The experimental of lost foam casting process

A schematic of the lost foam casting system shown. Flask size is 250 mm diameter and 300 mm in height, and size of the casting was 30 mm × 60 mm × 250 mm. Electric vibrator is attached under the bottom of the flask. The pattern was prepared by hot wire cutter from EPS block. Were used ceramic hollow tube of 30 mm inner diameter for pouring sprue. Double assembly was coated by dipping with refractory commercial coverage for lost foam pattern and then it was dried at room temperature for more than 24 h. 5-7 cm of packing materials was the first model in the bottom of the flask to form a base for the pattern. A pattern on the base, and vibration model packing material filling the flask with a frequency of 60 Hz.

Measured flask was 2.7 G accelerations in the x-direction, 0.8 G in y-direction and 2.7 G in z-direction to the acceleration sensor in areas determined respectively. Five types of EPS foam with a density of 12.5, 15.0, 17.5, 20.0, was used 25.0 kg / m3 to investigate the effect of foam density. Sodium silicate mold carbon dioxide (CO2 mold) was also prepared for comparison. To investigate the influence of cooling rate, selected three types of mold packing material, silica sand with AFS number of 66, zircon sand with AFS number of 111, with steel shots AFS number of 54 density seen the compacted bed silica sand, zircon sand and steel shots 103,2.54 was 1.49 × 103, 4.1 × 103 kg / m3, respectively. Experiments were made using A356.2 aluminum alloy ingot is widely used for various applications. A charge of 15 kg melted in a graphite crucible using electric furnace resistance.

Three types of treatment were thawing out, ie not treated, degassed, and filtered along with degassed. Degassing tablets were used Commercial and grain refiner. Degassing was conducted by dipping the tablet degassing crucible bottom. Had taken care to choose the right temperature to avoid melting violent convection. After degassing the melt was covered with flux and the temperature was increased to 883 K. Prerequisite grain size filter (0.1% of the weight melt) was plunged into the melt for grain refining, ran down to end all bubbling, and degassed. Gas estimated in melt at reduced pressure test (6.7 kPa pressure) in each heat. Reduced pressure was poured samples of about 150 g cup stainless steel preheated.

Melt was held to would remove degassing time and inclusion. When dropped the gas content to the desired level, the melt was poured at 983 K. many sets of castings made, and vacuum was not applied to the flask during pouring. Up to six chromel / alumel used thermocouples of 0.2 mm diameter to the casting temperature and the measurement model. Specimens were sectioned for density measurement after cooling. Density of the sample was determined by the traditional Archimedes principle. The pore area was measured using the image analyzer.

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