Purpose of Platen Deflection Test

I received this question over the weekend…

I heard about the platen deflection test. How should I do it and what information can I obtain from the test?

My Response
Most platen deflection occurs within the stationary platen due to the fact that it receives the least amount of support. It also has a large hole cut out of the center for the sprue bushing.
There are typically two different instances in which deflection of the stationary platen occurs. The first deflection happens when the mold is clamped under full tonnage. The second deflection takes place as the polymer is injected and packed into the mold.
The Platen Deflection Test is used to determine the amount of stationary platen deflection that occurs during the molding cycle. Basically, a dial indicator mounted to the machine base, and is placed as close to the center of the platen as possible.
The results of this test should be retained with the machine’s records and used as a baseline for future deflection comparisons. This is valuable information – as it allows you to track the degradation of the stationary platen’s integrity over time.
Additional Thoughts
You can often reduce platen deflection by increasing the nozzle forward force.
Our intelligent molder series of training covers this topic in much more detail. Also I discuss these tests in our free online webinars: http://www.traininteractive.com/free/webinar/player/

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