It is common that new, added technology requires staffing changes. Local two-year technical schools can be a good source of these types of people. In our current job market, some good people are “on the bench,”
so now is a time to hire. The other key issue is how to keep current manual labor productive when knowing their jobs will be eliminated? Best situation is when you’re adding automation to expand your business and
absorb those staff into new roles. This eliminates the threat of job loss weighing on current staff.

Frankly, it’s more difficult if you are intending to reduce staff as the objective. No easy answers, but probably keep the changes under wraps as long as possible and perhaps plan a “soft landing” of some sort such as outplacement or small severance. That might ensure that you’ll get their cooperation until the changes are complete.