The Alnico magnet(mainly composed of aluminum, nickel and cobalt) is manufactured through either the casting or the sintering process.
Compared to modern materials alnico has a lower coercivity.
The main advantage of alnico is the very low temperature coefficient and the wide temperature range from -250°C to over + 500 °C for practical use.
Alnico is very hard and brittle. Machining or drilling cannot therefore be accomplished by ordinary methods.
Holes are usually cored in at the foundry.
Magnets are cast or sintered as closely as possible to required sizes,
so that abrasive grinding to finish dimensions and tolerances is minimized.