As a key fastening component of the excavator chassis, track bolts must possess high strength, wear resistance, and fatigue resistance. Their production process is developed around material properties and precision requirements, with the core steps as follows:
1. Raw Material Selection and Pretreatment
High-strength alloy steels (such as 40Cr, 35CrMo, etc.) are preferred, as these materials can meet the load-bearing and impact resistance requirements of bolts after processing. The first step is to remove rust and oxide scale from the surface of the steel, and then cut the steel into blanks of appropriate weight and length using a cutting machine.Excavator shoe bolt
2. Cold Heading Forming (Core Shaping Step)
A cold heading machine is used to apply high pressure to the metal blanks, extruding them into the initial shape of bolts (including the head and shank) at room temperature. This process does not require high-temperature heating, so it can retain the original grain structure of the metal, improve the strength and compactness of the bolts, and reduce material waste. For bolts with complex specifications, multi-pass cold heading may be required for gradual forming.Excavator track shoe bolt
3. Thread Processing
According to the specifications of track bolts (e.g., pitch, thread profile), a thread rolling machine is used for thread processing (the mainstream process). Thread rolling forms threads through metal plastic deformation, which enhances the wear resistance and fatigue resistance of the threads compared with cutting processing. For bolts with special specifications, lathes may also be used for thread cutting, but this method has low efficiency and is mostly used for small-batch production.track shoe bolt
4. Heat Treatment Strengthening
To improve the mechanical properties of bolts, a two-step process of "quenching + tempering" is required:
Quenching: Heat the bolts to 800-900°C (adjusted according to the steel type), keep them at this temperature for a certain period, and then quickly immerse them in a cooling medium (such as water or oil). This converts the internal structure of the steel into martensite, significantly increasing its hardness.40Cr track shoe bolt
Tempering: Reheat the quenched bolts to 200-500°C, keep them at this temperature, and then cool them slowly. This process retains the hardness while eliminating internal stress to prevent bolt brittleness, ultimately achieving a balance of "high strength + high toughness".D9N 1"x90
5. Surface Treatment (Corrosion and Wear Resistance)
Track bolts operate in humid, dusty environments for a long time, so surface treatment is necessary to improve their corrosion resistance.01803-01824
Dacromet (excellent salt spray resistance, suitable for harsh environments);
Phosphating (enhances surface adhesion, often used as a base for subsequent coatings).
Some high-end bolts may additionally undergo blackening or chrome plating to balance rust prevention and appearance.
6. Quality Inspection
Precision and performance are controlled throughout the process, with key inspection items including:
Dimensional inspection: Use calipers and thread gauges to check the bolt length, diameter, thread precision, etc., ensuring compliance with drawing requirements;
Performance inspection: Conduct sampling tests such as tensile tests (to check tensile strength), hardness tests (e.g., using a Rockwell hardness tester), and impact tests (to verify toughness);
Appearance inspection: Check for surface cracks, burrs, coating defects, etc., and reject unqualified products directly.excavator bottom roller
7. Packaging and Delivery
Qualified bolts are classified by specification and packaged with anti-rust paper, cartons, or pallets to avoid collision and rust during transportation. Finally, they are delivered to suppliers or complete machine manufacturers.
No.506, Zikeng, Sihuang Village,Xiamei Town,Nan'an City,Quanzhou City,Fujian Province
+375(25)660-12-83
http://excavatorbottomroller.com
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