Manifold cartridge heaters

The DieMate manifold also functioned as the microreactor die heater since it had four driUed-through holes to accommodate %-inch-o.d. cartridge heaters where each provided 15 watt of power (60 W total). The holes are visible adjacent to the O-rings in Fig. 12.3. The temperature of the DieMate manifold was monitored using two 1 /16-inch-o.d. X 1-inch 100 O platinum Resistive Temperature Devices (RTDs). 

Fig. 7-5 shows an arrangement of multiple isothermal nozzles in a mold. The manifold is bolted to the mold backup plate to clamp the bushings in place. In this style of mold, the cartridge heaters in the manifold body are controlled by thermocouples inserted into the manifold. Temperature of the feeder bushings usually is controlled by variable voltage controllers. ... 

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. 

Cartridge heaters in a metal body (available on the market) have a very high heating power, which, in combination with their small dimensions, enables a power density of as much as 40 W/cm to be achieved (for comparison, the power density of a band heater is around 5 W/ cm ). To prolong the life of a heater and to reduce the risk of local overheating in the manifold, it is best not to exceed a value of 20 W/cm. This applies to cases where the user/mould manufacturer selects the heaters himself. The heaters are set in reamed holes symmetrically positioned on both sides of the flow channels (wall thickness minimum 10 mm). 

Figure 4.85 Example of temperature profile for a manifold with cartridge heaters [27]...

Manifolds with cartridge heaters running on 230 V current are usually part of the mould plate (see Figure 4.89) or stand alone as a plate manifold (see Figure 4.90). 

In the classic D-M-E version, the manifold has large-diameter (24-50 mm) drilled flow channels in which cartridge heaters in a tubular body are located. The melt thus flows through an annular channel between 4 and 9 mm wide (see Chapter 1). Because of the heating pipe in the centre of the channel, the channels cannot cross over as in externally-heated manifolds, but must be connected adjacently. Torpedoes must also be connected with a butt joint to the flow channels. This creates certain restrictions as regards the mould cavity arrangement, and it is not easy to achieve a natural flow balance (see Figure 4.91). 

Figure 5.4 Temperature drop in manifold on path between cartridge heater and flow channel [1]...

Figure 5.5 Manifold with clamping strips to fasten cylindrical cartridge heaters [1]...

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

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)...

Fig. 1 Coat hanger-type sheet die concept (A) (1) central inlet port (2) manifold (distributes melt) (3) island (along with manifold, provides uniform pressure drop from inlet to die lip (4) die lip (die exit forms a wide slit) and schematic of sheet die (B) (1) upper die plate (2) lower die plate (3) manifold (4) island (5) choker bar (6) choker bar adjustment bolt (7) flex die lip (8) flex lip adjustment bolt (9) lower lip (10) die bolt (11) heater cartridge.

Injection molds are machined from a variety of tool steels and then hardened or in some cases plated with chromium, nickel, or proprietary materials. Large molds use prehardened tool steels because they cannot be hardened after machining. 124 Stainless steel is employed for some smaller molds, particularly those used for optical and medical parts and for corrosion resistance. Since they provide better heat transfer and, thus, shorter molding cycles, materials such as beryllium copper are used as inserts in critical areas. Injection molds are usually cooled or heated with water, although oil or electric heater cartridges are employed for high-mold temperatures. Mold-temperature controllers pump water into the manifolds and then into cooling fine machine into the molds. 

Injection molds are usually cooled or heated with water, although oil or electric heater cartridges are used for high mold temperatures. Mold temperature controllers pump water into the manifolds and then into cooling Unes machined into the mold. 

The heaters used for external heating of plate manifolds are of the cartridge or tubular resistance type operating on 230 V AC current. Tubular manifolds are heated by 230 V coil heaters or low-voltage 24 V or 5 V, heaters. 

---