MT/T 321-2025
MT · 2025-06-30

Helical drum for shearers

ICS 73.100.99

2Expert Interpretation

This article provides an in-depth analysis of the MT/T321-2025 industry standard "Spiral Drums for Coal Mining Machines," examining the technical changes in the new standard regarding terminology, size series, connection methods, and technical requirements. It compares the differences between the old and new versions and provides a comprehensive implementation guide for the entire process of drum manufacturing, inspection, packaging, and transportation, thus facilitating the standardization and upgrading of coal mining equipment.

In-depth interpretation of the MT/T321-2025 standard for spiral drums in coal mining machines

The MT/T321-2025 industry standard for spiral drums in coal mining machines, released in 2025, is an integration and upgrade of the 2004 versions of MT/T321 and MT/T140 standards. As a core component in underground coal mining operations, the technical standards of spiral drums directly affect coal mining efficiency, safety performance, and equipment lifespan. The new standard, while inheriting the original technical framework, has undergone systematic revision and improvement in light of recent advancements in coal mining technology and increased safety requirements in coal mines.

Background and Technological Evolution of the Standard Revision

The background of this standard revision stems from the rapid development of coal mining technology and the continuous improvement of safety production requirements.

Since the implementation of the 2004 standard, my country's coal mining equipment has undergone a significant transformation from mechanization to intelligentization. High-power, high-extraction, and intelligent coal mining machines are widely used, placing higher demands on the load-bearing capacity, service life, and safety performance of spiral drums. Meanwhile, MT/T140-2004, "Coal Mining Machine Drum Connection Methods and Parameters," as a supporting standard, overlaps with MT/T321-2004 in practical applications. Integrating these two standards is beneficial for forming a unified technical specification system. The technological evolution is mainly reflected in three aspects: first, advancements in materials science have significantly improved the material performance of drum assembly welded components; second, improvements in manufacturing processes have placed higher demands on dimensional accuracy and welding quality; and third, the improvement of safety standards has strengthened the management of safety markings for mining products. The new standard is based on these technological developments and has comprehensively updated the relevant technical requirements. The new standard has made several important adjustments in structure, content, and technical requirements, reflecting the industry's technological development direction and practical application needs.

Optimization and Improvement of Terminology Definitions

The standard has reorganized key terms in Chapter 3:

  • New Terms: Two terms, "blade lead" and "drum assembly welded parts," have been added. Blade lead is defined as "the axial distance between adjacent corresponding points on the outer edge of the blade along the helix," a parameter crucial for the drum's coal loading efficiency and cutting performance. Drum assembly welded parts are defined as "a welded structure consisting of end plates, blades, drum rings, tooth seats, connecting plates, etc.," emphasizing the overall concept of the drum.
  • Revised Terms: The definition of "end plate tooth drop" has been changed to make it more precise and easier to measure and verify.
  • Deleted Terms: The terms "cutoff line" and "blade outer edge helix angle" have been deleted. These concepts are rarely used in practical applications or can be expressed indirectly through other parameters.

Reorganization of Connection Method Classification

Chapter 4 integrates the content of the original MT/T140-2004, forming a complete connection method specification system:

The standard specifies detailed parameters for the two connection methods. The square shaft connection parameter table includes 10 specifications ranging from 200mm to 900mm, while the tapered shaft connection offers two specifications: 220mm and 280mm. Notably, the standard indicates non-preferred parameters, providing clear guidance for manufacturers.

Technical Upgrades to Size Series

The drum diameter series has been expanded from a limited range in the 2004 version to a complete series covering 600mm to 5000mm, with 24 specifications, fully adapting to the mining needs of the entire range from thin to extra-thick coal seams. The cutting depth series has also been adjusted, forming 7 specifications ranging from 500mm to 1200mm. These improvements to the size series provide a standardized basis for the design and selection of coal mining machines.

Optimization of Model Naming Rules

The new standard has made minor adjustments to the naming method for roller models, retaining the "TZ" prefix (representing "roller"), followed by the codes for diameter, cutting depth, number of blade heads, cutting tooth type, and connection method. This naming method can intuitively reflect the main technical characteristics of the roller, facilitating equipment management and technical communication.

Comprehensive Improvement of Technical Requirements

Chapter 5, "Requirements," has undergone several substantial revisions:

Connection Method Scope of Application Key Parameters Technical Features
Square Shaft Connection All Power Coal Mining Machines Square Hole Size, Fixing Bolt Specifications High Load Capacity, Suitable for High Power Equipment
Conical Shaft Connection Small and Medium Power Coal Mining Machines Taper, Fitting Dimensions Easy Installation, High Positioning Accuracy
Technical Requirements Items MT/T321-2004 Provisions MT/T321-2025 Provisions Technical Improvement Analysis
Materials for Roller Assembly Welding General Requirements Clearly conforms to GB/T699, GB/T1591, and GB/T11352, with tensile strength ≥470MPa Material standards are specified, and strength requirements are quantified
Weld Quality Refer to relevant standards Not lower than the Class III requirements in Table 10 of JB/T5000.3-2007 Clear acceptance levels, strong operability
Internal spray water system Pressure test requirements 1.5 times the rated water pressure (not lower than 4.5MPa), pressure drop ≤0.5MPa Pressure standards improved, unobstructed flow requirements quantified
Dimensional tolerances Segmented by diameter Refined into four grades, with added requirements for blade lead deviation More reasonable grading, more comprehensive control parameters

Particularly noteworthy is the reclassification of linear dimensional tolerances in the standard. Different tolerance values are specified for four ranges: ≤1000mm, >1000~2000mm, >2000~4000mm, and >4000mm. This grading method is more scientific and reasonable, adapting to the manufacturing precision requirements of rollers of different specifications.

Improvements in Test Methods and Inspection Rules

The revisions to Chapter 6, "Test Methods," and Chapter 7, "Inspection Rules," reflect improvements in the standard's operability and scientific rigor.

Standardization of Test Methods

The new standard refines various test methods:

  • Linear Dimension Inspection: It clarifies the measurement method using a dedicated roller measuring device in conjunction with standard cutting teeth, and provides detailed calculation formulas. This method can comprehensively obtain the geometric parameters of the roller, including key indicators such as diameter, runout, and section distance.

  • Gear Seat Positioning Angle Inspection: This section distinguishes between different inspection methods for flat cutting tooth rollers and conical cutting tooth rollers. Specifically, for conical cutting tooth rollers, the positioning angle β is calculated by measuring angle α, which is more accurate.
  • Blade Lead Inspection: This newly added inspection item uses a calculation method that measures the axial height difference corresponding to a 30° rotation angle and then multiplies it by 12. This method is simple to operate and has reliable accuracy.

Improvement of Inspection Rules

The inspection item table (Table 7) has been redesigned, dividing inspection items into two categories: factory inspection and type inspection:

The triggering conditions for type testing are more clearly defined, including five situations such as new product launch, resumption of production after a two-year shutdown, and major design changes. This helps ensure the continuous stability of product quality.

Strengthened requirements for marking, packaging, transportation, and storage

Chapter 8 contains the most significant additions in this revision, reflecting the emphasis on product lifecycle management:

Standardization of marking requirements

It is explicitly required that product nameplates be fixed and made of copper or stainless steel to ensure long-term visibility in harsh underground environments. Special emphasis is placed on the requirement that safety markings for coal mine products must comply with AQ1043, which is a crucial guarantee for safe production in coal mines.

Systematization of Packaging and Transportation The new standard sets forth detailed requirements for packaging and transportation: Protective Measures: Water channels must be drained completely; inlet, outlet, and nozzle mounting holes must be protected with plugs; and connecting parts must be coated with anti-rust oil. Packaging Specifications: Packaging is generally required (unpackaged packaging may be negotiated), and must comply with GB/T13384. Cutting teeth and nozzles must be packaged separately. Transportation Conditions: Cutting teeth and nozzles should not be installed during transportation; they must be leveled, securely tied, and waterproofed. Freezing protection is also required in low-temperature environments. Scientific Storage Management Storage requirements are specifically stipulated for the first time: Water channels must be drained and dried before storage; the storage environment should be clean, dry, well-ventilated, and free from corrosion; prolonged exposure to sunlight should be avoided; freezing protection is required when the temperature is below 0℃. These regulations help extend the service life of the rollers and ensure equipment performance.

Technical Guidance Value of the Appendices

The two informative appendices included in the standard have significant practical guiding significance:

Appendix A: Dedicated Measuring Device for Rollers

Describes in detail the composition of the measuring device, including components such as a width square, a universal square, a positioner, a support rod, a radial ruler, a carriage, and an axial ruler. This dedicated device can accurately measure various geometric parameters of the roller, providing a reliable tool for quality control.

Appendix B: Standard Cutting Teeth

Provides detailed specifications for two types of standard cutting teeth: tapered cutting teeth and flat cutting teeth, including external dimensions, shank dimensions, and tolerance requirements. Standard cutting teeth serve as a measurement benchmark, ensuring the consistency and comparability of inspection results from different manufacturers and different batches of products.

Implementation Recommendations and Industry Impact

Recommendations for Manufacturing Enterprises

1. **Technology Upgrade:** Enterprises need to update their production processes and quality control systems according to the new standard requirements, especially in welding processes, dimensional control, and material selection.

2. **Equipment Investment:** Enterprises need to equip themselves with roller-specific measuring devices that meet the requirements of Appendix A and standard cutting teeth that meet the requirements of Appendix B to ensure inspection capabilities.

3. **Document Updates:** Product drawings, technical documents, inspection procedures, etc., should be revised in a timely manner to ensure consistency with standard requirements.

4. **Personnel Training:** Strengthen standard training for technical and inspection personnel, especially the operating methods for newly added inspection items.

Impact on User Units

1. **Procurement Basis:** The new standard provides the latest technical basis for drum procurement. Users should explicitly require compliance with MT/T321-2025 in the procurement contract. **2. Acceptance Standards:** Acceptance upon arrival should be conducted according to the inspection items and methods of the new standard, paying particular attention to key indicators such as the performance of the internal spray water system and dimensional tolerances. **3. Maintenance Reference:** The requirements for packaging, transportation, and storage in the standard provide standardized guidance for the storage and maintenance of drums. **Significance for Industry Development:** The implementation of MT/T321-2025 will promote technological progress and standardization in the coal mining machine spiral drum industry: **Promoting Technological Innovation:** Higher technical requirements will drive enterprises to innovate in materials, processes, and design. **Improving Product Quality:** Unified standards are conducive to improving the overall quality level of the industry and reducing quality differences.

  • Ensuring Safe Production: Strengthening safety mark management and performance requirements helps reduce the risk of coal mine accidents.
  • Regulating Market Competition: Clear technical standards provide a foundation for fair competition and are conducive to the development of high-quality enterprises.

    • Precautions During the Transition Period Between Old and New Standards

    During the standard transition period, relevant parties should pay attention to the following:

    1. **Timeline:** Pay attention to the implementation dates and transition period arrangements issued by the National Energy Administration and the coal industry standardization authorities.

    2. **Product Identification:** Newly designed and manufactured products should comply with the requirements of the new standards, including model naming and nameplate content.

    3. **Inventory Management:** Products already manufactured according to the old standards should be disposed of or undergo necessary technical upgrades during the transition period.

    4. **Certification Update:** Products involving safety marks for mining products should promptly apply for certification according to the new standards.

    The release and implementation of the industry standard MT/T321-2025, "Spiral Drum of Coal Mining Machine," marks a new stage in the standardization of coal mining equipment in my country. The standard not only integrates and optimizes technical content but also reflects a comprehensive consideration of safety production, quality improvement, and industry development. Relevant enterprises should thoroughly study the standard's content, promptly adjust their technical approaches and production management, and jointly promote the high-quality development of the coal mining equipment manufacturing industry.

    3Version History

    MT/T 321-1993 older 1993-02-25
    MT/T 321-2004 older 2004-12-14
    MT/T 321-2025 2025-06-30

    4Standard Metadata

    Standard Number
    MT/T 321-2025
    Status
    Current
    Publisher
    Professional Standard - Coal
    Publication Date
    2025-06-30
    Implementation
    2025-12-30
    ICS Classification
    73.100.99 (Other mining equipment) 

    5Citation Network

    0
    Cite this standard
    22
    Referenced herein
    Referenced by MT/T 321-2025
    AQ 1043 GB/T 10111 GB/T 11352 GB/T 13306 GB/T 13384 GB/T 15663.10 GB/T 15663.10-2008 GB/T 1591

    6Frequently Asked Questions

    What is MT/T 321-2025?
    MT/T 321-2025 — Helical drum for shearers is an international standard developed by Professional Standard - Coal.
    What does MT/T 321-2025 cover?
    This standard covers:
    Who should use this standard?
    This standard is intended for organizations, professionals, and stakeholders involved in various industries and sectors. It is applicable to manufacturers, service providers, regulatory bodies, and certification organizations.
    What is the latest version of MT/T 321-2025?
    The current published version is MT/T 321-2025, published on 2025-06-30. Always check for amendments or pending revisions.
    How do I purchase MT/T 321-2025?
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    Inspection Category Mandatory Inspection Items Sampling Requirements Pass/Fail Judgment
    Factory Inspection Appearance, Component Disassembly and Assembly, Internal Spray Water System, Main Dimensions Inspection Unit by Unit All Items Pass
    Type Inspection All 7 Items Randomly Select 1 Unit All Items Pass