New & Blog

What is friction stir welding (FSW)? How does this solid-state process deliver low-distortion, leak-free aluminum welds for EV battery trays and liquid cold plates? A manufacturer's guide.

Liquid cooling is going mainstream in AI servers and EVs. A look inside liquid cold plate manufacturing: flow channel design, FSW sealing, burst and leak testing, and mass production.

Every hardware generation asks the same question: can we combine two metals in one part — copper for conductivity, aluminum for weight, titanium for strength — without the joint becoming the weakest link?

Ask a manufacturing engineer how they join two overlapping aluminum sheets, and the answer is usually one of two things: resistance spot welding (RSW) or self-piercing rivets (SPR). Both work. Both also carry costs that product designers have learned to live with — until a solid-state alternative called refill friction stir spot welding (RFSSW) matured into mass production.

Modern battery trays are a metallurgy puzzle wearing a structural role. The tray must be light, crash-stiff, leak-manageable, and cheap — so designers mix material forms: die-cast nodes and bosses for complex geometry, extruded profiles for rails and frame members, and rolled plate for covers. Each form is easy to make alone. Joining them is the problem, and a recent bus battery tray program shows how one manufacturer solved it.

Most cold plate quality disputes trace back to the same root cause: the buyer and supplier never agreed on what "good" means, in test terms. A liquid cold plate can pass a visual check and still fail in the field — clogged channels, creep leakage at a pulse-loaded seam, or a heat-absorbing surface that is out of flatness. Here is the test matrix that serious manufacturers and serious buyers use to align expectations, item by item.

For most of computing history, "thermal management" meant fans. Air cooling defined the shape of servers, the layout of data centers, and the limits of every processor design. That era is ending. AI rack densities that once would have been measured in kilowatts are now quoted in multiples of 100 kW, and no quantity of fans can move that heat out of a rack economically. The industry's answer is direct-to-chip liquid cooling — and its rise is quietly rebuilding a supply chain around a component most data center buyers had never sourced before: the liquid cold plate.

Friction stir welding has a paradox at its center. The physics — a rotating tool that plasticizes and forges metal without melting it — is elegant, widely published, and more than three decades old. The equipment is now sold by several vendors worldwide. Yet weld outcomes between two suppliers running identical machines on identical alloys can differ by a wide margin. The variable that explains most of the gap is the smallest, least glamorous part of the system: the stirring tool itself.

The humanoid robot boom is usually told in terms of AI: control policies, dexterity benchmarks, foundation models. Less discussed is the mechanical bill of materials — and the fact that a humanoid's performance ceiling is set substantially by its joints. A robot that must run, reach, and recover from disturbance needs knee and elbow structures that are simultaneously light, strong, precisely finished, and able to survive millions of load cycles. Meeting all four at once is a manufacturing problem before it is a robotics problem.