An apparatus for preparing a charge of metal or metal alloy in semi-liquid condition for use in a forming device, including: - a crucible arranged to receive the charge in a molten condition from a source; - at least one solenoid induction coil positioned to encircle the crucible; and - a controller arranged to at least partially control a power supply to the at least one solenoid induction coil to generate a magnetic field to heat and stir the charge in the crucible; characterised in that - a sensing arrangement is provided for directly or indirectly sensing at least one electrical signal, wherein either (i) the at least one electrical signal is an electrical signal of the solenoid induction coil, or (ii) the sensing arrangement comprises a second coil in close proximity to the charge, the second coil being unpowered or independently powered, and the at least one electrical signal is an electrical signal of the second coil; and the controller is arranged, based on the sensed at least one electrical signal, to at least partially control the power supply to the solenoid induction coil to at least partially control cooling of the charge from a liquidus temperature to a temperature above a solidus temperature at which the charge is in said semi- liquid condition; wherein EITHER the solenoid induction coil is cooled internally by a coolant flowing through the solenoid induction coil, and the solenoid induction coil is encased within a coupling material, the coupling material being arranged to thermally couple the solenoid induction coil with the crucible, and the coolant flowing through the solenoid induction coil is arranged to cool the crucible and the charge through thermal coupling of the solenoid induction coil, the coupling material, and the crucible; OR a separate cooling coil is arranged to carry a flow of coolant, and the controller is arranged to adjust the flow of coolant in the separate cooling coil to cool the charge in the crucible; and wherein the controller is arranged to a) monitor resistivity of the charge, b) adjust solenoid induction coil power and frequency, and c) adjust the flow of coolant through the solenoid induction coil or the separate cooling coil, to cool the charge until a selected temperature and viscosity of the charge are reached as indicated by the resistivity of the charge. - a crucible arranged to receive the charge in a molten condition from a source; - at least one solenoid induction coil positioned to encircle the crucible; and - a controller arranged to at least partially control a power supply to the at least one solenoid induction coil to generate a magnetic field to heat and stir the charge in the crucible; - a sensing arrangement is provided for directly or indirectly sensing at least one electrical signal, wherein either (i) the at least one electrical signal is an electrical signal of the solenoid induction coil, or (ii) the sensing arrangement comprises a second coil in close proximity to the charge, the second coil being unpowered or independently powered, and the at least one electrical signal is an electrical signal of the second coil; and the controller is arranged, based on the sensed at least one electrical signal, to at least partially control the power supply to the solenoid induction coil to at least partially control cooling of the charge from a liquidus temperature to a temperature above a solidus temperature at which the charge is in said semi- liquid condition; (i) the at least one electrical signal is an electrical signal of the solenoid induction coil, or (ii) the sensing arrangement comprises a second coil in close proximity to the charge, the second coil being unpowered or independently powered, and the at least one electrical signal is an electrical signal of the second coil; and the controller is arranged, based on the sensed at least one electrical signal, to at least partially control the power supply to the solenoid induction coil to at least partially control cooling of the charge from a liquidus temperature to a temperature above a solidus temperature at which the charge is in said semi- liquid condition; the solenoid induction coil is cooled internally by a coolant flowing through the solenoid induction coil, and the solenoid induction coil is encased within a coupling material, the coupling material being arranged to thermally couple the solenoid induction coil with the crucible, and the coolant flowing through the solenoid induction coil is arranged to cool the crucible and the charge through thermal coupling of the solenoid induction coil, the coupling material, and the crucible; OR and the solenoid induction coil is encased within a coupling material, the coupling material being arranged to thermally couple the solenoid induction coil with the crucible, and the coolant flowing through the solenoid induction coil is arranged to cool the crucible and the charge through thermal coupling of the solenoid induction coil, the coupling material, and the crucible; OR a separate cooling coil is arranged to carry a flow of coolant, and the controller is arranged to adjust the flow of coolant in the separate cooling coil to cool the charge in the crucible; and a) monitor resistivity of the charge, b) adjust solenoid induction coil power and frequency, and c) adjust the flow of coolant through the solenoid induction coil or the separate cooling coil, to cool the charge until a selected temperature and viscosity of the charge are reached as indicated by the resistivity of the charge.