Die casting already used in different industries wildly.Manufacturer are requested to know procedure to fill up cavity and property of melted alloy,which is aim to improve fluidity of melted alloy and get better filling of cavity and meet requirement of surface finishing and mechanical property.
During filling of cavity,melted alloy flow along wall of cavity and change speed and direction when hit onto core,which will disturb flow of melted alloy and get air trapped in it.These affect speed of filling of cavity to some extent.On the other side,as temperature of melted alloy become lower,they are tend to stick onto wall of cavity ,which lower capacity of filling of cavity.Proper injection system can avoid these problem mentioned.
A380 is most common aluminum die casting alloy.By study on relationship between tensile strength and filling speed,the best filling speed is 50-60m/s.Although the shape and wall thickness are different from each die castings,the above filling speed is acceptable widely.
Following factors have negative influence on filling of cavity.
- Temperature of melted alloy need to be similar to mould.
- Pre-heating for mould.The filling of cavity is not good without pre-heating of mould.
- The melted alloy tend to stick onto cavity during filling of cavity.
Near shaped of castings mostly depend on good filling of cavity.Different runners design will get different casting result.Some castings can be suitable for different kind of runners layout.It is not requested for small die castings to make proper runners design while big die casting parts need it in order to have good filling of cavity.
From geometry of cavity,we can differ it into main cavity and not main cavity.For main cavity,melted alloy flow steadily and less energy and temperature lost and can get enough pressure.Therefore,it is better to have 70% of dimension of castings as main cavity,which improve filling of cavity.In most situation,the quality of castings is guaranteed if location of main cavity and runners are correct.Location of runners is more important than size of runners.It is difficult to change location of runners than size of runners.
For filling of cavity,we need consider about percentage of main cavity,location of runners and die casting setting.