Sidewall Injection Molding for Lower-Pressure Plastic Totes

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Solution Overview

Problem

Conventional injection molding systems for plastic totes require high clamp tonnage and injection pressure, leading to high stress points on the bottom walls, reduced durability, and degraded thermoplastic properties due to elevated melt temperatures.

Innovation Solution

A side shot injection molding system that injects molten material through the sidewalls of a mold, reducing the need for clamp tonnage and injection pressure, and allowing for lower melt temperatures, resulting in improved part quality and strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If bottom gates are used to supply plastic melt to the entire mold, then the mold can be completely filled, but relatively large amounts of clamp tonnage and injection pressure are required

Engineering Contradiction:

Improvemold filling completenessVSAvoidclamp tonnage and injection pressure

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

The injection system is segmented into multiple sidewall gates distributed around the mold perimeter, replacing the single bottom gate approach. This segmentation allows the mold cavity to be filled through multiple entry points along the sidewalls, reducing the pressure and force required at each individual gate while maintaining complete mold filling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The injection approach transitions from a vertical bottom-up filling method to a horizontal sidewall injection method. By injecting molten material through the sidewalls rather than from the bottom, the system changes the dimensional approach to mold filling, allowing gravity to assist flow and reducing the required clamp tonnage and injection pressure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If elevated melt temperatures are used to reduce viscosity and improve flowability, then injection pressure can be reduced, but thermoplastic physical properties are degraded

Engineering Contradiction:

ImproveflowabilityVSAvoidthermoplastic physical properties

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The system changes the injection parameters by using lower melt temperatures combined with sidewall injection. The sidewall gate configuration allows adequate flowability at lower temperatures due to the shorter fill distances and multiple entry points, thereby maintaining thermoplastic physical properties while achieving complete mold filling.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If bottom gates are used for injection, then the mold can be filled, but high stress points are created on the bottom walls

Engineering Contradiction:

Improvemold fillingVSAvoidstress points on bottom walls

Core Design Contradiction:

Manufacturing precisionVSStress or pressure

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of injecting from the bottom upward, the system inverts the approach by injecting from the sidewalls horizontally into the cavity. This inversion of the injection direction eliminates the concentration of stress on the bottom walls and distributes the filling process along the sidewalls where stress can be better managed.

Inventive Principle:

Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system achieves reduced stress and increased durability of the plastic totes by minimizing clamp tonnage and injection pressure, enabling lower melt temperatures and faster production times while maintaining part quality and strength.

Implementation Method 1

Material for a part is fed into a heated barrel, mixed, and injected into a mold cavity, where it cools and hardens

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

injected into a mold cavity, where it cools and hardens to the configuration of the cavity

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS20250360665A1Injection molding system, method, and tote manufactured therefrom

Publication Date: 2025.11.27 CREATIVE PLASTIC CONCEPTS LLC

AI summary

A storage container manufactured from an injection molding process which includes a mold and at least one injector. The mold has a top surface, a bottom wall, a plurality of side surfaces, and at least two separable sections. Where the at least two separable sections are in a closed position, a cavity is formed in the mold. The at least one injector is disposed through at least one of the plurality of sidewalls, and further disposed into the cavity. The storage container has a plurality of sidewalls, an upper edge, and a bottom surface. At least one of the plurality of sidewalls of the resulting storage container contains at least one sprue mark.