Automobile Door Panel Mold

I. Products and Materials

Typical dimensions: approximately 800–1200 mm (length × width), depth 100–150 mm, wall thickness 2.5–3.0 mm.

Common materials:

• PP + EPDM/T20: Good toughness, low cost, shrinkage rate approximately 1.011–1.018.
• ABS/PC + ABS: High rigidity, excellent surface quality, shrinkage rate approximately 1.006–1.010.
• Appearance requirements: Uniform texture (Ra 0.8–1.6 μm), no weld marks, shrinkage marks, gate marks, and a demolding slope of ≥ 5° (on the appearance surface).

II. Mold Structure Design

1. Mold base and materials

o Mold base: Standard large mold base (such as H13, P20), integral A/B plates, ensuring rigidity and precision.

o Cavity/core: S136 or NAK80, pre-hardened to HRC 48–52, surface polished to Ra≤0.2 μm. 

 

2. Gate System

o Hot runner + sequence valve control: 8–12 hot nozzles, distributed according to the flow gradient to ensure balanced filling.

o Gate: Fan-shaped gate or lapped side gate, hidden on the non-visible surface to avoid marks.

o Runner: Diameter φ8–10 mm, circular cross-section, polished to Ra 0.2 μm, pressure loss ≤ 15 MPa.

 

3. Cooling System

o Conformal water channels: Diameter φ12–14 mm, spacing 20–30 mm, close to the cavity surface, ensuring a temperature difference of ≤±2 ℃.

o Bell-shaped mesh / rib area: Use water-blocking plates or special-shaped water channels to prevent local overheating and deformation. 

 

4. Core-pulling and Ejection Mechanism

o Sliders (side cores): For undercuts such as window frames and handrails, with a stroke of 25–35 mm and an angle of 12°–18°, hydraulically driven and nitrogen gas locked.

o Rockers: For inner latches and grooves, with an angle of 8°–12°, guided by wear-resistant plates to prevent jamming and flash.

o Ejection system: Consisting of ejector blocks, ejector pins, and rockers, with 4–6 nitrogen gas springs for ejection to ensure uniform force and no deformation.

 

5. Guidance and Positioning

Square guide pins + taper positioning: 10° taper around the four sides of the A/B plates, with wear-resistant blocks to prevent mold expansion and misalignment.

Hot runner protection: The guide pins are 20 mm or more above the hot nozzle to avoid installation damage.

 

III. Key Technical Points

Appearance Quality Control

Elimination of weld lines: Sequential valve hot runner, controlling the injection sequence to move the weld lines to non-visible surfaces.

Uniformity of texture: Consistent etching depth, surface hardness ≥ HRC 48, gloss difference < 3% after 100,000 pieces in mass production.

Venting optimization: Open vent slots (0.02–0.03 mm deep) at parting lines, sliders, and inclined cores to prevent burning and short shots.

 

Deformation Control

Shrinkage compensation: Compensate differentially by area (e.g., 1.016 for textured surfaces, 1.020 for snap-fit holes).

Cooling balance: Optimize water channels through mold flow analysis to ensure uniform cooling and reduce internal stress.

Ejection balance: Use multi-point synchronized ejection to prevent excessive local force and warpage.

 

Life and Maintenance

Surface treatment: Hard chrome or nano-coating on the cavity to enhance wear resistance and corrosion resistance, with a lifespan of ≥ 1.2 million mold cycles.

Wear parts: Sliders, inclined cores, and inserts are designed to be detachable for easy replacement and maintenance.

 

 

IV. Typical Parameters

project	parameter
Mold size	About 1800×1200×800 mm
molding cycle	25–35 s
injection pressure	120–150 MPa
clamping force	2500–3500 kN
mold temperature	40–60 ℃(PP)/60–80 ℃(ABS)

 

 

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