Aside from that ascendancy in the tight, the Tongans proved a tough nut to crack as a slippery ball pretty much put paid to the Saxons ambitions to move the ball around.
As a result, the Gloucester duo of Henry Trinder and Charlie Sharples didn't receive much attacking ball to work with but looked dangerous when they did finally get some decent ball although the try line remained elusive.
Tonga did hit back with a couple of close range tries from their pack in the second half but it was a comfortable enough win for the Saxons and they will look forward to taking on Canada in the final at Worcester next weekend.
Stuart Lancaster's side started brightly and charged down a couple of Tonga clearance kicks in the opening 90 seconds but couldn't benefit.
The first score was a penalty try on 12 minutes as the Tongan pack buckled under pressure near their own line and Jordan Crane added the second on 16 minutes as he powered over from close range.
A frustrating period of play followed as the Saxons couldn't quite string enough possession and phases together to get an iron grip on the game although one gliding break from Trinder almost opened up the Tongans.
A second penalty try followed and Rory Clegg added a first half injury time penalty to earn the Saxons a comfortable enough 27-0 half time lead.
Tonga hit back in the second period as Sione Timani drove over from a metre out following a spell of pressure but a yellow card for replacement prop Ofa Fainga'Anuku led to a third penalty try as the Saxons continued to dominate the scrum.
The pick of the tries came on 72 minutes as a Mike Brown break was taken on by Jordan Crane who produced a neat grubber kick through for Billy Twelvetrees to touch down although the Leicester centre was yellow carded shortly afterwards and Tonga had the last word with a try for flanker Pepa Kolomatangi.
