North American workforces are changing fast. Older workers are retiring en masse, leaving gaps that younger workers may be unready to fill.

We don’t yet have enough data know how wide the chasm is now or could become, but the early statistics are startling. At the University of Michigan, 39% of faculty and 35% of staff will be eligible to retire within five years. More broadly, a GE study found that 22% of the workforce is now over 55.

Problems exist at the other end of the spectrum, as well. An overabundance of young PhD candidates in the biological sciences has led to a number of aspiring scientists struggling to find work. Then there is the manufacturing sector, where the unemployment rate in the U.S. has been falling steadily since February -- from 8.4% to 7.1% as of May -- but which also faces the prospect of losing a large number of pension age workers to retirement.

Experts tend to argue for a renewed emphasis on job training to replace retiring knowledge workers but the manufacturing sector has the same problem. According to a recent study from the National Association of Manufacturers, 80% of U.S. manufacturers say that finding qualified workers for advanced product assembly is a top concern. Roughly 600,000 manufacturing jobs remain open as a result, Deloitte Consulting found.

And yet replacing lost skills is only part of the issue. A more diverse factory floor presents new challenges for motivating and managing workers of differing age groups. Here are five ideas for how and when to engage them:

  1. Millennials. While there’s no specific birthday range for those who identify as Millennial, otherwise known as “Generation Y,” most accept that this group is typically not far removed from college, still in their twenties or early 30s, and hungering for experience and recognition. These workers are more likely to take to social networks, and as a result, they crave public accolades for a job well done – both in person and via technology networks. Engage early and often.
  2. Gen X. These middle-aged workers were born during the 20 years that stretched from the early 1960s to the early 1980s. They share an affinity for technology with Millennials, some of who may be their children, but that doesn’t mean they crave more recent big ideas such as social media. They’re also used to sharing the burden of making ends meet with a spouse and may prize a balanced lifestyle as a result. Consider using time off and flexible work arrangements as motivators.
  3. Baby Boomers. Traditionally known as those born in the aftermath of World War II, most Boomers are either approaching retirement or already retired. They face the prospect of leaving the workforce at a troubled economic time and with less saved than only a few years ago. Consider one-time bonuses for outstanding achievements in production or leadership. Create incentives for these workers to help train younger peers who will one day have to replace them.
  4. Mature Workers. Those either about to retire or working past the traditional retirement age have varied reasons for doing so. For some, income is a priority. For others, the prospect of not working is simply too scary. Get to know these workers individually and customize your rewards program accordingly. Assume nothing.

In fact, that’s probably good advice for managing workers of every age group. Manufacturing workforces are changing. The old rules for what works when it comes to motivating them -- i.e., a good paycheck, reasonable hours, a standard vacation -- no longer apply.

John Mills is executive vice president of Business Development at Rideau Recognition Solutions, a global leader in employee rewards and recognition programs designed to motivate and increase engagement and productivity across the workforce.