JCorsico
Aerospace
- Sep 5, 2020
- 33
Hello all.
We are working on a design where a carbon composite panel is fastened to a 4130 steel subframe. The subframe has flat mounting flanges for the carbon panel. The carbon will be attached to the mounting flanges using both an epoxy paste adhesive and Hi-Lok pins. Basically, the design is very similar to how a wing skin is attached to the stringers.
The mounting flanges are not perfectly flat (there is minor weld distortion). The carbon panels are also not perfectly flat (manufacturing tolerances). The largest gaps are about 0.030", but most gaps are 0.010" or less. We want to fill these gaps using a liquid shim paste adhesive.
What is the recommended process for installing the liquid shims? Some questions that we have:
1) Can we install the shim paste and the Hi-Loks at the same time, using the Hi-Loks as clamps? In other words, will our epoxy paste adhesive function as a shim? Or, do we need an entirely separate process to create and cure the shims first? And then after the shims are cured, then install the Hi-Loks and more paste adhesive?
2) If we need a separate process to create and cure the shims first, do we use mold release on the carbon panel? Or a release ply? How do we prevent the shim from adhering to the carbon panel?
3) If we need a separate process to create and cure the shims first, how do we clamp the carbon panels in place? Clecos? Does the shim material get all over the Clecos and glue them in place? Do we coat the Clecos in something so the shim material doesn't stick?
Thank you!
Jon
We are working on a design where a carbon composite panel is fastened to a 4130 steel subframe. The subframe has flat mounting flanges for the carbon panel. The carbon will be attached to the mounting flanges using both an epoxy paste adhesive and Hi-Lok pins. Basically, the design is very similar to how a wing skin is attached to the stringers.
The mounting flanges are not perfectly flat (there is minor weld distortion). The carbon panels are also not perfectly flat (manufacturing tolerances). The largest gaps are about 0.030", but most gaps are 0.010" or less. We want to fill these gaps using a liquid shim paste adhesive.
What is the recommended process for installing the liquid shims? Some questions that we have:
1) Can we install the shim paste and the Hi-Loks at the same time, using the Hi-Loks as clamps? In other words, will our epoxy paste adhesive function as a shim? Or, do we need an entirely separate process to create and cure the shims first? And then after the shims are cured, then install the Hi-Loks and more paste adhesive?
2) If we need a separate process to create and cure the shims first, do we use mold release on the carbon panel? Or a release ply? How do we prevent the shim from adhering to the carbon panel?
3) If we need a separate process to create and cure the shims first, how do we clamp the carbon panels in place? Clecos? Does the shim material get all over the Clecos and glue them in place? Do we coat the Clecos in something so the shim material doesn't stick?
Thank you!
Jon
