{"id":14178,"date":"2017-09-06T17:53:35","date_gmt":"2017-09-06T17:53:35","guid":{"rendered":"http:\/\/www.flxon.com\/?p=14178"},"modified":"2018-02-19T17:28:55","modified_gmt":"2018-02-19T17:28:55","slug":"tip-tips-pondering-what-edge-to-use-radius-beveled-or-lamella","status":"publish","type":"post","link":"https:\/\/www.flxon.com\/es\/tip-tips-pondering-what-edge-to-use-radius-beveled-or-lamella\/","title":{"rendered":"FLEXO 101 – Tip Tips: Pondering What Edge to Use\u2014Radius, Beveled or Lamella (4 of 5)"},"content":{"rendered":"

[et_pb_section bb_built=”1″ admin_label=”section” transparent_background=”off” allow_player_pause=”off” inner_shadow=”off” parallax=”off” parallax_method=”on” padding_mobile=”off” make_fullwidth=”off” use_custom_width=”off” width_unit=”off” custom_width_px=”1080px” custom_width_percent=”80%” make_equal=”off” use_custom_gutter=”off” fullwidth=”off” specialty=”off” disabled=”off” custom_padding_tablet=”50px|0|50px|0″ custom_padding_last_edited=”on|desktop”][et_pb_row admin_label=”row” make_fullwidth=”off” use_custom_width=”off” width_unit=”off” custom_width_px=”1080px” custom_width_percent=”80%” use_custom_gutter=”off” gutter_width=”3″ custom_padding=”27px|0px|0px|0px” padding_mobile=”off” allow_player_pause=”off” parallax=”off” parallax_method=”on” make_equal=”off” column_padding_mobile=”on” parallax_1=”off” parallax_method_1=”on” parallax_2=”off” parallax_method_2=”on” parallax_3=”off” parallax_method_3=”on” parallax_4=”off” parallax_method_4=”on” disabled=”off” background_position=”top_left” background_repeat=”repeat” background_size=”initial”][et_pb_column type=”4_4″][et_pb_text background_layout=”light” disabled=”off” module_alignment=”left” background_position=”top_left” background_repeat=”repeat” background_size=”initial” _builder_version=”3.0.86″]<\/p>\n

FLEXO 101<\/strong><\/h1>\n

Tip Tips:<\/h1>\n

Pondering What Edge to Use – Radius, Beveled or Lamella<\/h3>\n

Fourth in a 5 Part Series on The Importance of Basic Process Element<\/h4>\n

[\/et_pb_text][et_pb_text background_layout=”light” text_orientation=”left” use_border_color=”off” border_style=”solid” disabled=”off” module_alignment=”left” background_position=”top_left” background_repeat=”repeat” background_size=”initial”]<\/p>\n

The fundamental purpose of the flexographic doctor blade is to remove excess ink from the anilox roll surface. The remaining ink film on the anilox, combined with ink in the anilox cells, needs to be enough to achieve color density on the printed substrate.<\/p>\n

If the blade fails to remove enough ink, what remains on the anilox surface transfers more than is necessary to plate and substrate. The excess ink requires more dry time and energy consumption. In addition, the thicker ink film more rapidly overwhelms the plate\u2019s raised image resulting in dot gain, dirty print and mid run press stops to clean the plate.<\/p>\n

The converse is not always true. While it is possible to remove too much surface ink from the anilox, especially when metering a low line count surface used in heavy transfer applications, it rarely happens with higher line counts. In fact, flexo made its biggest print quality gains by moving to higher line anilox and all but eliminating the surface ink film. Today\u2019s HD flexo relies on a precise volume of ink from cells, not surface ink films.<\/p>\n

The importance of the blade contact area in the metering process can\u2019t be overstated. From the beginning, it was understood that the width of the blade at the point it contacts the anilox surface should be as narrow as possible. The wider the contact
\narea, the greater the ink\u2019s hydraulic impact. As press speeds increase, hydraulic pressure lifts the blade, allowing more ink to pass and resulting in the list of negatives already mentioned.<\/p>\n

[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row make_fullwidth=”off” use_custom_width=”off” width_unit=”off” custom_width_px=”1080px” custom_width_percent=”80%” use_custom_gutter=”off” gutter_width=”3″ custom_padding=”27px|0px|0px|0px” padding_mobile=”off” allow_player_pause=”off” parallax=”off” parallax_method=”on” make_equal=”off” column_padding_mobile=”on” parallax_1=”off” parallax_method_1=”on” parallax_2=”off” parallax_method_2=”on” parallax_3=”off” parallax_method_3=”on” parallax_4=”off” parallax_method_4=”on” disabled=”off” background_position=”top_left” background_repeat=”repeat” background_size=”initial”][et_pb_column type=”4_4″][et_pb_text background_layout=”light” text_orientation=”left” use_border_color=”off” border_style=”solid” disabled=”off” module_alignment=”left” background_position=”top_left” background_repeat=”repeat” background_size=”initial”]<\/p>\n

CONTACT AREA MANIPULATION<\/strong><\/h5>\n

Flexo adopted the use of doctor blades to meter ink from the rotogravure print process. In roto, the blade is used in a wiping position. The dynamics of \u201cwiping\u201d a gravure cylinder, especially in the area that is not engraved, to achieve and maintain optimum performance, are very different than in the sheering or scraping action of the doctor blade in flexo.<\/p>\n

The rotogravure press operator purposely manipulates the blade\u2019s contact area to achieve more or less wipe of the area that is not engraved. A very small amount of ink is allowed to pass beneath the blade to lower friction and wear of both the chrome cylinder and the blade. Both the beveled tip and a lamella tip were developed to aid in this process. Part of this manipulation also involves the use of more or less pressure to adjust the blade\u2019s flex.<\/p>\n

In the flexo process, the challenge is to set a blade to the anilox at roughly 30 degrees to 35 degrees and keep it there. Most doctor blade metering systems are preset to position the blade at the optimum contact angle. It is much easier to maintain the angle in a single blade system like those common to the label printing industry.<\/p>\n

[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row make_fullwidth=”off” use_custom_width=”off” width_unit=”off” custom_width_px=”1080px” custom_width_percent=”80%” use_custom_gutter=”off” gutter_width=”3″ custom_padding=”27px|0px|0px|0px” padding_mobile=”off” allow_player_pause=”off” parallax=”off” parallax_method=”on” make_equal=”off” column_padding_mobile=”on” parallax_1=”off” parallax_method_1=”on” parallax_2=”off” parallax_method_2=”on” parallax_3=”off” parallax_method_3=”on” parallax_4=”off” parallax_method_4=”on” disabled=”off” background_position=”top_left” background_repeat=”repeat” background_size=”initial”][et_pb_column type=”1_2″][et_pb_text background_layout=”light” text_orientation=”left” use_border_color=”off” border_style=”solid” disabled=”off” module_alignment=”left” background_position=”top_left” background_repeat=”repeat” background_size=”initial”]<\/p>\n

However, chambered blade metering systems are a challenge. Here\u2019s why: During a pressrun, anilox cells trap an increasing amount of air, thereby reducing the amount of ink they hold. To overcome this starvation, the pump\u2019s pressure can be increased to try to force more ink into the cells. Increased pressure within the chamber causes end seals to fail. To stop the end seals from leaking, the chamber and seals are pressed tighter to the anilox. Increased pressure causes blades to flex, bending\u00a0them over at the tip and increasing the contact area. As the blade tip bends, the contact area widens and the anilox ink film deepens. Dot gain and dirty print soon follow. Chart 1 indicates the contact area at different contact angles when zero flex is present.<\/p>\n

[\/et_pb_text][\/et_pb_column][et_pb_column type=”1_2″][et_pb_image src=”https:\/\/www.flxon.com\/test\/wp-content\/uploads\/2017\/09\/Tips-Chart-One-01.png” show_in_lightbox=”off” url_new_window=”off” use_overlay=”off” animation=”off” sticky=”off” align=”center” force_fullwidth=”off” always_center_on_mobile=”on” use_border_color=”off” border_color=”#ffffff” border_width=”1px” border_style=”solid” disabled=”off” \/][et_pb_image src=”https:\/\/www.flxon.com\/test\/wp-content\/uploads\/2017\/09\/Tips-Chart-Two-01.png” show_in_lightbox=”off” url_new_window=”off” use_overlay=”off” animation=”off” sticky=”off” align=”center” force_fullwidth=”off” always_center_on_mobile=”on” use_border_color=”off” border_color=”#ffffff” border_width=”1px” border_style=”solid” disabled=”off” \/][\/et_pb_column][\/et_pb_row][et_pb_row make_fullwidth=”off” use_custom_width=”off” width_unit=”off” custom_width_px=”1080px” custom_width_percent=”80%” use_custom_gutter=”off” gutter_width=”3″ custom_padding=”27px|0px|0px|0px” padding_mobile=”off” allow_player_pause=”off” parallax=”off” parallax_method=”on” make_equal=”off” column_padding_mobile=”on” parallax_1=”off” parallax_method_1=”on” parallax_2=”off” parallax_method_2=”on” parallax_3=”off” parallax_method_3=”on” parallax_4=”off” parallax_method_4=”on” disabled=”off” background_position=”top_left” background_repeat=”repeat” background_size=”initial”][et_pb_column type=”4_4″][et_pb_text background_layout=”light” text_orientation=”left” use_border_color=”off” border_style=”solid” disabled=”off” border_color=”#ffffff” module_alignment=”left” background_position=”top_left” background_repeat=”repeat” background_size=”initial”]<\/p>\n

WHEN\u00a0MORE IS LESS<\/strong><\/h5>\n

When it comes to doctor blades, a thicker blade will often result in a narrower contact area. A thicker blade had better resist flexing when pressure is applied. Consider the gain seen in Chart 2 when moving from 0.006-in. thickness to 0.008-in.\u2014that\u2019s 33 percent more material. There are three types of doctor blade tips:<\/p>\n

[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row make_fullwidth=”off” use_custom_width=”off” width_unit=”off” custom_width_px=”1080px” custom_width_percent=”80%” use_custom_gutter=”off” gutter_width=”3″ custom_padding=”27px|0px|0px|0px” padding_mobile=”off” allow_player_pause=”off” parallax=”off” parallax_method=”on” make_equal=”off” column_padding_mobile=”on” parallax_1=”off” parallax_method_1=”on” parallax_2=”off” parallax_method_2=”on” parallax_3=”off” parallax_method_3=”on” parallax_4=”off” parallax_method_4=”on” disabled=”off” background_position=”top_left” background_repeat=”repeat” background_size=”initial”][et_pb_column type=”1_2″][et_pb_text background_layout=”light” text_orientation=”left” use_border_color=”off” border_style=”solid” disabled=”off” module_alignment=”left” background_position=”top_left” background_repeat=”repeat” background_size=”initial”]<\/p>\n