Per Capfriendly:
Exemptions
A player does not need to pass through waivers if the player has not been on the NHL active roster for a cumulative 30 days since last clearing waivers, OR has not played in 10 or more NHL games. CBA Reference 13.2(b) (Despite the CBA reference saying 30 days AND 10 games, the rule is actually 30 days OR 10 games)
A player whom consented to a Conditioning Loan can be Loaned to a minor league club for a maximum of 14 days without passing through waivers. CBA Reference 13.8
A player whom was previously on long-term injured reserve (LTIR), may be loaned to a minor league club for a maximum of 6 days or 3 games for the purpose of determining if the player is fit to play. This player does not need to pass through waivers. CBA Reference 13.9