Job specialization is the process of focusing one's occupational concentration on a specific area of expertise. An increase in job specialization among employees can make them less flexible since it tends to reduce their ability to perform other types of work within the business that fall outside their particular specialty.

The method of job specialization involves breaking down a task to its lowest level and designing jobs around each part. This creates specialization, expertise, and improved quality. Job specialization design in the workplace is frequently seen in manufacturing and assembly lines where a worker focuses on one specific task and ability during the entire work shift. The task frequently repeats all day long.

Because job specialization allows significant expertise buildup in a specific task, the learning and speed of production happen faster. The job does not involve complex processes, so it can be taught faster to new workers. In theory, this approach reduces quality control costs and improves production efficiency.

The downside of job specialization tends to be that people can only do one task. They aren’t trained to multitask or handle multiple areas of a workplace. As a result, when a critical expertise is lost, the process can suffer. Additionally, workers under job specialization don’t have a wide array of applicable skills, so it becomes hard for them to adapt to a new function or need in the organization. As a result, unemployment is a significant problem when a company has to shut down a factory or assembly line. Many of the laid-off workers usually have a hard time adjusting to new occupations.

Source:  http://www.ehow.com/about_6721655_job-specialization-job-evaluation_.html#ixzz2BHUeWuc6