Why is the alloy tip intact, yet the cutting tooth has fractured at the root?
2025-09-11
In tunneling operations, cutter picks exhibit a wide variety of failure modes; however, one particular situation particularly puzzles construction managers: Although the carbide tip of a cutting tooth was still in excellent condition and its wear was within acceptable limits, the entire tooth body suddenly fractured at the root. This phenomenon not only leads to the premature failure of cutting picks but also poses a hidden threat to equipment and construction efficiency.
Why do cutting picks that seem “wear-resistant” turn out to be so “fragile”? Behind this lies a crucial principle in cutting pick performance design—the balance between “hardness” and “toughness.”
The dual mission of cutting picks
Wear-resistant “spear” and tough “shield”
To understand the issue of broken cutting edges, we must first clarify the dual role that a cutting tooth assumes during operation. It is not merely a simple cutting tool.
Front-end carbide tip: plays the role of the “spear.” Its core mission is to maintain sharpness even in high-speed contact with rock, thanks to its extremely high hardness, effectively resisting abrasive wear and achieving efficient rock fragmentation. Therefore, “wear resistance” is its primary performance indicator.
Rear-end steel gear body: serves as the “shield.” Its core function is to serve as a robust foundation, steadily transmitting the enormous impact force generated by the tunneling machine to the alloy cutterhead while simultaneously withstanding bending stresses and vibrations from all directions that arise during rock-breaking operations. Therefore, “impact toughness” is its lifeline.
The root cause of broken stems
The Overlooked “Resilience” Indicator
When selecting cutting picks, many users tend to overemphasize the brand and wear resistance of the alloy tip while neglecting to consider the performance of the pick body itself. However, insufficient toughness of the pick body is precisely the direct cause of handle breakage. There are two main issues in the manufacturing process underlying this problem:
Improper material selection
The cutting teeth bodies must be made from high-quality alloy structural steel. To reduce costs, some manufacturers may use ordinary steel that fails to meet performance standards. Its inherent strength and toughness reserves are inherently flawed from the very beginning.
Uncontrolled heat treatment process
This is the most fundamental—and also the most subtle—reason. The heat treatment process is the crucial step that gives the gear teeth their “toughness and strength.” The scientific heat treatment process is designed to form an ideal microstructure within the steel—“quenched martensite +” Tempered Troostite Strong and resilient organizations If manufacturers, in their rush to meet deadlines and reduce costs, fail to properly control critical parameters such as heating temperature, holding time, and cooling rate, it could lead to:
Insufficient quenching
Insufficient strength and hardness can easily lead to plastic deformation of the tooth body during use.
Overquenching or improper tempering
The excessive formation of coarse martensite or grain-boundary carbides leads to excessive internal stresses within the tooth body, making it extremely brittle and highly susceptible to fracture under impact.
Xinda’s solution
Pursuing the optimal balance between hardness and toughness.
As a professional manufacturer of cutting picks, Xinda deeply understands that a high-quality, wear-resistant cutting pick is by no means simply the result of maximizing a single performance attribute—it’s rather a perfect balance of multiple indicators.
Scientific material system
We We consistently select high-standard alloy steel as the raw material for gear bodies. And, for different operating conditions, steel with varying toughness levels is matched accordingly.
Precise heat treatment control
We have a fully computer-controlled heat treatment production line and have established a separate process database for each type of cutting pick. By precisely controlling temperature, time, and atmosphere, we ensure that each cutting tooth body exhibits the optimal combination of strength and toughness—enabling it to efficiently transmit impact forces while also fully absorbing vibrational energy.
Systematic performance testing
Our laboratory not only tests the hardness of products but is also equipped with devices such as impact testing machines. Conduct rigorous, quantitative testing of the product’s impact resistance to ensure that every batch meets the design standards.
Summary
In short, when you frequently encounter broken cutter teeth on construction sites, you should no longer simply attribute it to “bad luck.” This is very likely a clear signal. The product you are using has a serious flaw in its inherent “resilience.”
When choosing cutting picks, you shouldn't just look at whether their "spear" is sharp—more importantly, you need to see whether their "shield" is sturdy. Xinda Machinery is committed to providing you with reliable products that offer both strength and versatility, ensuring that they will be your most trusted excavation tool in even the harshest operating conditions.
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Email : info@cinda-tec.com
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