How Is A Steel Plate Transformed Into The Water Heater Inner Tank （Cylinder/Tank）——Planishing Machine

The manufacturing process of a water heater inner tank starts with a rectangular steel plate. The plate is first rolled into a cylindrical shape, and then the seam is welded using standard welding processes, typically TIG or MIG. While welding provides structural integrity, it creates raised and uneven weld beads on both the inner and outer surfaces along the welded seam.

At this stage, the planishing machine plays a crucial role. Its primary function is to transform the rough-welded cylindrical surface into a smooth, even inner tank, preparing it for subsequent enamel coating and final assembly. The planishing operation improves the grain structure of the weld, increasing its tensile fatigue strength up to 100% of the base material's strength.

Through customized design of the planishing rolls and mandrel inserts, the machine can accommodate various part shapes, including flat sheets, cylinders, cones, and recessed components.

Planishing machines come in two main configurations:

The workpiece moves during planishing, driven by an upper roll, while the planishing wheel remains stationary.

The planishing wheel moves along the weld via a carriage mechanism while the workpiece remains stationary.

Diameter:

Diameter range: 150-600 mm

Cylinder length: 300-1800 mm

Material thickness: 0.8-3.0 mm

Typical Applications:

Water heaters

Storage tanks

Stainless steel pipe fittings

Chemical processing tanks

Dairy equipment

Stainless steel containers