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Technology Focus

Tackling Multiple Pass Registration on a Cylinder

by Jim Kingsby

February-March, 2004
In the previous article (August/September 2003), we shared ideas that were designed to assist with stamping multiple passes of a foil product and then following it with a final embossing pass. In this article we will explore how multiple passes of foil stamping are very achievable utilizing a cylinder foil stamping press.

Although cylinder presses have been known to have limitations with detailed embossing, when using proper set-up and makeready techniques, it can be an extremely efficient machine for applying multiple passes of foil.

The cylinder machine offers several advantages for this type of work, which include the following:

  • Positive positioning of the sheet. This is especially true when your job calls for working with lighter weight stocks. This is an advantage because the sheet wraps around the cylinder during the impression cycle. In this position, air is removed between the cylinder and the sheet allowing the sheet to lay flat. Note: Because of the start and stop motion of the stream-fed platen machines and the laws of nature, the sheet will have a tendency to continue on a forward motion. Slower speeds as well as a sponge placed on the chase to flatten the sheet will usually solve the challenge. With advancing technology, some machine manufactures have eliminated this situation by engineering a sheet smoother or an air bar located at the platen outlet which is timed to send a blast of air on the sheet just before the impression cycle.
  • Greater pitch on the feed table/sheet feeder. This is an advantage because with a steeper pitch on the feed table and the sheet feeder, positive sheet control is achieved. No registration devices (rollers and brushes) are necessary. The sheet lays on the front and then the sheet stops until the side guide action is complete. When additional foil passes are necessary, the image registration is somewhat easier.
  • Cylinder rolling action. The mechanics of the cylinder for foil stamping is an advantage because you do not have to build up a huge amount of tonnage for foil transfer. The foil is simply rolled on along the length of the cylinder with approximately 1/16 of an inch in contact with the sheet during the stamping process. You can see the results of this when stamping large solids. Note: Both solids and smaller images can be stamped simultaneously with a cylinder press due to the way the foil is applied. The results should be a less intaglio look on the final product. In the previous article, we mentioned that with less impression around the image area each foil pass will lay better on top of those to follow. It was also mentioned that a hard makeready board must be used. A hard board such as the .030 epoxy glass board will not wrap around the cylinder. The IDEAL solution is to use a thinner
  • 015 epoxy glass board. From experience, we have discovered that the larger the .015 board is, the easier it wraps around the cylinder. So you could construct a cylinder jacket that is very functional as a spot makeready board.

Cylinder Jacket
The .015 epoxy glass board jacket will increase quality and speed up your set-up time in addition to eliminating excess punch on the image. This makes it an excellent tool when foil stamping multiple pass work. For construction, you will need a sheet of .015 epoxy glass board 24 x 24” or larger depending on the size of your machine. You should also have on-hand masking tape with a super adhesive. Cut several strips of .030 yellow cover board or something similar (cut 3/16” x 2” in length ). For a spot up sheet, we will use a sheet of the stock to be foil stamped. Continue with the following steps:

  • Cut the glass board to fit your cylinder. Cut to allow 1” on either side of the cylinder and allow approx. 2”- 3” at the tail end.
  • Using your super masking tape, cover the front edge of the jacket from side to side placing the glass board in the middle of the tape. (The other half of the tape will function as a support to secure the jacket to the cylinder.)
  • Turn the jacket to the backside and mount the strips of yellow cover to the exposed tape. The purpose is to increase the holding grip of the machine clamps by increasing the thickness of the tape.
  • Add the second piece of masking tape (adhesive to adhesive); press firmly and fold as close to the end of the jacket as possible. This also will serve our needs as a handy hinge allowing easy access to the spot sheet.
  • Open the jacket clamp and insert the hinged portion of the newly constructed jacket. Center left to right.
  • 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 along the end completely left to right.

Spot Makeready

  • Rotate the machine until the front edge comes into view. Lay on a spot up sheet and secure it to the cylinder (mark its position with a marker).
  • Start the machine and make a test stamp on the spot up sheet; add more sheets under the jacket as needed to level the cylinder image. When 85% coverage has been achieved, continue with a good M/R.
  • Remove the spot sheet, start the machine and rotate 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. We can proceed with the set-up.
    NOTE: When your image is marred with blister marks or the rainbow effect, you should insulate the chase with ¼” die foam. Insulate by attaching a good heat tape to the foam and positioning it in line with the die under the foil.

Pile Preparation
The final consideration for smooth and consistent foil passes would be the pile preparation. This step, while very critical, is considered general knowledge so we will only offer a limited explanation. A flat and level pile is necessary when feeding any type of a machine. When the pile is flat, the pile elevator can be set to its proper height. This will eliminate the possibility of mis-feeding or double feeding of sheets.

  • Level the pile by using wedges to raise low areas.
  • Always air the sheets to insure that separation is achieved.
  • Adjust suction, sheet combers and blower controls to offer positive sheet control. (See manufacturer’s recommendations.)

If the correct procedures are followed and specific makeready techniques are used, foil stamping multiple passes on a cylinder press can be a smooth, easy process.

Jim Kingsby is a long-time consultant to the foil stamping and embossing industry, whose expertise in this area has taken him to over 20 countries. Jim has conducted hundreds of foil stamping seminars and written several articles and manuals on the subject. He can be reached at JimKingsby@yahoo.com.