Two Color Storage Basket Mold Case Study

Two color injection molding can give a household storage basket a distinctive appearance without relying only on printing or secondary decoration. In this project, Focare Mould developed a two color storage basket mold for a rectangular basket with a contrasting inner and outer surface, integrated carrying handles and rounded corners.

The engineering work focused on three connected challenges: controlling the color boundary, filling a relatively large basket with handle openings, and managing cooling and deformation across the sidewalls and bottom. This case study explains the confirmed mold configuration and the design considerations behind the project.

Two color storage basket design with contrasting inner and outer surfaces.

Confirmed Project Specifications

• Mold configuration: 1+1 cavities

• Mold steel: 718H

• Steel hardness: HRC 30–33

• Injection system: four-tip hot runner with valve gates

• Mold size: 880 × 590 × 570 mm

The supplied project record does not identify the exact plastic grades or the transfer mechanism used by the two color molding machine. Those details are therefore not assumed in this article. For a new project, material compatibility and machine configuration must be confirmed before the mold concept is finalized.

3D mold structure and storage basket layout for the two color project.

Challenge 1: Positioning and Color-Boundary Control

Unlike a conventional single-color storage basket mold, a two color mold must coordinate two molding stages. The geometry formed in the first stage must remain in the required position for the next stage so that the second color follows the intended boundary.

The white interior and green exterior make the color interface highly visible. Misalignment, unsuitable shut-off conditions or inconsistent processing may lead to color overflow, flash or an irregular transition line. The handle openings and rounded upper rim require additional attention because the two colors meet around features that customers can easily inspect.

For this reason, part positioning, shut-off surfaces and the relationship between the two cavity stages must be reviewed together. The final acceptance standard should define the permitted color boundary and visible surface requirements before trial approval.

Close-up of the color transition around the integrated carrying handle.

Challenge 2: Filling a Large Basket with Handle Openings

A storage basket has a larger molding area than many small household products. Melt flow must reach the sidewalls, bottom, rim and handle regions while maintaining a balanced fill. The handle openings interrupt the wall geometry and may influence flow paths, weld-line locations and local packing behavior.

This project uses a four-tip hot runner with valve gates. The gate arrangement supports controlled melt delivery at the selected locations, but the complete result still depends on the part geometry, material behavior and processing conditions. Gate timing, filling balance, weld-line position, gate appearance and packing-pressure distribution must be evaluated during design and mold trials.

The mold layout also needs to allow practical access for manufacturing and maintenance. A hot-runner concept should be reviewed together with the cavity layout and machine requirements rather than selected as an isolated component.

Challenge 3: Cooling, Shrinkage and Warpage

The broad bottom and long sidewalls of a storage basket can respond differently during cooling. Uneven heat removal or an unbalanced wall-thickness distribution may contribute to sidewall deformation, bottom warpage or dimensional variation.

Cooling-channel layout, wall thickness, local ribs, material shrinkage and ejection support should therefore be considered as a connected system. The objective is not only to cool the part, but to release a basket that retains the intended shape and can be stacked or handled as designed.

Trial parts provide the practical basis for checking the sidewalls, base, rim and handle areas. Any cooling or processing adjustment should be based on measured trial results and the customer's approved dimensional and appearance criteria.

Finished storage baskets showing the long sidewalls and contrasting surfaces.

Mold Structure and 718H Steel

The confirmed mold configuration is 1+1 cavities, supporting the two-stage product structure. The project uses 718H mold steel at HRC 30–33. This pre-hardened steel is commonly considered when a project requires a balance of machinability, dimensional stability and surface-finish capability.

Steel selection for another storage product should not be copied automatically. Expected production volume, plastic material, surface requirements, mold size and maintenance plan all influence the appropriate steel and hardness specification.

At 880 × 590 × 570 mm, the mold also requires suitable injection-machine capacity and installation space. Machine compatibility, tie-bar spacing, shot requirements and the two color production method should be checked using the customer's actual equipment data.

What the Finished Basket Demonstrates

The finished samples show the visual objective of the project: a clean contrasting interior and exterior, integrated handle openings, rounded corners and a stackable household form. These features help differentiate the product, but they also make color alignment, surface quality and shape control important acceptance points.

Two color molding may be considered for storage boxes, baskets, containers, lids and other household products. The choice should be based on product value, required appearance, machine compatibility, expected production volume and tooling investment.

Stacked green and white baskets demonstrating the finished household product form.

Project Review with Focare Mould

For a new two color storage basket mold, please provide the 3D product drawing, selected material grades, color separation, surface requirements, expected output and injection-machine information. Focare Mould can then review the cavity concept, stage positioning, hot-runner arrangement, cooling and ejection approach for the specific project.

As a plastic injection mold maker in China, Focare Mould develops custom household molds, storage container molds and two color injection molds. You can also review the related two color storage basket mold product page for the product-focused overview.

Send your storage product design to Focare Mould for a project-specific mold review and quotation.