Cheap is not always economical – Quality knives instead of expensive, cheap knives
Whether you are looking for hollow knives, cutting crowns, flat
knives or reversible knives – the market for shredder rotor knives
offers an abundance of cheap knives. These knives are often made
from economical materials less suited for cutting tools, such as
CK45, for example, which is only surface hardened. The service life
of these knives is extremely short and their cost-effectiveness
therefore very poor in the majority of cases.
PR-Technik GmbH, Germany, specialises in developing,
manufacturing and selling industrial knife systems, relying entirely
on premium quality: the hollow knives or cutting crowns in the PR-Technik
range are provided with a 1.5 mm thick, hardened surface, a moderately
hard transition zone and a soft core. They are manufactured from
high-quality steel, specially suited to case hardening, and achieve
optimal hardness by repeated tempering. The high-quality of PR-Technik
knives comes into its own with regard to applications in which the
knives are exposed to impurity-related, sudden forces and loads,
in particular.
The differences compared to cheap, 1.2379 tool steel knives, can
be even more significant. It is common practice for the majority
of rectangular knives to be produced from a rolled, square steel
section. In terms of material and production costs, this production
method is comparatively economical, but presents a significant disadvantage
as a result of rolling (banding): The forces acting on the knives
during the shredding process act in exactly the same direction as
the fibre (cf. Figure 1). This results in a considerably higher
knife fracture hazard.
PR-Technik GmbH's hollow knives, cutting crowns, flat knives or
reversible knives, in contrast, are always produced from the more
expensive flat steel bar. In these knives the cutting forces act
perpendicular to the fibre with the result that the fracture hazard
is very substantially reduced (cf. Figure 2). In addition, the optimal
heat treatment with multiple tempering processes brings the knives
to the ideal hardness, positively impacting on the cutting force
and the throughput capacity.
Buying cheap knives, then, only has merit at first glance. In economic
terms the investment in expensive, but high-quality, knives is far
more economical, simply because they have much higher service lives
per cutting edge. This results in noticeably lower knife replacement
and time-consuming, expensive machine standstill times are distinctly
minimised.
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More than 20 years experience in shredding technology and intensive
collaboration with machine manufacturers and operators in the timber,
plastics and recycling industries create impetus towards new, innovative
products, opening the way to greater efficiency and profitability.
PR-Technik GmbH develops and produces high-quality industrial knife
systems for customers around the world, in Germany. Our aim is to
provide individual solutions and adaptations for all customer-specific
tasks.
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