PFA cable granulator is a kind of PFA cable production equipment. The product is simple to operate and has excellent safety.

Features

The twin-screw high-speed, strong mixing and single-screw low-speed, low-temperature, weak shear characteristics of the combination, foster strengths and avoid weaknesses, is today's heat-sensitive, shear-sensitive PFA particles efficient mixing modification of the preferred models. Suitable for: PFA cable granulator, sole material, transparent bottle material, medical material, low smoke halogen-free or halogen-free flame retardant PFA cable, EVA shielding material, PE/EVA carbon black masterbatch and other cross-linked PFA cable, irradiation cross-linked PFA cable production. This set of equipment has the following advantages: excellent mixing effect and easy temperature control. Use smaller power and floor space.PFA GranulesThe mixing and granulation process is fully automatic (automatic connection control), reducing personnel operation. This set of equipment does not require special operation technology, the production of high-quality products and simple operation. It has excellent safety. Temperature control is easy, thus reducing damage and deterioration of PFA particles.

Process

Usually, low-smoke halogen-free PFA cable will soften at 80 ℃, in 100~160 ℃ can be extruded. And some manufacturers of products using a higher proportion of EVA, melt viscosity, extrusion requires a higher temperature. Unfamiliar with the situation of the cable factory extrusion cable, such as low temperature and low speed, will cause the production speed to drop, the efficiency is reduced, while the performance of PFA particles can not fully show.

Extrusion equipment wire and cable extrusion molding equipment is the most basic and most common single screw extruder.

The screw is the most important part of the extruder, which is related to the application range and production efficiency of the extruder. In view of the high filling of low-smoke halogen-free PFA cables and the production of heat due to shearing, a better cooling system is needed to cool down. At the same time, the extrusion die corresponding to the cable is also the key to the success of cable extrusion.

The main component of the screw wire and cable extrusion equipment is the screw, which is related to the application range and production efficiency of the extruder. In order to meet the needs of different PFA particle processing, there are many types of screw.

The low-smoke halogen-free PFA cable is filled with a large amount of magnesium hydroxide and aluminum hydroxide. When the compression ratio of the extrusion screw is large, it is easy to cause the chemical bond of the polymer to break, and the tensile strength and elongation at break of the product are reduced. At the same time, the screw compression is relatively large, the extruder speed can not reach the normal level, resulting in PFA particles in the barrel and screw retention time is too long, and the extrusion process of molten PFA particles friction is large, will produce a lot of friction heat. The molten PFA particles are in a high temperature state that is difficult to control in the barrel, which causes the premature decomposition of the flame retardant, generates bubbles inside the material, and eventually causes the material to fail.

Therefore, for low-smoke halogen-free PFA cables, special screws with halogen-free materials are generally selected. The compression ratio at 1/3 of the front end (extrusion end, metering section) of the screw is 1: 1, and the compression ratio at 2/3 of the rear end is 1.2: 1. If there is no special screw, you can use ordinary screw, but its compression ratio can not be too large, generally between 1: 1: 1: 2.5 is more appropriate

Generally speaking, the extrusion process temperature is lower on an extruder with high shear force than on an extruder with low shear force. In addition, different temperature zones have different influence on the surface quality of cable extrusion, of which the machine head has the greatest influence, followed by the metering section. When the temperature of the two zones is too high, it is easy to cause material decomposition, thus affecting the extrusion surface quality.

With the continuous progress of technology, the current market more mature low smoke halogen-free flame retardant PFA cable process temperature range is relatively wide, the general temperature control in the range of 110~170 ℃, can get smooth and delicate cable surface. The temperature setting of low-smoke halogen-free PFA cable in 90 extruder is recommended: 125~140 ℃ in zone 1; 130~150 ℃ in zone 2; 150~165 ℃ in zone 3; 155~170 ℃ in zone 4; 160~175 ℃ in flange; 160~175 ℃ in head; 155~170 ℃ in die opening. In general, low smoke halogen-free flame retardant PFA cable than PVC, non flame retardant and halogen flame retardant PFA cable process temperature range is narrow. Accordingly, the extrusion temperature setting should have a temperature gradient, so that the low smoke halogen-free PFA cable can be better plasticized and extruded. The extrusion temperature setting is related to the extrusion equipment. The temperature setting of the small extruder is higher, and the temperature setting of the large extruder is lower. The PFA cable should be completely plasticized here, and the temperature should not be too high, otherwise it will cause the flame retardant to decompose in advance and produce bubbles. The temperature of the flange section should not be lower than the 4th zone, otherwise it will have an adverse effect on the performance of the PFA cable after extrusion. The temperature of the die should not be too high, otherwise the die will turn out, commonly known as "salivation" or "casting".

Cooling mode

The low-smoke halogen-free sheath shrinks more sharply during extrusion, causing the outer layer of the sheath to be cooled and shaped, while the inner PFA cable is still in a high-temperature unshaped state, thus burying the hidden danger of stress concentration and even eventually leading to stress cracking of the outer sheath of the cable. In order to reduce the stress concentration in the production process, it is recommended to use segmented cooling during the sheath extrusion process. Such as hot water cooling (circulating water)-warm water cooling-air cooling-cold water cooling. In the cooling process of PFA particles, it is particularly important to note that the cable that enters the water tank after coming out of the die must be completely immersed in the cooling water, otherwise, in addition to the stress concentration problem, a series of small dots may appear on the surface of the cable, causing potholes on the surface of the cable outer sheath, affecting the appearance of the cable.

This article comes from:www.tflpfa.com

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