In what ways is Hard Times a novel of social protest?

Hard Times protests the ill effects of industrialism, which was beginning to dominate life in England by the Victorian era. Much like many real mill towns in the mid-nineteenth century, Coketown was dominated by the economics of the factory. Skilled craftsman were replaced with unskilled factory laborers.
The philosophy of utilitarianism, which, in Dickens's depiction, focuses solely on facts, and tries to do everything in the most efficient possible way, has robbed Coketown of any charm. Soot from the coal that fuels the mill's machines covers the town. All the brick buildings are interchangeable and built with price, rather than beauty, in mind. Likewise, the factory workers are treated like objects out of which the owners want to squeeze the maximum amount of profit, rather than as human beings with hearts and souls.
Gradgrind's school and educational philosophy also reflect Dickens's critique of industrialism's obsession with efficiency. Gradgrind is only interested in facts, both in his school and with his children. There is no whiff of poetry, art, or feeling in either his teaching or his child-rearing methods. One way Dickens protests a society increasingly reliant on efficiency at the expense of people is to show the unhappy fates of Gradgrind's children as they enter adulthood.
Dickens didn't want England, once a country of quaint towns and villages, to turn into one giant, soot-covered factory devoid of beauty. He didn't want children educated to only know facts or to treat all of life as a financial calculation. He also didn't want poor people ground down by an inhumane factory system that put profits ahead of people.
Dickens hoped to move readers with his graphic descriptions of how the poor live and with a narrative tone that mocked the utilitarian theories that wreaked havoc on real people's lives.
However, while Hard Times critiques the suffering brought on by industrialism, Dickens's social protest does not extend to endorsing unionism or any sort of socialism. He hoped that changing people's hearts would encourage the people with money and power, as well as the workers, to join forces for mutual benefit. He hoped that if the rich could really see and understand what they were doing to the poor, they would work to improve conditions. This was unrealistic thinking on Dickens's part, but he nevertheless had his heart in the right place as he criticized the problems with uncontrolled capitalism.