It is crucial to make high-quality products with a low budget within a short period to survive in the competitive market. Beginners have to face many problems because of the quality of the poor product.
We can call a gating system a basic design. It’s essential to build a smooth and proper filling of the mould cavity of the casting. There should not be any discontinuity or solid inclusions. Properly made gating system and riser confirmed the uniform and finished filling of clean molten metal.
Risering system design
The efficiency or yield of casting is defined as the weight of the casting divided by the weight of the total amount of metal poured. Risers can add a lot to run weight, so optimizing their size and shape is crucial.
Because risers exist only to ensure the integrity of the casting, they are removed after the part has cooled, and their metal is remelted to be used again. As a result, riser size, number, and placement should be carefully planned to reduce waste while filling all the shrinkage in the casting.
- Riser placement: the spacing of risers in the gating system should be considered by accurately calculating the feeding distance of the risers.
- Riser shape: The recommended riser shapes are cylindrical. Though it’s usually used most of the time, the casting procedure is complicated with it. To develop the volume/surface area ratio, the lower surface of the riser can be shaped like a hemisphere. The essential thing is the riser solidification time should be longer than the casting solidification time.
Types of Riser
In the investment casting gating system design, we can categorize this according to the three facts.
- Where it is situated
- Whether it is open to the air
- How it is filled.
If the riser is situated on the casting, it is known as a top riser. But if it is located next to the casting, it is known as a side riser. Top risers are advantageous because they take up less space in the flask than a side riser, plus they have a shorter feeding distance.
When the riser is open to the atmosphere, it is known as an open riser. But if the riser fully has in the mould, it is known as a blind riser. An open riser is usually more significant than a blind because the open riser loses more heat to mould through the top of the riser.
Lastly, if the riser gets material from the gating system and is complete before the mould cavity, we can call it a live riser or hot riser. If the riser fills with material that has already flowed through the mould cavity, we can call it a dead or cold riser. Live risers usually are smaller than dead risers.