Lead is added to many copper alloys, making all types of free machining alloys. Lead does not affect the structure and properties of copper because it is practically insoluble in solid copper. Lead coppers are categorized as low lead alloys, or free machining alloys and high lead alloys. In the free machining alloys, the lead acts as chip breaker and lubricant making these alloys easier to machine than their non-leaded counter parts. The high lead copper alloys are used in bearing applications.