How and why did the woodman become the tin woodman?

The woodman, originally known as Nick Chopper, became the Tin Woodman after a series of unfortunate events where a wicked witch cursed him. While chopping wood, he accidentally struck his own leg with an axe, and each time he replaced a body part with a tin one to avoid further injury, ultimately losing his heart in the process. This transformation left him a tin figure, devoid of emotions, which is why he seeks a heart from the Wizard of Oz, hoping to regain his capacity to love and feel. His journey symbolizes the loss of humanity and the quest for compassion.