Multi-Color-Rotary Axis

Rotary Core Two-Color Injection Mould

Two-color and multi-material handles are widely used for toothbrushes, screwdrivers, knives, razors, tools and other products requiring a combination of rigid and soft-touch materials.

For products where the second material needs to wrap around multiple sides of the first-shot component, a rotary core two-color injection mould can provide an efficient solution for automated 2K injection molding.

Unlike a conventional rotary plate mould, the entire mould does not rotate. Instead, the core carrying the first-shot part rotates or transfers to the second injection position.

How Does a Rotary Core 2K Mould Work?

During the first injection stage, the first material is injected into the first cavity to form the base component.

After the first shot is completed, the injection moulding machine sends a signal to the mould's core rotation mechanism.

The core carrying the first-shot component then rotates to the second injection position. Once accurate positioning and locking are confirmed, the second material is injected around the first component to complete the two-color or multi-material product.

This process allows both materials to be moulded within one automated production cycle.

Rotary Core vs. Rotary Plate Two-Color Mould

The selection between a rotary core mould and a conventional rotary plate two-color mould depends mainly on the product geometry and the location of the second material.

A rotary plate mould is commonly used when the second material is moulded primarily onto one side or a specific surface of the first-shot component.

When the second material needs to wrap around multiple sides of the first-shot component, a rotary core structure can provide greater flexibility.

Typical applications include:

1.Toothbrush handles

2.Screwdriver handles

3.Knife handles

4.Razor handles

5.Tool handles

6.PP + TPE soft-touch handles

This makes rotary core technology particularly suitable for ergonomic handles and overmolded products.

High-Precision Core Rotation

Precision is one of the most important requirements in a rotary core 2K injection mould.

After the first injection, the rotating core must move accurately into the second-shot position. Any positioning error may cause mismatch, flash, interference or damage during the second injection process.

For this reason, the rotation, positioning and locking mechanisms must be carefully designed and manufactured.

Stable core positioning helps maintain a clean boundary between the two materials and ensures consistent product quality during continuous production.

Suitable for Insert & Overmolding Applications

Another advantage of the rotary core structure is its flexibility for products incorporating inserts or overmolded components.

Products such as screwdrivers, knives and certain tool handles may contain metal inserts that need to be combined with rigid plastic and/or soft-touch materials.

A properly designed rotary core mould can integrate these requirements into an efficient injection moulding process while reducing additional handling between separate moulding operations.

Better Two-Color Overmolding Quality

Compared with producing the first and second materials in two completely separate injection processes, an integrated 2K injection mould can provide better positioning accuracy and more consistent overmolding quality.

The first-shot component remains accurately located on the mould core before the second injection, helping reduce positioning variation between the two materials.

For PP + TPE and other hard/soft material combinations, proper product design, material compatibility and mould structure are also important for achieving reliable bonding.

Hot Runner & Production Stability

Depending on the product design and production requirements, hot runner systems can be incorporated into both injection stages.

An optimized runner and gating system can help improve filling balance, reduce runner waste and achieve better gate appearance on two-color products.

Cooling, venting and material flow must also be considered separately for each injection stage because the two materials may have different processing characteristics.

Focare Mould – Two-Color Mould Manufacturing

Focare Mould specializes in two-color, 2K and multi-material injection mould design and manufacturing.

Our experience includes rotary plate, rotary core and other customized two-shot mould structures for household products, handles and multi-material plastic components.

From product analysis and DFM to mould design, machining, assembly and mould trials, our engineering team focuses on:

1.Accurate first-shot and second-shot positioning

2.Reliable rotary core mechanisms

3.Stable overmolding

4.Material compatibility

5.Hot runner and gating design

6.Cooling efficiency

7.Long-term mould reliability

If you are developing a two-color handle, PP + TPE component, overmolded tool or other multi-material plastic product, Focare Mould can evaluate the product structure and recommend a suitable 2K injection mould solution

Why choosing Focare Mould as your work partner?

Brand Strength