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RoboTech · 10-24-2005, 08:36 PM

In regards to concerns about thermal shadowing of sensor holes...

One idea I planned to try in a future die sim was to bore/drill a tiny hole (1/16") up thru the center of the heat die, to within ~1mm of the top die surface. The hole would pass between two cartridge heaters and the bottom opening would allow sensor wires to exit out the bottom. One sensor would be inserted all the way up to the top, blind end. A second senor would then be inserted behind the first one to a desired distance from the first ( say 10 to 20mm). Omega makes some very small RTD's (all flavors: J,K,T, etc) that could be thermal epoxied in place inside the bore.

The top surface area would effectively be a square with a tiny hole in it (although not breaking thru to provide better top temp measurement). Building the die in this way would eliminate any shadow. The top surface area calc would exclude the area of the hole. The hard part will be drilling a very small hole that deep - especially if its in copper!

Edit: Alternatively, two (or three) parallel holes could be used, each for its own sensor if there was concern about spacing, clearance for multiple sensor wires, and possible heat conduction thru wires from one sonsor to another). This could also allow for a tighter fit of the sensor in the hole.

Just a thought...

10-24-2005, 08:36 PM	#39
RoboTech Cooling Savant Join Date: Sep 2002 Location: Cincinnati, OH Posts: 229	In regards to concerns about thermal shadowing of sensor holes... One idea I planned to try in a future die sim was to bore/drill a tiny hole (1/16") up thru the center of the heat die, to within ~1mm of the top die surface. The hole would pass between two cartridge heaters and the bottom opening would allow sensor wires to exit out the bottom. One sensor would be inserted all the way up to the top, blind end. A second senor would then be inserted behind the first one to a desired distance from the first ( say 10 to 20mm). Omega makes some very small RTD's (all flavors: J,K,T, etc) that could be thermal epoxied in place inside the bore. The top surface area would effectively be a square with a tiny hole in it (although not breaking thru to provide better top temp measurement). Building the die in this way would eliminate any shadow. The top surface area calc would exclude the area of the hole. The hard part will be drilling a very small hole that deep - especially if its in copper! Edit: Alternatively, two (or three) parallel holes could be used, each for its own sensor if there was concern about spacing, clearance for multiple sensor wires, and possible heat conduction thru wires from one sonsor to another). This could also allow for a tighter fit of the sensor in the hole. Just a thought... Last edited by RoboTech; 10-24-2005 at 08:46 PM.