Technical Guide5 min read

Venting Through Rectangular Ejector Blades: Flow Area Calculation

Key Takeaway: Rectangular gas release blades provide 3–5× more venting area than round gas release pins of equivalent cross-section. For a 4×2mm blade with dual flat-cut venting, the venting area is approximately 2.5 mm².

Venting Area Calculation

Venting area for a rectangular blade: A_vent = groove_depth × groove_width × number_of_grooves. For flat-cut designs, the groove width equals the blade width. Standard groove depths: 0.02mm (low vent), 0.03mm (medium), 0.05mm (high).

Blade Size	Single Groove	Dual Groove	Equivalent Round Pins
2×1mm	0.06 mm²	0.12 mm²	~2 ø2mm round gas pins
4×2mm	0.12 mm²	0.24 mm²	~4 ø3mm round gas pins
6×3mm	0.18 mm²	0.36 mm²	~6 ø3mm round gas pins
8×4mm	0.24 mm²	0.48 mm²	~8 ø3mm round gas pins

Frequently Asked Questions

Can groove depth be specified independently on each side?+

Standard gas release blades have symmetrical grooves (same depth on both flat sides). Asymmetric groove depths are available as special orders — useful when one side faces the cavity (needs venting) and the other faces the core (less critical).

How often should gas release blade grooves be cleaned?+

Clean every 100,000 cycles using ultrasonic cleaning. For gas-sensitive resins (POM, PVC), clean every 50,000 cycles. Clogged grooves reduce venting effectiveness progressively.