Manifold internal heating

Type of heating. Nozzles have external or internal heating, or both types at once. There are also heat-conducting nozzles. These are short nozzles made of a copper alloy warmed by the heat from the HR manifold. 

Nozzles with heated torpedo. The simplest kind of tip nozzle with torpedo (Figure 4.21a) is internally heated by a cartridge heater and attached directly to the manifold (mould plate) with internal heating. It thus serves at the same time to heat the feed channel in the manifold. The end of the nozzle is supported by three pins or short ribs in the bottom of the chamber. Sealing of the channel between the plates is provided by an external frozen layer of melt. 

A system with internal heating (EWIKON) makes it possible to employ side gating with the aid of a manifold and standard tip nozzles located parallel to the parting line (see Figure 4.53). 

The operating principle of an internally-heated manifold is described in Chapter 1.2. 

A distinction is made among internally-heated manifolds between ... 

Figure 4.89 Two-level manifold with internal heating, type COOL ONE...

In view of the low temperature of the manifold plate, the sprue bushings must be heated. Both external and internal heating is used (for the use of a torpedo, see Figure 4.92). 

The thermocouple in a manifold with internal heating is usually built into a cartridge heater. 

In a mould (see Figure 6.11) with an internally-heated manifold (EWIKON), the need arose to balance the flow to 15 injection points. 

Processing properties of plastics - thermal resistance. With internal heating there is melt hang-up and higher shear stresses during flow through the annular channel of the manifold, which hinders use of this system for plastics with limited thermal... 

In view of the advantages of HR systems with internal heating (described in Chapter 4.2.2), they are also used in stack moulds. Of particular importance here is the potential to reduce the mould height. Figure 9.14 shows a fragment of a stack mould with a long sprue bushing, internally-heated manifold and two-way torpedo. A characteristic feature of this system is that the manifold is the mould plate. 

Figure 9.14 Example of use of an HR system with internal heating in a stack mould 1 - sprue bushing 2, 3 - cartridge heaters 4 - manifold 5 - two-way torpedo Reproduced with permission from D-M-E Belgium)...

A system with external heating enables the channels to be purged relatively quickly. A system with internal heating does not allow the channels to be purged completely, and in some cases it is necessary to take the manifold apart and clean the channels, torpedoes and insulation chambers manually. Some systems are designed in such a way as to allow the channels to be opened up (see Figure 4.91) sometimes this can even be done on the machine without removing the mould. 

The difficulties with color change restrict the field of application of internally heated systems. The following combination can be found more often Externally heated manifold and internal heating in the nozzle area, equivalent to the design of the gate elements as a torpedo or as a thermal conductive tip. 

Biodiesel may be represented chemically as a mixture of fatty acid methyl esters. It is a naturally derived liquid fuel, produced from renewable somces which, in compliance with appropriate prescriptions, may be used in place of diesel fuel for both internal combustion engines and for producing heat in boilers. The advantages, especially environmental, which can potentially result from the widespread use of biodiesel, are manifold ... 

The sample of desorbed tritide is placed inside a quartz tube that is connected to a gas-handling manifold by a TorrSeal . A quartz sleeve with Silicon Carbide (SiC) in the annular space is placed around the end of the quartz tube, surrounding the sample with microwave susceptor. The quartz tube and susceptor sleeve are thermally insulated from the rest of the microwave cavity. An internal thermocouple measures the temperature of the sample and provides the temperature signal for process control of the desired temperature. A shine block (alumina foam), attached to the thermocouple, blocks radiant heating of the TorrSeal and the upper area of the quartz tube and manifold. An IR pyrometer is used as a secondary measure of the temperature of the susceptor, and therefore of the sample. A stainless steel shield reflects microwaves from the quartz tube not in the susceptor sleeve, eliminating the production of a plasma at low pressure in the quartz tube. 

Injection The injection blow moulding machine is based on an extruder barrel and screw assembly which melts the polymer. The molten polymer is fed into a manifold where it is injected through nozzles into a hollow, heated preform mould. The preform mould forms the external shape and is clamped around a mandrel (the core rod) which forms the internal shape of the preform. The preform consists of a fully formed bottle/jar neck with a thick tube of polymer attached, which will form the body. 

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