A lined bearing is made by tinning at least the radially inner surface of a bearing ring, providing an atmosphere of water vapour adjacent the tinned surface to which a flux is also supplied, and centrifugally casting on the lining material. Tinning can be achieved by applying a slurry of tin powder in a flux solution, e.g. an aqueous zinc chloride solution, followed by heating at least to a tinning temperature. Further flux solution can be sprayed onto the hot tinned surface in the centrifugal casting machine to form the desired atmosphere and to disperse the flux as fine particles. Quenching by spraying on cold water preferably commences immediately after casting of the white metal or other lining material begins.
A method of making a lined bearing which comprises the steps of
applying a layer of a metallic bonding material to at least the radially inner surface of a bearing ring,
heating the thus-treated bearing ring to a temperature at least as high as the melting point of the bonding material, said temperature being sufficient to cause vaporization of water to steam,
thereafter projecting water and flux, the flux being in the form of a solution, onto the hot radially inner surface of the bearing ring, thereby to cause sudden formation of steam, to cause a fine distribution of the flux, and to establish reducing conditions over the applied layer of bonding material, so that any metal oxides formed during application of said bonding material are reduced, and
then centrifugally casting a layer of lining material over said layer of bonding material, said centrifugal casting step being carried out in the presence of the flux and while said reducing conditions are maintained.
A method according to claim 2 in which the bearing ring is heated to a temperature of from about 280° to about 300° C prior to casting on the layer of lining material.
A method according to claim 2, in which application of the layer of bonding material and casting on of the lining material are effected in the same centrifugal casting machine.
A method according to claim 2, including the step of spraying water on the radially external surface of the ring immediately after commencing the casting of lining material in order to quench the ring.
A method according to claim 2, in which the flux is a halogen-containing flux.
A method according to claim 6, in which the flux is a chlorine-containing flux.
A method according to claim 6, in which the flux is selected from zinc chloride, stannous chloride, stannic chloride lead chloride, antimony trichloride, antimony oxychlorides, ammonium chloride and mixtures of two or more thereof.