The manufacture of a sintered wick copper heat pipe involves eleven discrete production steps, each of which directly determines the thermal performance and service lifetime of the finished product. This article provides a systematic engineering overview of the complete production sequence, with particular attention to the process parameters at each step that most significantly affect final heat pipe quality.
Step 1 — Automatic Pipe Cutting (±0.10mm, 1,500 pcs/hr)
The production sequence begins with cutting copper tube stock to the specified heat pipe length. Cutting tolerance of ±0.10mm is the production standard for sintered wick heat pipes. Burr-free chipless cutting is essential — any copper burr will contaminate the wick powder filling at Step 3 and create a nucleation site for NCG bubble formation in the finished heat pipe.
Step 2 — Pipe Shrinking
The degassing end of the heat pipe is shrunk to form the geometry required for the water injection process at Step 5. Shrinking precision determines the sealing quality — an inconsistently formed degassing end creates variable seal geometry that leads to micro-leaks detectable only at the helium leak test stage (Step 10), after significant production value has already been added.
Step 3 — Copper Powder Filling (4,000 pcs/hr)
Copper powder is filled into the annular space between the centre mandrel and the tube wall. This step determines sintered wick wall thickness (≥0.4mm standard), powder packing density, and circumferential coverage uniformity — all of which directly determine the wick's capillary pumping force and Qmax after sintering. A post-fill 180-degree tube flip ensures complete wall coverage without powder voids.
Step 4 — Vacuum Sintering (850–1,000°C, ±5°C)
The powder-filled tubes are sintered at 850–1,000°C, bonding the copper powder particles to each other and to the tube wall to form the permanent porous wick structure. Temperature uniformity of ±5°C is critical — hot spots cause over-growth that reduces wick porosity; cold spots produce insufficient bonding and a mechanically weak wick structure.
Step 5 — Vacuum Degassing and Water Injection (10⁻³ torr, ±0.05g)
The sintered tube is evacuated to 10⁻³ torr to remove NCG, then charged with a precisely measured volume of ultra-pure water (±0.05g accuracy). Ice-water immersion throughout both phases suppresses water vapour pressure, preventing suck-back and protecting fill volume accuracy. This step sets the working fluid fill ratio that determines whether the finished heat pipe operates at its designed Qmax.
Steps 6–11 — Welding, Hot Press, Bending, Straightening, Leak Test, Performance Test
Permanent sealing by automatic welding (550 pcs/hr), flat section forming by hot press (±0.05mm, 15-tonne), 3D geometry forming by automatic bending (99% yield), straightening (±0.2mm, 1,000 pcs/hr), helium leak testing (1,000 pcs/hr), and final performance verification measuring Qmax and thermal resistance via LabView at 240 pcs/hr.
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Written by
CoolingThermal Engineering TeamCoolingThermal is an automation equipment manufacturer based in Kunshan, China, specializing in heat pipe and vapor chamber production equipment since 2017. Our engineering team designs, builds, and commissions complete production lines covering forming, degassing, welding, testing, and assembly processes. The technical content on this blog is written by the same team that develops the equipment — based on real production experience, not secondary research.
