AlTech aluminum titanate riser and stalk tubes, sprue bushings and fill tubes, each tested for leaks.
Every casting cycle fills and empties the riser tube.
The tube has to stay tight, clean and in one piece.
For low pressure die casting of aluminum, Blasch recommends riser tubes of AlTech aluminum titanate: the material is not wetted by aluminum alloys, is gas tight, has a very low thermal expansion and takes the thermal shock of every cycle. In Blasch's applications, these tubes last considerably longer than cast iron, calcium silicate or fused silica tubes, and they avoid the freeze-offs common in iron tubes. Where a different property matters more, the same tubes are made in silicon carbide or fused silica.
In low pressure die casting, the holding furnace sits below the die and is closed and pressurized with gas. The pressure pushes molten aluminum up through the riser tube, also called a stalk tube, into the die cavity.
The casting solidifies under pressure. When the pressure is released, the metal still in the tube falls back into the furnace, and the next cycle begins.
That cycle defines what the tube must do. It is half immersed in the melt and half above it, it is filled and emptied with every casting, and it is the only path between a pressurized furnace and the die.
Riser tubes are replaced because of three things: attack by the melt, leaks and cracks.
A riser tube is filled and emptied with every casting, so it lasts as long as it resists the swing between melt and air, not as long as it resists the melt alone.
| Material | Why you would choose it |
|---|---|
| AlTech aluminum titanate | Non-wetting, gas tight, very low thermal expansion, thermal shock resistance |
| Silicon carbide (Blasch XD) | Higher thermal conductivity where the tube is heated |
| Fused silica | Low thermal expansion at lower cost |
Every riser and stalk tube is 100% leak-down tested. Tubes can be supplied with gaskets and ceramic foam filters as complete assemblies, ready to install.
The same aluminum titanate is used for sprue bushings, fill tubes, breaking spouts, thimbles and dosing tubes. Custom tubes are made to your furnace and die dimensions.
Riser tubes belong to the degassing and die casting group.
Rods and pins that control flow in dosing and bottom pour systems.
Non-wetting tubes that keep the holding furnace at temperature from inside the melt.
Protection tubes for the temperature reading in the holding furnace.
Both names describe the same part: the tube that carries molten metal from the pressurized holding furnace up into the die.
The furnace is pressurized to push the metal up. A tube that lets gas through loses pressure and can bring gas into the metal.
Yes. Every riser and stalk tube is leak-down tested, 100% of production.
Yes. Tubes are available with gaskets and ceramic foam filters as complete assemblies.
Send the tube dimensions, the alloy and how long your current tubes last. A Blasch engineer proposes the material and the assembly.
