{"id":1222,"date":"2026-08-18T08:28:49","date_gmt":"2026-08-18T08:28:49","guid":{"rendered":"https:\/\/ever-powers.com\/?p=1222"},"modified":"2026-08-18T08:36:21","modified_gmt":"2026-08-18T08:36:21","slug":"csd-vs-still-water-bottle-blow-molding-machine-specs","status":"publish","type":"post","link":"https:\/\/ever-powers.com\/ar\/application\/csd-vs-still-water-bottle-blow-molding-machine-specs\/","title":{"rendered":"CSD vs Still Water Bottles: Pressure Requirements and Machine Specifications"},"content":{"rendered":"

A carbonated soft drink (CSD) bottle and a still water bottle share the same resin, the same blow molding process, and often the same filling line. The machine settings, preform design, and container geometry that produce an acceptable still water bottle will produce a failing CSD bottle. Internal carbonation pressure \u2014 typically 3.5\u20134.5 bar at 20\u00b0C for cola formats, rising to 6.5 bar under thermal abuse conditions \u2014 imposes structural demands that still water bottles do not face. Every machine parameter that affects biaxial orientation, base geometry, and sidewall stiffness has a direct consequence for CSD bottle pressure integrity.<\/p>\n

\"Structural<\/p>\n

\n

The Structural Engineering Difference Between CSD and Still Water Containers<\/h2>\n<\/div>\n

A still water bottle operates at atmospheric pressure after filling and capping. Its structural requirements \u2014 top-load resistance for stacking, drop-test integrity, and label panel flatness \u2014 are set by distribution and retail display demands. A CSD bottle operates as a pressure vessel from the moment of carbonation to the moment the consumer opens it. The container must contain internal pressure without permanent deformation (creep), without loss of dissolved CO\u2082 (permeation), and without failure under thermal excursion (storage in a hot vehicle, for example).<\/p>\n\n\n\n\n\n\n\n\n\n\n
Design Parameter<\/th>\nStill Water Bottle<\/th>\nCSD Bottle<\/th>\n<\/tr>\n<\/thead>\n
Internal pressure at fill (20\u00b0C)<\/td>\n~0 bar (atmospheric)<\/td>\n3.5\u20134.5 bar<\/td>\n<\/tr>\n
Thermal abuse pressure (38\u00b0C, direct sun)<\/td>\nNot applicable<\/td>\nUp to 6.5 bar<\/td>\n<\/tr>\n
Base geometry<\/td>\nFlat or slight dome \u2014 optimized for stability and material saving<\/td>\nPetaloid (5- or 6-foot) \u2014 distributes hoop stress at base radius<\/td>\n<\/tr>\n
Recommended wall thickness (body)<\/td>\n0.22\u20130.28mm (lightweight design)<\/td>\n0.28\u20130.38mm (pressure-grade)<\/td>\n<\/tr>\n
Hoop stress at 4.5 bar (500ml, 65mm body \u00d8)<\/td>\nNot relevant<\/td>\n~7.3 MPa \u2014 within oriented PET strength envelope only if SRh<\/sub> \u2265 3.5\u00d7<\/td>\n<\/tr>\n
CO\u2082 permeability requirement<\/td>\nNot applicable<\/td>\nCO\u2082 loss \u2264 15% over shelf life (typically 6\u20139 months)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

Engineering consequence:<\/strong> The hoop stress at 4.5 bar internal pressure in a 500ml CSD bottle (65mm body diameter, 0.30mm wall) reaches approximately 7.3 MPa. Biaxially oriented PET has a yield strength of 140\u2013160 MPa in the hoop direction \u2014 well above this stress. But only if the hoop stretch ratio (SRh<\/sub>) is \u2265 3.5\u00d7 and the conditioning temperature was correct during blowing. Under-conditioned PET (low SRh<\/sub>, insufficient orientation) has a hoop strength of 50\u201380 MPa \u2014 below the failure threshold at thermal abuse pressure. The blow molding machine’s conditioning accuracy is therefore a structural safety parameter for CSD bottles, not merely a quality parameter.<\/p>\n<\/div>\n

<\/p>\n

\n

Blow Pressure Specification: Why CSD Bottles Need 35 kg\/cm\u00b2 vs 26 kg\/cm\u00b2 for Still Water<\/h2>\n<\/div>\n

Main blow pressure serves two functions: it inflates the preform to the mold cavity dimensions, and it forces the oriented PET against the mold surface to replicate fine surface detail and achieve dimensional accuracy. For still water bottles, 26\u201330 kg\/cm\u00b2 is sufficient \u2014 the smooth wall geometry does not require high surface-forming pressure, and the lightweight wall thickness (0.22\u20130.28mm) does not resist inflation at lower pressure. For CSD bottles, the petaloid base geometry demands higher pressure.<\/p>\n\n\n\n\n\n\n\n
Pressure Zone<\/th>\nStill Water Bottle<\/th>\nCSD Bottle<\/th>\nReason for Difference<\/th>\n<\/tr>\n<\/thead>\n
Pre-blow pressure<\/td>\n6\u20138 kg\/cm\u00b2<\/td>\n8\u201312 kg\/cm\u00b2<\/td>\nCSD preform wall is thicker \u2014 needs higher pre-blow to initiate inflation against greater resistance<\/td>\n<\/tr>\n
Main blow pressure<\/td>\n26\u201330 kg\/cm\u00b2<\/td>\n32\u201335 kg\/cm\u00b2<\/td>\nPetaloid foot geometry requires higher pressure to fully form the 5\u20136 foot radii and ensure no short-shot at foot tips<\/td>\n<\/tr>\n
Blow-hold duration<\/td>\n0.8\u20131.2s<\/td>\n1.2\u20131.8s<\/td>\nThicker CSD wall requires longer hold to cool below Tg before mold opening \u2014 prevents springback at petaloid feet<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

Compressor implication:<\/strong> Upgrading a still water line to CSD production requires verifying that the high-pressure compressor can deliver 35 kg\/cm\u00b2 \u2014 not just 26\u201330 kg\/cm\u00b2. Most compressors specified for still water production are rated at 30 bar maximum working pressure. Running at 35 kg\/cm\u00b2 on a 30 bar compressor exceeds the pressure vessel rating. This is a safety and insurance issue, not merely a performance issue. Confirm compressor rated pressure before switching a still water machine to CSD production.<\/p>\n<\/div>\n

<\/p>\n

\n

Petaloid Base Formation: The Machine Parameter That CSD Bottle Quality Depends On<\/h2>\n<\/div>\n

The petaloid base \u2014 the multi-footed hemispherical structure that replaces the flat base of a still water bottle \u2014 is the most mechanically demanding zone of a CSD container. It must resist radial creep under sustained internal pressure (a phenomenon called base rollout or base peaking), survive the drop-test impact at the foot tips, and maintain stable standing geometry so the filled bottle does not rock on a flat surface.<\/p>\n

Three machine parameters directly govern petaloid base quality:<\/p>\n\n\n\n
\n\n\n\n\n
\n
1<\/div>\n<\/td>\n
\n
Stretch Rod Bottom-Contact Timing<\/div>\n
The stretch rod must contact the preform base and establish full axial tension before main blow pressure is applied. If main blow fires before the rod reaches the preform base, the base zone inflates as a dome \u2014 material distributes to the dome surface instead of flowing into the petaloid foot geometry. Result: short-shot feet with wall thickness below 1.0mm at the foot tip. Standard correct setting: rod bottom-contact confirmed (via servo position encoder) \u2192 5\u201315ms delay \u2192 main blow trigger.<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n
\n\n\n\n\n
\n
2<\/div>\n<\/td>\n
\n
Base Zone Conditioning Temperature<\/div>\n
The preform gate zone must be conditioned to 108\u2013115\u00b0C surface temperature for CSD bottle production \u2014 8\u201312\u00b0C higher than the same zone for still water bottles. The gate zone feeds material to the petaloid foot geometry; if it is under-conditioned, the material does not flow into the foot cavities under blow pressure and the foot tips are underweight. On the HGA JS-series, the base zone IR lamp output is independently adjustable in 1% increments \u2014 set 12\u201318% above the body zone for CSD production vs 10\u201315% above for still water.<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n
\n\n\n\n
\n
3<\/div>\n<\/td>\n
\n
Cooling Dwell Time at Petaloid Base Mold Insert<\/div>\n
The petaloid base mold insert must have dedicated cooling channels within 8\u201310mm of the foot surfaces. Cooling water flow rate at the base insert: minimum 15 ltr\/min (dedicated circuit from the main 60 ltr\/min supply). Insufficient cooling of the base insert allows the foot geometry to warm above Tg during the blow-hold dwell \u2014 the foot wall remains plastic and springbacks when the mold opens, producing foot heights that are shorter than the mold geometry specifies. This shows in production as rocking on a flat surface \u2014 a standard quality check for CSD bottles that can be done in-line on a light table.<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\"Molding

Molding and Quality Control of Five-Petal Flower Bases<\/p><\/div>\n

<\/p>\n

\n

CO\u2082 Permeation and Biaxial Orientation: The Machine’s Role in Shelf Life<\/h2>\n<\/div>\n

Carbon dioxide molecules permeate through PET via a solution-diffusion mechanism \u2014 they dissolve into the PET matrix on the high-pressure (inside) face and diffuse through the wall to the low-pressure (outside) face. Biaxial orientation reduces CO\u2082 permeability by two mechanisms: it increases PET crystallinity (oriented chains pack more tightly, reducing free volume), and it creates a more tortuous diffusion path for CO\u2082 molecules through the oriented amorphous zones.<\/p>\n\n\n\n\n\n\n\n\n
Orientation Level<\/th>\nPlanar Stretch Ratio<\/th>\nCO\u2082 Permeability (relative)<\/th>\nShelf Life Impact<\/th>\n<\/tr>\n<\/thead>\n
Under-oriented (defect)<\/td>\n< 5\u00d7<\/td>\n1.8\u20132.4\u00d7 baseline<\/td>\nCO\u2082 loss \u2265 25% at 6 months<\/td>\n<\/tr>\n
Marginal orientation<\/td>\n5\u20138\u00d7<\/td>\n1.2\u20131.5\u00d7 baseline<\/td>\nCO\u2082 loss 15\u201320% at 6 months<\/td>\n<\/tr>\n
Target orientation (CSD grade)<\/td>\n8\u201312\u00d7<\/td>\n1.0\u00d7 baseline<\/td>\nCO\u2082 loss \u2264 12% at 6 months \u2713<\/td>\n<\/tr>\n
High orientation<\/td>\n> 12\u00d7<\/td>\n0.7\u20130.85\u00d7 baseline<\/td>\nCO\u2082 loss \u2264 8% at 9 months \u2014 marginal gain vs stress-cracking risk at SR > 14\u00d7<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The machine controls achieved orientation through conditioning temperature uniformity and blow pressure timing. On a JS-series machine with 10-zone independent IR conditioning, the body zone temperature uniformity of \u00b13\u00b0C around the circumference ensures that orientation is consistent across all points on the bottle surface \u2014 preventing zones of low local orientation that would become CO\u2082 permeation hotspots in the finished CSD bottle.<\/p>\n

<\/p>\n

\n

\u0627\u0644\u0623\u0633\u0626\u0644\u0629 \u0627\u0644\u0634\u0627\u0626\u0639\u0629<\/h2>\n<\/div>\n
\n\u25b6 \u00a0Can the same mold set be used for both CSD and still water bottle production by changing machine parameters?<\/summary>\n
No \u2014 the mold geometry itself is different. A CSD bottle mold has a petaloid base insert with 5 or 6 foot cavities; a still water bottle mold has a flat or dome base insert. These are physically different tooling components that cannot be swapped via parameter changes. The preform geometry is also different: CSD preforms have a heavier wall (more material for the thicker-wall bottle and petaloid base) than still water preforms of the same volume. If your production mix includes both CSD and still water bottles, plan for dedicated mold sets and dedicated preform specifications for each format \u2014 and confirm that the machine’s clamping stroke accommodates both mold sets before ordering.<\/div>\n<\/details>\n
\n\u25b6 \u00a0What is the base rollout test and how does it relate to machine settings?<\/summary>\n
Base rollout (also called base peaking) is the permanent outward deformation of the petaloid base under sustained internal pressure at elevated temperature. The standard test pressurizes a filled CSD bottle to 4.5 bar and stores it at 38\u00b0C for 24 hours \u2014 simulating thermal abuse in distribution. The base clearance (distance from the lowest point of the base to the supporting surface) must remain above zero (the bottle must still stand flat). Base rollout failure occurs when the petaloid feet soften and creep outward under pressure, reducing base clearance to zero and causing the bottle to rock. Machine-controllable factors that reduce base rollout risk: adequate base zone conditioning temperature (ensures orientation in the foot material); sufficient mold cooling dwell (ensures foot geometry solidifies below Tg before mold opening); and correct blow pressure (ensures full material contact with the petaloid mold geometry for maximum cooling contact area).<\/div>\n<\/details>\n
\n\u25b6 \u00a0Can PET CSD bottles be produced alongside still water bottles on the same machine in the same shift?<\/summary>\n
Yes, with a planned mold changeover between formats. The machine changeover involves: (1) physical mold swap (60\u201390 minutes for a trained 2-person crew); (2) PLC recipe switch from the still water recipe to the CSD recipe \u2014 different blow pressure settings, conditioning zone output map, blow-hold dwell, and stretch rod timing; (3) first-article inspection of 20 CSD bottles including base clearance measurement and CO\u2082 retention check before releasing to production. The PLC stores both recipes separately; recall time after the physical mold change is under 60 seconds. The key constraint is preform: CSD and still water preforms for the same volume class are different specifications \u2014 preform hopper must be emptied and refilled with the correct preform type before running the CSD recipe.<\/div>\n<\/details>\n
\n\u25b6 \u00a0What wall thickness specification is required for a 500ml PET CSD bottle at 4.5 bar carbonation?<\/summary>\n
For a standard 500ml PET CSD bottle (65mm body diameter, target carbonation 4.5 bar): body zone wall thickness 0.28\u20130.33mm; shoulder zone 0.45\u20130.60mm; base petaloid foot tip minimum 1.0mm, foot valley 0.50\u20130.65mm. Total bottle weight typically 27\u201332g for 500ml CSD format, compared to 9\u201312g for an equivalent lightweight still water bottle. The weight difference represents the additional material required to meet pressure containment, base rollout, and drop-test requirements simultaneously. Lightweight CSD bottle development (below 25g for 500ml) is an active area of industry development, but requires validated container designs and typically barrier coating to compensate for the thinner wall’s higher CO\u2082 permeability.<\/div>\n<\/details>\n

<\/p>\n

\n

Switching between CSD and still water on the same line?<\/p>\n

Share your bottle volumes, carbonation levels, and existing compressor rating \u2014 receive a machine configuration assessment and tooling changeover plan from the Ever-Power engineering team.<\/p>\n

View Water & Beverage Bottle Machine Range \u2192<\/a><\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

A carbonated soft drink (CSD) bottle and a still water bottle share the same resin, the same blow molding process, and often the same filling line. The machine settings, preform design, and container geometry that produce an acceptable still water bottle will produce a failing CSD bottle. Internal carbonation pressure \u2014 typically 3.5\u20134.5 bar at […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[43],"tags":[67,66,68],"class_list":["post-1222","post","type-post","status-publish","format-standard","hentry","category-isbm-machine-blog","tag-carbonated-beverage-bottle-machine","tag-csd-bottle-blow-molding","tag-pet-bottle-blow-pressure-specification"],"_links":{"self":[{"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/posts\/1222","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/comments?post=1222"}],"version-history":[{"count":4,"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/posts\/1222\/revisions"}],"predecessor-version":[{"id":1229,"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/posts\/1222\/revisions\/1229"}],"wp:attachment":[{"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/media?parent=1222"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/categories?post=1222"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ever-powers.com\/ar\/wp-json\/wp\/v2\/tags?post=1222"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}