What is Axis of rotation?

The axis of rotation is a fundamental concept in the design of plastic parts that require movement or symmetry around a central point. Geometrically, it refers to the imaginary line around which an object rotates or exhibits rotational symmetry. In the field of plastic injection molding, this axis is especially relevant in components that form part of mechanical systems, moving assemblies, or circular structures such as gears, threaded caps, shafts, valves, or symmetrical parts.

During the design phase, correctly identifying the axis of rotation allows for optimized functionality and manufacturing. When a part is intended to rotate around an axis—either to perform a mechanical function or to ensure proper assembly—precise definition of this axis ensures that the component operates as intended without excessive friction, premature wear, or functional failure.

In injection molding, considering the axis of rotation leads to more efficient mold design. For instance, in cylindrical or radially symmetrical parts, mold cavities can be designed to allow balanced material injection. This improves fill quality, reduces internal stresses, and prevents warping. Symmetry can also simplify demolding, enabling easier mold opening or automated rotary ejection systems.

The axis is also critical in parts that require tight tolerances in rotational movement. Any misalignment in the mold relative to the axis of rotation can result in functional mismatches, vibrations, or even failure during use. For this reason, both CAD design and mold manufacturing include dimensional verification methods to ensure perfect alignment of the axis with the functional elements of the part.

Furthermore, many assembled systems depend on the correct interaction of several parts with independent axes of rotation. In such cases, production repeatability and dimensional consistency are essential to ensure proper system performance without interference or efficiency losses.

At Plásticos Lezo, we carefully analyze each project involving rotating or symmetrical components. Our technical design team works closely with clients to precisely define the axis of rotation and assess how it impacts both performance and molding processes. We also run filling simulations and deformation analysis to validate that the part maintains its geometric integrity after injection and cooling.

When a part rotates during use, it’s also important to consider the type of material and how it behaves under cyclic stress. The axis of rotation becomes the center for load distribution, making it crucial to choose a polymer that resists fatigue, maintains shape, and minimizes friction. In some cases, metal inserts or reinforcements are added near the axis to enhance mechanical performance.

In summary, the axis of rotation is not just a geometric reference—it is a key technical element in the design, manufacturing, and functionality of many plastic parts. Its correct definition and control directly impact product quality, injection process efficiency, and the long-term durability of the component in its real-world application.