Foseco’s technical journal and is provided free of charge to the foundry industry. First published in 1932, Foundry Practice aims to keep customers informed of the latest developments in our proprietary products and services and encourage the implementation of best practice.
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For over 30 years, industry standard usage of filtration devices in the production of commercial iron castings has increased due to a continual rise in quality requirements and more severe end-use application. Properly filtering iron castings involves utilising optimally engineered filter print and gating system designs to ensure delivery of the cleanest and least turbulent metal into the mould cavity in order to produce the highest quality castings. Some filter print designs have dramatically improved the cleanliness of molten metal and casting quality, but some concepts have not always proven to be beneficial. As a result, some less than optimal designs exist in industry today, causing quality issues and unnecessary additional expense. The purpose of this paper is to utilise fluid flow technology to assess different filter print designs, and to recommend best practice application techniques to the iron foundry industry. Consider this work the result of initial study, which will be supplemented in the future with molten metal trials and additional analysis.
Cupola melting is a desirable method of producing large quantities of consistent iron for high volume foundry casting operations. The minimising of downtime for these furnaces is key to optimal productivity. Slag erosion of refractories in contact with iron and slag limits the campaign duration and thus reduces the potential iron output of the cupola. Typical refractory compositions for these areas are high alumina castables and ramming mixes enhanced with carbon, silicon carbide, and antioxidants. The application demands a product that can withstand rapid dryout since most repairs are conducted over a relatively short time schedule. Sol bonded castables have been used in refractory applications for many years due to the elimination of calcium aluminate cement.
An optimised composition has been developed utilising this technology to maximise performance. Through the careful selection of raw materials, properties have been significantly improved over existing best in class materials. Elimination of potential safety hazards caused by reactive metals has also been successful. Several case studies are presented showing improved performance in a series of progressively critical applications.
Currently, component design in compacted graphite iron (CGI) is limited by the degeneration of the compacted graphite (CG) in the rim zone of the castings. The reduction/elimination of this degeneration by using an active coating, will create significant values for the design engineers. This paper highlights the performance of a new FOSECO foundry coating, ACTICOTE* CG800, for CGI application to reduce CG degeneration at the rim zone. The ACTICOTE CG800 was specially formulated, produced and characterised for foundry application. Casting simulations were performed to validate the test models for the coating-casting test trials. The ACTICOTE CG800 was benchmarked alongside other commercial coatings for the same application using the customised test model and further on commercial CGI water jackets and cylinder heads, in a foundry known for series production of CGI castings. The microscopic investigation of the microstructures at the rim zone of the castings from the trials show that the ACTICOTE CG800 showed superior performance in the reduction of the CG degeneration at the rim zone of CGI castings compared to other commercial coatings.download PDF to read the full article
Monitoring and improving melt quality could facilitate the production of high quality castings. This paper introduces “Vmet” (Vesuvius Metal Quality Analysis) based on the microstructural analysis using a scanning electron microscope. By using the pre-defined selection rules and image processing algorithms, size, morphology, and composition of defects (pores and oxides) are recorded. Total counts and area fraction of defects in two sets of samples collected before and after degassing were analysed. Results show that degassing can effectively reduce the size, amount, and aspect ratio of defects. Statistical analysis based on the extreme value theory was applied to analyse the data. This technique can also detect bi-films and dendritic pores using spatial distribution of individual defects. As the Vmet rules are high customisable, analysis of TiB2 particles in Aluminum composite matrix was also demonstrated. To summarise, Vmet could be useful for monitoring the metal cleanliness and measuring the effectiveness of different treatment techniques.download PDF to read the full article
Grey cast iron cylinder liners for internal combustion engines have traditionally been machined on both the internal and external surfaces. However, more recently cylinder liner technology has changed with the trend moving towards liners where the outside is not machined, but left as an as-cast surface. These developments are driven by the demands of the automotive industries to reduce costs whilst also moving to liners with reduced wall thickness, improved contact and heat transfer between the aluminum block and the cylinder liner and improved physical connection to reduce possible movement. The coating and its application are the major parameters responsible for the outer surface structure of the liner, with each coating and application setting delivering a specific structure. This paper introduces the Spuncote SP range of coatings and their application parameters, highlighting the outer structures produced and how these can improve both the thermal and physical connection between the liner and the aluminum block, demonstrating that to ensure the right performance it is key to have the right coating and process controls.download PDF to read the full article
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