The home side scored eight tries in all, with a penalty try at scrum time and tries by Joseph Dweba (hooker) and his replacement, Reinach Venter, from line-out drives testimony of the forward dominance.
The Cheetahs struck early. After some good forward play and pressure, the ball was swung wide and Volmink was put in space by good passes from first Tian Schoeman and then Smith.
Volmink took full advantage of the early opportunity to score his first try in the competition.
He made it two 15 minutes later. The home side attacked from inside their own 25 and Volmink stepped one, stepped two and raced away to score 60 meters down the field.
Ulster had some moments thanks to good possession and struck back soon after Volmink's brace.
A great running line from flanker Matthew Rea helped lock Sam Carter across the try-line.
Smith scored his first soon after, courtesy of a fine, darting run, beating two players. It all started from a quick line-out throw inside their own half and Smith rounded off the movement in a blink.
The Cheetahs got their bonus point try after 30 minutes. Dweba scored after his pack drove well and the hooker got his third of the 2019 competition.
Ruan Pienaar converted all four tries and the home side were cruising at 28-7 at the break.
Early tries in second half seal the win
The second half started even better. Volmink struck two minutes into the second spell when he intercepted 30 meters out, before Smith scored his second, a gem of a try.
Replacement-flanker, Jasper Wiese, ran a great line from a line-out and found Smith on the inside, who confirmed his love affair with the try-line.
It was three unanswered tries in a flash as Louis Fouche scored their sixth try after Junior Pokomela ran hard and over two defenders.
Ulster missed 20 tackles at that stage and the Free Staters were rampant.
The visitors realised that attack was the best defence with a scoreline like that and it worked for a while.
James Hume (centre) and Dave Shanahan (replacement scrumhalf) got tries, before the home side's forwards grabbed the initiative back again.
First Venter scored from a line-out, with a clever switch of direction by Tian Meyer found the hooker unopposed and then the pack pummelled the Ulster eight in a scrum, with a penalty try the only option.
Ulster scored a late, but important try when Craig Gilroy's effort earned them a bonus point on a night they were outplayed in all departments.
Toyota Cheetahs - Tries: Anthony Volmink (3), Rhyno Smith (2), Joseph Dweba, Louis Fouche, Reinach Venter, Penalty try. Conversions: Ruan Pienaar (6), Tian Schoeman (2).
Ulster – Tries: Sam Carter, James Hume, Dave Shanahan, Craig Gilroy. Conversions: John Cooney, Bill Johnston (2).