Types, Process Planning, ISO Tool, Cutting Speed, Feed of CNC System

Types of CNC System

Manufacturers, Factories and companies of CNC machine tool adopt various systems as per their recognition and easiness. The same systems are used for all machines.

CNC milling machine provided with computer software and monitor. Various codes such as M code, G codes etc or part of software. As CNC milling machine operator must know how to read a program, what the program is planned for and type of program. Operator will accordingly select the necessary speed, feed depth of cut required for particular operation.

Note: The use or non use of the plus (+) sign is optional

Process Planning

Process planning is must in CNC machining. A slightest mistake may turn out to be closely affair in the form of loss of production time and damage to the tool and machinery. Careful planning and precautions will optimize production with accuracy. The following points must be observed while process planning sequence:

(a) Study of drawing of the work piece and the dimensions having close tolerances.

(b) Determine the number of setting required and method of clamping the job.

(c) Write down the machining sequences for each set up.

(d) Determine the cutting tool and machining parameter for obtaining the required accuracy, surface finish, productivity etc.

(e) Prepare the program and check the program in simulation. If any deviation is observed, make changes and reconfirm that the program is correct. If required, dry run may be made by shifting tool off set.

(f) Check the dimension on the job and give necessary correction for cutter off-set.

(g) Turn the second job in cycle mode; check that the dimensions are correct.

(h) Tool nose radius / cutter compensation must be checked after every half an hour. If required necessary correction should be made in ERE Menu.

(i) Machine/ mill the remaining job in either single block cycle or automatic cycle.

ISO Tool, Cutting Speed, Feed

CNC milling is mass production machine tool. Mass production requires special tool/cutter of high quality. Ordinary tool /cutter used on the conventional machine will not with stand as it operate on high speed. Speed, feed and depth of cut depend on type of cutter, quality of tool material. Recommended ISO designed tools and inserts are to be used to obtain maximum output.

(a) Preferably, coated grade insert (Titanium nitrate coated) are to be used for better surface finish.

(b) Tool and insert can be of Sandvik and Wadia make.

(c) For machining aluminium, brass or any non–ferrous material, tools with positive rake is used as recommended by Sandvik or Wadia.