Polyurethane scraper

A polyurethane scraper is a tool that leverages the material’s combination of high wear resistance and high elasticity to achieve efficient, non-damaging cleaning or coating application. Its operating principle relies on the flexible scraping action and close conformability between the blade and the surface being cleaned or coated—such as conveyor belts or screen meshes—to remove material or apply a uniform coat.

Physicochemical Properties

· Combines wear resistance with elasticity: a core competitive advantage. Its wear resistance is significantly higher than that of rubber (with some data indicating a service life 3–5 times longer), while it also maintains excellent elasticity to adaptively conform to the working surface, thereby reducing damage.
· Broad adjustability: wide hardness range (Shore A 40 to over 95), which can be tailored through formulation adjustments to meet various operating conditions.
· Excellent media resistance: exhibits strong resistance to mineral oils, weak acids, weak bases, and a wide range of solvents. Special formulations are available for applications in high-temperature and chemically corrosive environments.
· Temperature adaptability: The standard type is resistant to temperatures ranging from approximately -30°C to 80°C, while the high-temperature version can withstand temperatures of around 200°C for short periods.

Application Fields

· Conveyor belt cleaning: primarily used to remove residual material left on the belt after conveying coal, ore, grain, and other bulk materials.
· Printing and coating: Used in screen printing for blade application of ink, it is a critical tool for high-precision coating.
· Other industrial cleaning: used to remove deposits from surfaces such as rollers and plates.

Core Advantage Comparison

· Compared with metal or ceramic scrapers: it is gentler on the working surface (such as conveyor belts), with virtually no risk of damage; it operates quietly, can accommodate uneven surfaces, and is suitable for conveyor belts with mechanical joints.
· Compared with rubber squeegees: significantly improved wear resistance, strength, and service life, resulting in superior overall cost-effectiveness.
· Compared with plastic scrapers: superior elasticity, wear resistance, and tear resistance; less prone to brittleness and cracking; longer service life.

Precautions for Use

1. Strictly prohibit use beyond the specified limits: Avoid operating in extreme environments that exceed the material’s maximum temperature rating or involve contact with highly corrosive chemicals.
2. Proper installation and adjustment: Ensure the scraper is set at an appropriate angle (typically 45–75 degrees) relative to the working surface (such as a conveyor belt) and maintains uniform contact, with moderate pressure, to prevent uneven wear or failure.
3. Selection Based on Operating Conditions: Choose a scraper with the appropriate hardness and formulation according to the material characteristics (abrasiveness, moisture content, and temperature); for example, materials subject to severe abrasion require scrapers with high hardness or wear-resistant formulations.
4. Regular Inspection and Replacement: Inspect for wear at regular intervals; replace promptly when wear reaches the limit (e.g., remaining thickness is one-third of the original) or when cracks, chipping, or hardening due to aging occur.

Selection Guide

Equipment selection is a systematic process that, based on the specific application (e.g., cleaning or printing), requires a comprehensive consideration of the following steps:

Step 1: Define the core operating conditions and functions
· Main function: Is it belt cleaning, screen printing, or other surface treatment?
· Key parameters:
· Conveyor belt cleaning: material characteristics (abrasiveness, moisture content, temperature), belt speed, type of splice (polyurethane splices are required for mechanical splices), and installation location (primary or secondary cleaner).
· Screen printing: ink type (whether it contains strong solvents), print accuracy requirements, and screen mesh characteristics.

Step 2: Select the polyurethane type and key parameters
· Material formulation selection (tailored to address environmental conditions)
· General service conditions/wear environments: Select standard polyurethane (typically orange or purple, with a hardness of approximately 83A).
· High-temperature materials (such as clinker and slag): Must select high-temperature-resistant models (typically green or red, with a temperature resistance of 135°C or higher).
· Chemically corrosive environments: Select chemically resistant types (typically brown).
· Viscous/wet materials (such as cement slurry): Choose a low-viscosity or high-hardness formulation (typically navy blue, with a hardness of 91A).
· Food/Special Industries: Choose FDA-certified food-grade formulations (typically white).
· Determine hardness (balancing wear resistance and fit)
· For highly abrasive, dry materials requiring strong scraping force: select a material with high hardness (e.g., Shore A 90 or above).
· General-purpose cleaning, belt protection, and high adaptability requirements: select a hardness of Shore A 80–90.
· High-precision printing requiring excellent elastic conformability: select a specific print hardness (typically Shore A 70–90).

Step 3: Determine the Structure and Dimensions
· Structural design: Conveyor belt cleaners are available in integral, modular multi-blade (with buffer holes) configurations, with the latter offering superior belt tracking.
· Dimensional specifications: The squeegee’s length, width (thickness), and mounting interface shall be determined based on the conveyor belt/mesh screen width, the wiper model, or the printing doctor blade holder.

Step 4: Supplier Evaluation and Sample Testing
· Require submission of key data, such as wear resistance test reports (e.g., DIN wear values), hardness tolerances, and proof of operating temperature ranges.
· Always conduct sample testing: For critical applications, request samples for on-site installation testing to verify cleaning/printing performance, wear rate, and protection of the work surface.

In summary, polyurethane doctor blades are highly efficient tools that combine rigidity with flexibility. The key to successful selection lies in a deep understanding of their core value—“wear resistance without damaging the substrate”—and in precisely matching the formulation, hardness, and structure to the specific material, operating environment, and mechanical conditions.