Una-Dyn, a Piovan company, designs, manufactures and installs auxiliary products for the plastics-processing industry. Giorgio Santella, corporate vice-president of service and sales North America at Piovan, and Bob Harrison, product manager at Una-Dyn, discuss the purpose-built Size Reduction Group, improved cutting angles and how shredders can boost the power of granulators.
Una-Dyn recently launched its Size Reduction Group (SRG). Can you tell us more about this?
Giorgio Santella: Size reduction in plastics is the first step in optimising any production model. Plastics processing can generate a high quantity of rejects that are not necessarily defective parts, but rather sprues, trims, purges or other parts that can be granulated and reused. Knowledge of the various sectors in which the plastics industry operates determines the best size-reduction solution. Experience and competence are valuable when approaching size reduction; that's why Una-Dyn has developed the SRG, a team of application engineers who develop size reduction solutions, based on the part that will be granulated, the material used and the process supported. The SRG also determines how any product will be designed, configured, packaged and applied.
What value does the tangential cutting system add to the new range of machines?
Bob Harrison: The tangential cutting system is designed with a high-angle approach between the rotating and stationary knives. This cuts more efficiently and uses less power than the low approach angle that is found on most conventional machinery. When the angle of approach - or tool-rake angle is higher - the cutting force is stronger, the frictional force weaker and the resultant force greater. When the angle of approach and shear angle are higher, the frictional angle is lower, in regard to the resultant force.
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