It's more complicated than that. The torque ratings on the steppers are "holding torque" measured at standstill. To find out the torque at a given speed you need to consult a chart that should come with the motor specs. It will be lower than the holding torque, usually considerably less as the speed increases. Many servo motors will have peak torque at a certain speed, with less at very slow or very fast speeds. These need a speed reducer to get into the "sweet spot" of best performance. But looking at the torque curve of the particular one you're contemplating https://www.teknic.com/model-info/CPM-SDSK-2311S-RQN/, it seems more like a stepper in that regard, with torque steadily falling off as speed increases. You should be able to couple it directly to your screws, but whether the baseline ("continuous") torque is sufficient depends on the mechanics of your machine.