Charlie Chaplin did not receive an Oscar nomination for portraying a factory worker in Modern Times.
The way Modern Times is set up it can almost be looked upon as an origin for his tramp character since at the beginning of the film he is an employed factory worker. Well it's safe to say much hijinks will ensue, as it does from the first scene where the worker fails to maintain the assembly line as it simply becomes faster and faster. Chaplin's comic approach here is rather simple in that he plays every scene with a certain naivety with the worker. There is an enthusiasm about him in that he seems to want to try his best, but that probably means he's just going to screw up anyways. Chaplin's enthusiasm he brings in the improbable task is particularly enjoyable to watch. Chaplin adds a bit of extra comedy in this case though in that he gives a bit of "realism" in his worker as he has to deal with the line, as well as a torturous feeding machine, since he portrays the life wearing down the working to the point that he breakdown mentally. Of course this is all in good fun and most importantly quite funny.
The worker continues his transition to the tramp really by first endings up in the hospital after losing his job, then immediately finding himself in prison. What Modern Times is technically made up of is the worker failing at one thing from another. Whether it is failing not to get arrested by accidentally being mistaken for a communist organizer, or even failing at prison by thwarting a prison escape due to having mistakenly ingesting some cocaine. To be honest this whole setup seems like something that could become repetitive considering it is basically the same thing over and over again. Well Chaplin as a director and actor keeps it ever feeling as such. Chaplin no matter what brings such energy to every single one of the situation and never does it feel as though he will ever let a setup go half-baked. He's there to sell every bit to its fullest and here is quite good in bringing a certain variation to his reactions to the setups even though the idea behind each is basically the same.
Chaplin here also does rather quietly formulate into the Tramp character in that he bridges the worker of the first scenes who goes through the hardships of mental breakdowns and prisons to eventually become the bum he was always meant to be. Although of course that bum still tries his hand a various jobs always managing to goof them up in one way or another, and usually in ways that are quite humorous to be sure. Again the whole set up, since many of the mistakes made by the Tramp that either get him fired or in jail or both are usually his own fault. This could make the character become annoying but it never does because of how endearing Chaplin really makes the worker who has become the tramp. I suppose it should also be noted that the Tramp does actually speak here, although only in a musical number that is pure gibberish. Like pretty much everything that Chaplin does in the film it is a very entertaining moment, and kinda sums up the Tramp character since you still can't hear what it is that he saying yet you completely understand what he means.
With Chaplin it never is purely about the laughs, even if those are in abundance as they are here, but the comedy is never without a heart. That element is particularly strong in Modern Times well founded through the Tramp's relationship with a girl in similar circumstances only known as a Gamin played by Paulette Goddard. Chaplin and Goddard are wonderful together as there is such a strong warmth that comes out of even the tiniest interaction they share. One could not ask for a sweeter couple to follow in the film with Chaplin's shy little smile, and Goddard brightly shining grin that might be one of the cutest imaginable. Their relationship though is not simply about the joy they share together but as well as the hardship, which is what perhaps makes Modern Times just so special. They are incredibly moving together in their moments of failing as everything seems to go wrong for them, even after it seems like things go right, and the sadness of each defeat is palatable despite being funny when it happened initially. There is always resilience in the pair with that final unforgettable moment where Chaplin presents still such a beautiful tenderness as the Tramp encourages her to keep going on even when things look at their worst. This is a marvelous performance that is a worthy sendoff for perhaps the most iconic character in cinematic history.