Wear-Resistant Hardfacing of Brick Machine Spiral Cutters

Literature Overview

This 1990 paper, published in Welding Technology (Vol. 19, Issue 6) by authors from Northeast Heavy Machinery College and Qiqihar Ninth Brick Factory, addresses the practical problem of extending the service life of spiral cutters used in brick-making machinery. Brick machines operate under severe abrasive wear conditions, with the spiral cutters (also referred to as spiral augers or screw cutters) being subjected to continuous contact with abrasive clay materials. The paper evaluates multiple hardfacing processes and welding consumables, comparing their technical characteristics and economic benefits.

Operating Conditions and Wear Mechanisms

The spiral cutters in brick-making machines operate under uniquely demanding conditions:

• Abrasive wear: Continuous contact with clay containing silica, quartz, and other hard mineral particles.
• Impact loading: Periodic impact from hard inclusions in the clay material.
• Sliding contact: The cutter rotates against the brick mold, creating sliding wear on the cutting edges.
• High material throughput: The cutters must maintain performance for extended operating periods, often thousands of hours between replacements.

The primary wear mechanism is abrasive, but impact and adhesive wear components may also contribute to the overall material loss. Understanding the wear mechanism is essential for selecting the appropriate hardfacing material and process, as different mechanisms require different material properties for effective resistance.

Comparison of Hardfacing Processes and Materials

The paper evaluates several hardfacing approaches, which can be summarized as follows:

The economic analysis presented in the paper is particularly valuable from a practical standpoint. The cost-effectiveness of hardfacing depends on several factors:

1. Equipment cost: SAW equipment is more expensive than SMAW but offers higher deposition rates.
2. Consumable cost: Nickel-based and cobalt-based consumables are significantly more expensive than high-carbon steel electrodes.
3. Labor cost: Automated or semi-automated processes reduce labor requirements.
4. Service life extension: The primary economic driver – longer service life means fewer shutdowns and lower replacement costs.
5. Preparation and post-processing: Surface preparation, fit-up, and post-weld machining requirements affect total cost.

Technical Analysis of Hardfacing Materials

For brick machine spiral cutters, the selection of hardfacing material must balance hardness with toughness. Excessively hard materials (above 60 HRC) may be prone to chipping and spalling under impact loading, which is common in clay processing. The optimal hardness range for this application is typically 45–58 HRC, which provides adequate abrasive wear resistance while maintaining sufficient toughness to resist impact damage.

The microstructure of the hardfacing deposit plays a critical role in wear resistance. High-carbon martensitic deposits (M + M₇C₃) are commonly used for moderate wear applications, while high-chromium deposits (M + M₇C₃ with Cr₂₃C₆) offer better wear resistance at higher hardness levels. The presence of hard carbide particles dispersed in a ductile matrix is the key microstructural feature that provides wear resistance.

Engineering Practice Insights

This paper, despite its age, contains valuable practical insights that remain relevant:

• Process-material matching: The selection of hardfacing process must be matched to the geometry and production volume of the component. For spiral cutters, which have helical surfaces, the accessibility for welding and the need to maintain dimensional accuracy are important considerations.
• Multi-layer approach: For severe wear conditions, a multi-layer approach with a transition layer and a hardfacing layer can improve both bonding strength and wear resistance.
• Quality control: Simple but effective quality control measures such as visual inspection, hardness testing, and penetration tests are essential for ensuring hardfacing quality.

The paper's emphasis on economic comparison is particularly noteworthy. In many hardfacing applications, the technically superior solution is not always the economically optimal one. The paper demonstrates that a systematic comparison of technical performance and economic cost is essential for making informed process selection decisions.

Key Reflections

The brick machine spiral cutter application represents a typical industrial hardfacing scenario where the operating conditions are well-defined and the economic constraints are significant. The systematic comparison of multiple processes and materials provides a useful framework for process selection in similar applications. The paper's emphasis on economic analysis, in addition to technical performance, reflects a mature engineering approach that considers both technical and commercial factors.

One limitation of the study is the likely absence of long-term field performance data. Laboratory or short-term service tests may not fully capture the complex wear mechanisms that develop over extended operating periods. For critical applications, it is advisable to conduct extended field trials before committing to a particular hardfacing solution.

Conclusion

This paper provides a practical and economically grounded comparison of hardfacing processes and materials for brick machine spiral cutters. The systematic evaluation framework, combining technical performance with economic analysis, serves as a useful model for hardfacing process selection in similar industrial applications. The findings reinforce the principle that the optimal hardfacing solution must balance wear resistance, toughness, processability, and cost for the specific application.