Robot Transport Units (RTU)
Get More From Your Robot With A Transport Unit
The Robot Transport Unit, or RTU, is an often-overlooked way of reducing the number of robots needed. A robot is usually anchored to a single spot, but an RTU moves the robot through a cell or across a factory, allowing it to serve multiple machines or processes. This way there's no need to buy multiple robots and conveyors: the RTU takes the robot to each machine. Sometimes an articulated robot doesn't have the reach to tend all the machines in a cell, but an RTU will let it shuttle back and forth between two or more — saving the cost and complexity of a second robot. In some factories, machines are arranged in a linear fashion, in which case, multiple machine tending robots and conveyors are needed, even though individual utilization will be low. In cases like these it can pay to use an RTU.
Articulated robots have joints that move through circular paths, making them very effective when the machines they're tending are arranged in an arc. An RTU adds linear travel and an additional axis that lets the robot move up and down a line of machines. At it's simplest, an RTU is a linear track with a platform. The robot sits on the platform and is moved to wherever it's needed. The track can be just a few feet long or could span the length of a factory. Typical applications are tasks like moving castings or forgings through a sequence of machine tools, or tending a line of injection molding machines. RTU's are often floor mounted, but wall and overhead gantry-type configurations are also possible. While somewhat more complex, these have the advantage of not taking up floorspace or obstructing access to the machines. (Many machine tools are designed for top access by a gantry-mounted robot.) When floor mounted, a walkable cover can be added allowing easy access for maintenance or cleaning, protecting against contamination.
A floor-mounted RTU can handle a payload of 3000 pounds (1300 kilograms) or more (which includes the robot itself), and can move the robot rapidly between machines. Manufacturers quote velocities of up to 118 inches per second (3 meters per second), accelerations as high as 157 inches per second squared (4 meters per second squared) and positioning repeatability of plus or minus 0.008 inches (0.2 millimeters.) Some users have installed systems as long as 165 feet (50 meters), but even longer lengths are possible.
An RTU creates more options for laying out a factory, and is often a cost-effective alternative to additional robots. They are especially useful when individual operation times are lengthy, as this allows the robot to shuttle between a number of machines without stopping. Installation can be done quickly, either as an addition to an existing factory layout or as part of a production area rearrangement. In these situations an RTU is often a cost-effective alternative to purchasing multiple robots with low individual utilization.
To discuss known automation opportunities or discover new ones: