A system that leads molten metal to flow through a ladle to mold cavity consisting of pouring basin, Sprue, Sprue base, runner, runner extension, in-gates, riser called as gating system.
The design consideration of gates are given below:
1) The mold cavity should be completely filled within a smaller time without having to rise the metal temperature as huge higher metal head.
2) The molten metal should flow smoothly into the mold without any turbulence.
3) Unwanted materials such as slag and other mold materials should not be allow to enter the mold cavity.
4) The metal velocity should be controllable so as to avoid any aspiration of air ,erosion of mold cavity.
5) Should promote directional solidification.
6) Casting yield should be maximized.
The different elements of gating system are discussed below:
1) Pouring basin/cup
2) Sprue
3) Sprue base
4) Runner
5) Runner extension
6)In gates
POURING BASIN/CUP:: It is the first step where the molten metal is poured and act like reservoir from which it moves smoothly into the Sprue. The molten metal is not directly poured in Sprue because it may erode the wall of sprue and it also does not allow to enter the slag into mold cavity. The pouring basin should be full otherwise atmospheric air and slag may enter the mold cavity. The main function of a pouring basin is to reduce the momentum of the liquid flowing into the mold cavity.
SPRUE:: Sprue is the channel through which the molten metal is brought into the parting plane where it enters the runners and gates to ultimately reach the mould cavity. The molten metal when moving from top of the cope to the paring plane gains velocity and as a consequences requires a smaller area of cross section for the same amount of metal to flow at the top. To eliminate this problem of air aspiration, the sprue is tapered to gradually reduce the cross section as it moves away from top of the cope.
SPRUE BASE WELL:: This is the reservoir for the metal at the bottom of the sprue to reduce the momentum of the molten metal. The molten metals it moves down the sprue gains in velocity, some of which is lost in the sprue base well by which the mold erosion is reduced
RUNNER:: It is generally located in the horizontal plane , which connects the sprue to its in-gates , thus allowing the metal enter the moud cavity.The runners are normally made trapezoidal in cross section. It is a general practice for ferrous metals to cut the runners in the cope and the in-gates in the drag. The main reason for this is to trap the slag and dross,which are lighter and thus trapped in the upper portion of the runners.
RUNNER EXTENSION:: The runner is extended a little further after it encounters the in-gate. The extension is provided to trap the slag in the molten metal. The metal initially comes along with the slag floating at the top of the ladle and flows straight, going beyond the in-gate and then is trapped in the runner extension.
GATES:: These are the opening through which the molten metal enters the mold cavity. The shape and the cross section of the in-gate should be such that it can readily be broken off after casting solidification and also that it allows the metal to enter quietly into the mold cavity.
The design consideration of gates are given below:
1) The mold cavity should be completely filled within a smaller time without having to rise the metal temperature as huge higher metal head.
2) The molten metal should flow smoothly into the mold without any turbulence.
3) Unwanted materials such as slag and other mold materials should not be allow to enter the mold cavity.
4) The metal velocity should be controllable so as to avoid any aspiration of air ,erosion of mold cavity.
5) Should promote directional solidification.
6) Casting yield should be maximized.
The different elements of gating system are discussed below:
1) Pouring basin/cup
2) Sprue
3) Sprue base
4) Runner
5) Runner extension
6)In gates
POURING BASIN/CUP:: It is the first step where the molten metal is poured and act like reservoir from which it moves smoothly into the Sprue. The molten metal is not directly poured in Sprue because it may erode the wall of sprue and it also does not allow to enter the slag into mold cavity. The pouring basin should be full otherwise atmospheric air and slag may enter the mold cavity. The main function of a pouring basin is to reduce the momentum of the liquid flowing into the mold cavity.
SPRUE:: Sprue is the channel through which the molten metal is brought into the parting plane where it enters the runners and gates to ultimately reach the mould cavity. The molten metal when moving from top of the cope to the paring plane gains velocity and as a consequences requires a smaller area of cross section for the same amount of metal to flow at the top. To eliminate this problem of air aspiration, the sprue is tapered to gradually reduce the cross section as it moves away from top of the cope.
SPRUE BASE WELL:: This is the reservoir for the metal at the bottom of the sprue to reduce the momentum of the molten metal. The molten metals it moves down the sprue gains in velocity, some of which is lost in the sprue base well by which the mold erosion is reduced
RUNNER:: It is generally located in the horizontal plane , which connects the sprue to its in-gates , thus allowing the metal enter the moud cavity.The runners are normally made trapezoidal in cross section. It is a general practice for ferrous metals to cut the runners in the cope and the in-gates in the drag. The main reason for this is to trap the slag and dross,which are lighter and thus trapped in the upper portion of the runners.
RUNNER EXTENSION:: The runner is extended a little further after it encounters the in-gate. The extension is provided to trap the slag in the molten metal. The metal initially comes along with the slag floating at the top of the ladle and flows straight, going beyond the in-gate and then is trapped in the runner extension.
GATES:: These are the opening through which the molten metal enters the mold cavity. The shape and the cross section of the in-gate should be such that it can readily be broken off after casting solidification and also that it allows the metal to enter quietly into the mold cavity.
No comments:
Post a Comment