that was recognized as low service life of die-casting tools was presented in the paper. The next step was analysis of sources based on theory. In this case an interdisciplinary approach was applied. Problem sources were considered from the viewpoint of product design, tool design, material and heat-treatment of tool, tool manufacturing process, casting technology, and tool maintenance. Result of thorough analysis was a new concept of tool and of casting technology, expressed in numbers: 50% longer tool life, 75% lower tool maintenance costs, 30% shorter casting cycle. Emphasis was given to some applied innovative approaches of tool design. Some solutions that were accepted as compromise were immediately assessed as bad. However, all the solutions had final goal to prolong the tool life.
Key words: High pressure die-casting, thermal cracks, process optimization
na vrh
