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CASTING INNOVATIONS Preventing Flake Graphite Formation in High Volume CGI Blocks

As automakers seek ever great- er fuel economy, engine perfor- mance and durability, compacted graphite iron (CGI) engine blocks are becoming increasingly popular. CGI allows metalcasters to pro- duce a more compact block with thinner walls, without sacrificing stability or strength, at a weight comparable to aluminum. Tupy, a cast iron cylinder block

and head producer headquartered in Brazil, recently received an order for a new high volume CGI passenger vehicle cylinder block to be pro- duced at its North American base in Saltillo, Mexico. Following the start of production this year, the order calls for a ramp-up to more than 300,000 cylinder blocks per year, reportedly making the new program the highest volume CGI cylinder block in the world. Te challenge to producing CGI

The core shop at Tupy’s North American base in Saltillo, Mexico, is highly automated.

of the process,” said Luiz Tarquínio, president and CEO, Tupy. Process data will be compiled into a database to enhance control and traceability. Te Tupy system will be SinterCast’s most comprehensive installation, with capacity for up to 15 ladles per hour and more than 9 hours of production per day. In operation, the ladle will be deposited into a wirefeeder enclo- sure and the base treatment will be performed automatically with the required amounts of magnesium and inoculant wire, as determined by the ladle weight, temperature, sulphur content, and the thermal analysis

blocks lies in the formation of flake graphite, resulting in a reported 25% to 40% decrease in mechanical properties. CGI is stable over a range of approxi- mately 0.006% magnesium. At the upper end of the stable range, increases in magnesium or inoculation can quickly lead to porosity defects, resulting in leakage failures after machining. Process control is of the utmost importance in the production of complex components such as cylinder blocks and heads. In preparation for the start of series

production, Tupy ordered a System 3000 Plus process control system from Swedish CGI specialist SinterCast. It will automatically control the base treatment, process control measure- ment and final adjustment of magne- sium and inoculant prior to casting. “Te process flow and the design of

the wirefeeder enclosures were jointly developed by Tupy and SinterCast engi- neers based on the experience gained from more than 10 years of CGI series production and the running production of 18 series production components and more than 55,000 tons per year at the three Tupy foundries in Brazil and Mexico,” said Dr. Steve Dawson, president and CEO, SinterCast Ltd., Sunninghill, U.K. Tupy plans to continue to expand its CGI capabilities in Saltillo, including

56 | MODERN CASTING February 2013

The temperature profile during solidification is monitored by two reusable (up to 250 samples) thermocouples located in a protective steel tube within the sampling cup.

future CGI series production on its com- mercial vehicle line. “Te CGI process at Saltillo has been designed from a clean sheet of paper, in- corporating Tupy’s high volume CGI pro- duction experience and taking advantage of the latest technology in every aspect

results from previous ladles. After base treatment, the ladle will be conveyed auto- matically to a second wirefeeder enclosure, where the final correction additions of magnesium and inoculant will be added ac- cording to the result of the base treatment analysis. Following a correction treatment, the ladle can be transported to either of the two pouring stations on the line. “Te most unique feature is the size

The System 3000 collects melting, molding, pouring and shakeout data into a single database, including thermal analysis results and process data, for advanced traceability.

and handling capacity,” Dawson said. “Because of the high production volume, [it] incorporates more than double the hardware of a typical installation.” A new version of the sampling cup,

SP-05, incorporates an improved reactive coating that counteracts the influence of deleterious tramp elements that may be present in the base iron. Te new cup also extends the thermal analysis capability toward higher carbon equivalent levels. Te System 3000 is comprised of individual hardware modules that can be configured to suit any metalcasting facility, for both ladle production and pouring furnaces. Te basic configuration consists of two sampling modules (SAMs), one operator control module, a power sup- ply and a serial-linked wirefeeder. Tis configuration provides sampling capacity for approximately 15 ladles per hour. Ad- ditional SAMs can be added to increase the throughput rate. Te system provides one sample every

four minutes. Production results are compiled every month and delivered to each user for benchmarking purposes, with analysis and process improvement input

from SinterCast engineers. Visit for more information.

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