All products undergo two Quality inspections.

All Finished products and processes are 100% inspected, every month with the quality reviewing meeting to review problems and This is the quality control process during the Production process. so we just make sure every size of the Foam Transmission Belt is on the right According to the drawing, YONGHANG has 5 inspectors,1 for the incoming material inspection,3 inline inspectors for the production steps, and 1 inspector for the final products. All raw materials incoming are inspected, such as Sponge,Foam,Rubber and PU , Stainless steel raw materials, Nut and so on. Each step like cutting,Bonding,grinding,Slotting,drilling and so on ,reviewing meeting to review problems and make plans with tools, such as 8D reports,5WHY 3W2H and so on.

Our Commitments

Our Commitments

All products have passed rigorous factory test to ensure high quality.
We own patented products and SGS,ISO ，FDA,CE,Roshcertifications.
High-efficiency assembly and production lines ensure on-time delivery.
Two on-site supervisors will be assigned to closely monitor the production progress of the goods throughout the process.Before The belts packaging,QC Complete Quality inspection.

Timing Belts Quality inspection Control Process

Raw Material Quality Inspection Before Production

At the outset of synchronous (timing) belt production, we conduct rigorous inspections on all incoming raw materials—the cornerstone of ensuring product quality. We focus on testing core materials: the belt backing adhesive, reinforcement layer yarns, and tooth cover fabric.

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Raw Material Inspection

Before manufacturing a product, the molds need to be confirmed, and the materials and cores should be carefully checked against the drawings and work orders.

covering Quality

For the belt backing covering, we use a durometer and tensile testing machine to measure its Shore hardness, tensile strength, and abrasion resistance, ensuring its physical properties meet formulation requirements.

core reinforcement Inspection

For the core reinforcement cords (such as glass fiber, Kevlar, or polyester cords), we inspect diameter and twist, and conduct constant-load tensile tests to guarantee their tensile strength meets the load-bearing and transmission requirements of different synchronous belt specifications.

tooth fabric Inspection

For the tooth fabric, we examine its weave density and surface treatment to ensure excellent abrasion resistance and adhesion, preventing premature wear and delamination during operation.

Compliance control during the production process

During the manufacturing process, we ensure dimensional stability and structural integrity through monitoring critical operations.

In the compounding and calendering stages, we continuously monitor the uniformity of compound mixing and calendering thickness to guarantee consistent compound properties.

During the inline cord reinforcement and threading process, we ensure uniform tension and precise alignment for each cord strand—the core requirement for maintaining constant pitch and preventing misalignment during synchronous belt operation.

During vulcanization and molding, we precisely control three critical parameters—temperature, pressure, and time—to ensure full tooth profiles, dimensional accuracy, and optimal bonding between layers.

Using tools like projectors, we conduct random inspections of samples for pitch (e.g., MXL, XL, L, H models) and tooth profile contours, verifying exact conformity with design drawings.

in the packaging area

Final inspection of finished products

Before The belts packaging, each timing belt must undergo a comprehensive final inspection covering all items.

We conduct thorough checks on finished products for appearance, dimensions, and performance based on strict sampling standards (such as GB/T 2828 or AQL standards).

Visually, we inspect whether the belt body is flat, check for missing rubber, bubbles, or deformation in the teeth, and examine the cover fabric for scratches or wrinkles.

For dimensional accuracy, we use precision measuring tools to reconfirm critical dimensions such as pitch line length, tooth height, tooth thickness, and belt width, ensuring full compliance with customer tolerance requirements.

For each production batch, we archive detailed quality inspection reports documenting all critical data from raw materials to finished products. Only after confirmation are products cleaned, labeled with compliance certificates, Print the product logo and specifications and packaged according to customer requirements with moisture-proof and crush-resistant materials. This ensures every timing belt you receive delivers exceptional quality.

The evaluation provided by our partner.

We hope that our cooperation with you is not a one-time transaction, but a long-term partnership. We will work together to make money, help customers solve problems, and jointly explore the future of this industry.

This is a very good partner. They actively respond and solve problems, good prices and good services, and provide traceable logistics information.
Александр
Customer Manager

A good product, excellent quality, and a very good Chinese supplier. Looking forward to making progress together in the future..
Владимир
purchasing manager

Good quality product inspection, a very professional timing belt company. The coated timing belt are very good.
Анна
Organizational purchasing Manager

A trustworthy partner.We have been cooperating for over two years. They have provided us with a lot of technical support, enabling me to grow from a small team to a large enterprise in our country. Thank you, Asher; thank you, Lucy; thank you so much.
William
R&D Manager

FAQ for Regarding quality

Regarding our quality inspection, if you have any further questions, please feel free to contact us at any time.

Raw Material Inspection:Every batch of reinforcement core (such as fiberglass and Kevlar) undergoes sampling inspection before warehousing. Tensile strength is measured using a tensile testing machine to ensure compliance with our stringent standards.

Process Control:During production, we precisely regulate filament tension to ensure uniform stress distribution during lay-up. This critical step prevents premature failure caused by uneven stress on individual filaments.

Finished Product Validation: We regularly subject finished timing belts to fatigue strength and tensile strength testing to verify their ultimate load-bearing capacity.

Tooth profile and pitch accuracy are central to our production control. We ensure this through the following methods:

Mold Precision: We utilize high-precision vulcanized molds, subjecting them to regular inspection and maintenance to guarantee absolute accuracy in the mold’s own tooth profile and pitch.

Process Monitoring: During vulcanization, we strictly control temperature, pressure, and time to ensure the rubber compound fills the mold perfectly, forming full, precise tooth profiles.

Full Inspection and Sampling: For products with extremely high pitch requirements, we perform 100% inspection or high-frequency sampling of finished products using optical projectors or coordinate measuring machines to verify tooth profile contours and pitch, ensuring every millimeter meets design standards.

Of course, we place great emphasis on product consistency and ensure it through standardized processes:

Starting from the compounding stage, we implement strict standardized operations to guarantee consistent physical properties (such as hardness and tensile strength) across every batch of rubber compound.

During production, we employ statistical process control methods to monitor critical process parameters in real time, ensuring stable and controlled manufacturing.

We implement a comprehensive batch management system. Every product batch maintains complete traceability records from raw materials to finished goods, ensuring any deviation is traceable and controllable. Our finished product section length inspection further guarantees dimensional consistency across every batch.

Before The belts packaging, our final inspection is comprehensive and meticulous, with written documentation provided:

Full Item Inspection: We conduct a thorough examination of the finished timing belt’s appearance, dimensions, and performance against inspection standards. This includes: checking the belt body for defects, measuring tooth profile and pitch, and verifying belt length and width.

Performance Testing: We conduct regular durability and high-speed operation tests on batches of finished products to simulate real-world usage scenarios.

Quality Report: For every shipment, we provide a Finished Product Quality Inspection Report detailing the key performance metrics and inspection results for that batch. This report allows you to verify product quality and serves as the basis for your incoming material inspection.

We not only conduct quality inspections before shipment but also offer one year of after-sales service. Typically, one-piece vulcanized rubber belts can last over a year, while other synchronous(timing belts come with a three-month warranty. Should any quality issues arise, please contact us anytime for resolution.