Material preparation - Iron is melted along with carbon, silicon, manganese, and other elements. Magnesium is added to transform gray iron into ductile iron with spheroidal graphite structure.

Pattern making - Detailed wooden or metal patterns are created based on design specifications.

Molding - Sand molds are prepared using the patterns. The mold consists of two parts: the cope (upper half) and drag (lower half).

Core setting - If the manhole cover requires hollow sections, sand cores are placed in the mold.

Pouring - The molten ductile iron (typically at 1300-1400°C) is poured into the mold cavity.

Cooling and solidification - The metal is allowed to cool and solidify completely.

Shake-out - The solidified casting is removed from the sand mold.

Cleaning and finishing - Sand residue is removed through shot blasting, and excess metal is ground off.

Heat treatment - The covers undergo heat treatment to achieve desired mechanical properties.

Machining - Contact surfaces are machined to ensure proper fitting.

Inspection - Quality control checks for defects, dimensions, and material properties.

Surface treatment - Covers are typically coated with bitumen or paint for corrosion protection.