Cutting Machines and Cutting.
Subsection 11 2 in SME Mining Engineering Handbook 1:11-3to11-5
The techniques of preblast cutting in soft minerals is described in this article. The first step in conventional coal mining is cutting. Cutting also is done in mining certain other stratified minerals. Cutting to produce an opening called a kerf is desirable because it provides one additional free surface for the coal to break to. Further, undercutting or overcutting relieves the coal seam from the stress acting on it due to overburden pressure. A cut seam will require less explosive to blast, and the coal will be coarser than from an undisturbed seam. Further, less dust and methane are produced in blasting a cut seam.
Subsection 11.2 in SME Mining Engineering Handbook, V. 1, PP. 11-3 to 11-5