Linear Motor from TallMan Robotics in Laser Cladding Machines Direct-Drive Motion Precision for Powder-Fed Metal Deposition in Laser Processing Laser cladding builds a metallurgically bonded layer on a substrate. A coaxial powder stream meets a focused laser beam at the melt pool. The process depends on one variable above all others: motion axis velocity. Every speed change alters the energy input per unit length. Additionally, it alters the powder mass deposited per that same length. A Linear Motor from TallMan Robotics addresses this dependency directly. It drives the cladding head or the worktable through direct electromagnetic thrust. No ball screw sits in the chain. Likewise, no belt or gearbox sits between the motor and the load.

Direct Drive and Corner Path Accuracy

Direct drive removes backlash from the motion chain. In addition, it removes mechanical compliance from the same chain. The forcer couples straight to the moving platform. As a result, commanded velocity and actual velocity track each other with minimal lag. This precision matters most at direction changes and contour corners. At these points, traditional transmission components add settling time. They also add micro-vibration to the beam path. For example, researchers studying five-axis cladding of blisk blades documented this effect directly. Corner segments produced transient feed-rate fluctuations during their tests. At the same time, the powder feed rate stayed constant. Together, these conditions produced local over-deposition and surface nodules on the curved substrate . A zero-backlash linear motor axis shortens this transition window. In turn, it holds the commanded path more faithfully through the corner. Drive Type Backlash Position Feedback Path Typical Velocity Range

Fit for Cladding Axis

Linear Motor (direct drive) None Linear scale on moving platform Micrometers/s to several m/s Primary or high-speed cladding axis Ball Screw Present, grows with wear Rotary encoder through screw and nut Up to roughly 1 m/s Heavy load axis, moderate dynamics Belt Drive Present, belt stretch adds error Rotary encoder through pulley 0.5 to 3 m/s Long travel, lower precision transport Table 1. Drive technology comparison for laser cladding motion axes.

Powder Delivery Synchronization in Linear Motor Laser Cladding

Powder delivery synchronization depends on this same velocity signal. Tang and colleagues at the Missouri University of Science and Technology built a variable powder flow rate controller for this exact purpose. Their system reads motion velocity in real time. It then adjusts powder mass flow to hold a constant deposition target of 3.15 × 10⁻² g/mm along the toolpath. Consequently, the tracking controller held powder flow rate error to a standard deviation of 8.68 × 10⁻² g/min. Peak error reached only 1.21 g/min. Notably, this peak occurred mainly during the brief pause as the Z-axis stepped up between layers. A Linear Motor platform can feed this velocity signal to a powder controller directly. In this way, it closes the loop between motion and material delivery. Track morphology, in turn, stays uniform across acceleration, cruise, and deceleration segments. Process parameter studies on Inconel 718 single-track cladding quantify this speed sensitivity further. Specifically, one study clad Inconel 718 across a laser power range of 4200 W to 5400 W. The powder feed, meanwhile, ranged from 25 g/min to 50 g/min. Cladding speed ranged from 20 mm/s to 50 mm/s. Researchers then classified the melt pool cross-sections into shallow, flat, and fluctuating dilution types. Each geometry class tied back to the combined parameter set, including axis speed. Consistent axis velocity, therefore, keeps every parameter combination inside the target zone, layer after layer. Additionally, a Linear Motor sustains that velocity across long, multi-pass toolpaths. It does so without the periodic correction cycles a lead screw needs as it warms and expands.

Source

Process Parameter Studied Reported Value

Relevance to Motion Axis

Calleja et al., 2014 Corner feed-rate behavior in 5-axis blisk cladding Transient feed-rate spikes at corners with constant powder feed Zero-backlash axis shortens correction window Tang et al., 2008 Powder flow tracking vs. motion velocity Target 3.15 × 10⁻² g/mm; error SD 8.68 × 10⁻² g/min; peak error 1.21 g/min Direct-drive velocity signal feeds powder controller Bian et al., 2024 Inconel 718 single-track parameter mapping Laser power 4200–5400 W; powder feed 25–50 g/min; speed 20–50 mm/s Stable axis speed holds parameter set in target zone Table 2. Quantified reference data from cited laser cladding motion studies.

TallMan Robotics Linear Motor Series in Linear Motor Laser Cladding

TallMan Robotics manufactures its Linear Motor line in two configurations. First, the Economical Embedded Type falls under the PML series. Second, the Heavy Payload option falls under the PMK series. Engineers can therefore match motor thrust and moving mass to a specific cladding head, powder nozzle, and shielding gas setup. Both series eliminate the intermediate mechanical link between motor and load. In addition, both cut driving system inertia and raise elastic stiffness above typical mechanical transmissions. TallMan rates fast response at roughly one hundred times that of a mechanical system. This speed, in turn, lets the axis correct disturbances within the same servo cycle that detects them. A screw or belt axis, by contrast, needs several cycles to transmit the same correction. Long travel without loss of performance also supports large-format cladding work. Turbine casing repair and large die resurfacing both fall into this category. Here, the axis must hold the same dynamic response at the far end of the stroke as it does near home position. Furthermore, cleanroom-rated and general-environment configurations extend this direct-drive architecture into semiconductor and optical processing lines. These lines, similarly, share the same demand for repeatable, high-bandwidth motion.    

Selecting a Linear Motor for a Cladding Platform