Automated motion guidance systems with heavy-duty load capacities are experiencing a significant increase in demand. One reason for this revolves around the installation of flexible multi-axis robots onto long tracks. This allows engineers to greatly extend the work envelope while taking full advantage of a robot controller’s seventh axis.For many applications, a linear motion guided gantry system can accomplish the same tasks as a multi-axis robot while incurring less cost. Additionally, these gantry systems can be designed and supplied to end-users from standard heavy-duty subassemblies or components and can be tailored to the specific application.Here’s a look at five highly configurable systems that can be used in gantry configurations for factory floor automation in place of sophisticated robots. Let’s start by reviewing some of the basic gantry concepts.

Low to Medium Precision

Factory automation does not always require a high degree of precision. In many cases the task involves heavy products and awkwardly shaped or off-balanced materials. Most applications require high repetition, extended operating time, and long-lasting durability with minimal maintenance. Frequently, the requirement for precision positioning is low.Pick and place applications can require low precision when palletizing cases or placing the next item into the production queue. Material transfer applications may involve relocating products with an overhead robotic manipulator from one area to another. XYZ gantry robots (the Z-axis refers to the vertical direction) can position and reposition materials anywhere within a three-dimensional space or enable operations on many faces of a work piece. Spraying systems may require low precision over long distances to paint a rail car or airplane wing.

Heavy Duty Z-Axis

When moving a product, the first order of business is lifting that load. Great care is often taken in the design of end-effector grippers used for manipulating the product. A simple vertical lifting or lowering machine can be referred to a Z-axis system.After the item is lifted and supported by the system, all motion will generate additional loads due to accelerations of the mass. Significant loads may be generated during high-speed motion. Speed is typically determined based upon cycle time over the required distance. Loads are calculated based upon the acceleration (+ and -) of the mass.Speeds in typical gantries extend to 5m/s.Therefore, a heavy load capacity may be required to accommodate the expected motion. Additionally, a long service life can be designed into the application when working load requirements are a small ratio of the motion systems load capacity.Single-axis motion stages can be combined with other positioners in various gantry configurations. Attaching additional motion systems adds reach and functionality, and tasks can be performed over longer distances.

X-Z robot: When a Z-axis linear motion stage is mounted on an additional transverse axis of motion, it can be referred to as an X-Z robot. This configuration can lift an object vertically, move to another location in a straight line, and place the object there. This configuration is particularly useful for pick-and-place or transfer applications. The end of the X-Z robot can position and locate any­where within a rectangular plane.In some cases the main mounting plate for the X-axis can hold the linear guide bearings to the Z-axis and integrate all of the necessary pinion drive and automatic lubricator components. This greatly simplifies the design and reduces the overall moving mass.

X-Y-Z robot and X-X’-Y-Z robot gantry: The most flexible configuration of a robotic gantry system provides for three axes of motion to enable positioning anywhere within a three-dimensional work area. It is less common to have an X-Y-Z configuration because the axis attachment points become space constrained. However, this configuration is used extensively in automated welding where there are large travel reaches but no major loads. It is much more common to have a parallel X-axis solution where the Y-axis is supported on both ends. This configuration is called an X-X’-Y-Z gantry (pronounced X, X-prime). Examples of this configuration are easy to find in production machinery such as CNC routers.

Unlimited custom design configurations: There are many possible designs for a large-format automated motion system. A complete multi-axis XYZ gantry robot can be custom designed from the individual linear guide rails and linear bearings, enabling engineers to select the best products for each area of the design. Existing product lines provide standardized components and subassemblies, which speed configuration and development by using common gantry layouts while providing the freedom to create a custom design. This is not possible with preconfigured or premade equipment that restricts work within previously established limits.