Product Introduction

Plastic crates are containers made primarily of synthetic resin through injection molding, used for holding, transporting, storing, and displaying items. They are lightweight, durable, moisture-proof, and easy to clean, and can be designed in various specifications and structures to meet different needs, achieving standardization and modularization.

High-Density Polyethylene (HDPE)

Features: Good rigidity, high toughness, waxy matte surface.

Advantages: Strong impact resistance, good low-temperature performance, not easily cracked in cold environments.

Disadvantages: Slightly poor high-temperature resistance (usually <80°C), easily deformed.

Applications: General-purpose turnover crates, logistics boxes, refrigerated and frozen food crates, daily necessities storage crates

Polypropylene (PP)

Features: High rigidity, smooth and glossy surface, feels "harder".

Advantages: Good high-temperature resistance (up to 110°C and above), high fatigue strength, more wear-resistant.

Disadvantages: Less impact-resistant than HDPE at low temperatures, relatively more brittle.

Applications: Heavy-duty storage crates requiring stacking, covered parts boxes, and applications requiring high-temperature sterilization (such as agricultural products and food processing).

Common Sizes and Structural Classifications of Plastic Crates

Plastic crates come in a wide variety of sizes, but can be classified according to their structure and usage.

1. Classification by Structure

Standard Stackable: The crate has stacking slots or rails on both the top and bottom, allowing for safe and stable multi-layer stacking, saving space. This is the most common type.

Foldable: The sides or the entire crate can be folded up using a specific structure, reducing storage and logistics space by more than 75% when empty. Primarily used in logistics recycling.

Stackable (Perforated): The crate has ventilation holes around its perimeter for easy cleaning and ventilation, mainly used for the handling of agricultural products and food.

Lidded: Equipped with a sealed or non-sealed lid, used for dust protection, moisture protection, or stacking applications.

Parts Boxes/Divider Baskets: These baskets have internal slots for inserting dividers, separating a large space into multiple smaller compartments for the categorized storage of electronic components, small hardware, tools, etc.

2. Common Size Ranges

There are no national standards for the size of plastic baskets; they are all customized by manufacturers according to market demand. However, some common practices exist:

Common specifications include: 600×400 series, 500×300 series, and 400×300 series, which are commonly used sizes in the logistics field.

Plastic Basket Production Process: Large-Scale Injection Molding

Plastic baskets are primarily manufactured using the "injection molding" process, a highly efficient and automated process.

1. Raw Material Preparation and Drying:

The main material (HDPE or PP virgin or recycled material) is mixed with color masterbatch (for coloring), anti-aging agents (to prevent UV degradation), and additives according to the formula.

The raw materials need to be dried in an oven to remove moisture, preventing bubbles or silver streaks in the finished product.

2. Melting and Plasticizing: The mixed plastic granules are sucked into the hopper of the injection molding machine. Inside the barrel, the plastic is heated to a molten state (approximately 200-300°C) by electric heating and shear heat generated by screw rotation, becoming a homogeneous viscous fluid.

3. Injection and Holding Pressure: The screw advances forward, injecting a certain amount of molten plastic into the closed mold cavity at high speed and high pressure.

After injection, the screw continues to maintain a certain pressure (holding pressure) to replenish the plastic lost due to cooling shrinkage, ensuring a full, shrinkage-free product.

4. Cooling and Solidification: The mold has a complex cooling water channel, through which circulating cooling water is introduced, allowing the plastic to cool and solidify rapidly.

Cooling time depends on the product's wall thickness and is the longest part of the entire production cycle.

5. Mold Opening and Ejection: The mold opens, and the moving mold section retracts.

The injection molding machine's ejection mechanism pushes the ejector pins inside the mold, pushing the formed plastic basket off the mold.

6. Post-processing: The freshly ejected product will have some excess scrap (sprue material). Workers or robots will trim off these sprue scraps.

The trimmed sprue scraps will be collected, crushed, and mixed into new material in a certain proportion for reuse, thus reducing costs and waste.

Finally, they will be inspected, counted, and stacked for packaging.