In what ways and to what effect does Mulk Raj Anand use irony and juxtaposition in his short story "Lullaby"?

In the short story "Lullaby," Mulk Raj Anand juxtaposes Phalini's singing against the sounds of the jute machine. The machine sounds highlight the oppressing monotony in Phalini's life. On a deeper level, the repetitive industrial sounds represent a life of entrenched bondage for women like Phalini.
No matter what life brings, Phalini must be at her station feeding the jute machine. Her baby is sick, but there is no one to help her. As she sings to soothe the feverish baby, the machine sounds accompany her pleading, soulful melody.

The engine chuk-chuked; the leather belt khupp-khupped; the bolts jig-jigged; the plugs tik-tikked; the whole floor shook like the hard wooden seat of a railway train.

Above the sounds of the machines, the dominant voices of other women threaten to drown out Phalini's singing. The women are "sharp-tongued" and will tolerate no other songs in their midst. There is a certain irony in this. Despite their shared gender, Phalini's colleagues remain detached from the suffering mother. Phalini earns no sympathy from them for her sick baby. In this atmosphere of mechanized drudgery, the only valued traits appear to be resilience, strength, and competence.
There is a further irony as the story progresses. We learn that Phalini's lover does not know he has a son. Phalini is still married, so that means she can never reveal the truth about her son's paternal heritage to anyone. Phalini suffers alone. Meanwhile, her lover remains free to enjoy life as he desires. He is unencumbered by Phalini's burdens.
In the factory, life is an unrelenting struggle for Phalini. With a sick baby, the challenges increase. As long as Phalini sings to soothe her baby, she must breathe in fumes of jute fluff with every breath she takes. She cannot cover her mouth or nose with a rag because her voice is her baby's only comfort.
Meanwhile, the machine sounds continue without ceasing. The sounds mean that women like Phalini will be able to earn a living. However, they also mean the end of good health. In the story, we learn that Phalini has pawned her nose ring because she can no longer bear the thought of it adorning her sunken face. The irony of the machines is that they both provide and destroy. Interestingly, the machine sounds are described as "dithyrambic" by Anand. These sounds are juxtaposed against the baby's weak cries. A dithyramb was originally an ode to Dionysus (the god of wine, ritual madness, and spiritual ecstasy).
So, the machine sounds are intensely hypnotic, lulling Phalini into an emotional stupor. She does not realize that the "thick, sickly, tasteless air" will soon kill her baby.
The baby's name, Suraj Mukhi, is also ironic. In Sanskrit, "suraj" refers to the sun. The name points to the celestial realms and can also mean that one is "born of the gods." Meanwhile, "mukhi" has Hindu origins (cloud), which points to the heavens. Despite such an auspicious name, Suraj Mukhi's life is short and filled with unbearable suffering.