Overview of a Rotational Mold

Rotational Cast Aluminum Tooling or Molds

Tooling made from aluminum castings are by far the most common type of rotational molds. They are relatively inexpensive and can be cast, machined, and framed quickly. High quaility castings with low pourousity will produce a wide range of parts with fairly intricate detail, elaborate shapes and patterned finishes. Aluminum tools are well suited to produce air or water tight plastic parts  as well.

Aluminum molds are lightweight, and transfer and dissipate heat well making them ideal for repeated cycles through rotational molding ovens.  Cast tools can be modified after they have been put into production to accommodate slight changes to the parts design.

When your part goes into production, there is no substitute for using a quality mold. A poorly designed or built tool will inevitably lead to slower production runs and mold failure ad lost production time. Sterling Technologies will guide you through the process to ensure you select the right tool for your application.

Below is an overview of a typical tow cavity rotational tool.

This is a two cavity rotational mold producing a large, patterned rain barrel. It’s components include:

Aluminum Cavity
The cast aluminum cavity is built with three sides. In this particular tool, the sides are formed with one seam and the top forms a seam just below the lip of the barrel. This design produces a seam-free top.

Interior Finish
Each mold has a specific texture inside. This ranges from a highly polished, smooth surface to a deep patterned texture which forms the parts surface.

Steel Framework
These molds are filled repeatedly throughout the production run. A steel tube frame provides the structure to fasten the sides of the mold together creating a tight clean seal.

Bolted Fasteners
The steel frame contains regularly spaced spring-loaded fasteners, normally 6 to 8-inch harden steel bolts, to securely close the cavity during the molding cycle. Torque-limited power tools are used to carefully open and close the mold.

Alignment Tracks
Some mold components require precise alignment to ensure a clean seal and to improve cycle times. This mold used a track and wheel design to slide the top of the mold into exact alignment.  

Platform
The framework is welded to a steel platform. This allows the rotational mold to be clamped onto to the machine’s arm so they can rotate freely without obstruction.

Crain Hooks
Each mold will have four even spaced hooks to easily position the mold onto the machine arm.