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Danny R
10th October 2011, 11:11 PM
As molders, we tend to concentrate mostly on the molding process and of course the mold. But seldom times we neglect the molding machine and its reliability to give us a consistent shot to shot.

What are the steps/studies taken to fully qualify or validate a molding machine? Whether new or used machine.

rickbatey
10th October 2011, 11:31 PM
On my last job, we used a proven process/mold combination. Using a new mold was not acceptable! Then we set the tool, punched in the numbers, confirmed part weight, made any necessary changes, then start the press. We HAD to run more than 24 hours, NON-STOP, pulling samples from each hour. Then the parts were weighed, checked on the gauges, and passed or failed. Then we went through all of the machines collected data, graphing it and confirming the stability. Lastly, we made the final payment on the press.
Rick.

Suhas
12th October 2011, 03:20 AM
Liked rick's - 'Lastly we made the final payment!' Other than what Rick talks about, I think it is also a good idea to do two other tests -

1. Take 10 short shots in a row and see how consistent is the shot to shot part weight. Do this at a low speed, medium speed and a high speed. - since the viscosity will change at the three settings.
2. Do a Inj speed linearity test - at various injection speeds, find out what is the actual speed you are achieving and compare it to the actual. As the pump gets older, you will see that at the higher speeds you may see considerable variation.

Hope this helps,
Suhas

Maheshkumar Hiremath
12th October 2011, 06:40 AM
Suhas Sir,

1. To take 10 shots, is it required to turn OFF holding parameters ( time and pressure ) or with holding parameters turn ON.?

2.Please elabrate how to do Inj speed linearity test.


Rgds,
Maheshkumar.

pjhall
14th October 2011, 03:04 AM
You can take Suhas' suggestion one step farther. Do the 10 short shot procedure then completely shut the machine off for the night and try it again the next day. A full machine shut down is required on some of our medical OQ/PQ Process/Machine qalifications.

Suhas
14th October 2011, 06:22 AM
Yes, agreed with PJHall. Sure is a good idea. To make the shorts turn off your pack and hold. Also you must add a screw rotation delay time of approximately = the time it will take to freeze off the gates. If you inject (only) and start screw rotation right away, the back pressure will now push the plastic inside the mold and fill the part. Add some screw delay time.
Suhas

Danny R
19th October 2011, 11:48 PM
I made an excel sheet for the injection speed linearity test. Any one else has other worksheets that would like to share?

Suhas
20th October 2011, 10:16 PM
DannyR,
There are three tests: The Inj Speed Linearity test (you mention), the load sensitivity test and the short shot study test. I have this, not in excel but in my software :). But may be when I have the 25th hour in my day, I will make them up in Excel and post it on the web.
Reagrds,
Suhas

Danny R
21st October 2011, 03:47 AM
Seņor Suhas,

I have a 3 day weekend starting today and won't get a chance to think about work. When I get back to the office I'll start working on the excel worksheets and attach them to this thread. If anyone else has something similar, please feel free to post them.

Salud!

lakshilpa
5th May 2016, 03:51 PM
146
Hello Gents,
im lakshilpa
i just bought nizzy 75 old model machine. the machineneed some attention. so that i need help from expertise. actually im looking for schematic diagrams. if you can help me this situation that will be great. if you need more information about machine i can provide it.
thanks in advance. my e mail: lakshilpa@yahoo.com lkshilpa

Rendy
28th June 2016, 12:56 AM
IQ-OQ-PQ that will do it.. Read up on it..