Automotive A-Pillar PP+TPV Two Color Injection Mould

Automotive sealing components often require different material properties within a single part. The structural section needs sufficient rigidity and dimensional stability, while the sealing area requires flexibility to achieve proper contact and sealing performance.

For this automotive A-pillar sealing component, Focare Mould developed a two color injection mould using PP + TPV, combining the rigid PP structure and flexible TPV sealing section in one molded component.

PP + TPV Two Color Overmolding

The product uses two different materials:

PP (Polypropylene) provides the main structural body, while TPV (Thermoplastic Vulcanizate) forms the flexible sealing section.

The key challenge in this type of automotive two color injection mould is controlling the interface between the two materials.

The mould must maintain accurate positioning between the first and second injection stages so that the TPV can be overmolded consistently onto the PP structure.

Proper control of material shrinkage, product positioning and the PP/TPV bonding area is therefore critical to the final part quality.

6-Point Valve Gate System

According to this project specification, both materials use independent multi-point valve gate systems:

>PP: 6-point valve gate

>TPV: 6-point valve gate

For a long automotive component measuring approximately 763 × 113 × 151 mm, balanced filling is especially important.

The multi-point valve gate arrangement helps control the melt flow over the long part geometry and provides greater control over the filling sequence of both materials.

Gate positioning must also consider weld lines, surface quality, pressure distribution and the interface between the PP and TPV sections.

Material Shrinkage Control

PP and TPV have different shrinkage behavior.

For this project, the specified shrinkage ranges are:

1.PP: 1.1–1.3%

2.TPV transverse direction: 1.1–1.4%

3.TPV longitudinal direction: 1.1–1.4%

Because two materials are combined into one automotive component, shrinkage cannot be considered independently.

The mould design must take into account the dimensional relationship between the rigid PP section and flexible TPV section to reduce the risk of deformation, mismatch and dimensional variation after molding.

718H Steel for Automotive Mould Manufacturing

The project specifies 718H steel with a hardness of HRC 30–33.

For a large automotive mould with a long sealing component, mould precision is important not only for the external product dimensions but also for the positioning between the PP and TPV molding areas.

Accurate machining and assembly help maintain stable part geometry and repeatable two material molding during production.

Left and Right A-Pillar Components

The project includes left and right A-pillar sealing components.

For automotive parts, maintaining dimensional consistency between the corresponding left and right components is important for downstream assembly.

During mould development, Focare considers part geometry, material shrinkage, gate layout, two material positioning and production stability as part of the complete mould engineering process.

Automotive Plastic Injection Mould Manufacturer in China

Focare Mould is a plastic injection mold maker in China with experience in automotive plastic parts, large injection moulds and two color injection moulding with rigid + soft material combinations.

Our capabilities include:

1.Automotive plastic injection moulds

2.PP + TPV two color moulds

3.PP + TPE overmolding moulds

4.Large plastic part moulds

5.Multi-point valve gate systems

6.Left and right automotive component moulds

7.Custom two color injection mould development

From product analysis and DFM to mould design, manufacturing, assembly and mould trial, Focare provides customized injection mould solutions according to the customer's product and production requirements.

Looking for an automotive plastic injection mold maker in China?
Send us your 2D/3D product data, material specification, annual production requirement and injection machine information for mould evaluation.

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