Dean Shade, 32, of Turpington Lane, Bromley, was sentenced to life. He must serve at least 10 years before he can apply for parole.
James Russell, 24, of Leybourne Close, Crawley in West Sussex, was given an 11-year sentence.
The pair stole more than £415,000 worth of computer equipment in the robberies, between September 2010 and March 2011.
Russell had pleaded guilty and Shade was convicted of 12 counts of conspiracy to rob after a four-week trial at Brighton Crown Court.
They targeted a company in Sayers Common in West Sussex four times, a school and college, and five other businesses in Surrey, West Sussex and Kent.
The pair also robbed a private address in Charlwood in Surrey in January 2011.
In every case the robbers were masked and were armed with a variety of weapons including knives, baseball bats, chainsaws and angle grinders, the court heard.
The pair had threatened to cut victims' fingers off if they did not give Pin numbers to their cash cards, the jury was told.
Det Sgt Dennis Phelan of the South East Regional Organised Crime Unit, said after the trial: "The gang simply relied upon brute force and numbers to threaten and terrorise their victims, many of whom were tied up and marched round their premises before being left alone, restrained in the premises until the alarm was raised."
Two men who threatened to cut off their victims' fingers in robberies across the South East have been imprisoned.