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Hi Guys
What kind of test do you develop in your machines to determine if the check valve has some variations or trouble and need to be reviewed or replaced ,,
I know we have the quality control values, cushion, fill time, recovery times, etc.. but another test to determine if the check its holding the appropriate cushion
regards
Josue,
You can do a Check Ring Repeatability test based on shot weight. Set up your process to run a decoupled II process and remove the pack and hold time and pressure (I add the time removed to the cooling time to maintain the same residence time). Be sure that all parts are short. Run 10 shots and weigh the parts and runners. Calculate the percent variation of the ten shots. Less than 3% variation should be good.
Regards
Tim
Thanks TBramel
Good Advice
regards
Hello All,
another way to check the ring.
During normal production, stop the machine before machine dosing full dose.
Wait 30 seconds and try to inject manually next dose (you have a full parts inside the cavities).
During manually injecting you should check the stroke which you inject the material. If is only few mm then is ok, if you screw constantly going to zero position then you know you ring valve is damage.
p.s. sorry for my language, im still learn english :)
Best regards
Yellow
Hi,
and Your runner system is crying!
I don´t recommend this. Maybe in rare ocasions its ok.
j
Jendalf,
such a thing is done very rarely so in my opinion is ok.
Best regards
Yellow®
if you can see the screw turn when it injects that is a good sign that plastic is flowing backwards across flights towards throat, sometimes a bridged throat is a good sign of check ring trouble to.
You can try more screw suck back to seat the check ring