Dust Contamination

conversion process

Dust Anyone?

We recently discovered the problem that Angel Hair causes for Carton Convertors, particularly those in the food packaging sector. A similar issue for machine operators is that of Dust. It really is an issue that requires eliminating for Carton Convertors working in the food packaging industry as the dust is classed as contamination.

Where is Dust such a big problem?

Dust comprises of small particles of board which appear during the conversion process. They are created by friction when the shaved blade cuts through the often tough to convert recycled board substrates.

How Does Friction Cause Dust?

Dusting appears when the bevelled profile of the cutting blade passes through the fibres of the substrate being processed. This will cause particles of board to break free from the substrate being Diecut.

The dust will appear at its worst when cutting through tough recycled board, due to the boards short fibres. Recycled product breaks down far easier than virgin board.  The more we recycle the substrate, the shorter the fibres become. With shorter board fibres, the converting conditions become more difficult to control.

Are there any other contributing factors to Dust?

When the operation of shaving the cutting blade takes place at the Bohler steel mill, i.e. the process of  shaving the sharp tip onto the blade, large coils of steel around 1000m-1500m in length (2pt), run through the shaving machines. Each shaving line has several shaving tool tips, each tooling tip will take off slightly more than the last, until the blade is perfectly symmetrical and the rule has been taken down to the required height. During the shaving process, microscopic lines can appear along the length of the bevel. When the blade is placed into a die, and the machine goes under impression, the blade doesn’t always cut through the substrate smoothly, and can cause friction. The friction creates small particles of board which, can be seen in volume on the converted product

How do you solve the problem?

The best way to eliminate dust is to remove friction from the die cutting process.  We can do this by protecting the bevel of the cutting blade, by the application of a thin anti-friction coating.

As the sole UK supplier of Bohler rule, Partwell would recommend the use of the Bohler universal supreme. A standard Universal blade, the supreme rule would be 2pt or 3 pt, 2380mm in height and Centre Bevel (CB) or Long Centre Bevel (LCB).

The blade is sprayed with a Teflon style, microscopic anti friction layer just along the bevel. This fills in all of the microscopic pits and imperfections that are created during the shaving process. If you spray Supreme coating on to a 2pt/3pt Universal blade, the tip remains at the same hardness, 640v, but it becomes extremely smooth. The benefit of the Supreme coating is its ability to reduce the friction during the cutting process, therefore eliminating board dust. The cutting blade remains the same hardness, so it can still run through an automated bender without requirement for further bend configuration; this means there are no issues for the die maker.

The true benefits are seen by the Carton Convertor. Dust is reduced and under the right conditions, the Supreme die will last longer than a standard die.

Another product to eliminate dust would be Bohler Tinit. This is a slightly different product in that it does change the hardness of the tip of the steel. The rule is identifiable with its Gold finish on the rule bevel. The Tinit layer is approximately 0.002mm in thickness when it is sprayed onto a 2pt/3pt 23.80mm Centre Bevel Universal rule. It will harden the tip from 640Hv up to 2400Hv making the rule tip four times harder. This comes with two advantages for the packaging company. Not only will the smooth Tinit coating reduce friction in the converting process and eliminate dust, but the packaging company will also have the added advantage, if machine conditions are correct, of extended tool life.

I recently had a die maker whose packaging company frequently had dust contamination and was constantly re-ruling the tools, but the specification has been changed from Universal to Supreme Universal. The product is now a standard for the die maker and all of his customers are benefiting from dust elimination.





15th March 2017, 13:30