Large heat sink extrusions usually produced by aluminum material as it has a good melting point and extension character.the dimensions can be customized, anodizing or wash surface treatment are based on consumer's requirement. of course all the ACG products are Rohs products.
Extrude, the extrusion come from the aluminum ingot through the extrusion tooling.
Cross cut, we need to use the machine to cut the length of the extrusion bar.
Etching, to remove the burrs and oil.
CNC, to drill and rremove some fins.
Anodize, black anodized or customized.