ТОР 5 статей:
Place the plan items in correct order according to Text A.
a) Types of sand mold.
b) Application of green-sand mold.
c) Properties and advantages of green-sand mold.
d) The process of producing damp molds.
e) The time of pouring damp molds.
Retell Text A according to the plan in a previous exercise.
Read Text B and translate it.
When the entire mold is dried, it is known as a «dry-sand mold». It is formed by mixing sand, bonding material and water. These molds have a hard surface and produce little gas or steam during casting.
They are stronger than green-sand molds. Dry-sand molds allow the use of finer sands with lower permeability, since nearly all of the moisture is removed. This produces smoother surfaces on the castings.
Dry-sand molds are usually made up one day, dried overnight, and assembled and cast the next day.
The drying is usually done in large ovens at temperatures about 450 degrees of Fahrenheit. Drying can also be done on the foundry floor using heated air or torch.
Dry-sand molds require the use of metal flasks because heat is used to dry them.
Dry-sand molds are recommended for steel castings and may be also used for many types of non-ferrous castings.
Since dried molds are more expensive than green-sand molds, they are used only when green-sand molds would be unsatisfactory.
entire – весь; вся
moisture – влага
overnight – ночью
oven – печь
torch – горелка; пламя; факел
on the foundry floor – на плацу (полу)
would be unsatisfactory – не удовлетворяют требованиям.
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