Reinhold Würth, head of the Würth Group tech company which began as a screw manufacturer and specialises in all fixing technology sent a seven-page to his workers this week.
"Are you at your first customer at 7:30?" Würth asked his sales reps, pointing out that the in-house employees at headquarters were at work from 7:30am to 5:15pm every day.
"The early bird catches the worm," Würth preached to his workers in the letter, quoted in the Stuttgarter Zeitung newspaper.
The company achieved 3.3 percent growth in the first half of 2012, well below the rate needed to meet its aim of doubling current turnover to reach €20 billion by 2020.
"I have no intention of getting rid of the external sales service, but I call on you not to try the patience of head office," he wrote.
He also warned that because of the "miserable turnover growth rate," the company "might have to part company with the sales reps that only earn their own costs."
The 77-year-old Würth added that his 63 years' experience had taught him that a large proportion of sales reps only use 60 or 70 percent of their work time.
The German Metalworkers' Union IG Metall condemned Würth's letter. "One only hears this harsh tone from the Würth company," said union commissioner Heide Scharf. She said that the union had long had its eye on Würth Group, whose wages are not regulated by a tariff contract and whose staff are not represented in a workers' council.
Würth took over his father's wholesale screw company aged 19, and built the group up to its current size of 66,000 employees worldwide.