Patent ID: 7205873

Claim:
A magnetiser ( 100 ) for magnetising successive groups, each of at least one portion ( 210 ) of magnetisable material, the magnetiser ( 100 ) being arranged to magnetise the portions ( 210 ) sequentially, one group after another, the magnetiser ( 100 ) including a field generator ( 142 ) operable to generate a magnetic field, flux of which passes through each portion ( 210 ) in the group that is being magnetised, thereby at least partially magnetising each portion ( 210 ), characterised by the magnetiser ( 100 ) including a controller ( 142 ) operable to control the magnetic field such that flux thereof follows a preferred path through each portion ( 210 ) that is being magnetised and through the magnetiser ( 100 ) in a substantially closed loop and whereby uncontrolled flux leakage from each portion ( 210 ) and the magnetising means ( 100 ) is minimized, and wherein the field generator and the controller ( 142 ) include at least one pair of coils ( 142 ) in side-by-side juxtaposition so as to create a series of coils ( 142 ), each coil ( 142 ) being for placing adjacent the surface of a respective one of the portions ( 210 ), the magnetiser ( 100 ) being operable to supply a current to each coil ( 142 ) such that a respective magnetic field is set up therearound that passes through the surface of the respective adjacent portion ( 350 ), thereby at least partially magnetising that portion ( 350 ), the direction of the respective current in each coil ( 142 ) being opposite to the direction of the current in the or each juxtaposed coil ( 142 ) such that flux passes through the or each juxtaposed coil pair in opposite directions and forms a substantially closed path through that coil pair and the respective pair of adjacent portions ( 210 ), wherein said flux passes without the use of an iron core for routing the magnetic flux.