Cleaning at the Cutting Edge
- Published: August 18, 2008
RENFREWSHIRE, UK | Teknek contact cleaners are said to differ from other methods of web cleaning in the their effectiveness. The company reports even with the most modern of slitting and rewinding equipment, it is essential to ensure that a machine is optimised for the process. In commercial shear slitting, blades are rotating and circular and are set at an angle to the product being slit. Shear cutting for the most part produces good edge quality and a clean cut. However, in certain circumstances some substrates do generate dust, and there are a number of reasons for this. For example, inappropriately set blade angles or poor knife geometry when used on moderately rigid materials such as clay-coated boxboard can result in brittle coatings breaking off and causing dust.
Too much upper speed overlap and insufficient over-speed can be a cause of dust related problems in sheer slitting. When slitting quality decreases an operator may increase blade overlap. A drawback, says the compay, is that this can cause a reduction of top blade speed, which in turn loosens fibres of paperboard or non-woven materials, which in turn raises dust. To further complicate matters many of these particles can become statically charged, so they cling to the slit edges and become wound with the roll(s).
This surface dust or slitting edge debris can be problematic in instances of further processing. For instance, in a printing operation slitter dust can cause hickeys, line voids, and other imperfections that can render even the most carefully crafted of print jobs worthless. Some slitting methods are more prone to dust and debris generation than others. In score or crush slitting there is only one circular blade. This blade is pressed against a hardened roll and cuts the material as it passes between the blade and the roll. As there is only one blade to position, this method is generally easier to set up and is less expensive to run. On the downside, says the company, it generally does not give as good a clean edge and creates more dust.
Keeping blades sharp and setting them optimally makes good sense, says the company, to reduce slitter dust. Equally important, the fitment of a Teknek contact web cleaner with anti-static bars can address the problem of surface-borne contamination, says the company, and the problem of static charging. Dust and debris created by the slitting process can affect final product quality, particularly when further value added processes are involved, but airborne contaminants can be problematic as well.
The company's contact web cleaners are suitable for narrow and wider web width applications. Wider web units such as the XCH can be integrated with coating, laminating, extruding machines, with printing presses, and with slitter rewinders. For instance, an XCHP double -sided cleaner has been installed on a Kampf slitter, before the knives in order to clean the material before entering the slitting area. Both standard and bespoke contact cleaners can be provided.
In operation, the company claims web cleaners must penetrate the boundary layer of air surrounding a moving web. The faster the material is moving determines the depth of the layer and the difficulty of removal. Some methods, high velocity air for example, says the company, simply disperse contaminants elsewhere; traditional vacuum systems cannot meet the increasingly demanding requirements of customers, and can only clean moderately effectively. Developed initially for the demanding electronics industry, Teknek contact cleaners penetrate the boundary layer to remove particles down to the micron level, reportedly minimizing material waste and machine downtime for cleaning, while improving throughput and product yield.
Company's contact web cleaning concept involves the use of a specially configured elastomer roller that rotates in contact with the web material. This high surface energy roller removes contaminants from the material surface, transferring them to a high coat weight reverse-wound pre-sheeted adhesive roll where the contaminants become trapped. When the outer pre-sheeted adhesive layer becomes saturated with contaminants, it is simply removed, exposing the next underlying adhesive layer ready for use.
