20L Barrel Blow Molding Machine Processing

November 27, 2025

wanplas

Industry Blogs

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The plastic drums market has experienced steady growth in recent years. For example, the global plastic drum market was valued at approximately USD 4.5 billion in 2024 and is projected to reach approximately USD 6.5 billion by 2034, representing a CAGR of approximately 3.7%. The plastic drum market (including HDPE drums) is a multi-billion dollar market. Although one report indicates slower growth for HDPE drums, overall demand for plastic drums from packaging and industrial storage and transportation, chemical, and food and beverage sectors continues to increase.

1.  20L HDPE Container Introduction

Material: HDPE (High-Density Polyethylene)

• Most reports indicate that HDPE is one of the mainstream materials for plastic containers due to its excellent chemical resistance, corrosion resistance, moisture resistance, relatively light weight, and lower cost. For example, reports mention that “polyethylene (PE)” accounts for approximately 62% of the plastic container market.
• Because your customer base (such as chemical containers) highly values chemical resistance, corrosion resistance, and leak prevention, HDPE containers are the standard choice for applications involving chemicals, oils, solvents, and lubricants.

Capacity: 20L Size vs. Larger Sizes

• Most reports differentiate between larger capacities (e.g., 35–60 gallons (≈132–≈227 L)) as the mainstream.
• The 20L (≈5–6 gallons) size falls under the category of small to medium-sized industrial containers or medium-sized packaging containers. While not explicitly listed as the mainstream capacity in public reports, there is still demand for certain niche markets (such as chemical auxiliaries, small-batch specialty liquids, food additives, coatings, and lubricant repackaging).
• Market trends indicate that medium-capacity containers (e.g., 10-30 gallons, 30-55 gallons) are also growing.

Application Industries and Driving Factors

• The chemical and petrochemical industries are among the largest users of plastic containers (including HDPE containers) due to the need to transport and store large quantities of hazardous chemicals, solvents, lubricants, etc. The report indicates that the chemical and petrochemical industries account for over 40% of the plastic container market.
• The food, beverage, and pharmaceutical industries are also driving demand for plastic containers, particularly for food-grade/hygienic materials and recyclable and reusable designs.
• Sustainable and circular economy trends: Plastic container manufacturers are increasingly adopting recycled materials, highly recyclable HDPE, lightweight designs, and reusable designs.
• Regional growth: The Asia-Pacific region (such as China and India) is the fastest-growing region for plastic containers due to rapid industrialization and expansion of the chemical industry. The report states that the Asia-Pacific region will account for approximately 37% of the plastic bucket market share in 2024.

20L HDPE drums are mainly used in the following industries:

• Chemical auxiliaries, cleaning agents, solvents
• Coatings, inks, dyes
• Lubricating oils, greases, automotive care products
• Food additives, sauce ingredients
• Pesticides, fertilizer concentrates
• Adhesives, adhesives
• Personal care liquids (detergents, disinfectants, etc.)

20L HDPE drums are primarily targeted at the following markets

• Middle East (Saudi Arabia, UAE, Iran)
• India, Bangladesh, Pakistan,
• Southeast Asia (Indonesia, Vietnam, Thailand)
• Eastern Europe (Poland, Romania, Bulgaria)
• Africa (Egypt, Kenya, South Africa)

2.  Complete processing flow of 20L HDPE drums (from raw materials to finished products)

WANPLAS boasts a factory spanning over 20,000 square meters, specializing in blow molding technology for twenty years. They possess expertise in producing hollow containers ranging from 1L to 250L, with particularly mature solutions for 20L chemical drums, lubricating oil drums, and pesticide drums. Their equipment stability and finished product yield are among the highest in the industry.

WANPLAS offers more than just purchasing a machine; they provide a complete end-to-end solution. They provide 20L HDPE drum process consultation, mold structure optimization suggestions, formula and raw material selection, factory planning and production line layout, equipment installation and commissioning, operator training, and rapid after-sales response.

They take you from “no experience” to “high-efficiency mass production”—all you need to do is accompany you on your journey.

Processing Steps

1. Material Preparation

20L drums typically use HDPE (high-density polyethylene, such as 5000S, TR571, B5500, etc., blow molding grade).

Your steps:

• Check the raw material for dryness (HDPE generally does not absorb water and usually does not require drying, but it is recommended to dry for 30–60 minutes during humid seasons).
• Add color masterbatch (3%–5%).
• If used for food or pharmaceutical applications, food-grade raw materials should be used.
• If permitted by the customer, a certain proportion of recycled material can be added (generally 10–30%, lower is recommended for sealed drums).
• Key control points: The melt flow index (MFI) of the raw material must be stable, as it affects the drum’s toughness and wall thickness uniformity.

2. Color Mixing

• Use a high-speed mixer to thoroughly mix HDPE and color masterbatch.
• Avoid color spots and color differences.
• If recycled material is added, the proportion must be strictly controlled.

3. Filler Delivery → Feeding System

• The mixed raw materials are sucked into the extruder hopper. The hopper must have a dust removal device to prevent impurities from entering.
• An automatic feeding machine can reduce labor and maintain a stable material supply.

4. Extrusion → One of the most critical steps

The blow molding machine screw melts HDPE in the heated cylinder and extrudes it through the die to form a parison.

Key control points:

• Temperature zone control (typically 160–200°C, adjusted according to raw materials)
• Screw speed
• Stable extrusion rate (affects parison wall thickness)
• Die wall thickness control (PWDS) ，Crucial for 20L buckets，Determines the uniformity of thickness across the shoulder/bottom/body
• Common temperature zones (reference values):

5.Blow Molding & Molding Operations

After the preform is extruded, the mold closes → a blow needle is inserted → compressed air is injected → shaping is achieved.

Steps and Flow:

• Automatic Mold Closure (Left and Right Molds Close)
• Cutting the Preform Tube with a Cutting Edge
• Insertion of the Blow Needle into the Bottle Neck or Special Blow Needle Hole
• High-Pressure Air Inflation (0.6–1.0 MPa)
• Cooling and Shaping
• Mold Opening and Product Output

Key Control Points:

• Blowing Pressure: Determines if the barrel wall is fully expanded
• Cooling Time: Too short and deformation will occur; too long and production efficiency will be low
• Clamping Platen Pressure: Sufficient pressure is required; otherwise, loose mold closure will result in large burrs or air leakage
• Mold Water Cooling:The 20L barrel has a large volume, and the cooling speed affects production capacity.

6. Cooling

• In-mold cooling + external air cooling. Key control points:
• Maintaining cooling water temperature at 12–15°C
• Ensuring unobstructed water flow in the mold
• Supplementing cooling with air cooling to make the plastic shape more stable
• Further cooling time is required for thicker parts of the material (e.g., barrel bottom, handles)

7. Trimming

• The barrel removed from the mold will have burrs, which need to be trimmed manually or by equipment.
• Operation Procedures: Remove burrs from the opening. Remove burrs from the mold parting line. Remove excess material from the bottom.
• Example: The handle, opening, and bottom of a 20L drum usually require special treatment.

8. Quality Control

20L drums are industrial packaging, making quality inspection crucial. Routine Tests Required:

Capacity and Weight Check

• Wall Thickness Measurement (Ultrasonic Wall Thickness Gauge)
• Drop Test (Generally from 1.2–1.5 meters)
• Stacking Test (Stacking at 55°C for 24–48 hours)
• Leakage Test (Airtightness Testing Machine)
• Visual Inspection (No black spots, no impurities, uniform bulges)
• For export chemicals → UN certification testing is required

9. Packaging and Stacking

Packaging Methods:

• Plastic Bag Packaging (Most Common)
• Pallet Packaging (Commonly Used by European Customers)
• Container stacking method needs to be confirmed in advance.
• Approximately 7,000–8,000 20L drums can be packed in a 20GP container.
• Approximately 15,000–18,000 40HQ drums can be packed.

10.Key Controls in the Blow Molding Process of 20L Drums

Wall Thickness Uniformity (Most Important): Requires

PWDS wall thickness control system, die head temperature, screw stability, and mold design (uniform runner).

Sufficient Drum Bottom Strength is Essential; Otherwise, Drop Tests Will Fail.

Solutions: Thicken the bottom, slightly increase the blowing pressure, and extend the cooling time.

Preventing Bubbling (A Common Problem with Chemical Drums)

Solutions: Use high-strength HDPE raw material, adjust crystallinity (temperature control), and increase the drum wall thickness (especially in the drum belly area).

Handles Must Be Molded in One Piece Without Gaps.

Recommended Use: Built-in Handle Mold Design; Separate Injection Molded Handles are also possible (but more expensive).

3.Common Defects and Solutions

Wanplas blow molding machines feature a high-strength frame structure, energy-saving screw and pre-plasticizing system, servo hydraulic control, intelligent temperature control system, and proprietary industrial control software. Even under prolonged full-load production, they ensure stability, energy efficiency, and ease of maintenance, and have been operating continuously for over 10 years in multiple countries worldwide.

Wanplas offers customized solutions to meet diverse market needs. Whether you’re preparing to enter the chemical, lubricant, food, coating, or agrochemical industries, we can provide: single-station/double-station 20L blow molding machines, multi-layer co-extrusion (acid/alkali tanks, barrier tanks), automatic cutting, automatic leak detection, and robotic automation systems, making your production line more automated, efficient, and labor-saving.