Profile of a Surface on a Honeycomb Composite Core

[brokensoul]

Does the Profile of a Line or Surface have any special interpretaion when it comes to composite core. I have a coworker telling me that the profile of a line or surface tolerance can be measured at any point along the line/surface. This creates an issue with our attempt to define the profile of a cut on a piece of core.

In this situation with the honeycomb core, the cell diameter is 0.1875 in and the profile tolerance is .003.

If his definition is still the current one accepted even for composite cores then the .003 tolerance can not be held if the profile line/surface intersects any cells of the core, which is inevitible.


Does anyone know?

Thanks,
BsK

 

[drawoh]

brokensoul,

A profile tolerance can be measured at any point along the surface, and must pass at each and every point along the surface.

Is the profile being applied to the top surface, or to the profile of each honeycomb?

JHG

 

[brokensoul]

The profile is being applied to a plane that intersects the walls of the honycomb core at an angle. The desired effect is to control the imaginary sloped plane which in essence is only a true surface every .182 in for ~.005 in. At the edge of every intersected cell of the honeycomb.

This question came about because we are trying to find a GDNT method to communicate the desired part edge. Of a feathered honeycomb core.

Any Ideas?

 

[drawoh]

brokensoul,

The top of your honeycomb is at least approximately a continuous surface. The non-presense of 95% of the material is irrelevant. A plate with 95% of the material removed by machining is precisely analagous.

JHG

 

[powerhound]

If I understand what you are trying to communicate, flatness is what you should use. It seems that all the edges are continuous, even if the edges are only .005 wide if they are all connected then flatness will control it unless it needs to be relative to another surface then profile of a surface or angularity is what you should use depending on the application of the feature. I hope I understood what you were trying to say.

Powerhound, GDTP T-0419
Production Supervisor
Inventor 2008
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
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[CatMann]

Brokensoul,

Could you provide an image of the part you are talking about.

CatMann

 

[Compositepro]

Don't neglect to consider issues of mesurement method along with tolerances. Cut honeycomb has fuzzy or deformed edges on cell walls. How do you measure that to 0.003"? You could define the position of a flat plate pressed onto the core with a certain pressure.

 

[powerhound]

Perhaps "Tangent plane" is in order for this application.

Powerhound, GDTP T-0419
Production Supervisor
Inventor 2008
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[joejack7]

We had the same problem for First Article Inspection. The way we resolved it was to machine a "substitute" material to the same specifications ie. phenolic, fiberglass and measure that object to accept the fact that the machine was capable of producing the desired surface, knowing that the honeycomb cells were not truly a flat surface. Once this is proven you can produce this sample material as part of your inspection plan or SPC to maintain your confidence that the desired surface is obtainable over time.

Although like others here, I question the fact that your trying to hold a known irregular surface to .003" We struggled with a profile of .010".

I too think the profile of a surface is possibly too stringent for this material and that profile of a line should suffice depending on the application. You simply want some level of assurance that the cut line is within a certain range, or if it's a mating surface then possibly a flatness callout is necessary. Hope this will help.



joejack7
Mfg. Engineer
"Fighting the 'Good' Fight"