Cast Polyurethane Wheels

Established in 2007, our company has been dedicated to the research, development, production, and sales of polyurethane products for nearly two decades. Our product portfolio includes polyurethane wheels, polyurethane screens, polyurethane sheets, polyurethane air hoses, polyurethane forklift sleeves, polyurethane pipeline pigs, and various other polyurethane items.Over the past 20 years, we have built a strong and experienced team covering R&D, production, and sales. We are equipped with multiple advanced extrusion production lines and state-of-the-art testing equipment, ensuring that every stage of manufacturing for our cast polyurethane wheels meets the highest quality standards.We also offer customized production services based on your drawings or samples. Your specific requirements are always welcome.

Cast Polyurethane Wheels Production Process

The production of cast polyurethane wheels is a process that transforms liquid chemical raw materials into high-performance solid elastomers through chemical reactions. The core process can be summarized into four main stages: metal hub treatment → raw material casting → curing and molding → post-processing. The entire process demands high precision in material ratios, temperature control, and operational accuracy.

Below is a step-by-step breakdown of the technical highlights at each stage:

Step 1: Metal Hub Pretreatment

This is the critical step for ensuring strong bonding between the polyurethane layer and the metal hub, preventing delamination during service.

Cleaning and Roughening: The metal hub must first be thoroughly cleaned to remove oils, rust, and other contaminants. This is followed by sandblasting or grinding to increase surface roughness, providing mechanical interlocking for the subsequent adhesive bond.

Adhesive Application: A special primer (adhesive) is uniformly applied to the cleaned hub surface, typically by spraying. This adhesive layer is key to chemical bonding-it forms strong chemical links with both the metal and the polyurethane material, with bond strengths reaching over 15 kN/m. After application, the coated hubs are usually heat-dried to activate the adhesive.

Step 2: Raw Material Preparation and Metered Mixing

This is the core stage that determines the final performance of the wheel.

Material System: Cast polyurethane typically uses a prepolymer method, consisting of Component A (polyurethane prepolymer) and Component B (chain extender/crosslinker). By adjusting the chemical structures and ratios of these two components, wheel properties can be tailored-from soft to high-hardness, from wear-resistant to oil-resistant, among others.

Precise Metering and Mixing: Components A and B are delivered to the mixing head by high-precision metering pumps at strictly controlled ratios. Since the reaction proceeds rapidly once initiated (gel times for some systems may be as short as ~20 seconds), mixing must be extremely fast and uniform. For special formulations containing fillers (such as tire rubber powder), specialized mixing equipment capable of handling solid particles is required.

Step 3: Casting and Curing/Molding

The mixed liquid material is poured into preheated and assembled molds.

Casting: To prevent air entrapment, the pouring process must be smooth. Rotational casting is sometimes employed, where centrifugal force helps the material uniformly fill the mold cavity.

High-Temperature Curing: The filled molds are placed in a curing oven for vulcanization (crosslinking). This is where the core chemical reaction (chain extension and crosslinking) takes place, converting the liquid material into a solid elastomer. Mold temperatures are typically maintained between 65°C and 95°C (150°F to 200°F), with heating times ranging from several minutes to tens of minutes, depending on the formulation. For systems with extremely fast gel times, the entire casting and curing sequence must be completed within a very short window, placing high demands on equipment capability.

Step 4: Demolding and Post-Processing

Demolding and Post-Curing: After initial shaping, the wheel is removed from the mold. However, the reaction is not yet complete-internal crosslinking continues slowly. Therefore, a post-curing stage is required, during which the wheels are kept under specific temperature and humidity conditions for several hours or even longer to achieve optimal material properties.

Finishing: Once fully cured, the wheels undergo machining operations such as turning and grinding, as required by the design, to remove flash, ensure dimensional accuracy, and achieve the desired surface finish.

Quality Inspection: Finally, the cast polyurethane wheels are subjected to rigorous dimensional, hardness, and performance testing to verify compliance with specifications.

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