The essence of pressure casting （short form die casting）is to fill liquid or semi-liquid metal into the die-casting mold cavity with a high speed and high pressure,through which the high quality die casting components were manufactured.
High pressure and high speed filling are the two characteristics of die casting.it’s frequently-used pressure of injection is from thousands to tens of thousands of KPa.Its filling speed is about 10~50m/s,sometimes even more than 100m/s.the filling time is very short,generally within 0.01~0,2s.compared with other casting methods,die casting has the following three advantages:
1.The product quality is good
The accuracy of die casting part is high,generally equivalent to 6~7 levels,even up to level 4;surface roughness is relatively good,generally equivalent to 5~8 grade;the strength and hardness are higher,the strength is generally increased by 25~30% compared with sand casting,but the elongation is decreased by about 70%;size stability,good interchangeability;thin-walled complex castings can be produced by die casting.
2.Higher production efficiency
Higher machine productivity
Higher life span for the die casting mole,which ban be up to hundreds of thousands of times,or even millions of times
Mechanization and automated production can be easily realized.
3.Economical production solution
With accurate die casting size,clean and smooth surface and other advantages,no additional machining processing will be needed.Or only a little extra machining processing is needed,which can improve the utilization rate of metal and reduce a lot of machining equipment and labour as well, and with lower cost.
1)During die casting process,due to the high velocity of filling cavity with liquid metal and the unstable flow state,some porosity may be arised,so it cannot be heat treated
2)It is difficult to produce parts with complicated internal structure;
3)Low volume production is not suitable,the main reason lies in that the high cost of die casting mold manufacturing,high production efficiency of die casting machine,which makes it not a economical way for small batch production.