An apparatus and a method for powder bed fusion additive manufacturing involve a multiple-chamber design achieving a high efficiency and throughput. The multiple-chamber design features concurrent printing of one or more print jobs inside one or more build chambers, side removals of printed objects from build chambers allowing quick exchanges of powdered materials, and capabilities of elevated process temperature controls of build chambers and post processing heat treatments of printed objects. The multiple-chamber design also includes a height-adjustable optical assembly in combination with a fixed build platform method suitable for large and heavy printed objects. A side removal mechanism of the build chambers of the apparatus improves handling and efficiency for printing large and heavy objects. Use of a wide range of sensors in the apparatus and by the method allows various feedback to improve quality, manufacturing throughput, and energy efficiency.