Expert guide to blow moulds for carbonated soft drinks, cola, soda and sparkling beverages. Pressure ratings, petaloid base design, wall thickness, machine compatibility.
Carbonated soft drink (CSD) bottles face significantly more demanding performance requirements than still water or juice bottles. The CO2 in carbonated beverages creates internal pressure of 4–6 bar inside the bottle. This pressure stresses the bottle walls, base, and neck — requiring specifically engineered bottle profiles and, by extension, specifically engineered moulds.
Ultra Mould has supplied CSD bottle moulds to beverage manufacturers across India, including producers of cola, lemon soda, orange soda, flavoured sparkling water, and energy drinks. Our CSD moulds are designed to produce bottles that pass the standard drop test (1.2m drop), burst test (>8 bar), and creep test (48-hour pressurisation).
The most distinctive design feature of a CSD bottle is the petaloid (flower-shaped) base. Unlike the flat base of a water bottle, the petaloid base has 5 "petals" — curved feet that distribute the internal pressure stress away from the base corners, preventing base failure. The petaloid geometry is critical to CSD bottle performance and requires very precise machining in the mould.
Our mould design team uses FEA (Finite Element Analysis) to optimise the petaloid geometry for each specific bottle volume and wall thickness, ensuring maximum pressure resistance with minimum material weight. A well-designed petaloid can reduce base failures by 60% compared to a poorly designed one.
💡 Key Fact: A CSD bottle with a flat base would fail at pressures above 3 bar. With a properly designed petaloid base, the same bottle withstands 8+ bar. The mould determines the base geometry — so mould precision directly determines bottle safety.
| Parameter | CSD Mould Standard |
|---|---|
| Burst Pressure Design | >8 bar (double safety factor) |
| Base Type | Petaloid (5-foot standard) |
| Wall Thickness | 0.30–0.40mm (vs 0.23mm for water) |
| Neck Finish | PCO-28 or PCO-38 |
| Cavity Finish | Ra 0.1µm (high-clarity) |
| Base Thickness | 3.5–4.5mm (reinforced) |
| Machine Compat. | Sidel SBO, Krones Contiform, Nissei |
CSD bottles require biaxial orientation (stretching in both directions) to achieve the crystallisation that gives PET its strength at carbonation pressure. The axial stretch ratio (height stretch) should be 2.8–3.2, and the hoop stretch ratio (diameter stretch) should be 3.2–3.8 for optimal CSD performance. Our mould design accounts for these ratios and recommends appropriate preform specifications to match.
Ultra Mould has manufactured CSD bottle moulds for beverage producers across Gujarat, Maharashtra, Rajasthan, Karnataka and Telangana. Contact us for a free design consultation and quote for your CSD project.
Tell us your CSD bottle volume, target weight, and machine brand. We will design the perfect pressure-rated mould.