Blow Molding Machine

What is a blow molding machine?

How does a blow molding machine work?

Blow molding is a manufacturing process used to create hollow plastic parts. The process involves several steps and specialized machinery to shape plastic into items such as bottles, containers, and other hollow forms. Here’s a detailed explanation of how a blow molding machine works:

1. Material preparationThermoplastics such as polyethylene and polypropylene are fed into the machine as small pellets or granules.
2. Melting and extrusionAn extruder screw heats and melts the pellets, then pushes the melt through a die head to form a hollow tube called a parison.
3. Parison formationThe parison is extruded downward between two mold halves, continuously or intermittently depending on the machine.
4. Mold clampingWhen the parison reaches length, the two mold halves close around it. The mold carries the shape of the final product.
5. BlowingA blow pin or needle enters the parison and compressed air presses it against the mold walls.
6. CoolingThe part cools and solidifies inside the mold, usually through water channels, air, or both.
7. Mold opening and ejectionThe mold opens and the formed part is taken out. Flash beyond the cavity is left for trimming.
8. Trimming and finishingFlash is trimmed, parts are checked, and the trimmed material can be ground and reused.

Extrusion blow molding machine vs PET bottle blowing machine

Extrusion blow molding (EBM) machines and PET bottle blowing machines (typically referring to stretch blow molding or SBM machines) are both used in the production of hollow plastic products, but they operate differently and are suited for different types of materials and products. Here are the key differences between the two:

	Extrusion blow molding (EBM)	PET stretch blow molding (SBM)
Material	PE, PP and PVC, for products that need durability and flexibility	PET, chosen for strength, transparency and barrier properties
Starting form	A parison extruded from pellets	An injection-molded preform
Process	Extrude the parison, close the mold, blow, cool, eject and trim	Mold the preform, reheat it, stretch and blow it, cool and eject
Typical products	Bottles with handles, jerry cans, drums, IBC tanks, technical parts	Beverage bottles and jars

Tongda builds extrusion blow molding machines. Injection blow molding is compared as well in extrusion vs injection vs stretch blow molding, and the full range of processes is in how the blow molding process works.

Blow molding machine applications

See all twelve on the blow molding applications page.

Types of blow molding machines

Important systems of blow molding machine

Blow molding machines consist of several important systems that work together to produce hollow plastic products. Each system plays a crucial role in ensuring the efficient and high-quality production of items such as bottles, containers, and other hollow forms. Here are the key systems of blow molding machines:

Extrusion system EBM

Melts and extrudes the plastic into a parison.

Injection system IBM · SBM

Injects molten plastic into a mold to make a preform.

Clamping system

Holds the mold halves together while the part is blown.

Blowing system

Inflates the parison or preform to the shape of the mold.

Cooling system

Cools the plastic so it solidifies and keeps its shape.

Ejection system

Removes the finished product from the mold.

Parison control system EBM

Controls the wall thickness and uniformity of the parison.

Stretching system SBM

Stretches the preform axially and radially to improve material properties.

Automation and control system

Manages and coordinates the operations of the machine.

Material handling system

Moves raw material in and finished products out.

HDPE and PP blow molding machines

Most extrusion blow molded containers are made from HDPE, with PP used where a product needs more heat resistance or stiffness. Tongda machines are configured for the resin you run: the screw, die head and parison wall thickness control are matched to the material and container. Many customers also add regrind from trimmed flash back into production; ask our engineers how much your product can take. See HDPE blow molding machines by container size, and read what is the best material for blow molding and using recycled HDPE in blow molding.

For jerry cans and drums that need a visible fill level, machines can be fitted with a view strip, and single-layer or multilayer configurations are available for selected models.

Fully automatic blow molding production lines

A blow molding machine is the centre of a production line. Deflashing, conveying, leak testing and labeling can be integrated according to your plant layout, and manipulators take finished parts out of the mould. Automation lowers labour per part and keeps quality consistent from shift to shift. See how a fully automatic jerry can line is put together, and the ancillary equipment that completes a line.

Hydraulic, servo or fully electric blow molding machine?

• Hydraulic blow molding machines: proven technology, a lower purchase price and the widest size range.
• Servo blow molding machines: a servo-driven hydraulic system that uses less energy than a conventional pump.
• Fully electric blow molding machines: clean, quiet and precise, for small and medium containers.

To compare running costs, ask for the energy consumption per hour for your own container. The blow molding machine price guide explains how drive type, stations and automation affect cost.

Blow molding machine FAQ

What is the difference between a blow molding machine and a blow molder?

They are the same equipment. “Blow molder” is a common name for a blow molding machine. Tongda builds extrusion blow molders for hollow HDPE and PP products.

How much does a blow molding machine cost?

Price depends on container size, number of stations and cavities, drive system and automation. See the price guide, or send your container details for a quotation.

Which blow molding machine do I need for jerry cans?

For 5 to 30 L jerry cans, double station HTS II and HS II models are the usual choice. See the jerry can blow molding machine page and the guide to choosing a 5 L jerry can machine.

Can a blow molding machine make PET bottles?

PET beverage bottles are made on stretch blow molding machines from preforms. Tongda extrusion blow molding machines make HDPE and PP containers such as bottles, jerry cans, drums and tanks. The comparison above explains the difference.

Can I visit the factory and see machines running?

Yes. Customers are welcome to visit the Tongda factory in Zhangjiagang, Jiangsu, to see machines in production before ordering.

Can I use a published kg/h figure as accepted containers per hour?

No. Model pages publish extruder output in kg/h. Some also publish a dry cycle. Neither figure is accepted containers per hour. Piece output is quoted from the container drawing, the weight, the cavities and the cooling. Start from the page for the product: jerry cans, chemical drums, IBC tanks, 5-gallon PC bottles or HDPE machines. Parison programming can cut material use by 20–30% versus an unprogrammed parison. Confirm that on your container. It is a material figure, not an energy figure. How the model name differs from hourly output is explained in real output versus the model name.

What spare parts and after-sales support come with a Tongda machine?

Tongda’s after-sales covers installation and commissioning, operator training, remote technical support, and on-site service when the project requires it. Spare parts are supplied for the quoted machine. Published company material describes 27 overseas and 14 domestic sales and service centres. The warranty runs for 14 months from the ex-factory date, the date the machine is shipped from the factory. It covers the whole machine and excludes damage caused by human factors, such as misuse or operator error. Most spare parts ship within 3 days. Special or custom parts are quoted case by case. Overseas spare-parts warehouses are in Mexico and Egypt, and more are being added. Online support is free and available 24 hours. An on-site engineer visit can be arranged. The machine interface can be set to English, French, Spanish, Arabic, German, Russian and other major languages. Customer engineers can train at the Tongda factory. When Tongda engineers carry out installation and commissioning, they also train on site. Training length depends on the customer’s needs and is typically 3–5 days. Read warranty, spare parts and after-sales.

Send the model through the contact page.

How do factory acceptance, site acceptance and payment milestones work?

A factory acceptance test uses a written plan to record the agreed container, the accepted output and the operating conditions before shipment. Site acceptance is separate. Plant utilities, installation and downstream equipment can differ from the factory trial, and any site test is defined in the project scope. For the machines the customer buys, factory acceptance covers machine inspection and confirmation, running-stability confirmation, mold confirmation and product confirmation. The length of a stable run is agreed case by case, so this page does not publish a fixed number of hours or cycles. Payment is 30% in advance and 70% before shipment. See FAT, SAT and payment and the all-electric acceptance checklist.

Start the request on the contact page.

What plant utilities does a blow molding line need?

Plan for the plant electrical supply (voltage and frequency), cooling water or a chiller, and compressed air for blowing and pneumatic movements. When the quotation includes them, a crusher, dryer and leak tester are sized with the machine. See ancillary equipment. Voltage and frequency are built to the customer’s plant power supply. Compressed air, chiller capacity and drying requirements, including any drying humidity, depend on the machine model. This page does not publish installed power, water flow, air volume or a humidity figure. See plant utilities for a blow molding line.

Send the plant supply with the container drawing through the contact page.

Will Tongda make the mold, or can I supply one?

Tongda can machine the blow mold to the container drawing and to the platen, opening stroke and blow pins of the selected machine. The mold is quoted separately from the machine. An existing mold can be reviewed after its envelope, mounting, head spacing, blow pins and utility connections are checked. Physical fit alone does not establish product quality or output, and a machining inspection does not replace a production trial on the agreed machine. The blow mold design guide lists what to record. A typical jerry-can or drum mold takes 50 working days. Mold prices are not published. See cost and lead time.

Ask for a Tongda mold or a review of your mold through the contact page.

Related products

Daily chemical bottle machinesJerry can machinesPE milk bottle machinesChemical drum machinesIBC and water tank machinesStacking barrel machines