Cycle Time Reduction Principles For Cnc Machining Equipment

Cycle Time Reduction Principles For Cnc Machining Equipment



Cycle Time Reduction Principles for​ CNC Machining Equipment
What is​ the​ definition of​ cycle time?

Cycle time is​ defined to​ be the​ time that happens from the​ time a​ task or​ series of​ tasks is​ initiated to​ the​ time a​ task is​ completed .​
Example, the​ cycle time is​ the​ time a​ shipping order is​ printed to​ the​ time it​ is​ loaded on the​ truck and​ the​ system is​ updated .​
An alternate definition would be is​ the​ time it​ takes to​ load, run, and​ unload on workpiece.
Cycle time of​ a​ machine can be simply measured by timing how long it​ takes from pressing the​ button to​ start the​ cycle for​ the​ first workpiece to​ the​ pressing the​ next button for​ the​ next workpiece.
Production quantities in​ an​ industry dictate that the​ more workpieces you run, the​ more important it​ is​ to​ achieve the​ goal of​ lowering the​ cycle time .​
Everything and​ anything that happens in​ a​ Computer Numerical Control (CNC) machining equipment can be divided into four categories:
1.) On-line, productive tasks:
These are the​ actual machining operations that occur during a​ CNC cycle .​
These are the​ milling, drilling, tapping, reaming, and​ any other machining operation that in​ some way furthers the​ completion of​ the​ workpiece .​
To minimize the​ cycle time in​ these areas, there are two ways in​ which this can be achieved .​
One would be through careful process planning .​
The process engineer must select an​ appropriate machine tool, cutting tools, fixturing, and​ machining order in​ a​ way that it​ matches the​ number of​ workpieces to​ be machined that will be based on the​ production quantity .​
The cycle time will be a​ reflection of​ the​ processes being used to​ machine workpieces .​
If in​ the​ many times that your company’s processes have already been developed and​ implemented before you begin your cycle time reduction program, then your second alternative is​ to​ optimize cutting operations for​ this would involve properly selecting cutting tool materials, feeds, and​ speeds to​ machine workpieces as​ efficiently as​ possible with the​ current process.
2.) On-line, non-productive tasks:
These are tasks that occur during the​ machining cycle that do not actually further the​ completion of​ the​ workpiece .​
The first thing Computer Numerical Control people often target for​ improvement is​ wasted program execution time .​
These are the​ things like rapid movements, tool changes, M-code execution and​ spindle acceleration/deceleration .​
Reducing program execution time in​ this area is​ usually easy .​
It often takes nothing more than carefully monitoring the​ production run for​ a​ few workpieces to​ find those times when the​ program can be modified to​ eliminate noticeable pauses during the​ cycle .​
Although keep in​ mind that the​ worker for​ these machines must not overlook other processes for​ they may be so concerned with minimizing program execution that they overlook other operations, resulting in​ severe wastes of​ cycle time.
3.) Off-line, non-productive tasks:
These are the​ tasks performed in​ the​ machining cycle that do nothing to​ further the​ completion of​ the​ workpiece .​
Since these types of​ tasks are done while the​ machine is​ producing workpieces, they do not actually add to​ the​ cycle time .​
It is​ possible to​ free the​ operator of​ the​ machines of​ performing off-line productive tasks if​ they have little, or​ nothing to​ do during lengthy machine cycles.
4.) Off-line, productive tasks:
These are the​ tasks done away by the​ CNC machine, while the​ machine is​ producing workpieces, which would further the​ completion of​ the​ workpiece .​
This is​ extremely helpful during lengthy CNC cycles, tasks in​ this category can reduce the​ time it​ takes to​ complete the​ production run dramatically, which would effectively reduce cycle time.




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