Here is what I found from our citeHR.com- Workers category - skilled, semi skilled, unskilled - case study
There are generally four skills catagory of workmen working in factory/establishment.
1. Highly Skilled - The person who possess excellant knowledge and skills in his area of work and can teach to other people. He can do any difficult job in his area or produce best quality produce.
2. Skilled- The person who possess knowledge & skill in his area of work and can produce best production.
3. Semi-skilled- The person who possess certain skill in his area and can able to perform job in his area. But clsoe supervision is required to find quality / productivity. Normally, people after training period may considred as SEmi-skilled.
4. Unskilled- The person who are performing any casual job and does not require any skill for the job. viz. Helper, Peon, Sweeper etc.
Hope this helps. Please feel free to post further concerns.