A summary of the Blasch white paper that uses finite element analysis to find the lowest stress orientation of a core setter.
A setter has to hold a ceramic core in shape through every firing.
This paper looks at the stresses that decide how long it can.
A core setter is the ceramic support that holds an investment casting core, such as an airfoil core, while it is fired, and it has to keep its own shape through repeated heating and cooling. The Blasch white paper on thermal stresses on core setters uses finite element analysis to compare the stresses in a setter in different orientations and identifies the orientation with the lowest stress.
| Item | Detail |
|---|---|
| Title | Effects and Analysis of Thermal Stresses on Core Setters for Aerospace Applications |
| Type | White paper, presented at the 65th Investment Casting Institute Technical Conference, Kansas City, October 2018 |
| Authors | Phil Geers, Senior Market Manager Molten Metals; William Russell, Blasch Precision Ceramics |
Ceramic cores for turbine blades and vanes are fragile and complex. During firing they rest on a setter whose surface follows the core geometry, so the core does not sag or move. The setter goes through the same cycle every time, and producers who push their kilns to heat up and cool down faster load it with more thermal shock each run.
A setter that slumps, moves or cracks after repeated firings no longer supports the core where it should. That shows up later as cores out of tolerance and scrap in the casting line.
The paper treats the setter as a stressed part rather than a simple tray. With finite element analysis the authors calculate the stresses in the setter in different orientations and compare them. The result is the orientation with the lowest stress, which then guides how the part is designed and fired.
The full paper with the model, the load cases and the stress plots is available on request.
How a setter sits in the kiln can matter as much as what it is made of, because the same ceramic carries less stress in one orientation than in another.
If your setters slump, warp or crack after a number of firings, look at three things together: the material, the geometry that matches the core, and how the setter is loaded and oriented. The paper addresses the third, which is often fixed by habit rather than by calculation.
Blasch casts core setters for investment casting to tight tolerances and with geometry that follows the core, in several high purity grades. A related on demand presentation names the properties a setter needs in the firing environment: resistance to slumping and movement after repeated firing, high tolerance capability and geometry that matches the core.
A year later, the authors followed with a second paper on thermal conditions and process costs for core setters. For setters and saggers in other sintering work, see plates, saggers, boats and setters.
It supports a ceramic casting core during firing, with a surface that follows the core, so the core keeps its shape and position until it is fully fired.
Because the setter fails from stress caused by heating and cooling. The analysis shows where that stress concentrates and how orientation changes it.
Blasch offers several high purity grades, including mullite. The right grade depends on firing temperature, atmosphere and the core material.
Yes, on request. Use the button at the top of this page and a Blasch engineer sends it to you.
Send the core geometry, the firing cycle and what happens to your current setters. A Blasch engineer looks at material, shape and orientation.
