Blow Molding Die Cap

Blow Molding Die Cap must maintain controlled axial melt flow to prevent deviations in parison thickness. Uneven flow results in asymmetrical bottle walls, particularly with high-MFI materials or complex neck geometries. A high-precision Blow Molding Die Cap ensures uniform die swell by maintaining concentric alignment and optimized annular gap, critical for dimensional repeatability. 

Material Specification

P20, H13, Stainless Steel (420/440C), Aluminum (7075-T6 for prototypes)

Hardness (HRC)

28-32 HRC (P20), 48-52 HRC (H13), 50-54 HRC (Stainless Steel)

Surface Finish (Ra/RMS)

Flow Path – 0.2–0.4 µm, Non-Critical Areas – 0.8–1.6 µm, Mounting Surfaces – 0.4–0.8 µm

Dimensional Tolerances

Critical Dimensions – ±0.025 mm, Profile – ±0.05 mm, Overall Length – ±0.1 mm

Die Cap Profile Geometry

As per 3D CAD Model (STEP/IGES) with ±0.02 mm profile tolerance

Product Description

Excessive flash during blow molding indicates poor sealing or thermal imbalance at the die exit. Blow Molding Die Cap with thermally balanced steel grade and exact surface roughness minimizes flow turbulence at the interface. This reduces downstream material removal, essential in applications demanding high neck-finish tolerance or post-decorative processing. 

Parison Exit Orifice Dimensions

Diameter Tolerance – ±0.05 mm, Concentricity – 0.03 mm TIR, Edge Radius – 0.1–0.3 mm

Cooling Channel Design Cooling Channel Design

Diameter – 8-12 mm, Pitch – 30-50 mm, Position Tolerance – ±0.2 mm, Flow Rate – 5-10 L/min

Mounting/Alignment Features

Bolt Holes – ±0.02 mm, Alignment Pins – H7/g6 fit, Flatness – 0.02 mm/m

Coating/Surface Treatment

Hard Chrome Plating (0.02–0.05 mm), Nitriding, or PTFE Impregnation (for non-stick)

Certification Standard

ISO 9001, FDA Compliance (for food/medical), NADCA #207-2003, ASTM A681 (Tool Steel)

Technical Advantages

Die caps experience repeated exposure to molten polymer at temperatures exceeding 200°C. Blow Molding Die Cap constructed with hardened H13 or ESR-grade tool steel resists scaling and deformation across extended thermal cycles. This metallurgical resilience is essential for high-cavity systems operating under continuous extrusion with abrasive or filled resins. 

Production lines with frequent product variation require modular tooling. Blow Molding Die Cap designed with quick-mount interfaces and repeatable axial positioning ensures fast changeovers without die body re-machining. This capability supports flexible manufacturing systems requiring SKU changes without affecting parison flow uniformity.

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Industry Applications

Automotive Fluid Reservoirs

Used in forming coolant, washer, and brake fluid tanks requiring controlled parison wall thickness and dimensional repeatability. 

Pharmaceutical Bottles

Enables precise neck and thread geometry essential for sealing integrity in sterile liquid packaging and dropper-fitment applications. 

Industrial Chemical Containers

Handles aggressive resin blends for producing corrosion-resistant HDPE drums with uniform wall thickness and minimal flash formation. 

Consumer Beverage Bottles

Maintains neck finish tolerance and clarity during PET extrusion for high-speed bottling lines with carbonation or thermal load demands. 

Household Cleaner Packaging

Supports extrusion of multi-layer parisons with barrier materials to contain volatile compounds in detergent, bleach, and disinfectant packaging. 

Agricultural Pesticide Containers

Provides accurate parison control for large-capacity containers requiring UV-resistant wall thickness and non-reactive threaded neck finishes. 

 

Resin-Specific Surface Interactions

Material compatibility between melt and tooling surface affects flow and thermal behavior. Blow Molding Die Cap with application-specific coatings—such as CrN for barrier polymers or DLC for recycled HDPE—reduces melt hang-up and maintains steady-state thermal transfer. This control enhances parison clarity, surface finish, and overall moldability. 

Structural failure in bottle threads often originates from inconsistent parison preform in the critical neck region. Blow Molding Die Cap configured with tight radial and axial guidance minimizes eccentricity at the parison exit. This ensures that blow-up ratios remain consistent, preventing ovality or distortion in pharmaceutical and closure-sensitive designs. 

Blow Molding Die Cap

Having Doubts? Our FAQ

Check all our Frequently Asked Question

How does Frigate design Blow Molding Die Caps to handle parison sag in large container molds?

Frigate uses computational flow modeling to optimize the die cap profile for large-diameter parisons. This prevents gravitational sag by ensuring uniform axial flow and minimal melt residence time. Special die land geometry is applied to control elongation under extrusion head pressure. This design improves weight distribution and reduces base thinning in large blow-molded containers. 

What material selection strategies does Frigate follow for Blow Molding Die Caps used in high-cycle production?

Frigate selects vacuum heat-treated H13 or ESR tool steel with high thermal fatigue resistance for long production cycles. These materials reduce microcracking from cyclic heat stress. Coatings like CrN or TiCN are applied to prevent erosion and resin adhesion. This extends die cap life and reduces cleaning frequency.

How does Frigate maintain tight tolerances in multi-cavity Blow Molding Die Cap assemblies?

Frigate uses precision CNC machining with digital coordinate measurement verification for each die cap. Axial and radial tolerance is held within ±5 microns across all cavities. This ensures uniform parison extrusion and identical blow-up behavior in every cavity. The result is consistent part dimensions and balanced mold filling. 

 

What steps does Frigate take to reduce melt hang-up in Blow Molding Die Cap for barrier-layer resins?

Frigate uses mirror-polished internal surfaces and optimized die entry angles to eliminate dead zones. Special coatings are applied to reduce surface energy and prevent resin buildup. Flow channels are thermally balanced to avoid cold spots that cause layer separation. These techniques ensure clean separation of layers in co-extruded structures.

How does Frigate ensure compatibility of Blow Molding Die Caps with high-viscosity engineering polymers?

Frigate evaluates shear sensitivity and thermal behavior of engineering polymers like PA and PC before die cap design. The cap is machined with optimized land length to maintain pressure without overheating. High-temperature alloys with stable conductivity are selected to match resin processing windows. This prevents premature cooling and ensures melt homogeneity. 

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LOCATIONS

Global Sales Office

818, Preakness lane, Coppell, Texas, USA – 75019

Registered Office

10-A, First Floor, V.V Complex, Prakash Nagar, Thiruverumbur, Trichy-620013, Tamil Nadu, India.

Operations Office

9/1, Poonthottam Nagar, Ramanandha Nagar, Saravanampatti, Coimbatore-641035, Tamil Nadu, India. ㅤ

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