Excessive pressure, what is it?

[Rockers]

Once in a while I come across the term excessive pressure when talking about printing on an automatic press. So how do you exactly define excessive? When we print white on black shirt through a 150-S at 30PSI is that considered excessive or are 50PSI to print through a 272 mesh excessive?
Where does excessive start or what is considered reasonable pressure?

[ScreenPrinter123]

150s with 65/95/65, we are at 19-23psi with Tidy and 23-27psi with superior, running anywhere from 8" second to 20" per second. We have our squeegee cylinders all the way up meaning the carriage is all the way down at those psi's - so it's really not comparable to anyone unless we know how low they drop their carriage vs how much pressure they use and how much off contact and height between the carriage and pallet. What I can say, which should be similar across the board, is very little deflection on the blade once we are rolling, which is obviously harder to achieve with the softer rubber than the 70+ Duros.

[Rockers]

150s with 65/95/65, we are at 19-23psi with Tidy and 23-27psi with superior, running anywhere from 8" second to 20" per second. We have our squeegee cylinders all the way up meaning the carriage is all the way down at those psi's - so it's really not comparable to anyone unless we know how low they drop their carriage vs how much pressure they use and how much off contact and height between the carriage and pallet. What I can say, which should be similar across the board, is very little deflection on the blade once we are rolling, which is obviously harder to achieve with the softer rubber than the 70+ Duros.

Hm kind of hard to get the pressure reading the precise on a Diamondback but I guess we have days when we do 25 psi at lowest off contact with a 65/90/65 and Wilflex Olympia White.

[brandon]

I honestly think anything above 30 or 40 but then again there are a lot of variables just like everything else we do. But I know several shops where buddies work (some of them with several autos) and they run around 80, 90, 100 or more. No joke. Walking in there and watching the deflection is amazing but in their owners opinion it is all about "banging them out" instead of actually understanding and realizing doing it the correct and efficient way will actually save you time and money. But hey if they have been open 20+ years it must not be broke so why fix it, right? Think of all that money they are loosing with multiple strokes and whatnot. One of those above mentioned shops does three strokes on every print on average. I know one of the press ops so his words not mine. Crazy!

[ScreenPrinter123]

150s with 65/95/65, we are at 19-23psi with Tidy and 23-27psi with superior, running anywhere from 8" second to 20" per second. We have our squeegee cylinders all the way up meaning the carriage is all the way down at those psi's - so it's really not comparable to anyone unless we know how low they drop their carriage vs how much pressure they use and how much off contact and height between the carriage and pallet. What I can say, which should be similar across the board, is very little deflection on the blade once we are rolling, which is obviously harder to achieve with the softer rubber than the 70+ Duros.

Hm kind of hard to get the pressure reading the precise on a Diamondback but I guess we have days when we do 25 psi at lowest off contact with a 65/90/65 and Wilflex Olympia White.

Definitely easier to do with digital readouts at each head, but definitely do-able without them provided there is some type of gauge. I remember with our Freedom press - i wish that was a feature they would've added - we were just turning the knob never knowing the psi since there was no gauge. So be thankful you have a gauge at all!!! :-)

[NiteOwlGraphics]

Pressure alone is a little vague in my opinion.  Squeegee angle, screen mesh, stroke length, stroke speed, squeegee durometer, ink color, garment color and ink type all play a role in what pressure would be necessary.  I tend to think that if you can't get a high quality print WITHOUT "excessive" pressure then there's a pretty good chance that something wasn't done properly pre-press or during set-up.  In the past I have used 30 psi as sort of a rough "ceiling" as far as squeegee pressure.  Interesting question though.

[Sbrem]

I would think you back off the pressure for your combination of materials until it doesn't print, and keep increasing the pressure until you get exactly what you are looking for. After that, the pressure is excessive; push it far enough and it's detrimental. After all, with plastisol, you're trying to lay it down on top of the shirt, not through it to the top of the platen. With discharge you are driving it into the shirt more, but again, after a point the pressure will be detrimental.

Steve