How to heat and cool a silicone rubber extruder?

How to heat and cool a silicone rubber extruder?

The extrusion temperature of silicone rubber wire cable is between 150 - 180℃, so the extrusion barrel needs to be heated or cooled.

一、Extruder barrel heating

The heating methods of the silicone extruder barrel include resistance heating, electric induction heating and heat carrier heating. The most commonly used heating method now is resistance heating, and thermocouples are used to achieve segmented temperature control and detection.

1、resistance heating

  It is to let the current pass through the wire (resistance wire) with relatively large resistance, thereby generating heat, which is then conducted to the material through the barrel wall. Resistance heating method is a commonly used cast aluminum heater. It installs a resistance wire in a metal tube, fills the tube with insulating materials such as magnesium oxide powder, and then casts the metal tube in aluminum alloy. This kind of cast aluminum heater is widely used. Its characteristics are: the resistance wire is in a metal tube filled with insulating material, which is well sealed, not easy to oxidize, and has a long operating life; the aluminum alloy sleeve has a large contact area with the barrel and has good heat transfer performance.

2. Electric induction heating

The outer circumference of the barrel is equipped with a coil, and a magnetically conductive silicon steel sheet is installed around the coil: when current passes through the coil, the silicon steel sheet and the barrel form a closed magnetic circuit, and the alternating magnetic flux induction causes the barrel to generate current, and the machine The barrel generates heat due to its certain resistance value. Using the electric induction heating method, the barrel screw heats up quickly and the components have a long service life, but the structure is relatively complex.

3. Heat carrier heating

It refers to using water vapor or oil as heat transfer medium to heat the barrel. The water vapor needs to be transported by boiler equipment and pipelines, and the oil is heated by a resistance heater. Both types of heating equipment are complex, expensive and difficult to control, so they are rarely used now. However, the temperature of this heating method is soft and even, which is very suitable for heating heat-sensitive plastics.

二、Cooling of extruder barrel：

1. Under normal circumstances, the barrel does not need to be equipped with a cooling and control system, and natural cooling can meet the process requirements. However, if the temperature of the feed port is too high, a "bridging" phenomenon will occur at the feed port, making feeding difficult or even impossible.

2. In order to ensure good feeding and solid material transportation conditions and prevent the heat of the extruder barrel from being transferred to the transmission components, a cooling jacket (trough) should be installed at the feeding port of the barrel, and it can be used according to process requirements. Adjust the amount of cooling water. In addition, when processing heat-sensitive plastics at a higher speed, the machine must be cooled and controlled to prevent thermal decomposition of the heat-sensitive plastics.

3. The barrel is blown to cool down. It is to use an electric fan to blow air to the parts of the extruder screw barrel that need to be cooled, so that the cold air can take away the heat of the barrel to achieve the purpose of cooling the barrel. The fan cools down the barrel. The equipment has a simple structure, small thermal shock, low cost, and is easy to repair and disassemble, so it is currently widely used. The disadvantage is that the cooling speed of the barrel is relatively slow.

Silicone rubber wire cable extrusion line

our company have all kind of diameter silicone rubber wire cable extrusion line

Model	GF60 GF65	GF80 GF85	GF90 GF100
Pay-off  Type	Drivng Type	Dual-Shaft Type	Dual-Shaft Type
Screw L/D Ratio	10:1	10:1	10:1
Screw Rotation Speed (R.P.M)	0~35	0~35	0~35
Extrusion(kg/h)	70~80	85~90	120~180
Main Power(KW)	11	15	15~35
Wire Dia(mm)	0.8~6.0	2.0~12	3.0~20
Cooling Trough	20m Power:7kw/4m	20m Power:3.5kw/2m	20m Power:3.5kw/2m
Haul-off Power(KW)	2.2	4	4~5.5
Line Speed(m/min)	0~300	0~300	0~300
Take-up Power(KW)	2.2kw	4kw	5.5kw