Step 1: Understand what an expendable pattern means.
An expendable, or expandable, pattern is one that gets destroyed once during the mould making process, unlike a reusable metal pattern that can be pulled out intact and used again for the next mould.
Step 2: Screen the given processes.
Shell moulding relies on a durable metal pattern that survives each cycle, so its pattern is reusable. Squeeze casting and centrifugal casting both use permanent metal dies or moulds rather than a separate pattern at all, so neither fits the description.
Step 3: Match investment casting to the description.
Investment casting, also called the lost wax process, starts with a wax (or sometimes polystyrene) pattern that is coated with a ceramic shell, and once the shell hardens, the wax is melted and drained out, destroying the pattern completely to leave behind the mould cavity. Because a fresh pattern must be made for every single casting, this is the classic example of an expendable pattern process.
\[ \boxed{\text{Investment casting}} \]