Cycle Time
For any production operation, the cycle time is defined as the time that one work unit spends being processed or assembled. It is the time between when one work unit begins processing and when the next unit begins. Cycle time is the time an individual part spends at the machine, but not all of this time is productive In a typical processing operation, such as machining, cycle time consists of actual machining operation time, work part handling time and tool handling time per workpiece. (Mikell P. Groover, Automation,production and computer-integrated manufactoring, Prentice-Hall Pub., 2008, p.49)
Lead-Through Programming
Lead-through programming requires the operator to move the robot arm through the desired motion path during a teach procedure, thereby entering the program into the controller memory.There are two method of performing the lead-through teach procedure:
-Powered Lead-Through Programming, is commonly as the programming method for playback robots with point-to-point control. It involves the use of a teach pendant which has toggle switches or contact buttons for controlling the movement of the manipulator joints. Using the toggle switches or buttons, the programmer power drives the robot arm to the desired positions, in sequence, and records the positions in the memory. During subsequent playback, the robot moves through the sequence of positions under its power.
-Manuel Lead-Through Programming, is convenient for programming playback robots with continuous path control in which the continuous path is an irregular motion pattern such as in spray painting. This programming method requires to operator to physically grasp the end-of-arm or tools attached to the arm and manually move through the motion sequence, recording the path into memory. The motions are recorded as a series of closely spaced points. During playback, the path is recreated by the controlling the actual robot arm through the same sequence of points.
(A.K. Gupta, S.K.Arora, Industrial automation and robotics, Laxmi Pub. 2007, p.324)
Walk-Through Programming
The teacher physically moves the robot through the desired position within the robot's working envelope. During this time, the robot's controller may scan and store coordinate values on a fixed time interval basis. These values and other functional information are replayed in the automatic mode. This may be at a different speed than that used in the walk-trough.
This type of walk-through programming uses triggers on manual handles that move the robot. When the trigger is depressed the controller remembers the position. The controller would than generate the movement between these points when the program is played. The walk-trough method of programming require the teacher to be within the robot's working envelope with the robot's controller energized at least in the position sensors. This may also require that safeguarding devices be deactivated. (A.K. Gupta, S.K.Arora, Industrial automation and robotics, Laxmi Pub. 2007, p.324-325)
Slab Mill
The plain horizontal milling machine used primarilly for machining flat surfaces is known as a slab mill. Because the basic idea is to accurately create parallel top anf bottom surfaces, it is usually not necessary to square the workpiece or workholding device to table travel.
For slabbing operations, the cutter should be wider the part being machined; this permits the operation to be completed with one pass. The cutting speed must be correct for the material being machined, and cutting fluid should be riberally applied at the point of cut. Rigidity of the setup is important. Since the cutter will be mounted on an arbor, the idea is to keep the cutter as close to the column as possible to ensure maximum rigitidy while allowing for tool clearance and for the cutter width to slightly exceed the workpiece widht.(Arthur R. Meyers,Thomas J. Slattery,Basic Machining Reference Handbook, Industrial Press Inc., 2001, p.127-128)
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