OBJECTIVE : To give knowledge to the student what is are speed,feed,depth of cut and chip formation.
APPRATUS : Lathe machine ,HSS and carbide toolbit,center drill bit vernier caliper and PPE.
THEORY :
For all metal cutting process,Speed and feeds are important parameters.The colloquial term ‘speeds and feed’ refers to the speed,feed and depth of cut of a metal cutting process.To describe these paraneters,we will be using turning process.The figure shows the important geometry.The speed is cutting speed,which is a measure of the part cut surface speed relative to the tool. 1. SPEED/CUTTING SPEED is a velocity unit,which is typically listed in terms of feet/min,meters/second, or meters/min. 2. FEED is the amount of materials removed for each revolution or per pass of the tool over workpiece . Feed is measured in un its of length/revolution,length/time, or others appropriate units for the particular process. 3. THE DEPTH OF CUT represents the third parameter for metal cutting. For turning DOC is the depth that the tool is plunged into the surface. The DOC is half of difference in diameters the initial and final diameters.
TITTLE : CUTTING EXTERNAL THREADS.
OBJECTIVE : TO expose and practically hand on in cutting external threads.
APPARATUS : Lathe machine ,HSS and Carbide toolbit, live center, center gauge , screw pitch gage and PPE.
THEORY ;
Threading can be performed on the lathe machine .two basic requirements for thread efficiency for thread cutting are an accurately shaped and mounted tool is needed because thread cutting is a form cutting operation. The second by requirements is that tool must movelongitudinally in a specific relationship to the rotation of the work piece ,because this determines the lead of the thread.This requirements is met through the use of the lead screw and the split unit, Whichj provide positive motion of the relative to the rotation of the