Combiblock Capacity Selection — From 2,000 to 48,000 BPH

1. How a combiblock actually works, step by step

On a conventional line, a blow moulding machine produces empty bottles, an air conveyor floats them across the room, and a separate rinser-filler-capper monoblock fills them. A combiblock deletes the middle step. The blow moulder and the filler sit on one base frame and share one transfer path — an empty bottle goes from mould to filling valve in seconds without ever entering an air conveyor.

The sequence inside a Sunswell combiblock:

1. Preform feeding. Preforms are tipped into an unscrambler, oriented neck-up and fed into the heating furnace on a chain.
2. Heating. Infrared lamps heat the preform body. Ceramic reflectors behind each lamp are individually adjustable to preform length — this controls wall-thickness distribution in the finished bottle.
3. Stretch blow moulding. A stretch rod pulls the heated preform axially while low-pressure air initiates expansion; high-pressure air then forces the material against the mould wall.
4. Neck transfer. The bottle leaves the mould gripped by the neck ring via a transfer starwheel. It never rides on its base and never rubs against a conveyor rail.
5. Filling. The bottle is handed to the filler carousel. Depending on valve type, product is dosed by weight, volume, gravity or isobaric counter-pressure.
6. Capping. Caps feed from a hopper and elevator, sorted, and applied by a rotary capping head with controlled torque.
7. Discharge. The sealed bottle exits on a chain conveyor towards labelling and packing.

2. The three modules inside the block

2.1 Blow moulding module

A rotary stretch blow moulder built into the block. The commercially relevant features are the individually adjustable ceramic reflectors and the air-recovery circuit that reclaims part of the high-pressure blowing air. Blowing air is typically the single largest utility cost in PET bottle production, so recovery directly affects per-bottle cost.

2.2 Filling module

A rotary carousel in SUS 304 stainless steel, with valve count scaled to output. For carbonated products the carousel becomes a pressurised isobaric filler: CO₂ pre-pressurisation equalises bottle and tank pressure before the liquid valve opens, and displaced CO₂ returns to the tank — no venting, no foaming. CIP-ready as standard.

2.3 Capping module

Cap hopper, elevator, chute and rotary capping turret, all on the same frame and same mechanical drive. Because the capper shares the drive with the filler, it can never fall out of phase — a common downtime trigger when three independent machines are synchronised electrically across a plant.

3. Capacity ranges by product and bottle size

Output depends on preform design, bottle volume, wall thickness and product temperature. The table below shows the working envelope for Sunswell combiblocks:

Capacity confirmed after preform and bottle drawings are reviewed. Higher-output configurations beyond 36,000 BPH are available on request for dedicated water lines.

4. Choosing the filling valve

The valve is the decision that most affects accuracy, cleaning and capital cost. Four configurations:

A practical rule: if the label declares litres, start from volumetric; if it declares kilograms or the product is expensive per litre, start from load cell; if you are filling plain water at the lowest possible capex, mechanical is still the right answer.

5. Where the savings really come from

Ranked by financial impact:

1. Lighter bottles. On a separate line the bottle must survive the air conveyor — pushed by air, guided by rails, with a safety margin built into the design weight. Inside a combiblock the bottle is only held by its neck ring, so the body can be designed for the product rather than the conveyor. Preform resin is the largest recurring cost in PET bottling — every gram removed goes straight to gross margin, permanently.
2. No air conveyor. You delete the conveyor, blowers, filtration, cleaning routine and electricity. On a wide plant the air conveyor can be tens of metres of ducting running 24/7.
3. Labour. One control system, one HMI, one set of alarms. The block is designed for a single operator instead of one per machine — a real saving of 2 operators per shift vs a conventional 3-machine setup.
4. Floor space and building cost. Expect ~30% less floor area vs separate machines. Most relevant when constructing a new plant or retrofitting into a building you cannot extend.

6. When a combiblock is the wrong choice

A combiblock is not the right answer when:

• You already own a good blow moulder. If your blower has years of life left, a separate filler is cheaper than replacing both.
• You sell empty bottles as a separate business. A combiblock has no bottle-only output — every bottle it makes gets filled immediately.
• You run extremely high SKU variety. Frequent changeovers across many bottle families favour decoupled machines with a buffer between them.
• You need a large accumulation buffer. A separate line's air conveyor doubles as several minutes of buffer. A combi has none — a stop in one module stops the other. Reliability engineering manages this, not inventory.
• Glass, cans or non-PET. A blow-fill-cap block only makes sense for PET. Glass and aluminium need conventional rinser-filler-capper monoblocks.

Full trade-off analysis in Combiblock vs separate blowing and filling line.

7. How to specify one: a checklist

Bring these eight items to a first technical call:

Frequently asked questions