8.0 ROBOTIC SAFETY AND MAINTENANCE

8.1 Understand the robot manufacturing operations

8.1.1 Explain product specifications supplied by robotics

manufacturers and relation to robotics operations

•       Performance Specifications:

      There are some general performance specifications that can make a great deal of difference when selecting a robot for a given industrial application.

  (1) Payload: - 

–      The robot can hold a much heavier weight than they can swing about at the maximum speed. 

–      The shape of the object held and its surface conditions affect the ability of the robot to handle it efficiently. 

–      Payload capacity at arm positions close to the base obviously tends to be higher than capacities at full arm extension. 

–      Some robot manufactures specify two payload capacity: normal and maximum, static and rated or static and dynamic. 

–      The potential robot user should check carefully to ascertain exactly under what conditions the robot manufacturer is determining the rated payload, especially if only one figuration is specified.

(2) Repeatability:- 

–      Accuracy is the ability to go to prescribed pointing space defined in terms of x-y-z or some other coordinate system. 

–      Machine tools are concerned with accuracy. 

–      Repeatability is the ability to return to the same spot again and again after that point has already been taught. 

–      For industrial robots with a teach pendant, the repeatability is more important at first. 

–      The important test is whether the robot can continue to perform procedure as taught without slipping of target.

(3)Speed:- 

–      Pick-and-place cycles used in machine loading and unloading are typically rated at two to three seconds for small pneumatic axis-limit robots. 

–      Some of these robots can achieve one-second cycles and can operations by mechanical manipulators can be even faster. 

–      A typical speed for a large servo-controlled, hydraulic robot is in around (50) inches per second.

(4)Robot Utilization and Justification:

–      Robots are effective at, repetitive jobs that require little or intelligence judgment. 

–      Robots are also good for extremely fatiguing, hot jobs or for jobs that must be performed in toxic or otherwise dangerous environments. 

–      Robots have higher repeatability on intricate repetitious tasks. 

–      Jobs that require handling heavy work pieces may be either humanly impossible or extremely fatiguing, there by impossible for a human to sustain for a full work-shift. 

•       For these jobs, robots may be more than desirable- they may be essential. 

–      Many hydraulic models, and some electric ones, have superior lifting strength when compared to humans. 

–      Robots are excellent candidates for both spot-welding and arc-welding jobs. Like welding, spray painting and other spray-finishing operations present hazard but require precision. 

–      Although economics is the common denominator of all robot decisions, some of decision criteria may be so difficult to quantify that they should be considered separately.

  (source; http://hafidzfazli.files.wordpress.com/2012/11/chapter-5.pdf)