Gate cooling optimization is important in thermal gate design | Forum

advertisement
Topic location: Forum home » General » General Chat
alisa yan
alisa yan Sep 10
Valve gate hot runner nozzles were unveiled in the injection molding industry soon after the first hot runner systems appeared in the marketplace check here . Until recently, valve gates ended up being chosen primarily for applications where thermal gate vestige is unacceptable.The differences together are vast. First off, yes, the knife gate valve DOES have a sharpened disk (thanks to you). This is supposed to sever any stringent solids which could keep the valve from closing and causing it to leak. But there’s more that creates their designs quite different.

The biggest difference between those two types of valves is the fact gate valves are made to ANSI standards while knife gate valves stick to TAPPI standards. Therefore, dimensionally the gate valve is wider, flanged, and ANSI pressure rated. It also has API leak tightness standards have to be met. They're bi-directional, and widely used in steam applications along with fluid applications. The gate valve is simply available with metal seats.

Another significant difference between an ANSI gate valve plus a knife gate valve is within the packing gland area. A gate valve can have a v-ring packing set that seals the shaft linked to the gate, while a knife gate valve features a packing gland that seals throughout the gate.

A part molded using a thermal gate retains a standing vestige in the gate interface. Thermal gate vestige is especially dependent on the gate diameter. A larger gate will create a larger vestige gate valve . Thermal gate vestige stands 1/3 to 1/2 as being the height in the gate diameter. In addition, thermal gate quality can alter significantly as processing conditions vary.

Gate cooling optimization is very important in thermal gate design. The solidified polymer within the gate acts as a possible insulating barrier between plastic inside the cavity along with the viscous melt inside the hot runner nozzle. Mold open cannot occur till the gate is solid enough to get rid of cleanly in the part and also "hold back" the melt within the hot runner. Insufficient gate cooling requires cool time over that important for part solidification - adding unnecessary seconds to cycle time. Mold open just before complete gate solidification will lead to drool or stringing. Excessive gate cooling can also be problematic; a frozen gate can prevent or delay gate opening. This can lead to short shots or unfilled cavities.
advertisement