Today I will be discussing the definition, applications, advantages, and disadvantages of evaporative pattern casting. previously, an article was published on investment casting. make sure you check it out!
Read more: Understanding investment casting
What is evaporative pattern casting?
Evaporative pattern casting is a sand casting process that uses foam to form a replica of an item in order to evaporate in a sand mold in replacement of molten metal. This casting process is also known as consumable or Eva-foam casting. it is similar to investment casting.
Read more: Working principles of investment casting
Evaporative pattern casting is of two forms; lost-foam and full mold casting. They are widely applicable due to complex designs that can be produced with relative ease. Their difference is that in lost-foam casting, sand is bounded. whilst, in full mold casting the sand is bonded (greensand). As of 2010, the evaporative casting process is predicted to be used for 29% of aluminum and 14% of ferrous casting.
Evaporative pattern casting is widely used for aluminum casting. It is also used for steel casting, and for iron parts like a water pipe and pump parts.
Working principle of evaporative casting
The working of evaporative pattern casting is achieved by producing a foam patter, which is the replica of an item to be cast. This pattern is brushed with refractory substances in order to add extra life to the pattern when molten metal is poured or to make it resistant to high temperatures. The pattern is then attached with sprues and gates using adhesives. It is placed into a mold surrounded and packed by sand. Another way of doing this is by dipping the pattern into a ceramic slurry, just as investment casting. it forms a shell around it when it dries
Read more: Understanding centrifugal casting
The mold is kept at a specific temperature in order to allow the liquid metal to easily flow and reach all parts and cuts of the pattern. After this, molten metal is poured into the mold and the pattern-foaming material vanishes out of the mold as molten metal reaches it. As the pattern vanishes, the molten metal takes its shape and solidifies. After it solidified, the casting is removed from the mold.
Watch the video below to learn more on the working of evaporative casting:
Read more: Understanding die casting
The difference between evaporative casting and sand casting methods is that in evaporative casting the pattern is not removed from the mold. This helps to reduce the need for draft provision. The evaporative casting method is determined by the grain fineness number, time of vibration, degree of vacuum, and pouring temperature on surface roughness, etc.
- Ability to cast lightweight parts
- It is easy to perform when compared with other casting processes
- It offers high dimensional accuracy
- Intricate and complicated shapes can cast without using cores or drafts
- It offers a high surface finish (smoothness) to the casting
Read more: Understanding sand casting process
That is all for this article, where the definition, applications, advantages, and working of Evaporative pattern casting is being discussed. The difference between evaporative and sand casting is also explained. I hope you got a lot from the reading, if so, kindly share with other students. Thanks for reading, see you next time!