What Is Laser Cladding Technology, What Are Its Characteristics, and How Is It Applied?

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  Key takeaways
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  What laser cladding technology actually does
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  How the melt pool forms and why dilution matters
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  Powder feed vs wire feed: which to pick
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  Parameter ranges that keep a clad layer sound
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  Why post-clad machining is part of the plan
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  Step by step: running a laser cladding job
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  When laser cladding beats the alternatives

Laser cladding technology feeds a filler material into a moving laser spot on a metal surface. The filler and a thin skin of the substrate melt at the same time, then freeze in milliseconds. The result is a dense layer bonded to the base metal through the melt, not glued or sprayed onto it.

Because the melt pool is small, most of the substrate never sees high temperature. That is the difference from arc welding or thermal spray. A shaft can be rebuilt without pulling straightness out of the whole part.

The process covers two jobs. One is repair: restoring a worn journal, a scored seal face, or a corroded flange. The other is new-part protection: putting a wear or corrosion resistant skin on a surface that will otherwise erode in service.

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  RepairRebuild undersized or damaged metal instead of scrapping the part.
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  HardfacingAdd a wear resistant layer where abrasion or erosion is expected.
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  Corrosion barrierDeposit a more noble alloy on a cheaper or stronger substrate.

Dilution is the share of substrate metal that melts into the clad layer. It is usually quoted as a percentage of the finished layer volume. On a good laser clad job it sits between 3% and 10%. Push it higher and the layer is no longer the alloy you specified.

Dilution is driven mostly by laser power density and travel speed. More power or slower travel deepens the pool and pulls more iron up into the deposit. Faster travel with the same power gives a shallower pool, lower dilution, and a thinner layer per pass.

A shallow pool is the goal, not a deep one. Laser cladding is not meant to penetrate like a structural weld. The bond needs to be continuous and metallurgical, and the layer needs to keep its intended chemistry.

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  Watch the iron numberOn a nickel or cobalt deposit, rising Fe content is the first sign of excess dilution.
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  Shallow beats deepA 0.5 mm penetration under a 1 mm layer is healthier than 1.5 mm penetration.

Powder feed is the common choice. Metal powder is blown through a nozzle coaxially or off-axis into the pool, and the same head can also be used for pre-placed powder. It handles almost any alloy that can be gas atomized, including carbides and blends. Capture efficiency runs roughly 60% to 90%, so some powder is overspray.

Wire feed is cleaner on the shop floor. No powder cloud, no overspray collection, and a uniform deposit chemistry because the wire is already the alloy you want. It works well for nickel, cobalt, and steel wires in rotationally symmetric repairs. The limit is the wire catalogue. Exotic carbides and blends are hard to source as wire.

The choice usually comes down to geometry and alloy. Freeform surfaces, small local spots, and particle-reinforced layers favor powder. Long straight beads on a lathe or a rotationally symmetric shaft favor wire.

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  PowderBest alloy range, more overspray, needs shielding gas and dust handling.
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  WireCleaner and denser deposit, narrower alloy choice, tighter aiming tolerance.

Start with the laser spot. A 1-3 mm spot at 1,000-3,000 W gives a power density that melts powder and substrate without keyholing. Spot diameters above about 4 mm spread the energy so thin that the powder may not fuse fully.

Travel speed typically runs 300-1,200 mm/min. Powder feed sits around 5-30 g/min, and wire feed around 1-4 m/min. Shielding gas, usually argon at 10-20 L/min, protects the pool from oxygen. On titanium or aluminium, add a trailing shield or a glove box; oxygen pickup shows up as porosity and colour change.

Preheat is often skipped and often should not be. For medium and high carbon steels, a 150-300 °C preheat slows the cooling rate and reduces cracking in the heat affected zone. For large castings that have absorbed oil or moisture, clean and preheat before you start.

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  Overlap 40-60%Track width overlap below 40% leaves valleys; above 60% reheats the previous bead.
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  One variable at a timeChange power or speed, not both, when dialling in a new alloy.

Cladding leaves a rough, slightly wavy surface. Layer thickness of 0.2-2 mm per pass is normal, and the edges of each track leave a step where it overlaps the next. Almost every functional surface then needs milling, turning, or grinding back to size.

This is where the job links back to CNC work. Hardfaced and laser clad surfaces are often 45-60 HRC, so the finishing cut has to be planned before the layer is deposited. Leave enough stock for a carbide or ceramic insert to take a real cut, not just a skim.

Measure after cladding, not before. Thermal cycles move the part a little, and a cladding job that ends undersized on a bearing journal is an expensive mistake. On a shaft, machine the layer to size and check roundness on the machine before unclamping.

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  Leave 0.3-0.8 mmStock for finishing after a typical single-pass clad layer.
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  Expect some movementCheck runout and straightness after cooling, before the finish cut.