After obtaining the 1.96 Nm servo, we were able to test it on the proof of concept design and compare the performance to the DC motor.
It became clear very quickly that the servo was too slow. While the servo was able to visually squeeze the bag approximately the same amount, the slow speed would certainly result in insufficient air pressure.
After further investigation, it was suspected that the servo was faulty. The advertised speed was higher than the speeds we were observing, and online reviews included videos of it operating at a noticeable faster speed. Therefore, we will be returning this servo and ordering a replacement.
The replacement servo will actually be a slightly improved model than the previous one. With a maximum torque of 25 kg-cm, or 2.45 Nm. This decision was made based on qualitative observation of the DC motor and first servo. Neither motor is able to compress the bag fully, which we suspect may result in insufficient volume delivered. A higher torque motor should improve the performance.
For testing at Conestoga College later this week, we will be using the DC motor. We should then be able to quantitatively determine if a higher torque is indeed required.
