The melt supply method

The melt supply method, i.e., locating the gate on the front or side surface of the moulded piece, governs whether an in-line or angle nozzle is used. As with CR systems, this choice depends on, among other things  

In-line nozzles may also be led at a certain angle to an inclined piece wall. Angle nozzles are generally run to a side wall. 

The number of injection points in a nozzle depends on, among other things  

Type of nozzle body. The body is a mechanical and thermal screen, and its type depends primarily on the plastic structure. In the case of amorphous plastics, which feature slow freezing, intensive heat removal is needed, and thus the use of what are called cold gates. In the case of semi-crystalline plastics (apart from PE and PP), which feature fast freezing (crystallisation), gradual heat removal is needed, and so the use of hot gates (see Chapter 4.1.1 and Table 3.2). In the case of PE and PP, moderate heat removal is needed, with the use of elevated temperature gates. 

When selecting a nozzle for a specific plastic and production type, the manufacturer s recommendations must always be checked, since the specifics of the nozzle design may give rise to a shift away from the stated selection principle or increase the universality of the nozzle. Further, the process parameters, and particularly a long cycle time, may cause restrictions to use of the nozzle or the need to modify it. Depending on the size of the range, suppliers offer universal nozzles or nozzles tailored for strictly defined applications. 

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