User login

Best Practice in Screen Printing

(January 2001) posted on Thu May 31, 2001

The authors discuss the most commonly overlooked variables in the screen-printing process and how to control them.


By Carol Swift, Peter Kiddell

It is vital that the frame be robust enough to resist distorting under the forces of the tensioned mesh, or the printing process will suffer. A frame measuring 1 m (39 in.) per side holding mesh tensioned to 20 N/cm have approximately 200 kg (440 lbs) of force exerted on each beam. Also be aware that temperature has a considerable effect on mesh tension. Screens need to have time to stabilize when brought from an environment with a different ambient temperature.

Floodbar

The purpose of the floodbar is to charge the mesh openings with ink before the ink is displaced by the action of the squeegee. The floodbar is basically an inhibited squeegee. Angle, profile, speed, contact or off contact with mesh, are all key issues in determining how much the floodbar prefills the mesh, and as a result, how much ink is deposited by the squeegee. By controlling the amount of prefill, the floodbar indirectly influences the required drying time for the print.

The floodbar is a much-misunderstood part of the process. Some printers don't even use the floodbar and, instead, rely on ink sticking to the squeegee to feed the wave on the next pass. With a manual press, this is to be expected since the squeegee is used both as a squeegee and a flood coater. In manual printing, it takes a skilled printer with greater dexterity to manipulate the squeegee and achieve the desired results.

For most applications on an automatic or semiautomatic machine, the floodbar should only slightly contact the stencil during the flood stroke. The shape of the contact edge is a critical factor here. Sharp-edged coaters prefill the mesh with less ink, whereas rounded coaters prefill the mesh with more ink. Using the floodbar off-contact from the screen means you are relying on the ink to flow into the mesh openings on its own, and you essentially give up all control.

The press

Every printing machine (even the same make and model) will have a slightly different print characteristic. In all but the most precise applications, these variations are irrelevant. On press, 80% of all production problems are caused by improper setup.

Attempting to remember press settings or use the \"magic touch\" to tweak the machine into submission is a recipe for disaster. Consistent setup is crucial, and the only way to get it is through accurate recordkeeping. Production control cards detailing all the parameters of press setup are the foundation of good process control.

A simple rule is to record enough information so that any printer familiar with the machine controls can use your information to set up a job and achieve the required print characteristics without having to ask for more information. In a situation where multiple colors are being printed on the same machine, or several machines are arranged as an inline printing system, the setup characteristics should ideally be the same. Variations will result in changes in image size and ink deposit.<P>Having material on hand to support the production run is a related press-setup concern. Make sure to gather everything you need for a print run before you start. This results in minimal down time and far fewer rejects.

Finally, keep in mind that continuous operation is the most effective way of running a press. Stopping to clean the stencil alters the consistency of ink flow, and, if you clean it without care, you shorten stencil life and degrade printed-edge definition. If possible, you should avoid touching the print side of the stencil at all. Preventing squeegee wear (which can lead to an increased ink deposit) is another way to keep the press running. Applying low squeegee pressure reduces the potential for wear.

Other concerns

Beyond these areas, you also need to make sure that the substrates you print are clean and uncontaminated and that you maintain a proper printing environment with controlled temperature and humidity. By taking these steps and striving to reduce the previously mentioned variables, you'll see rejects decline, press productivity rise, and the overall quality of your printed products improve.
 


Terms:

Comments

doloresfx says: Youre so cool! I dont suppose Ive learn something like this before. So nice to search out any individual with some original ideas on this subject. realy thank you for beginning this up. this website is ...

Youre so cool! I dont suppose Ive learn something like this before. So nice to search out any individual with some original ideas on this subject. realy thank you for beginning this up. this website is something that's needed on the web, somebody with a bit of originality. helpful job for bringing one thing new to the internet!
Cam Frog gametic

posted on: Thu, 10/06/2011 - 4:28pm
barker says: A great oyster band may be the best function about the Rolex Yachtmaster Observe. To visit along with this kind of, any platinum eagle frame as well as switch get this watch luster throughout the day ...

A great oyster band may be the best function about the Rolex Yachtmaster Observe. To visit along with this kind of, any platinum eagle frame as well as switch get this watch luster throughout the day lengthy. Buyers interested in a wrist watch that will make sure they are stand out should contemplate the actual Yachtmaster. This kind of Replica Watches timepiece includes a list price associated with roughly $7,500.

posted on: Sun, 10/30/2011 - 9:34pm
peterbawz says: online pharmacy Crust lucubrate Generic Viagra occurs shrike Communicative prideful posted on: Mon, 01/23/2012 - 12:23am
DCDSDS says: causes oakley sunglasses discount the stabilizing factor for economic development. "The phenomenon of Wenzhou, Said that if development of the silver cheap oakley radar sunglasses market can not keep ...

causes oakley sunglasses discount the stabilizing factor for economic development. "The phenomenon of Wenzhou, Said that if development of the silver cheap oakley radar sunglasses market can not keep up, the additional funds not only can not help the entity sending oakley development, but also provides oakley dispatch perhaps the social question. Considered the structure of capital markets at several levels that in the stock market of the United oakley dispatch sunglasses States, hands over all Niu 2311 to be registered, NASDAQ 2717, the electrons on the ground outside the market counter trading (OTC oakley frogskin sunglasses ) 2386, powdered 6199 single market, the market gray of over 60,000, take the form about Pyramid, the relative stabilization structure Oakley Oil Rig Sunglasses is reasonable. But our country market mechanism like a pyramid but in fact: Until Ao t 2011, the parent company to all made in 1405, oakley frogskins 610 platelets, undertake board 258, charge d'affaires ad interim of Zhongguan Village Oakley Frogskins sale System 115. Oakley Frogskin Sunglasses cheap oakley frogskin sunglasses Oakley Radar Sunglasses oakley sunglasses for discount oakley frogskin

posted on: Thu, 05/10/2012 - 1:11am
DCDSDS says: causes oakley sunglasses discount the stabilizing factor for economic development. "The phenomenon of Wenzhou, Said that if development of the silver cheap oakley radar sunglasses market can not keep ...

causes oakley sunglasses discount the stabilizing factor for economic development. "The phenomenon of Wenzhou, Said that if development of the silver cheap oakley radar sunglasses market can not keep up, the additional funds not only can not help the entity sending oakley development, but also provides oakley dispatch perhaps the social question. Considered the structure of capital markets at several levels that in the stock market of the United oakley dispatch sunglasses States, hands over all Niu 2311 to be registered, NASDAQ 2717, the electrons on the ground outside the market counter trading (OTC oakley frogskin sunglasses ) 2386, powdered 6199 single market, the market gray of over 60,000, take the form about Pyramid, the relative stabilization structure Oakley Oil Rig Sunglasses is reasonable. But our country market mechanism like a pyramid but in fact: Until Ao t 2011, the parent company to all made in 1405, oakley frogskins 610 platelets, undertake board 258, charge d'affaires ad interim of Zhongguan Village Oakley Frogskins sale System 115. Oakley Frogskin Sunglasses cheap oakley frogskin sunglasses Oakley Radar Sunglasses oakley sunglasses for discount oakley frogskin

posted on: Thu, 05/10/2012 - 1:12am

Did you enjoy this article? Click here to subscribe to the magazine.