Process Overview

Quoting process

The customer provides a 3D electronic solid model and drawing for casting quote. Engineering reviews the models and drawings to ensure they are castable. Along with the drawing all alloy specifications, heat treatment or additional requirements are considered for quoting. Upon all reviews the quote is generated and sent to the customer.

Quoting process

The customer provides a 3D electronic solid model and drawing for casting quote. Engineering reviews the models and drawings to ensure they are castable. Along with the drawing all alloy specifications, heat treatment or additional requirements are considered for quoting. Upon all reviews the quote is generated and sent to the customer.

Wax Process

A 3D electronic model of the casting is submitted to the tool maker and the tooling is cut from a block of Aluminum alloy. This tooling is then used in a wax injection press to produce wax patterns. These wax patterns are inspected for defects and if acceptable assembled on a sprue to create a wax tree assembly. The wax patterns are glued to the sprue using a special wax based glue. The trees are placed on racks and prepared for the shelling process.

Shell Building (investment) process

 

The term Investment refers to the shell built around the wax trees to create the ceramic mold. For ease of understanding we will refer to this process as shell building. This process involves a face coat for fine detail and low reactivity and then subsequent back up coats to build the shell strength during the foundry processes to follow. The wax tree is dipped into the primary slurry which is Zircon based, the slurry is drained in a specific way to create a smooth uniform coating and then is covered with fine sand to create a stucco effect. This stucco provides the following coats with the ideal surface for the next coat. The backup coats are applied in the same manner as the face coat with coarser sand and a silica based slurry several hours dry time is provided between coats. Once the shell has dried completely it is ready for the next steps.

Shell Building (investment) process

The term Investment refers to the shell built around the wax trees to create the ceramic mold. For ease of understanding we will refer to this process as shell building. This process involves a face coat for fine detail and low reactivity and then subsequent back up coats to build the shell strength during the foundry processes to follow. The wax tree is dipped into the primary slurry which is Zircon based, the slurry is drained in a specific way to create a smooth uniform coating and then is covered with fine sand to create a stucco effect. This stucco provides the following coats with the ideal surface for the next coat. The backup coats are applied in the same manner as the face coat with coarser sand and a silica based slurry several hours dry time is provided between coats. Once the shell has dried completely it is ready for the next steps.

Autoclave Process

Spokane Industries uses an autoclave system to remove the wax from the shell. The autoclave is essentially a very large steam vessel. The finished shelled molds are loaded into the autoclave and the unit is pressurized to 120 psi of steam. The molds remain in the autoclave at pressure long enough to melt all of the wax out of the ceramic mold. The mold is then removed from the autoclave and inspected. The wax is collected and sent back to the manufacturer for recycling.

Mold Preheat Process


The mold is now a ceramic negative of the wax trees. These molds require a preheat process in order to be ready to accept molten metal. The molds are loaded into a specially designed kiln and allowed to preheat for 2 to 4 hours somewhere around 1700 degrees Fahrenheit. Once the molds have been preheated they are ready to accept molten metal.

Mold Preheat Process

The mold is now a ceramic negative of the wax trees. These molds require a preheat process in order to be ready to accept molten metal. The molds are loaded into a specially designed kiln and allowed to preheat for 2 to 4 hours somewhere around 1700 degrees Fahrenheit. Once the molds have been preheated they are ready to accept molten metal.

Foundry Process

While the molds are in the kilns metal is being melted to pour into those molds. We use induction furnaces to melt the alloy. A heat of alloy takes about an hour to melt. During melting we utilize the Argon Spal process which drips liquid Argon over the meniscus of the melt to push out the oxygen and keep the alloy cleaner. Once the alloy has become liquid we take a sample test coupon for chemical analysis. The test coupon is prepared and then analyzed on an optical emissions spectrometer. The chemistry is then adjusted to meet customer specifications and the melt is brought up to temperature. Molds are pulled from the oven and the metal is poured directly into them. Once cooled they are ready for the finishing process.

Finishing Process

Molds are processed and castings removed to be processed separately. First the ceramic shell material is removed from the tree. Castings are then cut from the feed metal. The casting ingates are removed and any remaining ceramic material is removed by shot peening or other blasting method. The castings are inspected and either shipped to the customer or sent for further processing.

Finishing Process

Molds are processed and castings removed to be processed separately. First the ceramic shell material is removed from the tree. Castings are then cut from the feed metal. The casting ingates are removed and any remaining ceramic material is removed by shot peening or other blasting method. The castings are inspected and either shipped to the customer or sent for further processing.