Investment Casting Process
The Investment Casting Process (lost wax) process has been used for thousands of years to produce very complex and detailed metal castings. This process is used today to produce precision castings for aerospace applications. It is a very labor intensive process that relies on the skills of highly trained artisans. The employees at Cera-Met have had many years of experience to hone their skills.
The process begins with wax patterns.
Wax replicas of the desired parts are produced by injecting a specially formulated wax into precision machined dies. The individual wax patterns are inspected and assembled onto wax “gates” and “runners” to form a cluster, which both supports the patterns during shell building and provides proper metal flow and feeding during casting.
9 Wax Injection Presses
Conveyor system tied directly to Shell Department
Extensive use of wax holding fixtures
Water soluble wax used to form internal configuration
The wax clusters are then covered with a ceramic shell.
Wax clusters are dipped into a ceramic slurry mixture and then coated with a refractory sand. This process is repeated about 6-8 times with proper drying between layers to produce a completed shell. Care is taken to drain excess slurry and ensure loose sand is blown off prior to each subsequent layer. Cera-Met uses robots to apply the ceramic materials to ensure consistency and uniformity. Statistical Process Control is used extensively in this area.
Two independent Shell Robots
Capable of handling 450 lb molds
State of the art environmental controls
Rapid shell drying formulation
Complete shells produced in 2 days
The wax is then removed from the ceramic shell.
Following a final dry, the shell molds are quickly loaded into a steam autoclave to remove the majority of the wax material. This is followed by running the molds through a high temperature kiln or “burn-out” oven to remove all traces of wax and organics in the shell and “fire” the ceramic for strength.
Molds are preheated and then filled with liquid aluminum.
Once melted, the aluminum alloy is degassed and the exact chemistry is verified using a spectrometer. A transfer ladle is used to pour the liquid aluminum at the precise temperature into the preheated molds. Solidification takes place in a pressure vessel.
Six electric melting pots
In-House Spectro-analysis to verify melt chemistries
Robotic transfer of molds within casting process
Seven Pressure Solidification Chambers
Conveyor system moves completed products to Water Blast
Water Blast shell removal reveals the resulting castings.
High Pressure water blast removes the ceramic shell without damaging the aluminum castings.
Finished castings emerge after cut-off, grinding and blending.
A large band saw is used to remove the castings from the gates and risers. Gate attachment points are ground flush using abrasive belts and cosmetic blending, and sandblast completes the job.
Castings are then heat treated.
Mechanical properties are achieved by heat treating the castings. The typical heat treat cycle for aluminum castings is a Solution Anneal cycle followed by an Age cycle.
Four “T-6” and Six “T-4” ovens available
Can employ a variety of quench materials
All castings are inspected to insure the highest quality parts are delivered to our customers.
Cera-Met uses X-Ray and Florescent Penetrant inspection to compliment the visual and dimensional inspection of every casting. Highly trained and certified inspectors insure the highest integrity of the castings delivered to our customers.
First Article qualification samples are measured on a “CMM”.
Cera-Met has three Coordinate Measuring Machines (CMM), used for both production and First Article dimensional inspection.