Blow molding:
hollow bodies, technical parts,
high-performance packaging
Jerricans, bottles, PET bottles, multilayer fuel tanks - plastic blow molding covers a huge range of applications. Since 1996, CadNov steers your blow molding projects and guides you to the optimal technology based on your part, your material and your volumes.
What is blow molding?
Plastic blow molding is a process for making hollow bodies: a hot plastic blank (parison or preform) is placed in a mold, then inflated with compressed air until it perfectly matches the cavity walls. After cooling, you get a thin-walled hollow part.
It is the essential process for any hollow plastic body: bottles, jerricans, tanks, cosmetic or pharmaceutical bottles. Each of the 4 variants meets specific requirements of precision, volume and material.
What CadNov brings
CadNov is not a blow molder. We are your design office and integrator: we select the technology suited to your part, write the tooling specifications, choose the material and exact grade, and steer the trials through to quality validation.
Our added value: keeping you from choosing the wrong technology - a mistake that can cost 6 to 12 months of development and tens of thousands of euros of useless tooling.
Which blow molding process to choose?
| Part type | Criterion | Recommended technology |
|---|---|---|
| |-- Technical hollow body (tank, jerrican, auto part)? | Monolayer | EXTRUSION BLOW MOLDING (EBM) |
| Multilayer (fuel, O2 barrier) | CO-EXTRUSION BLOW MOLDING | |
| |-- Bottle with precise neck, controlled thickness, small size (< 500 ml)? | - | INJECTION BLOW MOLDING (IBM) |
| PET bottle drinks, water, CSD | < 5M parts/year | ISBM - 1 stage (single-step) |
| > 5M parts/year | ISBM - 2 stage (stored preform) |
The extrusion screw plasticizes the material and pushes a parison (hot plastic tube) downward. The mold closes around this parison, air is blown in at 4-10 bar - the parison presses against the mold walls. After cooling, the part is ejected and deflashed.
It is the most versatile blow molding technology: it covers volumes from a few centiliters to 200-liter tanks. Two main variants: continuous EBM (small parts, high output) and intermittent EBM with accumulator head (2-200 L tanks).
Extrusion
Parison (hot tube) extruded downward
Closing
Mold closes, pinches the parison
Blowing
Air 4-10 bar inflates the parison
Ejection
Cooling, opening, deflashing
EBM applications and materials
Jerricans, cans, water tanks
Chemical resistance, flexibility, economical. The great classic of industrial blow molding.
Engine-oil tanks, medical
Higher thermal resistance than HDPE, can be translucent, steam-sterilizable.
Automotive technical parts
PA for the fuel barrier and chemical resistance. ABS for rigidity and appearance.
Indicative EBM pricing
Single-cavity aluminum mold for 500 ml bottle: €4,000 - 8,000. Steel mold for 5 L jerrican: €8,000 - 20,000. 30 L auto tank (accumulator head): €40,000 - 120,000. HDPE 500 ml part, 100,000/year run: €0.15 - 0.40/part.
IBM takes place in three successive stations. At the injection station, a preform is injected onto a core rod - which guarantees perfect precision of the threaded neck. At the blowing station, the cores carrying the hot preforms are transferred into the blow mold. At the ejection station, the part is cleanly ejected - no sprue, no flash.
Result: bottles with a perfectly dimensioned neck, uniform wall thickness and no visible weld line at all. The reference technology for premium cosmetic and pharmaceutical packaging.
IBM applications and materials
Pharma bottles, droppers
Chemical resistance, inertness, sterilizable. Medical and pharmaceutical standard.
Luxury cosmetic bottles
Crystal clarity, BPA-free, premium look. PETG for complex shapes.
Shampoo bottles, clear cosmetics
Transparency, rigidity, good blow-molding ability. Moderate cost.
Squeeze bottles
Very flexible, compressible. Eye drops, medical squeeze bottles.
Indicative IBM pricing
3-station tooling (injection + blowing + ejection): €25,000 - 100,000. PP 30 ml bottle, 4 cavities: €30,000 - 60,000. PP 30 ml part price, 500,000/year run: €0.10 - 0.25. Tooling lead time: 12 - 20 weeks.
ISBM adds a decisive step to IBM: mechanical axial stretching simultaneous with radial blowing. This biaxial orientation of PET is what turns a fragile material into a light, transparent wall that resists internal pressure.
Biaxial orientation multiplies internal-pressure resistance by 4 to 6 - which makes it possible to contain CO2 in carbonated-drink bottles with walls of only 0.3 mm. It is the process behind every PET drink bottle in the world.
Injection + blowing in line
Less energy, fast format changeover. Ideal for complex parts, runs of 1M - 50M/year.
Stored preform + dedicated blower
Very high output (80,000+ bottles/h). Runs over 50M/year.
ISBM materials and grades
Water, CSD, juice, oil, cosmetics
IV 0.80 dl/g for still water - IV 0.84-0.86 dl/g for carbonated drinks. Hot-fill grades for hot filling.
Medical bottles, hot food
Stretch T 140-160°C. Sterilizable, resistant. Borealis Daplen, SABIC, Braskem.
Cosmetics, crystal clarity, BPA-free
Stretch T 70-80°C. Exceptional optical clarity, complex shapes possible.
Indicative ISBM pricing
PET 500 ml bottle, 2-stage line: 96-cavity preform mold shared €200,000-400,000 + 2-cavity blow mold €15,000-30,000. Empty bottle price: €0.04-0.10. PET 200 ml cosmetics, 1 stage: tooling €80,000-180,000, part €0.08-0.20.
Co-extrusion blow molding uses several extrusion screws feeding a co-extrusion head - they simultaneously generate a parison with several distinct layers. These layers are blown together in the mold, creating a hollow body where each layer has a precise function.
This is the technology required by fuel-emissions regulations: modern automotive tanks are all multilayer HDPE with an EVOH barrier. There is no other way to meet hydrocarbon anti-emission standards.
Typical structure - Automotive fuel tank (6 layers)
EVOH barrier material - suppliers
Kuraray EVAL (eval.eu) - world leader. EVAL F171B: maximum food O2 barrier. EVAL SP605B: E10 fuel grade. Nippon Gohsei Soarnol (soarnol.com). Tie layers: Arkema Orevac (arkema.com), DuPont Bynel, LyondellBasell Plexar.
Co-extrusion blow molding applications
6-layer fuel tanks
EVOH barrier mandatory. 100% of modern auto tanks are multilayer.
O2 barrier bottles (ketchup, mayo)
5-layer structure HDPE/tie/EVOH/tie/HDPE. Extends shelf life up to 18 months.
AdBlue, washer-fluid tanks
3 to 5 layers depending on fluid aggressiveness. HDPE/EVOH/HDPE for AdBlue (32.5% urea).
Solvent and acid packaging
HDPE/PA/tie/HDPE structures depending on the stored product. UN/ADR certifications for dangerous goods packaging.
Comparison table - 4 blow molding technologies
Each technology has its area of excellence. The right choice depends on the part, the volume and the precision requirements.
| Criterion | EBM | IBM | ISBM | Co-extrusion |
|---|---|---|---|---|
| Principle | Extruded parison | Injected preform | Preform + biaxial stretch | Multilayer parison |
| Neck precision | Medium (deflashing) | Excellent | Excellent | Medium |
| Wall thickness | Variable (PWDS) | Homogeneous | Very homogeneous | Variable |
| Transparency | Good (PVC/PC) | Good | Excellent (PET) | Good |
| Pressure resistance | Medium | Good | Very good | Good |
| Barrier properties | Low (mono) | Low (mono) | Good CO2 (PET) | Excellent (EVOH) |
| Typical volumes | 5,000 to M parts | 50,000 to M parts | 500,000 to billions | 50,000 to M parts |
| Max part size | 10 ml to 200 L | Under 500 ml | 100 ml to 5 L | 1 L to 200 L |
| Tooling cost | Low - Medium | Medium - High | Medium - High | High |
| Applications | Jerricans, tanks | Pharma/cosmetic bottles | PET drink bottles | Fuel tanks, barrier |
Plastic materials for blow molding
Material choice determines the barrier, mechanical, thermal and regulatory properties of your hollow body. CadNov recommends the exact grade based on your requirements.
| Material | Processes | Key strengths | Typical applications | T max |
|---|---|---|---|---|
| HDPE | EBM, co-extrusion | Chemical resistance, flexibility, economical, food-safe | Jerricans, cans, water tanks, detergent bottles | 80 C |
| PP | EBM, IBM, ISBM | Higher T than HDPE, can be translucent, sterilizable | Medical bottles, engine-oil tanks, auto parts | 110 C |
| PET | ISBM (main) | Transparency, lightness, CO2 barrier, recyclable | Water bottles, CSD, juice, cosmetics, oil | 70 C |
| PETG | ISBM, IBM | Crystal clarity, BPA-free, complex shapes | Premium cosmetic bottles, medical | 70 C |
| PVC | EBM, IBM | Transparency, rigidity, good blow-molding ability | Shampoo bottles, clear cosmetics (declining) | 60 C |
| LDPE / LLDPE | EBM | Very flexible, hand-compressible | Squeeze bottles, flexible tubes, dispensers | 60 C |
| PA (Nylon) | EBM, co-extrusion | Fuel barrier, chemical and thermal resistance | Fuel tanks and lines, under-hood parts | 130 C |
| PC | EBM, IBM | Optical transparency, exceptional impact resistance | Refillable water carboys, hollow optical parts | 120 C |
| EVOH | Co-extrusion only | Exceptional O2 and hydrocarbon barrier (barrier layer) | Central layer of fuel tanks, food packaging | - |
| ABS | EBM | Rigidity, surface finish, impact resistance | Technical hollow bodies, aesthetic automotive parts | 80 C |
Fields of application
Plastic blow molding is present in every sector where the part is hollow - from the water bottle to the automotive fuel tank.
Automotive and Transport
Multilayer fuel tanks (mandatory anti-emission standard), washer-fluid tanks, AdBlue tanks, air-intake ducts, technical hoses.
Packaging and Food
PET water and drink bottles, HDPE milk jugs, barrier ketchup/mayo bottles, oil jerricans. ISBM dominates drinks, EBM dominates the jerrican.
Cosmetics and Hygiene
High-clarity ISBM perfume bottles, precise IBM shampoo bottles, dispensers, atomizers. Surface finish is critical - IBM and ISBM guarantee no weld line.
Medical and Pharmaceutical
Dropper bottles, serum bottles, laboratory bottles, sterile containers. Pharmaceutical-grade PP and HDPE, often IBM for neck precision.
Industry and Chemicals
Chemical jerricans, solvent cans, agrochemical packaging. UN certifications for transport of dangerous goods.
Toys and Childcare
Hollow toy bodies (balls, animals, vehicles), childcare accessories. Phthalate-free PP or HDPE, compliant with EN 71 and REACH. Smoby in our portfolio.
Our blow molding approach
From your need to the part in production - CadNov steers every step to save you from costly mistakes.
Needs analysis
Geometry, volume, content, regulations
Technology choice
EBM / IBM / ISBM / Co-extrusion based on criteria
Material choice
Exact grade, number of layers, supplier
Tooling
Specifications, molder selection
Production
Part qualification, control plan
The mistakes we save you from
Choosing EBM for a precise bottle
EBM requires deflashing the neck. If neck precision is critical (dispenser, tight threaded cap), IBM is mandatory.
Forgetting the barrier on a fuel tank
Every automotive fuel tank must have an EVOH layer. Without it, hydrocarbon emissions don't meet current standards.
Underestimating thinning at pinch points
In EBM, pinching the parison creates thinning zones. These zones must be anticipated at design stage to avoid in-service failures.
Innovation Tax Credit (CII)
CadNov is approved by the French Ministry (MESR). Design, prototype-tooling and blow-molding trial costs within an innovative project are eligible for the CII - up to 30% recovered.
A plastic blow molding project? Let's talk.
Free feasibility analysis within 48h - technology, material, volume, indicative budget.
Submit my projectSee injection moldingAntoine ERRIGO · +33 (0)4 74 32 23 60 · direction@cadnov.fr · CadNov, 240 rue des Câbles de Lyon, 01000 Saint Denis Lès Bourg · CII-approved