Tuesday, February 24, 2009

Melting & Pouring in Spokane Industries Steel Foundry

By Dave Davis

Spokane Industries Steel Foundry Division has two electric arc furnaces. We utilize one for our steel products and we use the other one for iron wear parts that are high chrome. Each furnace has been updated with a computer touch screen which controls all of the roof movements for charging the furnace and also controls the amperage and tap position. We also can keep track of which heats we have run and the alloys used in each heat along with brick life for each furnace which helps maintain and control furnace life.

We average 5 tons of material per heat in our Steel Foundry Division . We use only recycled steel in the charge, which is loaded from the scrap pile once it is weighed. Our overhead crane transports it down to the furnace area and using an orange peel type bucket it is positioned over the furnace for loading. Once the furnace is loaded and running it takes about ninety minutes from start to finish during which time we monitor chemistry and also the temperature of the melt.

Three different samples are taken by the melters. The first is to check for carbon content and chemistry for the blow down. To ensure proper cleansing of the metal, we blow down at least 30 points. The melters then take the chemistry and calculate exactly what alloys are needed to meet our customers specification. After we tap the furnace, another final sample is taken to make sure that every element is within specification.

At Spokane Industries the melters use an ARL 3460 spectrograph to analyze each sample taken in the Steel Foundry. Once the final sample is taken and verified to be within customer specification it is then allowed to be poured.

The metal is transferred to the proper pouring station by overhead crane. First the crane picks up the holding ladle from the ladle area and transfers it to the furnace for filling. Once the chemistry sample has been taken it travels to the designated pouring station to wait for verification that everything is within specification before continuing on and pouring.

We are equipped to pour everything from 50Lbs to 11500Lbs in the Spokane Industries Steel Foundry ladle department. We have many different ladles at our disposal. Our bottom pours ladles can accommodate 1200Lbs and all the way up to 12000Lbs while the side pour ladles range from 500Lb capacity to 1200Lbs. We also have a 3000Lb tea pot and a 3000Lb lip pour.

Most of our ladles are prepared using the board lining materiel that in turn provides a cleaner metal with less refractory. It also allows faster turnaround times and ease of building. This method accommodates both iron and steel pours. Each heat poured is monitored for who poured, which ladle is used, and we keep track of temperature to insure that a quality casting is produced.

Our pouring ranges vary by specification and part. The steel can be anywhere from 2850 to 2920 degrees and the high chrome iron range is 2500 to 2560. The temperature is taken throughout the heat so as to maintain quality and consistency.

Andy Kruse, Process Control Engineer states We also utilize a digital scale on our crane to monitor and capture weights which allows us to be more accurate with pour weights and allows us to not have short pours or a lot of end metal. This information also helps the melt side as well. We can maximize the heat size to what has to be poured and reduce end metal. We can also capture melt loss - all of which helps us to conserve power and be more efficient in this ever-changing field we love.

Spokane Industries Steel Foundry Division is a state of the art and well managed facility prepared to meet and exceed our customers expectations and specifications. On-time delivery, fast turn-around and industry leading quality controls are what our customers expect and exactly what we deliver.

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