SELECTING ROBOTIC POSITIONERS

Most robots have six axes that can reach various regions of a part or assembly. While this sufficient for many applications, adding the right positioner exponentially expands your robotic capabilities. A positioner like a 5-axis positioner can present a simple or complex part to a robotic arm for repeatable welds. A Robot Transport Unit can move a robot around an assembly or part, which is why an RTU is also known as a 7^thaxis positioner. A robotic positioner should be customized for your application, footprint, and part geometry, so that it can work in unison with a robot performing an articulated motion. The geometry of your part (e.g., capacity and size) and process (e.g., duty cycle) will influence which positioner(s) you select.

Popular positioners for simple and complex parts:

RTUs | Floor Turntables | Robotic Tilt-Rotate Positioners | Headstocks/Tailstocks | Ferris Wheel Positioners | 5-Axis Positioners | H-Frame Positioners

Each positioner provides specific capabilities. For instance, floor turntables are used to rotate parts along a vertical axis while robotic tilt-rotate positioners and 5-axis positioners are used to weld parts at various degree angles. Alternatively, headstocks / tailstocks and H-frame positioners rotate parts along a horizontal axis.

This guide will help you consider the right positioner for your operation, but our expert engineering staff can walk you through every step of selecting the right solution for your project. We know robotic and welding positioners, and we’ve been industry leaders for over 50 years. Our job is presenting your team with actionable intelligence about robotic positioning. We take a consultative approach, where we learn more about the problems you are solving. We then provide custom solutions that meet or exceed project requirements, often with positioners that were not initially considered by the customer.

RTUs / 7^th AXIS

Use a Robotic Transport Unit (RTU) (i.e. robot track, robot traversing unit, or 7^th axis) to add an additional linear axis to a robot. The additional axis is especially useful if you need to extend the robot’s reach. For example, an RTU can be used to reach both ends of a 150-foot airplane wing for welding, sanding, or finishing. Furthermore, multiple robots can be mounted on independently-driven carriages on the same track to increase the productivity of a system.

In general, RTUs are used in conjunction with a robotic positioner and can transport robots between weld cells or move alongside a part in an assembly line.

Preston Eastin - Floor Turntables

Floor Turntables

Fabrication shops and integrators choose floor turntables when, for example, they need to weld a part along a vertical axis and allow a robot arm to reach the part. In some cases, floor turntables can rotate two parts at once, meaning that the arc time for the robot is maximized, which increases efficiency by keeping the robot in constant motion. When the robot is done welding the first part, it rotates 180˚ to weld the next part, while the first part is changed out by the operator, which may be another robot.

Preston Eastin - Floor Turntables

Tilt-Rotate

Consider a robotic tilt-rotate positioner to manipulate a part on either the vertical or horizontal axis. Both the tilt and rotate functions add a level of flexibility for thermal/cold spray, or for laying down the puddle of the weld efficiently, so that you can weld at flat, horizontal or vertical angles (if the table height allows it). Positioners can be configured with various tilt options, such as 0° to 135° or +/- 90°.

Preston Eastin - Floor Turntables

Headstocks / Tailstocks (Trunnions)

If you need to rotate a part along a single horizontal axis, then a robotic headstock/tailstock is a likely solution. A headstock / tailstock can be used in conjunction with a robot to consistently complete quality welds while rotating a vessel in a horizontal position, for example. A powered headstock can be used independently for small parts. However, larger parts will require a non-powered tailstock to support one end.

Preston Eastin - Floor Turntables

Ferris Wheel

A ferris wheel positioner is similar to an H-frame positioner in that it has two headstocks/tailstocks to allow an operator to load and unload parts for a robotic application such as welding or grinding/sanding. However, the Ferris wheel specifically uses a third horizontal sweep axis. It typically requires less floor space than an H-frame positioner, and it is ideal for smaller parts due to the larger drive system required for the sweep axis.

Preston Eastin - Floor Turntables

5-Axis

If you need the flexibility of a robotic tilt-rotate positioner as well as the loading and unloading capability of a turntable, then a 5-axis positioner is an ideal solution because it adds a sweep axis to maximize the arc time. It combines a turntable and two tilt-rotate positioner together, allowing operators to tilt and rotate complex geometries while staging the next part for welding, or another robotic application.

Preston Eastin - Floor Turntables

H-Frame

An H-frame positioner has two headstocks/tailstocks, which allows an operator to load and unload parts while the robot is welding, for example. Select this positioner if you need to rotate a part along a horizontal axis along with an added vertical rotation sweep axis to maximize the arc time.

Preston Eastin - Floor Turntables

Positioning Parts With Advanced Geometries

Parts with advanced geometries, such as a bulldozer bucket or truck cab, present unique challenges because a robotic arm cannot easily reach certain regions or perform repeatable actions (such as welding) without the aid of a positioner. Skyhooks and Drop-Centers allow robots to repeatably perform welds on parts with advanced geometries. Both of these positioners provide infinite positioning for parts with advanced geometries.

Skyhook

Use a skyhook positioner for individual parts with complex geometries, or for reduced floor space requirements.

Preston Eastin - Floor Turntables

Drop-Center

A drop-center positioner is essentially a skyhook positioner with supports on both ends of the arm. It is popular for larger part geometries than a skyhook positioner, but it requires more floor space due to its secondary support structure.

Preston Eastin - Floor Turntables

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