Ship-and-offshore equipment manufacturing belongs to the high-end heavy-industry sector. High-strength marine steel plates including AH36, DH36 and EH36 are widely used for core structural components. Plate thickness mostly ranges from 20 mm to 100 mm, while plates for deep-sea platforms, ship keels and bulkheads can even exceed 120 mm. Heavy-plate blanking, bevel forming and precision control directly determine the assembly accuracy of hull blocks, welding quality and non-destructive testing (NDT) pass rate, and represent a key process for shipyards to improve quality and reduce costs.
Compared with general steel-structure cutting, heavy-plate cutting for shipbuilding faces typical challenges: difficult piercing, heavy dross, unstable bevel quality and constraints for on-site operations.
I. Four Core Industry Challenges in Shipbuilding Heavy-Plate Cutting
1. Piercing defects in heavy plates create hidden risks for structural safety
When piercing high-strength marine steel plates thicker than 20 mm, heat cannot dissipate rapidly. This easily causes piercing collapse, slag accumulation and arc-starting offset. Minor defects at the piercing point may trigger welding problems such as porosity, incomplete penetration and slag inclusions, which directly endanger hull structural integrity and compromise ship acceptance standards.
2. Poor cut-face squareness, heavy bottom dross and extensive grinding work
Large temperature difference between the top and bottom of thick plates often produces tapered kerfs (narrower at the top, wider at the bottom) and unsatisfactory cut-face squareness. Heavy dross and thick scale adhere to plate bottoms. Conventional processing requires massive manual grinding and rework, greatly prolonging block-manufacturing cycles and driving up labour costs. Cutting high-strength steel may also generate hardened surface layers and raise the risk of micro-cracks.
3. Unstable welding-bevel accuracy leads to assembly and welding deviations
Hull keels, bulkheads and deck components generally require V-type, X-type or Y-type welding bevels. Manually adjusted torches and unstable parameters of traditional equipment cause large deviations in bevel angles and margins. This results in uneven assembly gaps among blocks, severe welding deformation and a significantly higher NDT failure rate.
4. Immovable large hull blocks create difficulties for on-site trimming
Completed ship blocks and large cabin structures are oversized and cannot be transported to fixed machine-tool workshops. On-site work including edge trimming, hole drilling, insert-plate cutting and dimension modification must be performed on slipways and in dry docks. Large fixed gantry machines cannot access these areas, forming a major production bottleneck for many shipyards.
Real-World Application Cases
Case 1: Medium-sized shipyard in Shandong — Rectification project for mass blanking of 80-100 mm super-thick marine plates
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Project pain points: The customer’s legacy cutting machine suffered frequent piercing collapse, severely tapered cut faces and heavy bottom dross when processing 80-100 mm DH36 marine steel. The grinding-and-rework rate exceeded 40 %. Inconsistent bevel quality led to repeated welding-test failures and serious schedule delays in ship construction.
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Adopted solution: Deployed Honeybee’s heavy-duty dual-purpose gantry cutting machine for flame and plasma cutting, equipped with dedicated pre-heat piercing technology for heavy plates and an automatic bevel-cutting system with optimized cutting parameters for super-thick marine steel.
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Improvement outcomes: The piercing success rate reached nearly 100 %. Cut-face squareness was greatly improved with minimal dross and no need for extensive grinding. Standard welding bevels were formed in a single pass with angular tolerance controlled within ±0.5°. Welding rework dropped by 90 %, and monthly plate-blanking capacity rose by 35 %, fully meeting ship-construction acceptance criteria.
Case 2: Offshore-engineering enterprise in Dalian — On-site block-trimming retrofit project on slipway
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Project pain points: Frequent on-site edge trimming, hole cutting and insert-plate modification were required for completed offshore-platform and large-hull blocks. Large stationary machine tools could not be moved to site. Traditional manual torch cutting delivered low accuracy, rough cut surfaces and poor repeatability, resulting in extremely high rework rates.
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Adopted solution: Deployed Honeybee portable CNC plasma-and-flame cutting machines. The lightweight equipment with quick-assemble rails can be transported directly to slipways, dry docks and elevated working platforms. It supports fully-programmed automatic cutting and one-pass bevel forming.
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Improvement outcomes: Manual torch operation was completely replaced. On-site cutting delivers precise dimensions and smooth surfaces without secondary grinding. The flexible system adapts to on-site modification of extra-large components and solves the long-standing problem of immovable hull blocks. On-site working efficiency increased by 60 %, yielding substantial labour-cost savings.
Case 3: Ship-steel-structure supporting manufacturer in Jiangsu — Mass bevel-cutting and automation-upgrade project
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Project pain points: This factory produces large volumes of structural parts for shipbuilding and required high-volume bevel blanking. Conventional equipment ran slowly and produced uneven bevels, failing to match the cycle of automatic-welding production lines and restricting overall output.
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Adopted solution: Adopted Honeybee multi-torch gantry cutting equipment with intelligent CNC thermal-compensation system. It enables simultaneous cutting of multiple plates and fully-automatic one-pass bevel forming, and connects seamlessly with downstream welding robot production lines.
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Improvement outcomes: A seamless workflow of “heavy-plate blanking — bevel preparation — automatic welding” was realized with greatly enhanced overall automation. The qualification rate of finished products reached 99 %, satisfying the requirements for standardize and mass production in shipyards.
III. Targeted Practical Solutions for Different Shipyard Scenarios
1. Mass heavy-plate blanking in workshops: Heavy-duty gantry CNC cutting solution
Suitable for plate-per-processing workshops and mass-blanking procedures in shipyards, stably processing marine high-strength steel from 20 mm up to 120 mm. Multi-torch parallel cutting, automatic bevel forming and CNC thermal-deformation compensation are supported. Flame cutting handles extra-thick plates, while fine plasma cutting delivers superior surface quality for medium-to-heavy plates and greatly reduces grinding and rework.
2. On-slipway / in-dry-dock operations: Portable CNC cutting solution
Used as a flexible supplement to main workshop equipment. Lightweight and easy to transport without work-piece hoisting, it covers on-site edge trimming, hole drilling, insert plate cutting and modification of all types of large hull blocks. It represents a cost-effective solution for on-site-processing bottlenecks.
3. Supporting process improvisation solutions
Customized processes tailored for ship-grade heavy-plate characteristics: plate per-treatment to remove scale, pre-heat piercing for thick plates, application of marine-specific consumables and CNC thermal-deformation compensation. Equipment and process work together to eliminate cutting defects and stabilize product quality.
4. Full-process automation package
Gantry machines perform standard mass blanking indoors; portable cutters handle non-standard on-site trimming. Combined with welding robots, they form complete production lines to realize end-to-end automation of blanking, bevel preparation and welding for ship steel structures, supporting the upgrade of modern shipyards.
Conclusion
Heavy-plate cutting in shipbuilding is far more than simply severing steel plates. It is a systematic engineering process balancing structural safety, precision standards, production efficiency and on-site repeatability. Proven by multiple real-world shipyard cases, the rational combination of gantry-type mass-production cutters and portable on-site cutters together with customized heavy-plate cutting processes can effectively resolve core pain points including piercing failures, heavy dross, unstable bevels and difficult field operations. It reduces rework costs, shortens ship-construction cycles and helps shipyards achieve higher quality, better efficiency and lower costs.
