Extrusion Blow Moulding Machines Explained: Bottles, Jerry Cans, Drums & IBC Tanks

An extrusion blow moulding machine turns HDPE or PP pellets into hollow containers by extruding a soft tube (the parison), clamping a mould around it and blowing it to shape. It is the process behind milk and juice bottles, detergent and shampoo bottles, engine-oil and lubricant bottles, pesticide bottles, jerry cans, drums, IBC tanks, water tanks and many large technical parts.

The challenge for buyers is that "EBM machine" covers equipment ranging from a compact pneumatic unit for 1 L bottles to a heavy accumulator-head machine for 500 L parts. This guide explains how to narrow that down using real figures from our extrusion blow moulding range, which HassanPlas sources and supports from our Taizhou office. If you are still comparing processes, read blow moulding process types compared first.

How an extrusion blow moulding machine works

1. Plasticising. A single-screw extruder (in our standard table, 55–120 mm screw diameter with an L/D of 25:1) melts and homogenises the resin, regrind and masterbatch.
2. Parison forming. Melt flows through the die head and exits as a vertical tube. Die tooling (die and mandrel) sets the parison diameter and wall.
3. Mould clamping. The mould halves close on the parison, pinching off the bottom and sealing it. A knife or hot cutter separates the parison.
4. Blowing. A blow pin or needle introduces compressed air; the parison expands against the cooled mould.
5. Cooling and ejection. After cooling, the mould opens and the part is removed — manually, by a robot arm or on to a conveyor.
6. Deflashing. Top, bottom and handle flash is removed, usually automatically, and granulated for reuse.

Continuous extrusion vs accumulator head

The most important architectural choice is how the parison is delivered.

Continuous extrusion

The extruder runs non-stop and the parison drops at a steady rate. The mould carriage shuttles under the die head to collect a length of parison, then moves aside to blow it while the next length forms. This is efficient for bottles, cans and containers up to around 30 L, and multi-cavity die heads multiply output on smaller items.

Accumulator head (storage cylinder)

For large parts, a continuously falling parison would stretch under its own weight and cool unevenly before enough length existed. An accumulator head stores melt in a cylinder, then a ram pushes it out quickly as one heavy parison. Our accumulator-head machines cover 20 L to 500 L products with accumulator volumes of 3–30 L, clamping forces of 130–1,500 kN, HDPE melting capacity of 80–300 kg/h and total installed power of 65–220 kW. They can produce 1–6 layer products and use servo energy-saving drives.

Choosing machine size by container volume

Machine size is normally named by the largest container it is designed to blow. The table below shows the spread of our standard continuous machines from 2 L to 60 L, followed by the accumulator range.

Sizing is not just about volume. Check four things:

• Melting capacity versus shot weight and cycle. Hourly output in kg (part weight plus flash, multiplied by parts per hour) must sit comfortably below the extruder's melting capacity for your resin.
• Mould space and stroke. The mould must fit between the platens with room for the opening stroke; multi-cavity moulds widen the requirement.
• Clamping force. Enough to hold the mould shut against blow pressure and to pinch off thick parisons cleanly — critical on handles.
• Power supply. Total installed power from around 40 kW for a 2 L machine to over 200 kW for large accumulator machines affects transformer and generator sizing.

Clamping types: pneumatic, hydraulic, toggle, all-electric

Our standard range covers hollow products from 0.1 ml to 30 L in four clamping structures:

For a jerry can making machine in the 5–30 L range, toggle-arm clamping is a common choice because uniform clamping force gives a strong, neat handle pinch-off. Hydraulic three-platen machines suit cost-conscious lines up to 12 L. All-electric is worth considering when electricity is expensive or the product is food-contact and oil-free operation is preferred.

Die heads, cavities, layers and view stripes

The die head defines what the machine can make. Options in our range include:

• Single-layer heads for standard HDPE and PP containers.
• Double-layer heads, for example a coloured outer layer over a recycled or differently coloured inner layer.
• Double-layer with transparent view stripe, giving a clear vertical strip so the user can see the fill level — standard on engine-oil and lubricant bottles.
• Three-layer heads for barrier structures, such as multi-layer pesticide bottles.
• Multi-cavity heads with 2, 3, 4, 6 or 8 cavities that produce several parisons at once for small bottles.

For lubricant, fuel and detergent bottles of 1–12 L, a dedicated engine-oil bottle machine uses a streamlined die head with no dead angles in the flow path, which shortens colour changes and reduces degraded-material streaks.

Parison wall-thickness control

A parison of constant wall thickness does not produce a container of constant wall thickness. Corners, handles and the base stretch more than flat panels, so they come out thin. A parison wall-thickness controller varies the die gap as the parison is extruded, adding material exactly where the part needs it.

The benefits are direct: lower part weight for the same drop and stacking performance, fewer thin-corner failures and more consistent quality between shifts. On drums and jerry cans, where every gram multiplies across thousands of parts, the controller is one of the fastest-paying options on the machine. We recommend it on almost every container above a few litres.

Product examples: from lube oil to IBC tanks

Lubricant and engine-oil bottles (1–12 L)

Usually HDPE with a transparent view stripe and a handle. The dedicated engine-oil bottle machine with a no-dead-angle die head is designed for this market, which also covers fuel and detergent bottles.

Pesticide and agrochemical bottles

Many agrochemicals need a barrier layer to limit permeation and panelling. Our multilayer pesticide bottle machine builds the barrier into the wall in one step.

Detergent, shampoo and household bottles

HDPE or PP, often with handles and offset necks, made on hydraulic three-platen, toggle or all-electric machines with multi-cavity heads for smaller sizes.

Jerry cans (5–30 L)

HDPE cans for edible oil, chemicals, water and fuel. Toggle-arm machines are a strong fit, with the parison controller to keep handle and corner walls even.

HDPE drums (20–220 L)

An HDPE drum blow moulding machine is an accumulator-head machine. Tight-head (L-ring) and open-head drums both depend on accurate parison control and strong clamping to form thick, even walls.

IBC tanks, water tanks and large parts

IBC tanks, water tanks, pallets, toolboxes, car parts, playground slides, road barriers and hospital-bed panels are produced on the larger accumulator-head models. Tell us the exact volume, weight and dimensions and we confirm the model and mould size.

Options, auxiliaries and energy

Options available on our extrusion blow moulding range include electric mould shifting, a servo oil pump, the parison wall-thickness controller, a transparent view-stripe line, in-mould labelling, a leak tester, automatic deflashing, a robot arm and conveyors. Key components come from established international brands including Moog, Siemens, Mitsubishi, Festo, SMC, Gefran, Delta, Yuken, AirTAC, Rexroth, Schneider and Hiwin, which also simplifies sourcing spare parts locally.

Around the machine, a complete line normally needs a chiller for mould cooling, an air compressor with dryer and receiver, an automatic loader and colour mixer, and a granulator for flash. All are available from our auxiliary equipment range. Caps and closures are a separate line — see cap moulds if you plan to make your own.

Energy. Extrusion heating and hydraulics are the largest consumers. Servo-driven hydraulic pumps run only when motion is required instead of circulating oil continuously, and all-electric machines remove the hydraulic system altogether. On large accumulator machines with total installed power up to 220 kW, specifying servo drives is usually a straightforward payback decision.

Common defects and how to avoid them

Most of these defects are decided at the specification stage — machine type, die head and options — rather than on the shop floor. HassanPlas engineers review the drawing, check machine and mould choice, and support installation, commissioning and operator training so the line starts with good parts. Our factory preparation guide lists what to have ready before the machine arrives.

Frequently asked questions