Executive Summary
We engineered, manufactured and breakbulk-shipped a 67-ton, 22FT mill head for a major SAG mill project - a turnkey example of our capacity to deliver ultra-large ball mill parts with export-grade QA and logistics. From pattern design and controlled casting to stress-relief heat treatment, heavy-duty CNC finishing, multi-stage NDT and pre-trial lifting, every step was coordinated with the client. The result: a precision mill head delivered ready for installation, minimizing onsite rework and project risk.
Product Profile - Technical & Performance Summary
- Item: Mill Head (22FT) - 67 tons gross weight
- Material: BS3100-A2 cast steel - selected for toughness and fatigue resistance in heavy grinding environments
- Critical tolerances: interfaces to ±1.0 mm, radial/axial runout ≤0.20 mm after final machining
- Surface finish: Shot-blast + primer/topcoat; critical contact faces machined to Ra ≤1.6 μm where required
- Thermal process: Multi-step stress-relief heat treatment tailored to casting mass
- QA package: Full dossier - MTC, MPI/UT reports, laser tracker maps, hardness logs, coating reports, bolt-trial documentation
Manufacturing Excellence - How We Delivered Precision at Scale
Manufacturing a 67-ton mill head is a systems engineering task - metallurgy, solidification control, heat-treatment scheduling, jigging strategy, and heavy-duty machining must be designed together. We implemented: engineered gating and chill placement to avoid macro-segregation; staged heat-treatment cycles with thermocouple mapping to remove residual stresses; heavy gantry CNC machining with multi-point fixtures and live runout monitoring; and interim third-party NDT checkpoints before committing to finish machining. Pre-trial bolt-ups and shop lift tests validated the assembly and lifting design, avoiding surprises at site. All manufacturing records were compiled in a traceable dossier for the client.
67-Ton Manufacturing Challenges & Engineered Solutions
- Metallurgical segregation & shrinkage: solved by melt chemistry control, gating/chill strategy and staged cooling; early NDT verified internal soundness.
- Residual stress and distortion: multi-cycle stress-relief heat treatment with intermediate inspections; jigged finish machining to lock geometry.
- Large-scale machining accuracy: heavy gantry CNC with bespoke fixtures achieved target runout ≤0.20 mm; continuous in-process metrology.
- Safe handling and lifts: engineered swivel lifting lugs, backing plates, certified lift procedures, and pre-trial shop lifts minimized risk.
- Logistics complexity: custom sea-fastening design (timber blocking + saddles), moisture control and customer-witnessed loading ensured safe export.
Quality Assurance - Traceability & Independent Verification
QA Program
For a project of this value, QA is non-negotiable. Our program included: early third-party checks during rough machining to confirm cast integrity; full MPI and UT scans of critical load zones; laser-tracker dimensional mapping for flange flatness and bolt patterns; hardness mapping across sections to verify heat-treatment uniformity; bolt-trial assemblies with torque curves; and coating adhesion/film thickness verification. All test reports and certificates were compiled into a single technical dossier and shared with the client before loading - essential for risk mitigation on high-value ball mill parts.
Breakbulk Logistics - Execution & Customer Benefits
Breakbulk (lift-on / lift-off) was the only practical shipping mode for this oversized 67-ton geometry. Advantages realized for the client: reduced handling stress compared with containerization, customized sea-fastening that protects contact faces, capability for port heavy-lift discharge, and direct coordination with the customer's erection team to align arrival windows with site readiness. Our logistics scope covered certified lifting plans, heavy-lift crane coordination, sea-fastening design, moisture protection, and customer witness points during NDT and loading.
Mill Head vs Feed Head vs Discharge Head - Engineering Comparison & Buyer Guidance
Mill Head (general term / end cover)
structural assembly that may refer generically to either feed or discharge end covers; for procurement, specify function, orientation (feed/discharge), and mating geometry.
Feed Head (inlet end)
designed to guide bulk ore into the mill, manage axial load transfer, and provide precision liner seats.
Discharge Head (outlet end)
optimized to control slurry exit, maintain classification performance and withstand cyclic loads.
optimized to control slurry exit, maintain classification performance and withstand cyclic loads.
Machining & metrology
Heavy gantry CNC centers, portable CMMs and laser trackers for in-process control.
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Heat treatment
Furnaces and cycles sized to reduce residual stress for large masses; multi-zone control.
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Handling
In-shop heavy cranes, engineered lifting frames and pre-trial lift capability.
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Practical limits
We design manufacture and logistics solutions for mill heads of comparable or greater scale; for specific max-size capacity please contact engineering for confirmation (site constraints and configuration dependent).
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Why Choose ZM INDUSTRY CO., LTD.
- Integrated Manufacturing Chain - pattern, casting, heat treatment, precision machining and coating in one coordinated workflow, reducing lead time and alignment risk.
- Engineering Rigor - in-house process control, thermocouple-verified heat cycles and staged inspections reduce variability and distortion risk.
- Traceable QA - full technical dossiers with third-party NDT and metrology records handed to clients for procurement and compliance.
- Heavy Cargo Logistics Expertise - proven breakbulk execution, certified lift planning and port coordination for oversized ball mill parts.
- Client Collaboration Model - regular engineering syncs, on-site witness points and shared documentation for transparent project governance.
- Post-Delivery Support - installation guidance, bolt/tensioning protocols and availability of replacement components and liners.
FAQ - Technical Buyer Questions
What makes a mill head suitable for a 22FT SAG mill?
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What makes a mill head suitable for a 22FT SAG mill?
How is a 67-ton mill head safely lifted and loaded for shipment?
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Safety relies on engineered lifting points and pre-trial validation. We design swivel lifting lugs and backing plates, conduct shop lift trials, produce certified lift plans, and supervise heavy-lift crane operations during breakbulk loading to ensure safe, predictable handling at every stage.
What NDT and inspection reports are provided with delivery?
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We provide a complete dossier including MPI and UT reports, laser tracker dimensional maps, hardness logs, coating film thickness/adhesion tests, and bolt-trial records. All reports include timestamps, inspector IDs and, where required, third-party witness signatures for procurement traceability.
How does breakbulk shipping protect an oversized mill head better than containerization?
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Breakbulk avoids container size constraints and concentrated crating stresses. It allows bespoke sea-fastening-timber blocking, welded saddles and tailored lashing-that distribute loads safely, enable port heavy-lift discharge, and permit customer witness points during loading for final QA acceptance.
Can you manufacture and ship multiple mill heads for a single project on a schedule?
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Yes. Our integrated workflow and logistics partners support multi-unit programs. We coordinate production slots, staged inspections, and periodic shipping windows to align with customer erection schedules, reducing on-site waiting and enabling predictable commissioning sequences.
Call to Action
If your project requires ultra-large mill heads or critical ball mill parts, partner with a manufacturer that combines metallurgy, precision machining, rigorous QA and breakbulk logistics. Request the 67-Ton Mill Head Technical Dossier, arrange an engineering review, or get a custom quotation from ZM INDUSTRY CO., LTD. today.
Our address
Head Office: 4#-1616, No.296 Liuquan Road, Zibo City, Shandong China
Branch Office: 208-7B, No.2 Penglai Road, Jianxi District, Luoyang City, Henan Province,China
Phone Number & Whatsapp
+8618606381772
sun@zmindu.cn
