The guys at Gotta Groove are having a problem with something they are calling stitching. An issue where a scratchy noise is introduced into the pressing by water that is too cold. Is there a a connection between a lacquer, the way it is plated and the stampers, or is this simply a pressing issue.
Any input from you plating/pressing guys would be welcome. Mossboss, any ideas?
As always, thanks!
Stitching...pressing issue.
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concretecowboy71
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There are a couple of reasons for stitching or non-fill.
If the vinyl is too hot and the closing speed of the molds is too fast, the vinyl can flow over the grooves without filling them.
Another cause is the moulds moving slightly when opening and the record is released. In this case you will see a second impression of the groove along one wall.
So the first questions are...
Is this happening on more than one press at the same time?
What does it look like under the microscope?
If the vinyl is too hot and the closing speed of the molds is too fast, the vinyl can flow over the grooves without filling them.
Another cause is the moulds moving slightly when opening and the record is released. In this case you will see a second impression of the groove along one wall.
So the first questions are...
Is this happening on more than one press at the same time?
What does it look like under the microscope?
non fill
OK The man that sets HARD
Hey
Here is a bit of food for thought
1.Speed at the last 1/2-3/4 of an inch has to be as slow as possible so as to stop the press entraping air
2.Vinyl to hot out of the extruder gassing off
3.Hydrogen entrapment on the plates But that usually dissapears after a few pressings about 20 odd sees it out of the plates
4.Second stage heating to long prior to cooling stage
5.Dies where plates are mounted are a little loose on the guide pins and bushes
Important
6.Calcium build up on the cooling galleries of dies causing uneven heating cooling causing non fill
7.If there is a mix of regrind and virgin material no more than 20% of regrind should be used You are better off using straight reground or straight virgin material
Note: PVC compounds today as not as tolerating as they used to be due to missing additives like lead and cadmium which has been banned
8.Press has slack on its columns Doubtfull on the smt but possible
Good check list Hey Start looking
Cheers
Hey
Here is a bit of food for thought
1.Speed at the last 1/2-3/4 of an inch has to be as slow as possible so as to stop the press entraping air
2.Vinyl to hot out of the extruder gassing off
3.Hydrogen entrapment on the plates But that usually dissapears after a few pressings about 20 odd sees it out of the plates
4.Second stage heating to long prior to cooling stage
5.Dies where plates are mounted are a little loose on the guide pins and bushes
Important
6.Calcium build up on the cooling galleries of dies causing uneven heating cooling causing non fill
7.If there is a mix of regrind and virgin material no more than 20% of regrind should be used You are better off using straight reground or straight virgin material
Note: PVC compounds today as not as tolerating as they used to be due to missing additives like lead and cadmium which has been banned
8.Press has slack on its columns Doubtfull on the smt but possible
Good check list Hey Start looking
Cheers
Last edited by mossboss on Fri Jul 16, 2010 2:46 pm, edited 2 times in total.
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Chris
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concretecowboy71
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