Quality Control

At Handan Dongchao Hardware Products Co., Ltd., quality control is integrated into every stage of production, from raw material sourcing to final shipment.

Our objective is not only to manufacture fasteners that meet specifications, but also to maintain consistency between production batches for long-term supply projects and distribution customers.

Each production order follows a structured inspection process to reduce quality risks and improve product reliability.

The quality of a fastener begins with the quality of its raw materials.
Before production starts, incoming wire rods and steel materials are inspected to verify:
• Material grade 
• Diameter tolerance 
• Surface condition 
• Mechanical properties 
• Supplier documentation 

Materials that do not meet production requirements are isolated and prevented from entering the manufacturing process.
This helps ensure stable performance throughout subsequent forming, threading, and heat treatment operations.

During manufacturing, dimensional inspections are conducted at key production stages.
Inspection items may include:
• Head diameter 
• Head height 
• Shank diameter 
• Product length 
• Point geometry 
• Thread formation 

Production operators and quality inspectors monitor product dimensions throughout the manufacturing process to identify deviations before large quantities are produced.

Thread quality directly affects fastening performance and installation efficiency.
Thread inspections are carried out using measuring tools and thread gauges to verify:
• Thread pitch 
• Thread depth 
• Thread angle 
• Thread consistency 
• Fit accuracy 

Particular attention is given to self-drilling screws and self-tapping screws where thread performance is critical during installation.

For products requiring heat treatment, hardness testing is performed to verify mechanical performance.
Inspection may include:
• Core hardness 
• Surface hardness 
• Heat treatment consistency 

Proper hardness control helps ensure sufficient strength while reducing the risk of cracking or brittleness during installation.

Depending on product type and customer requirements, mechanical testing may include:
• Tensile strength testing 
• Torque testing 
• Pull-out testing 
• Shear performance evaluation 

These tests help verify that products meet application requirements for construction, steel structures, and industrial assemblies.

Surface coatings play an important role in corrosion resistance and service life.
Inspection items include:
• Coating appearance 
• Coating coverage 
• Surface defects 
• Coating consistency 

Available surface treatments include:
• Zinc plating 
• Hot dip galvanizing 
• Black oxide 
• Ruspert coating 

Additional coating verification can be arranged according to customer specifications.

Before packaging and shipment, finished products undergo final inspection.
The inspection process may include:
• Product dimensions 
• Product appearance 
• Packaging verification 
• Label verification 
• Quantity confirmation 

Only products that pass final inspection are released for shipment.

To support long-term supply projects and customer quality management requirements, production batches are recorded throughout the manufacturing process.
Traceability records may include:
• Raw material source 
• Production date 
• Machine records 
• Inspection records 
• Shipment records 

This allows production information to be reviewed when required and helps improve quality consistency over time.