Improved service life of circular knives by using new materials and refining processes

Service life is an important pararameter when determining the quality of circular knives and cutting edges. For the paper, synthetic and textile converting industry tool changes represents an undesired machine standstill, reducing productivity.

For many applications, the service life of knives made from conventional tool and chrome steels sufficiently meets the requirements. Both service life and cutting results depend on choosing the correct cutting geometry. Adjustment of the contact pressure and as to the overlapping of bottom and top knife has to be adjusted individually.

To meet customer's demands for greater service life, the machine manufacturer, Dienes Werke at Overath, offers knives with greater durability. Depending on the range of applications, cutting problems can be solved with coated, tungsten carbide or ceramic tipped cutting edges. Highest quality and precision are necessary to obtain small enough minimum roughness values and the desired cutting results. In addition to the standard ground finish Dienes offers as well a polished knife edge to drastically reduce dust accumulation.

Coatings

An increasing number of users are moving towards using coated knives which have a highly improved service life. That is why Dienes has developed a coating process for top knives with superior penetration. Reservations against a regrinding of coated knives are, therefore, not justified. The right procedure allows the regrinding of the coated knives as often as uncoated knives. The comparatively higher charges of the coated knives amortisize quickly thanks to the considerable improvements in service life.

Tungsten carbide tipped knives

The use of tungsten carbide tipped bottom knives improves service life and reliably cuts difficult with comparable bottom knives made from "standard" tool steel. The tungsten carbide tipped bottom knives have a service life 8 to 10 fold times greater than bottom knives made from standard tool steel.

Ceramic tipped knives

The Dienes Werke achieves the longest service life with circular ceramic bottom knives. Compared to tungsten carbide tipped cutting edges, a further improvement in service life can be obtained by two to fourfold. When manufacturing technical ceramics, different procedures can be used having an effect on service life and prices.

To be able to decide in favour of a suitable material, the user should contact the machine manufacturer to discuss special applications. The check list has proved its worth for tungsten carbide and ceramics.

Further information please contact:

Dienes Werke GmbH & Co. KG
Postfach 1320
D-51484 Overath, Germany
Phone: ++49-2206-605-160
Fax ++49-2206-605-111
eMail: sales@dienes.de
Internet: www.dienes.de

Dienes check list for tungsten carbide and ceramics

• Testing the material specification
• Optimizing the top knife material
• Transforming the material advantage by the peripherie (f. ex. knife holder)
• Exact definition of knife shear angle and cutting force