This question highlights an often overlooked concern when using pressure sensors mounted underneath ejector pins.
Milan
How much of a gap should be used between the pressure sensor and the ejector pin?
My Response
The general recommendation from most manufacturers is between 0.25-0.5mm or 0.010-0.020in.
In reality, this specification refers to the clearance between the top of the ejector pin head and the counter-bore in the ejector plate. Most mold makers use a similar ejector pin clearance even when a sensor is not being used.
Additional Thoughts
The purpose of this clearance is to ensure there is no preload on the sensor, especially if any dirt gets beneath the sensor. Such a preload will destroy the sensor and provide erroneous pressure readings.
-Andy
Sensors come with the specifications from the supplier. There are installation kits available that come with the machining tools for the sensor pockets and plug gagues to check for fit.
Also available are sensor test kits, these are also nice. They will check the sensor to see if it is working after the mold is assembled on the bench. It might save you from setting the mold up and then finding that the sensor is working.
Good point. The blogger actually asked about a specific brand, but I simplified the question to avoid specific brand names... though most brands have specifications within the range I mentioned.