We know what the most important force for retention is: your boss. Your direct boss has the greatest impact on both productivity and morale
On the shop floor, that direct boss is usually the foreman. So the best thing you can do to retain good shop-floor employees is to make sure they have a good boss.
Start by promoting people who have the ability and desire to do the job. People who will make good bosses in manufacturing situation should like helping people succeed, be willing to make decisions and be willing to confront people about their behavior and performance. They should also know enough about the work to supervise it and to be credible.
Once you've promoted a supervisor, make sure he or she gets some training in the supervision part of the job. American companies currently spend less than 10 percent of their training budget on first-line supervisors. Many newly promoted supervisors get no training at all.
Help your supervisors grow and develop in their leadership roles. Supervision is an apprentice trade, so the strategy is to help folks learn and develop. Peer-based discussion groups like the one I dramatize in Performance Talk are excellent. Mentors help a lot.
Whatever your supervisors do there should be regular feedback. This can be from peers or mentors. The supervisor him or herself should always self-critique significant behavior.
It's pretty simple. If you want to keep good people, give them good bosses. People on the shop floor may join a company, but if they quit it's usually because of their boss.