August 25, 2025
In industrial storage and transportation, chemical logistics, and emergency storage, jerry cans have become indispensable packaging containers due to their excellent sealing, impact resistance, and space efficiency. The large-scale production of this practical product relies on the technical support of extrusion blow molding machines, a core piece of equipment. From raw material melting to finished product formation, extrusion blow molding technology, with its high efficiency, stability, and low cost, enables jerry cans to be precisely transformed from design drawings to industrial products, meeting the stringent packaging container requirements of various industries.
I. Jerry Cans: Why They Have Become an Essential Item for Industrial Storage and Transportation
Jerry cans were originally designed to address the safe storage and transportation of liquid and granular materials, and their core advantages are highly compatible with the characteristics of the extrusion blow molding process. Compared to traditional welded and injection-molded drums, stacking drums offer superior structural strength, sealing performance, and adaptability to various usage scenarios:
High strength and impact resistance: Made from high-density polyethylene (HDPE) and other polymer materials, these drums are extruded and blow-molded in one piece, resulting in seamless, weak points and a barrel body that can withstand temperature fluctuations from -40°C to 60°C. This effectively prevents material leaks even in the event of drops and collisions, making them particularly suitable for transporting sensitive materials such as chemical solvents, lubricants, and food additives.
Efficient space utilization: Precise stacking structures are designed on the top and bottom of the drums, allowing them to be nested and stacked when empty, saving over 50% of storage space. When fully loaded, they can be stacked in multiple layers (typically 3-5 layers), eliminating the need for additional supports. This significantly improves loading efficiency in trucks and warehouses, reducing logistics costs. Environmentally friendly and recyclable: Stacking barrels produced using the extrusion blow molding process are 100% recyclable and reusable. Through crushing and melting, they are remade into raw materials, aligning with the global trend of reducing carbon emissions and reducing environmental impact while also reducing packaging costs for businesses.
II. Extrusion Blow Molding Machine: The "Core Engine" of Stacking Barrel Production
Extrusion blow molding machines are specialized equipment that process thermoplastics into hollow products through an "extrusion-blowing-cooling-setting" process. Their operating principle perfectly matches the "hollow, one-piece molding" requirements of stacking barrels and can be divided into four key steps:
1. Raw Material Melt Extrusion: Laying the Foundation for the Barrel Body
First, HDPE pellets (the primary raw material for stacking barrels) are fed into the extruder's hopper. Heating coils outside the barrel heat the plastic to a molten state of 180-220°C. Simultaneously, the screw inside the barrel rotates at a constant speed, pushing the molten plastic forward. The shearing action of the screw further mixes and plasticizes it, ultimately forming a continuous "tubular plastic blank" (abbreviated as "parison"). The key to this process is to ensure uniform thickness and sufficient plasticization of the parison. If the parison thickness is uneven, the subsequently formed stacking bucket will have localized weak points, affecting its load-bearing performance.
2. Mold Closing and Air Blowing: Shaping the Barrel Body
When the parison reaches the preset length, the extruder pauses feeding, and the molds on both sides rapidly close, encasing the parison in the mold cavity. (The mold cavity's shape exactly matches the final shape of the stacking bucket, including the barrel body, handles, and stacking grooves.) Compressed air is then injected into the parison through a "blowing needle" at the top of the mold. The air pressure forces the molten plastic into the mold walls, gradually expanding and filling the entire mold cavity, ultimately forming the initial shape of the stacking bucket. At this stage, the compressed air pressure (typically 0.3-0.8 MPa) and blowing time require precise control: Insufficient pressure will result in an incomplete barrel mold, while excessive pressure can cause material to overflow from the mold seal, affecting the product's appearance.
3. Cooling and Shaping: Ensuring Barrel Stability
After the stacking barrel is formed in the mold, cooling water is introduced through the mold's internal cooling channels to rapidly cool the barrel. This cooling time typically ranges from 10-30 seconds (depending on the barrel's thickness). This is to solidify the plastic from its molten state into a stable solid form, preventing deformation after demolding due to excessive temperatures. Cooling efficiency directly impacts the dimensional accuracy of the stacking barrel. Insufficient cooling can lead to uneven shrinkage, making it difficult to precisely align the barrels during stacking and affecting storage efficiency.
4. Demolding and Subsequent Processing: Completing the Finished Product
Once the barrel has cooled to the set temperature, the mold opens, and the demolding mechanism ejects the formed stacking barrel from the mold. After demolding, stacking barrels undergo subsequent processes such as trimming (removing burrs from the mold), leak testing (checking for pinholes or leaks through airtightness testing), and printing (printing product specifications, warning labels, and other information on the barrel) to ultimately become finished stacking barrels that meet industry standards.
III. The "Technical Advantages" of Extrusion Blow Molding Machines for Stacking Barrel Production: Why Are They So Difficult to Replace?
Compared to other hollow product processing techniques such as injection molding and rotational molding, extrusion blow molding machines offer irreplaceable advantages in stacking barrel production, primarily in three aspects:
1. High Production Efficiency, Suitable for Scaled Production
Modern extrusion blow molding machines achieve "fully automated continuous production"—from raw material input to finished product output, the entire process requires no human intervention. A single machine can produce 20-60 stacking barrels per hour (depending on barrel specifications). For large-volume orders in industries such as chemicals and logistics, extrusion blow molding machines can further increase production capacity through multi-die designs (such as dual or quad dies) to meet the scaled production needs of enterprises.
2. Highly adaptable product, meeting customized needs
Stacking barrels vary widely in size (capacity ranges from 5L to 200L, and barrel structure also requires adjustments based on material characteristics, such as corrosion resistance and anti-static properties). Extrusion blow molding machines can quickly adapt to production requirements of varying sizes by replacing molds and adjusting process parameters (such as screw speed, blow pressure, and cooling time). For example, when producing large 200L stacking barrels, the extruder's screw diameter can be increased to increase parison output. When producing anti-static stacking barrels, simply add conductive masterbatch to the raw material without requiring major equipment modifications, offering far greater flexibility than other processes.
3. Controllable costs, reducing enterprise investment
Extrusion blow molding machines require relatively low equipment investment (compared to rotary molding equipment) and offer high raw material utilization—overflow and burrs generated during production can be crushed and recycled back into the hopper, resulting in a raw material loss rate of only 3%-5%. Furthermore, the equipment boasts low energy consumption (a single unit consumes approximately 15-30 kWh per hour), resulting in significantly lower long-term operating costs than traditional processes. This helps companies effectively control production costs while ensuring product quality.
IV. Industry Trend: Synergistic Upgrading of Extrusion Blow Molding Technology and Stacking Buckets
With the increasing demand for lightweight, high-strength, and environmentally friendly industrial packaging, extrusion blow molding technology and the production of stacking buckets are also undergoing continuous upgrades:
Material Innovation: In addition to traditional HDPE, modified plastics (such as glass-fiber-reinforced PP) and biodegradable plastics are increasingly being used in stacking bucket production, further reducing product weight and environmental pollution while maintaining strength.
Intelligent Equipment: New-generation extrusion blow molding machines are equipped with PLC control systems and IoT modules, enabling real-time monitoring of key parameters such as parison thickness, blow pressure, and cooling temperature. These machines automatically adjust the process based on data feedback, avoiding manual errors and improving product quality. Some high-end equipment also supports remote diagnosis and maintenance, reducing equipment management costs for companies. Structural Optimization: Finite element analysis technology enables more precise structural design of stacking barrels. For example, wall thickness is increased in areas of the barrel where stress is concentrated (such as the stacking groove at the bottom), while wall thickness is reduced in non-stressed areas. This achieves a balance between lightweight and high strength, further reducing raw material consumption and logistics costs.
Conclusion
As the "essential vehicle" for industrial storage and transportation, the performance and production efficiency of stacking barrels directly impact a company's logistics costs and safety. Extrusion blow molding machines, the "core equipment" for stacking barrel production, have become a key driver of the stacking barrel industry's development with their high efficiency, flexibility, and low cost. From raw material melting to finished product molding, every step of extrusion blow molding technology precisely controls the quality and performance of stacking barrels. The coordinated development of these two technologies not only meets current industrial packaging needs but will also continue to create greater value for the industry in the future trends of "green manufacturing" and "intelligent production."
