Our company can design and manufacture various types of large-scale granulation die plate based on user's demand, with die plate diameter ranging from **0mm to ***0mm and hole diameter from 0.7mm to 3.2mm as well as the production capacity of *0~**0 thousand ton polyolefin per year.

 

Number of the die plate holes ranges from *0 to ***0 in accordance with orders and the holes diameter is from 0.7 to 3.2mm. Material flow channel is fluent, the ejection speed is even and opening rate of holes is more than *9%.

 

The die plate is mainly used to pelletize LDPE, LLDPE, HDPE, PP, ABS masterbatch and other polymers such as EVA, SAN, etc.

PE granulation die plate is made of WC-CoNiCr material and has excellent anti-wear, corrosion resistance and high bending strength.

PP granulation die plate is made of new and high-performance cobalt-free TiC/NiCr cermet composites. This material has good wear-resistance, heat and corrosion resistance and so on.

 

Die plate heating medium: steam pressure of 6MPa or oil temperature up to **0℃ (PE ******0℃ PP ******5℃);

Working pressure of the die plate up to *0MPa;

 

 

Main technical specifications of material for the granulation part

1. TiC-NiCr cermet

Hardness (HRC): ****2;

Bending Strength (σb): ≥ ***0MPa;

 

2. WC-CoNiCr Hard alloy

Hardness (HRC): ****6;

Bending Strength (σb): ≥ ***0MPa;

 

3. The welding strength between the body and granulation part of die plate should be higher than **0MPa;

 

4. The final product should meet user's requirements and the service life reaches the advanced level of similar products abroad.

 

 

 

 

 

 

 

Our company can produce a wide range of the metal-ceramic composites pelletizing knives.

 

PELLETIZING KNIFE MUST HAVE THE FOLLOWING CHARACTERISTICS

 

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

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 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.

 

 

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

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

 

 

Knife blade is welded with the knife body by vacuum reactive diffusion welding technology. Its main principle is to use interdiffusion among Ni, Cr and Fe atoms and they form solid solution at elevated temperatures for knife body and blades. With increasing temperature, the vibration of atoms rises and the gravitational force between atoms reduces. A solid transition zone is formed from this solid solution between these two materials. The comprehensive performance (resistance to external force and deformation ability) of the two-layered metals is significantly improved than that of a single steel or TiC-NiCr. Its bending strength reaches up to ***0MPa.

 

1、 Knife body: alloy steel or stainless steel

2、 Vacuum diffusion welding interface

3、 Cermet blade

 

 

 

 

 

 

 

 

 

 

 

 

 

 

With the enhancing of single-line granulation production capacity and the range of melting index, the diameter of granulation die plate and granulation band width increase, as well as the number of holes. They will make materials run through the die plate faster, and lead to the increase in elastic deformation of the die plate. At the same time, the axis of the die plate is uneasy to completely coincide with the power cutter shaft axis. These will cause unequal contacts between the edges of cutters and the cutting surface of the die plate. This is prone to decrease granulation quality, such as increasing waste product. Furthermore, (e.g. for high melting index plastics) it will make pad knife, wrapped around a knife, and even wax irrigation.

 

DESIGN PERCEPTION OF THE FOLLOWING CUTTER HOLDER

 

The concept to design the following cutter holder is: Ensure driving shaft of cutter holder to have sufficient driving torque, enable the cutter holder to achieve axial swing under a certain external force by the choice of connection mode or joining materials.

Cutter holder designed and produced in our company with independent intellectual property rights is characterized by a special flexible rubber as the transmission of tensional and axial forces. A special design ensures normal work when driving force of axis goes beyond the capacit limit of the special rubber. So, it can not only meet the requirements of the scope of random moving, but increase the service life of cutter holder as well. At the same time, it can avoid degloving in case of overloading, and system wax irrigation etc.

 

 

FOLLOWING CUTTER HOLDER

 

New type of Following Cutter Holder can ensure the homogeneity of the contact distance between the cutter edge and the cutting surface of the die plate and significantly improve the pelletizing quality. This will make its service life and reliability superior to the similar products in France and Germany and can meet the demand of granulation for high melting index.

The company repaired or manufactured nearly *0 sets of cutter holder for Lanzhou Petrochemical Co., Ltd., Dushanzi Petrochemicals Co., Ltd., Zhongyuan Ethylene Co., Ltd., Tianjin ethylene Co., Ltd., Fujian Petrochemical Co., Ltd., Sinopec Qilu, Panjin Ethylene etc., and get good results.