Laser diecutting, or laser digital finishing, is the direct, high-speed laser processing of flexible materials without the use of hard tooling. Laser processing systems are used to cut, score, etch, kiss-cut, and perforate roll- or sheet-fed materials with precision, flexibility, and speed. This non-contact process is an alternative to traditional diecutting and is ideal for applications that feature locations, tolerances, sizes, or material characteristics that would be difficult or cost-prohibitive to process the liner altogether. These elements play an important role in the diecutting process. To be sure your diecutting is successful, be on the lookout for the following influencers:
1. CLEARANCE - This refers to the distance the die blade is set to properly cut through the film and adhesive without deep striking the release liner. To determine the proper clearance, the exact thickness or caliper of the liner material is required.
2. CALIPER CONSISTENCY - If the liner caliper is not consistent when kiss cutting, two things can happen: 1)The die fails to cut completely through the facestock and adhesive, in which case the matrix may pull labels off the web when stripped. 2) The die cuts too deep into the release liner and the web may break or the adhesive may be pushed down into the die strike. This is why the clearance is set to the thickness of the liner and is so important for successful kiss cutting.
Since all diecutting is based on the caliper consistency of the liner, we have outlined below how different liners can affect your diecutting process. Die strikes on the liner should be even and light. Any irregular or inconsistent die strikes should be reviewed with your die company.
Polyester liners provide one of the best diecutting bases because of their caliper consistency, smoothness, and strength, making it an ideal “anvil,” and thus it can help to limit web breaks, as well as potential problems resulting from human error. These liners are ideal for high-speed roll-form converting. While polyester liners may cost more per unit area, the efficiencies realized from fewer web breaks and less waste can help drive down the total applied cost.
Polycoated kraft liners (papers with polyethylene or polypropylene applied between the release chemistry and base paper) also provide a smooth cutting surface, and can therefore lead to improved diecutting. Polyolefin coatings, in particular, allow for deeper diecutting. Choosing between the two is mostly a function of whether you are converting roll- or sheet-form products.
Similarly, a clay-coated paper liner offers better smoothness than plain papers. The clay provides a smoothness lacking in densified paper liners. Unlike polyester liners, the coated papers are backside printable, which can be an attractive option for some applications and although generally less expensive than polyester, coated paper liners are best used for sheet applications. When a clay-coated liner is used with roll-form converting they tend to experience more web breaks than polyester.
Densified kraft paper liners may also be used. The 50 lb. densified kraft liner is the industry standard for roll form applications. The library of dies of most converters is tooled to this liner. Though not as consistent in smoothness or caliper as coated or polyester liners, densified paper liners have some important pluses: they are generally more economical in terms of per unit costs than polyester or even polycoated/clay coated papers, they won’t stretch or slide, and they provide excellent registration in addition to backside printability. During hand dispensing, they are generally easier to handle than other liner options.
3. APPARENT DENSITY - In general, the higher the apparent density of the liner, the easier it is to diecut (this means the liner is more densified). However, this does not mean that you cannot use a less dense sheet to diecut, say an MF sheet (Machine Finish). It just takes the right expertise and the right tooled die for the application and liner.