OEM Rotomold Storage Tank Molds

A roto mold tank is a hollow plastic storage vessel produced through the rotational molding process, where powdered plastic resin is loaded into a closed aluminum mold that is heated and rotated simultaneously. This produces seamless, uniform-walled tanks ideal for storing water, chemicals, and other materials. The quality of the aluminum mold directly determines the tank's surface finish, wall consistency, and durability.

Rotational moulded polyethylene water storage tanks are commonly governed by standards such as ASTM D1998 in North America, which specifies requirements for polyethylene upright storage tanks. Additional standards may apply depending on the application, including NSF/ANSI 61 for potable water contact. Mold manufacturers like Rotocast Technologies engineer tooling to support compliance with these dimensional and quality benchmarks.

A356.2 grade aluminum alloy is widely regarded as the superior choice for rotational mold tooling. It offers greater elongation, higher tensile strength, and considerably higher ductility compared to standard aluminum grades. These properties allow for thinner walls, better heat transfer, longer mold life, and resistance to the thermal cycling stresses inherent in the rotational molding process.

Cast aluminum rotational molds typically feature wall thicknesses ranging from 1/4 inch to 3/8 inch. This thin-wall design is intentional — it minimizes the thermal mass of the mold, enabling faster heat-up and cool-down cycles. Rotocast Technologies' in-house foundry specializes in maintaining uniform wall thickness throughout complex geometries to ensure consistent and efficient heat transfer during production.

Rotocast Technologies offers a wide range of surface finishing options to meet diverse product requirements, including shot peened, sandblasted textures, acid etching, hand-polished surfaces from light hand-sand to mirror polish, and Teflon coating. The interior surface finish of the mold directly impacts the exterior appearance and texture of the finished rotomolded part or storage tank.

Yes, rotational molds can be repaired and modified by experienced foundry professionals. Rotocast Technologies provides expert mold rebuilding, repair, and modification services to extend the productive life of existing tooling. This is a cost-effective alternative to full mold replacement and allows manufacturers to adapt molds to new product specifications or restore worn tooling to original performance standards.