Abstract: A hot runner nozzle structure provides insulation to reduce heat transfer to a utilizing tool and to increase accuracy of temperature measurement and control. A shaft foot of extremely low heat conductivity is used to separate a point of contact between a feed tube shaft and the tool. The shaft foot may be formed of titanium for example. An insulating cap of extremely low heat conductivity is surrounds the shaft foot in the vicinity of the nozzle tip. The cap may be formed of PEEK or of titanium for example. Gaps may be provided between the insulating cap and shaft foot and between the shaft foot and feed tube shaft. In an alternate embodiment having smaller dimensions, an insulating ring is provided at the end of the feed tube shaft. The structure, combined with a positioning sleeve surrounding the feed tube shaft, permits placing a heat sensor much closer to the nozzle tip in order to obtain more accurate temperature measurements.

Abstract: A hot runner (10) with an externally heated material pipe (16) and die tip (26) comprises a pre-mounted heating unit (20) with a sealing body (24) which supports a pipe (40) for a heat sensor (34) in a circumferential segment (46). The sealing body (24) made in particular of brass encloses concentrically an insulated heating coil (23) in a steel pipe (22) which is mechanically protected by a partly sleeve-shaped retaining element (42). For example the sensor pipe (40) is supported in the sealing body (24) and is positively and/or adhesively retained between the edges of peripheral ends of a perforated sheet (42). The steel pipe 22) has a lateral recess (44) for inserting the connection points (36) of the heat sensor (34). The material pipe (16) is insertable into the heating device (20) and is able to conduct heat with the close positioning of its shaft (17) against the inner wall (25).