vinyl dishing problem

Once you have cut a master laquer, you have metal stampers created and have records pressed from them. Discuss manufacturing here. (Record Matrix Electroforming- Plating, Vinyl Record Pressing.)

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vinyl dishing problem

Unread postby CK Li » Wed Jan 20, 2016 4:46 am

Hello, i am a beginner in vinyl pressing and facing some difficulty in pressing process.

The problem is that slight dishing may be happened after cooling. Is somebody in this Forum able to share experience of how to make an absolute flat vinyl?

Thanks!
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Re: vinyl dishing problem

Unread postby Aussie0zborn » Wed Jan 20, 2016 9:40 am

You want to make an absolute flat vinyl? I think you mean an absolutely flat vinyl record, right?

JIt's not a "vinyl" it's a "record". You are making RECORDS from vinyl, you are not making "VINYLS". Please remember this at all times.

There are a few reasons for dish warpage, but first....

What press are you using?
New moulds or old?
Are both stampers the same thickness?
Steam pressure?
Where are you?
Please introduce yourself and we will answer your question. Thanks.
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Re: vinyl dishing problem

Unread postby CK Li » Wed Jan 20, 2016 10:27 pm

Yes, I mean an absolutely flat vinyl record.

I am in Hong Kong. The press I am using is a 150tons hydraulic press which developed by myself. The thickness of both side stampers is controlled to around 0.25mm. The output steam pressure from the boiler is set to around 11bar.

Thanks in advance for sharing your experience in vinyl records.
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Re: vinyl dishing problem

Unread postby Aussie0zborn » Thu Jan 21, 2016 4:22 am

Dishing is mostly caused by uneven heating and cooling of each half of the mould.

A couple of things to check...

1. Are the channels of one half of the mould blocked, impeding the flow of steam/water?
2. Does each half of the mould heat from the centre outwards?
3. Is the thickness at the edge of the record identical to the thickness of the edge of the label area? If not, the records will sag once they are stacked for cooling.
4. Once all the above is OK, be sure to place an aluminium disc on the stack after each fifth record or so. This can be an old lacquer disc and it acts as a heat sink.

Which moulds are you using? Is there a dedicated A-side and B-side mould or are both halves of the mould the same? If you have severe dish warpage, it could be that each half is identical in which case one half would be heating from the centre out, and the other half heats from the outside edge to the centre. If so you will need to swap the inlet/outlet hoses so the heating/cooling on both halves of the mould starts from the centre.

Good luck.
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Re: vinyl dishing problem

Unread postby CK Li » Thu Jan 21, 2016 9:13 pm

Thanks for your advices!

The mold I am using is a new mold which supplied from US. The piping of steam/water of my system has been inspected and all looks fine. The problem I am facing is that the centre of record will gradually rise up a bit after I put it on a flat surface for cooling and finally become dishing. I am wondering if it is a normal phenomenon of records when they are stacked for cooling. And, do I have to place an aluminium disc on records for cooling right after trimming the edge?
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Re: vinyl dishing problem

Unread postby Aussie0zborn » Fri Jan 22, 2016 12:16 am

Hmmm. So is it a mould made by RPA?

You didn't say if the label area is thicker than the edge of the record. Have you cut a record in half and measured the thickness? Is the mark on the record left by the centre bush standing proud? If so, this will be your thickest point on the record and this can be a real problem. Can you post a good quality photo of the label area?

Yes, after each 5th record on the spindle, you place an aluminium disc on top and then another five records on top of that, followed by an aluminium disc and so on. This is assuming the thickness if the record when measured at the outside of the label area and the edge of the record are identical.
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Re: vinyl dishing problem

Unread postby CK Li » Fri Jan 22, 2016 12:34 am

Yes, the mold is from RPA.
The thickness of label area and edge of the record has been measured before. Label area only 0.1 - 0.15mm thicker than record edge. Is it a significant factor to cause dishing?
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Re: vinyl dishing problem

Unread postby Aussie0zborn » Fri Jan 22, 2016 2:40 am

Then the edges should only sag by 0.1 - 0.15mm but it sounds like you have more to give you a dishing problem.

Do both halves of the mould heat from the centre, out ?
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Re: vinyl dishing problem

Unread postby CK Li » Fri Jan 22, 2016 3:55 am

As I mentioned before the centre of record I pressed will gradually rise up a bit after I put it on a flat surface for cooling and finally become dishing much more than 0.1 – 0.15mm.

The connection of pipes to the mold for steam / water has been checked and all are following the markings shown on the mold.
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Re: vinyl dishing problem

Unread postby montalbano » Mon Feb 01, 2016 6:36 pm

Hi
The dishing problem can be caused by a different speed in the heat exchange of the upper and lower mould and/or by the combination between the mould profile and the integrity of the plates of the press you are using. Wrong settings in the I/O hoses for steam and water will result most likely on warped records, not dished records.

1. Have you checked the hardness of the water you are using to cool down the record? Dished records are the very first clue of a bad heat exchange caused by the hardness of the water.
2. Cut a record with scissors and measure its thickness in the center and in the edges, using a Vernier gauge. Not in the grooveguard area of course, but just in the center and in the outer edge. If the difference between the edge and the center is .02 mm or more, then there is a problem you have to correct. This test is normally done to check why records tend to warp, a different problem than yours, but it might be very telling for your issue too.

If your record is dished, and you hit it with your finger in the center just like you want to "correct it" to bring it to the proper shape, and you see that it gets flexed, but at the same time it makes a sort of "click" and goes back to its original shape, then it means that it is too weak in the center. Most likely, you will find out a remarkable difference between the thickness of the center and the edges.

If your moulds are new, I suggest you to check the plates below the moulds. And the heat exchange.

Assuming that the heat exchange is OK, if you want to try an immediate solution, just to test: take two nickel mothers, cut out their center, keep just their outside diameter (let's say a 13" wide outside circle and a 10" inner circle) and place them below the moulds. If the records come out flat, than it means that you have to rectify your press plates, to make them perfectly flat. It's a 500$ job here, maybe you can find there a cheaper solution.
Phil from Phono Press, Milan, Italy
http://www.phonopress.it
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Re: vinyl dishing problem

Unread postby CK Li » Fri Feb 05, 2016 5:12 am

Hi montalbano,

Thanks for your help. Well, i will check the heat exchange efficiency of cooling water.

CK
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Re: vinyl dishing problem

Unread postby SUNBEARS » Fri Dec 01, 2017 9:36 am

Yo! So in my experience, if you are using metal stacking plates, they need to be warmed to a room temp or the temp of the record. Stainless steel and aluminum are usually cold to the touch, so I just have a little lamp warming them (the metal ones)

If you put a warm record on a cool stacking plate, it will cause the disc to dish because one side is cooling significantly faster than the other. The side that cools faster will condense, thus causing the disc to dish.

You can also try, like Aussie said, using old lacquers. 1/8 acrylic discs could work too and be easily sourced.

Good luck!

Cheers,
J
The loudness war is over, if you want it! - http://www.berlinmastering.co
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