Pelletizing knife

PELLETIZING KNIFE MUST HAVE THE FOLLOWING CHARACTERISTICS

Pelletizing knife can effectively work with fixed knife (granulation die plate) under water at *0 ~ *0 C.

Hardness of pelletizing blade must be HRC **5 lower than that of the cutting surface of die plate so that it can reduce the wear of the die plate.

It should have high temperature resistance, corrosion resistance, cavitation resistance and wear-resistant properties.

It should have a lower affinity to the molten plastics, i.e. uneasy to stick a knife.

Pelletizing knife should not be uneasily broken under abnormal condition.

CHOICE OF PELLETIZING KNIVES

With the increasing grades and extending melting index of the plastics, not only smooth die plate granulation surface, sharp edge and small gap between cutting surface and knife blade are required, the sharpness of pelletizing blade is also strictly required in the granulation process of high melting index plastic.

In order to adapt to the production requirement of high melting index plastics, the following measures should be taken for the pelletizing knives:

When the cutting surface of die plate is very flat and the cutter runs with it easily, metal-ceramic composite pelletizing knives can be used. The edge width should be controlled below 2.5mm.

When the cutting surface of die plate is not very flat, instrument steel with composite coating or fused composite pelletizing knife may be used.

Adjustment of the hardness of the pelletizing blades makes them more suitable with the hardness of cutting surface of the die plate. Reducing the hardness of cutting edge of granulation knife to HRC **9difference with the hardness of the granulation part of die plate to ensure that the wear of die plate is lower than that of the cutter.

 

METAL-CERAMIC COMPOSITE PELLETIZING KNIFE

 

THE FIRST TECHNICAL CHARACTERISTIC OF CERMET PELLETIZING KNIVES-MATERIAL (COMPOSITION)

 

The so-called cermet is sintered by powder metallurgy technology with a metal or alloy as the bonding phase and a refractory metal compounds (mainly titanium carbide or tungsten carbide) as the hard phase. The microstructure is characterized by small hard-phase grains homogeneously distributed in metal or alloy matrix.

 

The chemical composition of the metal ceramic materials developed in Jinfeng Company mainly contains Ti, C, Ni, Cr etc., where NiCr is used as binder. Its heat and corrosion resistance are better than that of Fe-based materials manufactured in Germany or Japan. The reason is that Ni forms solid solution with Cr and the hardness is maintained at elevated temperature of up to **0℃. This can ensure that hard phase works well and the wear resistance of cutter edge is improved.

 

THE SECOND TECHNICAL CHARACTERISTIC OF CERMET PELLETIZING KNIVES - MATERIAL CHOICE FOR THE KNIFE BODY

 

Suitable material of knife body should at least meet the 2 following requirements. ① a sufficiently high strength and toughness. ② excellent welding performance with the cutting edge. We have chosen high quality structural alloy steel or high quality martens tic stainless steel of granulation knives for different devices.

These two materials have respectively different characteristics: ① Structural alloy steel knife body production of abnormal devices under weak alkaline pelletizing condition. ② martens tic stainless steel knife body with good corrosion resistance and is used in stable operation with adaptive devices under acid pelletizing condition.

 

Knife body: alloy steel or stainless steel

Knife blade: Cermet blade