Low Pressure - Sand Casting-Process and MPS (Multi Pouring System)

The centre of our innovations is the low pressure-sand casting-process. This process enables the easy, fast and economical production of for example thin walled castings of a high quality on our tight flask moulding plants. Furthermore, complicated castings such as cylinder heads, crankcases or structural parts for vehicles can be manufactured without any complications. In principle every requested alloy is mouldable. This technology also offers a meaningful alternative to the gravity die casting / permanent mold casting and pressure die casting / die casting.
With the classical kind of mould filling, the gravity-casting-process, it is difficult to avoid turbulences during pouring (picture: 4-cylinder-motor unit in gravity sand casting). Because of that gases from the atmosphere are carried away. The formation of oxides, micro- porosities and the hydrogen pick-up in the melt are found again in the casting and are a undesirable consequence. A further disadvantage is that the feeder is paradoxically filled with the coldest metal and a large need of return scrap will be required.

For the optimum mould filling now the known low pressure casting-technology combined with one of the closing method of the sprue channel patented by HWS can be used at our high duty moulding plants.     
At this pouring method (picture: low pressure casting-crucible furnace) a feed tube dips into the clean melt in the pressure sealed, closed furnace. When the furnace is pressurized, the molten metal rises through the feed tube into the mould. The filling process is extremely quiet and is precisely checkable and reproducible by the pressure control. However, a disadvantage is that after every filling operation waiting periods of up to 15 minutes can arise until the melt in the sprue channel is solidified.

Therefore HWS developed a solution for the fast and easy closing of the sprue channel. For this an opening is drilled through the back of the mould up to just before the sprue (picture 49, sprue channel locking cylinder). Immediately after the filling process, the cylinder locks the sprue channel safely and quickly by means of the remaining moulding material or a sand stopper respectively. An usual ceramic filter prevents that possibly crumbling sand falls into the furnace during closing.

The success with this method of mould filling, however, is not completely satisfactory because the coldest metal still reaches the feeder (picture 44, motor unit with feeder arrangement above). The pattern was arranged such that the feeder is placed directly above the sprue. (picture: motor unit with feeder arrangement below). During the filling process the flowing metal heats up the feeder area and then this area is filled with hot melt. After the pouring process the mould rotates by 180° in the roll over, so that the feeder is placed above.

To test this system a testing device (picture: low pressure-test pouring station) consisting of an electric resistance low-pressure crucible type furnace with feed tube, a lowering device for moulding boxes and a sprue channel-locking cylinder was installed at HWS.

Therefore, the optimum feeding effect by rolling over of the mould could be shown for example by a 4-cylinder aluminium motor unit with a weight of 40 kg (picture: 4-cylinder aluminium-motor unit with various feeder arrangement). On the left the picture shows the feeding with pouring from below without rolling over and on the right it shows pouring from below through the feeder with rolling over.

MPS - Multi Pouring System

Heinrich Wagner Sinto developed this trend-setting pouring technology up to putting it into practice and by that offers the foundryman completely new possibilities - which were unthinkable in gravity casting - regarding the production of high quality castings.
This method can be integrated easily and reliably in our worldwide proved SEIATSU moulding plants and can be delivered completely as so-called MPS Moulding Plant including low pressure-furnace plant. With the MPS moulding plant pouring can be executed by means of low pressure-pouring plant and/or conventional by gravity respectively.

The advantages of this technology can be summarized as follows:

- exactly programmable filling process

- precise filling pressure control

- saving of return scrap

- pouring with less circulation is possible

- mould filling can be repeated and documented exactly
- completely closed pouring process
- rising, gentle, laminar mould filling
- very practical oriented simulation of the pouring process is possible
- minimization of iron spillage and slag formation
- no penetration caused by height of pouring
- optimization of the feeding
- prevention of iron spillage
- reduction of plant failures and increase of availability
- clear improvement of the workplace conditions
- no loss of temperature during pouring
- lower pouring temperature is possible
- thinner walls are pourable