Pressing defects

[llex87]

Hello, I really hope that they will help us here with this problem. We are a small record pressing plant in Russia. We are pressing records on Alpha Toolex AD1202 presses. Records often cause defects such as in the photo. When listening, a crunch or click occurs. Mostly such defects occur when pressing 180 grams records. In the process, defects can appear unexpectedly, and also disappear. Do not understand the reason for their appearance.

[misjah]

The stamper looks the same or defects are only on the record?

[llex87]

Defects on Records Only. They look like risks, sometimes they are scattered over a large recording surface, sometimes they are concentrated in a spot of 1-2 cm. Under the microscope it is visible that they are located between the tracks, and sometimes they touch their edge, which clicks when playing.

[jannovotny]

Hi, it really looks the same as the problem we currently have! We also use Pheenix Alpha AD-12. There are two types of these defects:
1) small dots (or short lines) spread randomly across the record - sometimes on a large area, sometimes just a few dots along the groove. The same thing you depict, I guess.
2) defect that looks like a sink mark, with an adjacent area damaged - grainy surface.
Type 1 appears mostly on the A (upper) side, while type 2 is always (as I recall) on the lower side of the pressed record. Most of the time it is either the first one or the second one. Sometimes they also appear together.
And it often goes like: one record OK, two or three bad, then one almost OK, then two bad and then one OK again...
And yes, it is also a matter of a 180-gram record. Never occurred on 140g record...
Any hints, please? Bad material flow/cooling/heating? It happens regardless of material used. What helped the most was using the lower part of the 140g mold
Stamper is OK, it is just on the records.
Thanks a lot,
Jan
P.S.: Photos are not the best, but I think it is clearly visible.

[Aussie0zborn]

Jan the first photo "Defect - type 2" looks like non-fill caused by too-cold vinyl biscuit.
The other two photos show "stitching" (or "white lines" or "release damage". There are numerous reasons for this and some have been outlined in this forum.

Do you have different extruder cups for 140g and 180g records or do you use the same cup?

[llex87]

Our problem looks like type 1.
There are defects that are similar to type 2, but are always located in one place, in the region of the last track. They look like a large shell with half the width of the track, or as a strip of small shells that can be seen only by shining a flashlight. This happens when the temperature of the biscuit is too high. By lowering the temperature, this defect disappears. When the cold biscuit or the mold is not warmed up enough, the shells appear in the area of the opening track or on the first track.

[jannovotny]

Thanks for your input!

Do you have different extruder cups for 140g and 180g records or do you use the same cup?

Well, we have different cups. We have two machines, one is set up for 140g records, the other for 180g records. As this problem occurred on 180g, we tried to fix it by modifying parameters first - heating and cooling times. Nothing helped much, so we switched to the second press. This seemed to cure the problem, as the first 20 records (or so) were clean. So we pressed some 120 - 150 records and then it started again. We had some minor flaws on the lower mold part surface which were carefully sanded out. Could this cause a problem?

[Yasiek]

Check your rims.

We had same problems last time(AD12) - looks like places with "silver shine" places on the record. Changed parameters - allmost no matther, only shift the places of this issue.
After installing new mounting rims, the problem disappeared.

If the stampers are cut too long before forming, there is more material to be formed on the outer bend and it starts to ripple. Unfortunately, this kills the mounting rims.
But try the opposite way, if you already have the mounting rims worn out - try to give less stamper space under the rim and check if the problem disappears - if that helped, order new rims.
I am not saying that this solution, but it helped us.

[llex87]

I noticed that our cooling water is too low. They raised the water temperature to the recommended 20 degrees and our problem almost completely disappeared. It seems to me that the low temperature of the cooling water and the strongly worn clamping rings are the cause of our problems.

[jannovotny]

Interesting...how quickly can the rims get worn out? But I suspect the cooling water temperature is the cause. But how it comes the two records are flawless and the next one has the stitching marks again?

[llex87]

"But how it comes the two records are flawless and the next one has the stitching marks again?"
This question also worried us. Some kind of mysticism.
The rings were already used, worn out when we bought the machine. The machine was also inoperative, everything was restored. We did not have new original rings. We made some rings ourselves, but they cannot be compared with the original.

[Scottjames]

Those marks are easily fixed by changing your parameter for centre pin in (ram parameters) its releasing to fast. Checking your heater arm is sitting right helps too. It can happen if the arm is moving as the press opens. Just to be clear these marks are like little hair scratches right?