Pinpointing issues and providing solutions of lost foam casting

The first task was to improve the consistency of the ceramic slurry everyday. The ceramic coating, as it comes to GM Powertrain from the supplier, concentrated and much higher viscosity, and has to be mixed and diluted with the production viscosity. Historically, there was a batch of 10,000-pound shield divided into dozens of 50 gallon drums for shipment. Each drum was then mixed and adjusted individually at GM Powertrain personnel as required to the coating.

This introduced the possibility of variations in operator combination and adjustment methods. By switching to 350 gallon totes, was the manufacturer of ceramic coating able to eliminate some variance; However, in the end, this only confirmed that some variance were other problems outside of the shipping container distinctions. Recognizing the need for a deeper understanding of the variance coating, adapted to the team medical profession measurement tool recently developed called the Flow Particle Image Analyzer used to measure blood platelets. With this, the project team analyzed the wet slurry (before applying the foam pattern) by measuring the particle size and shape ceramic. Changes identified and traced to various sources of raw material used by the seller to make the ceramic slurry. In addition, through testing, the team discovered that the mixing time of the coatings also critical. Excessive mixing not only wasted time and energy, but changed the characteristics of the coating, as much as chef might overwhipping ruin through the egg souffle.

The complex fluid flow characteristics, such as the ketchup flow resistance until the bottle is tilted a certain incline, can be measured with sophisticated laboratory equipment. In this project, to several rotational rheometer used wet slurry parameters, two of which showed correlations decisive quality measurement solutions: The amount of yield point, and thixotropic loop area. Parameters affect both the coating thickness and uniformity were used foam patterns, and to quantitatively describe, evaluate, and optimize coatings from different suppliers. Some shapes were simplified solutions using enhanced coatings offered by commercial suppliers.

During the trials, used real-time x-ray radiography to study the molten aluminum front before it was poured inside the mold cavity and the complex process of pyrolysis byproducts generated from the EPS foam. Coating developed quantitative ratings using criteria from observations of gas generation and ease escape from the ceramic coating. Novel methods were developed to study the dried coating, using pyrometry capillary flow and coating thickness analyzer. They were useful in quantifying the ability of coatings allow pyrolysis products and liquid gas to escape during the metal pour.

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