Companies need to keep knowledge within the organization; especially with the current demographic shift, explicit and tacit knowledge needs to be passed on directly from to new employees.

It’s almost a commonplace to say that once an old man dies, a library closes.
Companies whose managers have “keen” vision, already realized the need to keep all the knowledge inside organization; many of them have specific mentoring programs in place for hosting new employees, where the experienced ones make this know-how passage.
Very often, these seniors are part-time workers or even retired people, allowing them to continue to contribute socially and helping the company convey precious knowledge.
Another way to keep knowledge within the company is to integrate it into the operational process.
In an industrial environment or services area, the internal organization should be designed to make use of all accumulated know-how by the various people throughout their experience and company lives.

An investment in knowledge pays the best interest.
Benjamin Franklin