The Samsung brand is best known for its smartphones and wide-screen TVs. Yet behind the scenes the conglomerate is also making a name as a contract manufacturer of complex medicines to treat diseases like cancer.

On a piece of reclaimed land along the western coast of South Korea, Samsung BioLogics Co. is building a $740 million factory that will give it the capacity to become the No. 1 producer by volume of a class of drugs called biologics, many of which are derived from mammal cells.

The Samsung group diversified into the pharmaceutical sector in 2011. Now, it's mobilizing its expertise in semiconductor making and engineering know-how to make the way biologics are produced on behalf of Big Pharma more efficient. The market for biologic medicines, which are used for everything from cancer to arthritis, is projected to exceed $223.7 billion by 2021, according to a Bloomberg Intelligence analysis.