Themocouples and Aluminum molds

You seem to know you have a 10° gradient across the mold, and you seem to think that this is a problem, so, you need to regulate your heaters to achieve the desired temperature across the tool.

A single thermocouple will only report the temperature at a single point.

Is the difference varying over time or fairly consistent? Is the difference causing a problem?

If the diff. isn't causing a problem then move the sensor to the most 'accurate' part of the mold and forget about the difference.

If the diff. is a problem but it is fairly consistent then all you need to do is redistribute the heaters to minimize the diff. while still leaving them on one controller.

If the diff. varies over time then you will need to go zones or modify the mold to improve the thermal conductivity.

Gordie.

use optical pyro meters .

As I understand it, the problem is not the measurement, but the number of controllers.

Also, I have heard that optical temperature sensors don't work properly on aluminium for some vague reason, although I have no specific experience to confirm or refute this claim. Even if it is true it may only apply to cheap handheld units.

The design of flow channels in the mold is probably different at places other than the location of thermocouple and is creating frictional heat. The solution would be to create two more heating zones by splitting the heaters into three sections with individual controllers.

Ragotham