TechTalk #11: Die Not Cutting?
At Wilson, we’re always focused on the technical aspects of flexography. TechTalk is your quick snapshot of key topics in our industry. Let us know what you think.
Die Not Cutting?
Labels going up in the waste can be a common cutting issue. To determine the optimal solution, it’s important to identify what is happening. Let’s examine a few common scenarios.
Does it repeat with the die?
For example, if the tool is four around, is it every fourth label? If this is the case, you may have a low spot in the blade on the cavity. If it’s a solid tool, it must be retooled. If it’s a flexible tool, a new die must be ordered.
Does lifting repeat at a length that doesn’t correspond to the repeat of the die?
This is generally an anvil issue. Inspect the anvil for wear and try the tool on a different anvil. If the issue goes away by changing the anvils, then send the anvil to us. We’ll inspect it and return in working condition.
Do the labels lift on the entire side of the operator or opposite side?
This can cause the steel not to adhere to the magnetic cylinder properly. As a general rule of thumb, the inches of engraving on the tool should not be more than three times the square inches of the plate. For example: A 2.00″ across x .375″ around rectangle. If we go 4 across and 20 around on a 80 teeth 10″ tool, the formula for figuring the inches of engraving is (2 * (2 + .375)) * 80 = 380″, the area of tool is 10″ across x 10″ around = 100 sq. in. 380″ is greater than 100″ x 3, so this tool would have an issue adhering to the roll. However, if we cut the number across down to 3 the engraving inches fall to 240″ which is now less than 3 x 100 and should not have issues when adhering.
Is it not cutting the center?
You may have applied too much force to the tool and are causing the tool to flex, or bend. Try releasing some force until you get an even die cut across the tool.
Do the labels lift on both sides, but not the center?
You are probably experiencing an issue where the tool is not parallel with the anvil. Try using a fresh set of journal blocks in this situation.
Are the labels lifting sporadically?
Check to make sure the die was tooled to the material you are cutting. Did you send test material when it was ordered? Send the tool back with the current material and have it retooled. If this is a flexible tool, order a new one and send in material for it to be tooled to. This could also be a material issue. If there is a large amount of variation to the liner on the material, you may have to use a deeper die strike to make up the difference.
Are all of the labels lifting?
Check to make sure the die was tooled to the correct material. Also, if there is a heavy coat weight of adhesive, you may not be able to have an auto die strike. The material may require a hand or hit-hard die strike to ensure the blades separate the adhesive.
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