ABS Mold Vent Depth

In ABS (Acrylonitrile-Butadiene-Styrene) injection molding, mold vent system design directly impacts product quality, molding efficiency and mold lifespan. As a core parameter, vent depth must precisely match ABS material properties and molding process requirements. Insufficient depth traps cavity gas, causing burns, short shots and flow marks; excessive depth leads to flash and burrs, increasing post-processing costs. This guide details the optimal vent depth range, influencing factors and design essentials based on ABS molding characteristics.

I. Optimal Vent Depth Range for ABS Molds

ABS melt has moderate viscosity and flowability, with no corrosive gas emission during molding. The baseline vent depth ranges from 0.01–0.03mm, adjustable by product structure, molding area and ABS type:

General cavity areas (non-critical surfaces, non-thin walls): 0.02–0.03mm, balancing gas exhaust efficiency and flash prevention.

Critical surfaces & thin-walled sections (wall thickness ≤1.5mm): 0.01–0.015mm, avoiding melt overflow under high pressure.

Sprue, runner & gate areas (gas-concentrated zones): 0.03–0.04mm to accelerate gas discharge, paired with 8–15mm width vents to prevent local flash.

Glass fiber-reinforced ABS (10%–30% GF): 0.01–0.02mm (0.005–0.01mm shallower than standard ABS), reducing fiber accumulation at vents.

II. Key Factors Affecting Vent Depth

1. ABS Material Properties

Higher MFR (melt flow rate ≥20g/10min) requires shallower vents (≤0.02mm); lower MFR (≤5g/10min) allows 0.025–0.03mm depth. Modified ABS (flame-retardant/weather-resistant grades) needs 0.005mm deeper vents to expel additive volatiles.

2. Molding Process Parameters

High injection pressure (≥120MPa) or fast filling speed: reduce vent depth by 0.005–0.01mm to prevent flash.

High mold temperature (≥70℃): shallower vents; low temperature (≤50℃): slightly deeper vents to ensure smooth gas exhaust.

3. Product Structure & Dimensions

Complex, corner-rich or enclosed cavities need 0.025–0.03mm vents at gas traps. Large products (projected area >500cm²) adopt multi-stage vents (0.03mm at inlet, tapering to 0.02mm at outlet) to avoid full-length deep vents causing flash.

III. Practical Vent Depth Design Tips

Vent Slot Configuration: Match depth with width (5–20mm: 8–15mm for general areas, 5–8mm for critical zones) and length (10–30mm). Vents run along melt flow direction, extending outside the mold, with rounded edges (R0.1–0.2mm) to prevent product scratches.

Parting Line Venting: Use parting line gaps as vents, with 0.01–0.03mm gaps only at gas-concentrated areas; non-vent zones maintain ≤0.005mm gaps. Auxiliary venting via ejector pin clearances (0.01–0.02mm) works for complex products.

Trial Molding Optimization: If burns/flow marks occur, deepen vents by 0.005–0.01mm per adjustment; if flash appears, reduce depth. Install adjustable inserts for mass production molds to fine-tune vent depth per process fluctuations.

IV. Common Issues & Solutions

Flow marks/poor gloss: Insufficient vent depth → deepen by 0.005–0.01mm or add more vents.

Edge flash/burrs: Excessive depth or wide vents → reduce depth, narrow vents (≤8mm for critical zones) or add flash traps at vent outlets.

Gate burns/discoloration: Gas trapped at gates → deepen vents to 0.03–0.04mm, widen slots and lower molding temperature (200–250℃ for ABS).

Clogged vents (reinforced ABS): Excessive depth causing fiber buildup → reduce depth to 0.01–0.02mm, clean vents frequently or use narrow-deep slots (5mm width, 0.02mm depth).

V. Conclusion

ABS mold vent depth design follows the principle of "precision matching and synergistic optimization", with 0.01–0.03mm as the baseline. Adjustments based on ABS type, product structure and molding process, combined with proper slot dimensions and auxiliary venting, ensure efficient gas exhaust without flash. Trial molding and parameter fine-tuning further enhance vent system stability, guaranteeing product quality and production efficiency.