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Question and Answer

Foil Stamping/Diecutting on Cylinder Presses

by Staff

February-March, 2010
Foil stamping and/or diecutting with a converted cylinder press continues to be a popular choice by many finishers and printers in the industry. Although not ideal for all types of jobs, it does provide actual benefits for certain applications. InsideFinishing called upon several experts who have worked with cylinder presses to help answer a number of questions in regards to cylinder work.

What should a buyer look for when considering a cylinder press with a hot foil stamping attachment?

Several types of cylinder presses exist on the market, including what is referred to as an A frame, T type, or overhead foil pull. The overhead foil pull unit is mounted directly above the bed of the press on the very early cylinder models. This severely limits the access of the press operator to the bed of the machine for adjusting the positioning of the blocks and access to the packing on the cylinder face. An A Frame has the foil pull units mounted in a static unit connected to the bed by a scissor action A frame hence the name. This layout provides much better access to the bed; although due to the geometry of the A frame, the gap between stamping images is approximately 3/4 ", thereby limiting the use of tight step and repeats. The T type of cylinder press (the T signifying traverse) is the latest configuration with the foil pull unit mounted on the end of the bed and traveling in and out with the stroke of the machine. With the T type, the gap between foil images can be as little as 1/16 ", allowing for step and repeats that the other types of cylinders cannot achieve.

The following list of tips should be considered when purchasing a cylinder press:

    Know the company that is selling the press and gather as much information as possible as to how that press was run in production and how well it has been maintained. Many of the cylinder presses that have been converted more recently include software that will help run the machine properly and decrease the set-up time. Making sure the software is still readily available and can be updated is important. Double check the configuration of the chase on the cylinder press. Some models may be equipped with only bunter posts or drilled and tapped holes. Make sure it is a honeycomb-style chase, which will allow the use of toggle hooks when securing down the foil dies, providing more flexibility with the registration and set-up. Having a unit that has the ability to adjust the temperature in different zones on the chase also is a benefit. More up-to-date cylinder units with a heated bed should have 4 or 6 different heater zones depending on the size. Make sure to check on the size of the foil roll that can be utilized on the machine. Some older cylinder models may only handle up to a 400-foot roll. This would result in excessive foil changeovers. Newer conversions will allow as much as 2,000-foot rolls, which is a much better choice.

What are the major advantages and disadvantages of foil stamping and/or embossing with a cylinder press?

The main advantage of flat foil stamping with a cylinder press is the ability to lay down a medium to large solid area of foil. Because the foil is rolled onto the sheet versus the die coming straight down on the sheet as with a platen or clamshell press, the air is pushed out and is not trapped between the sheet and the die. This is especially helpful when laying foil down on a coated or laminated sheet that may have a low dyne level where the air cannot pass through the sheet.

The major disadvantage of foil stamping/embossing with a cylinder press is the lack of pressure and tonnage it can apply to the sheet for deep embossing. It is not as well suited for embossing, though it can still work adequately for shallow embossing when the right set-up and makeready procedures are followed (see details on makeready in question 4).

How should you perform spot makeready on a cylinder press when foil stamping?

Makeready for foil stamping on a cylinder should be started with a thin 0.015 epoxy glass board that is at least 24"x24" or larger depending on the size of the cylinder press. Allow 1" on either side of the cylinder and 2" to 3" at the tail end. Using a masking tape with a super adhesive, cover the front edges of the cylinder jacket from side to side, placing the glass board in the middle of the tape. Add a second piece of masking tape (adhesive to adhesive); press firmly; and fold as close to the end of the jacket as possible. This will allow easy access to the spot makeready sheet. Start the machine and while holding the end of the jacket, rotate the cylinder until the tail end comes into view. Attach the end securely with the super adhesive tape completely along the end from left to right.

Utilizing a spot makeready sheet to build up any areas on the foil stamped image also is suggested. This is accomplished easily with the recommended makeready board set-up discussed above. Simply rotate the machine until the front edge comes into view and then lay a spot-up sheet on the cylinder (mark its position with a marker). The spot-up sheet can be an actual sheet from the foil stamping job. Then make a test stamp on the spot-up sheet to see where the build-up is needed. More sheets can be added under the cylinder jacket as needed to level the cylinder image. Once the makeready has been built up to at least 85 percent coverage, remove the spot sheet and rotate the press until the tail edge comes into view. Open the jacket by lifting the tape and inserting the spot sheet into position. Align on the marks and close the jacket. This will provide an easy way to spot makeready any further low spots as the job begins to run.

What tips are recommended if you are embossing on a cylinder press?

It is well documented that a cylinder press is not going to achieve an embossed image with the detail of a flat bed or clamshell press. However, for single-level or shallow multi-level embossing, cylinder presses can adequately emboss if the right procedures are followed. To obtain a quality, sharp emboss it is always best to utilize a pre-made counter mounted on a sheet of epoxy glass board. As with a foil stamping makeready, using a 0.015 board is recommended that can be taped down easily on the cylinder face. To increase pressure and to make sure the embossing die is bottomed out, a good trick is to slip packing under the embossing die. Shims made out of aluminum litho plates work well, too.

Another suggestion when embossing on a cylinder is to try to be involved with the layout of the sheet if at all possible. The best layout is to have the embossed images running parallel to the gripper edge of the press opposed to away from it. This will reduce the overall stretch in the image. Lastly, to produce the best results when embossing on a cylinder, a heated chase should be used. Using a cold chase to emboss is not recommended unless it is a very shallow, single-level emboss.

Does a cylinder press work well for kisscutting pressure-sensitive label stock?

When working with a kisscut job on a cylinder press, it is best to make sure that the paper includes a heavy backing, which makes it much easier to run through the cylinder. Also, the steel rule die should include supporting scores that are the same height as the cutting rule. The scores provide depth control on the kisscut as well as a leveling feature to help maintain a consistent cut throughout the job.

If the sheet is fairly large with several-up to kisscut, it is best to set up the job as a work and turn, so only half of the sheet has to be makereadied and cut at one time. This can help level out the kisscut and not have too large of area to cut in one pass. Another suggestion for kisscutting is to use a gray board as the makeready to cut against. It is hard enough to hold a good makeready but not too hard to dull out the die. A soft makeready will not hold up and cut consistently even if it works initially. Also, sand down the areas on the steel rule that are hitting the hardest to even out the pressure as it kisscuts the sheet. Carbon paper can be used to see how the makeready is progressing.

InsideFinishing would like to thank CMI Print Services (foil stamping conversions for Heidelberg letterpress equipment) www.cmi-printservices.com; Jim Kingsby, JK Hot Stamping Consultants (816) 564-6594; and several FSEA active members who contributed to a FSEA HelpLinks question on kisscutting on cylinder presses.