Addithive

Tag: construction

  • 3D Printing in Construction: Process, Reinforcement, Codes and Real Economics

    3D Printing in Construction: Process, Reinforcement, Codes and Real Economics

    Construction 3D printing usually refers to additive construction using a pumpable cementitious material deposited through a large nozzle. In most projects, the printer produces wall sections or structural components—not a complete finished building. Foundations, reinforcement, floors, roofs, utilities, windows, doors, insulation and finishes still require additional construction processes.

    “Printed in 24 hours” often describes nozzle-on printing time for selected walls. It should not be confused with total project duration, completed-building cost or occupancy readiness.

    What additive construction includes

    RouteDescriptionTypical use
    On-site concrete extrusionA gantry or robotic system deposits cementitious material directly at the building siteWalls, partitions and selected structural elements
    Off-site printed componentsParts are printed in a controlled factory and transported for assemblyPanels, façade elements, formwork and infrastructure components
    Printed formworkPolymer, sand or cementitious forms are printed and later filled or castComplex concrete geometry without printing the final structural material
    Robotic shotcrete or depositionMaterial is sprayed or deposited along controlled pathsCurved surfaces, repair and freeform structures
    Metal additive constructionArc, wire or other metal AM routes create structural or architectural elementsBridges, nodes and specialized steel components
    Earth and bio-based extrusionLocal soil, clay or fiber-containing mixtures are depositedResearch, low-rise demonstration and region-specific construction

    ISO/ASTM 52939:2023 provides qualification principles for additive construction used for structural and infrastructure elements. It covers process-oriented quality assurance for load-bearing and non-load-bearing applications but excludes metals.

    The complete construction-printing system

    1. Digital design and structural engineering: Geometry, loads, reinforcement, interfaces and construction sequence are defined.
    2. Toolpath preparation: The model is sliced into deposition paths with layer height, bead width, speed and start/stop strategy.
    3. Material batching: Cement, aggregate, water, admixtures, fibers and other ingredients are measured and mixed.
    4. Pumping and delivery: The mixture is transported through hoses without segregation, blockage or unacceptable property change.
    5. Deposition: The nozzle places layers while the motion system controls position and speed.
    6. Layer interaction: Each layer must support subsequent material and bond to the previous layer.
    7. Reinforcement and embedded items: Steel, cables, meshes, anchors, conduits or inserts are introduced according to the design.
    8. Curing and protection: Temperature, moisture, wind, rain and early-age damage are controlled.
    9. Conventional completion: Floors, roof, services, insulation, glazing and finishes are installed.
    10. Inspection and acceptance: Geometry, material, interfaces, reinforcement and structural performance are verified.

    Material requirements: pumpable, printable and buildable

    A printable cementitious mixture must satisfy requirements that can conflict with each other:

    • Pumpability: Move through the delivery system without excessive pressure, segregation or blockage.
    • Extrudability: Leave the nozzle as a continuous, consistent bead.
    • Shape stability: Retain deposited geometry rather than slump.
    • Buildability: Carry the weight of subsequent layers without collapse.
    • Open time: Remain usable during the required production window.
    • Interlayer bonding: Create adequate adhesion despite time gaps and surface drying.
    • Hardened performance: Meet strength, durability, shrinkage and environmental requirements.
    • Process consistency: Tolerate realistic variation in raw materials, temperature and equipment.

    A mixture that is easy to pump may be too fluid to support layers. A rapidly stiffening material can improve buildability but shorten open time and increase cold-joint risk. Material and machine therefore must be qualified as a system.

    Reinforcement is a central constraint

    Concrete performs well in compression but typically relies on reinforcement for tensile, flexural and ductility requirements. Layer-wise extrusion makes conventional reinforcement difficult to integrate continuously.

    Reinforcement approachPotential benefitControl challenge
    Conventional rebar placed before or during printingFamiliar structural behaviorNozzle access, congestion and bonding around steel
    Printed hollow walls filled with reinforced concretePrinted geometry acts partly as permanent formworkComposite action, filling quality and interface performance
    Horizontal bars, meshes or cables inserted between layersLayer-compatible placementContinuity, anchorage and automated insertion
    Fiber-reinforced mixturesCrack control and improved toughnessFiber orientation, pumping and insufficient replacement of structural steel
    Post-tensioningEfficient force transfer in selected geometriesDucts, anchors, tolerances and long-term losses
    External reinforcement or hybrid framesSeparate load-bearing system from printed enclosureConnections, fire, durability and architectural integration

    Fiber addition alone should not be assumed to replace code-required steel reinforcement. The structural concept and load path must be established by qualified engineering and applicable building rules.

    Interlayer bonds and anisotropy

    Printed construction can behave differently parallel and perpendicular to the deposited layers. Bond strength can be affected by:

    • Time between layers
    • Surface drying, contamination or rain
    • Material rheology and moisture
    • Nozzle pressure and layer deformation
    • Bead geometry and contact area
    • Temperature and wind
    • Start/stop locations and unplanned delays
    • Curing and subsequent finishing

    Test specimens should represent production orientation, material age and realistic interruption conditions rather than only conventionally cast cubes.

    What is—and is not—saved

    Potential savings

    • Reduced conventional formwork for suitable geometry
    • Fewer manual placement steps during wall deposition
    • Digital customization without a unique mold for every shape
    • Complex cavities, curves and integrated service channels
    • Potential material reduction through geometry optimization
    • Faster production of selected wall or component stages

    Costs that remain or are added

    • Printer transport, setup, calibration and protection
    • Material batching, pumping and quality testing
    • Reinforcement and conventional structural work
    • Foundations, floors, roofs, windows and utilities
    • Engineering, permits and project-specific approval
    • Weather delays and equipment downtime
    • Surface finishing, insulation and waterproofing
    • Inspection, repair and qualification tests
    • Specialized operator and material expertise

    Sustainability is not automatic

    Reduced formwork or optimized geometry can reduce material and waste, but the carbon impact depends heavily on cement content, mixture design, reinforcement, transport, durability and the building’s full lifecycle. Printable mixtures may require fine materials and higher binder or admixture content to achieve rheological performance.

    A sustainability comparison should include:

    • Embodied carbon of the complete mix
    • Material used per functional square meter
    • Formwork, reinforcement and finishing
    • Printer and material logistics
    • Service life, repair and moisture durability
    • Operational energy and insulation performance
    • End-of-life recovery or demolition

    On-site vs off-site printing

    FactorOn-siteOff-site
    EnvironmentWeather, ground and site variabilityMore controlled factory conditions
    TransportPrinter and material transported; large finished elements avoidedPrinted components must be transported and lifted
    Quality controlHarder to stabilize temperature, moisture and workflowEasier repeatability and equipment utilization
    GeometryLarge continuous structures possibleComponent size limited by transport and assembly
    UtilizationProject setup and idle time can be highCentral equipment can serve multiple projects
    InterfacesFewer component joints but more field operationsMore transport and assembly interfaces

    Codes, qualification and project acceptance

    Additive construction must satisfy the applicable building code, structural design rules and local approval process. ISO/ASTM 52939:2023 supplies process-oriented qualification principles, but it does not replace jurisdiction-specific design and construction requirements.

    1. Define whether the printed element is structural, nonstructural or permanent formwork.
    2. Establish material and reinforcement specifications.
    3. Qualify the printer, pump, mixer, nozzle and control software.
    4. Validate bead geometry, interlayer strength and hardened properties.
    5. Control weather, interruptions and material open time.
    6. Inspect reinforcement, embedded items, geometry and interfaces.
    7. Demonstrate fire, moisture, thermal, acoustic and durability performance as required.
    8. Define repair methods and acceptance criteria.
    9. Retain project data and production records.

    Common misconceptions

    • “The whole house is printed.” Usually only selected walls or components are deposited.
    • “No workers are required.” Material, reinforcement, setup, quality and conventional trades remain essential.
    • “No formwork means no structural challenge.” Reinforcement, interlayer bonds and interfaces can become harder.
    • “Printed concrete is automatically greener.” Mix design and full lifecycle determine the result.
    • “Print time equals project time.” Completion and approval include many nonprinting operations.
    • “Curved walls prove economic scalability.” Commercial viability depends on utilization, codes, labor integration and repeatability.

    Project-selection checklist

    • Geometry meaningfully reduces formwork or assembly
    • Structural concept and reinforcement can be executed
    • Material is available and stable under site conditions
    • Printer setup and utilization justify the project scale
    • Conventional completion trades are integrated into the schedule
    • Applicable authority accepts the qualification plan
    • Durability, insulation, moisture and fire requirements are addressed
    • Total project cost is compared—not just wall-printing cost

    Conclusion

    Construction 3D printing can reduce formwork, enable complex geometry and accelerate selected deposition stages. Its real industrial constraint lies in the complete system: printable materials, reinforcement, interlayer performance, weather, codes, finishing and project economics. The best applications use printing where it creates unique value and integrate it with conventional construction where conventional methods remain stronger.

    Related Addithive resources: Introduction to Additive Manufacturing · Scaling AM Production · Wire Arc Additive Manufacturing

    Reference

  • Impossible Objects Shatters 3D Printing Speed Limits with the Launch of CBAM 25

    Impossible Objects has made a groundbreaking announcement, revealing their revolutionary CBAM 25 3D printer, capable of printing fifteen times faster than the closest competitor. Set to be unveiled at the RAPID + TCT tradeshow in Chicago next month, this innovative 3D printer will have a significant impact on the world of mass production and industrial applications.

    Impossible objects CBAM Slice
    Impossible objects CBAM Slice

    The CBAM 25 will become commercially available in early 2024, promising to bring 3D printing into the realm of volume manufacturing. By breaking the speed barrier, the CBAM 25 will deliver advanced materials with superior mechanical properties and tolerances, providing manufacturers with an unprecedented advantage over existing technologies.

    Robert Swartz, Founder and Chairman of the Board at Impossible Objects, stated, “The CBAM 25 is the world’s fastest printer, and we are entering a new era of 3D printing with nearly unlimited material options at the speed of true mass production. This is a Moore’s law moment for 3D printing, and this is just the first step.”

    The CBAM 25 utilizes high-performance composite materials, enabling engineers to design stronger, lighter, and more durable parts. Notably, the Carbon Fiber PEEK material set offers high chemical and temperature resistance and mechanical properties superior to most engineering plastics. Carbon Fiber PEEK parts are a suitable alternative for aluminum, tooling, spares, repairs, and end-use parts.

    Impossible objects CBAM Layer
    Impossible objects CBAM Layer

    Impossible Objects is currently producing and selling parts in untapped 3D markets such as electronic tooling and for a broad range of applications, including aerospace, defense, and transportation industries. It is also replacing CNC machining with greater geometric freedom.

    Steve Hoover, Impossible Objects’ CEO, emphasizes the importance of production speed with the new CBAM 25, stating, “With a fifteen times speed improvement over existing 3D printers, our new CBAM 25 completes the transition of 3D printing from its roots in prototyping to the heartland of manufacturing.”

    Impossible objects CBAM Machine
    Impossible objects CBAM Machine

    The CBAM 25 is indeed a giant leap forward, pushing 3D printing into volume manufacturing, and opening new opportunities for industries to reshape and rethink their manufacturing processes.

    The launch of the CBAM 25 marks a turning point for 3D printing, demonstrating the potential for exponential advancements in speed, material capabilities, and applications. For readers interested in learning more about this revolutionary technology, we recommend attending the RAPID + TCT tradeshow in Chicago, where the CBAM 25 will be unveiled. Additionally, stay informed on the latest developments in the 3D printing industry by following Impossible Objects and other leading companies.

    By embracing the CBAM 25 and its potential, businesses can optimize their manufacturing processes, reduce costs, and create innovative products that push the boundaries of what’s possible in the world of 3D printing.

  • Wire Arc Additive Manufacturing: Process, Applications and Limitations

    Wire Arc Additive Manufacturing: Process, Applications and Limitations

    Wire arc additive manufacturing (WAAM) uses metal wire as feedstock and an electric arc as the heat source to deposit material layer by layer. In current standards-oriented terminology, it sits within directed energy deposition using wire and arc, often written as DED-Arc/M.

    WAAM is best understood as a high-deposition-rate near-net-shape process. Its value comes from reducing material waste and lead time for large parts — not from producing finished geometry directly from the torch.

    How WAAM works

    A welding power source, wire feeder and torch are integrated with a robot, gantry or multi-axis motion platform. The arc melts the incoming wire and a local region of the substrate or previous layer. Toolpaths build the component bead by bead and layer by layer. Common arc variants include gas metal arc, gas tungsten arc and plasma arc processes.

    Cold Metal Transfer (CMT) is a controlled gas-metal-arc process developed by Fronius and widely associated with lower heat input and controlled droplet transfer. It is one implementation route, not a synonym for WAAM.

    Wire arc additive manufactured component after machining
    WAAM component originally credited to Fronius

    Where WAAM fits best

    • Large titanium, aluminum, steel or nickel-alloy near-net-shape components
    • Low-to-medium production volumes where tooling cost is difficult to justify
    • High buy-to-fly components traditionally machined from large billets or forgings
    • Repair, remanufacture and addition of features to existing components
    • Preforms that will receive substantial finish machining
    • Applications where wire is safer, easier or more economical to handle than fine metal powder

    WAAM is usually a poor fit for very small features, tight as-built tolerances, fine internal channels or surfaces that cannot be machined.

    The real advantages

    High deposition rate

    Wire-and-arc systems can deposit material much faster than most powder-bed processes. The practical rate depends on alloy, arc mode, geometry, heat input, interpass strategy and quality requirements. A higher deposition rate only creates value when downstream machining and inspection remain manageable.

    High feedstock utilization

    Wire delivery places most feedstock into the melt pool and avoids the powder handling, sieving and recovery systems required by powder-bed routes. This is particularly attractive for expensive alloys, although start/stop waste, machining stock and rejected builds still affect total material yield.

    Large build envelope

    The motion platform rather than a sealed powder bed often defines the envelope. Robots and gantries can produce structures far larger than conventional LPBF systems, provided shielding, path planning and thermal control are maintained.

    Repair and hybrid manufacturing

    WAAM can add material to forgings, plates or existing components. Hybrid routes can combine a conventionally manufactured substrate with additively deposited features, followed by machining. This often creates a stronger business case than printing the complete part.

    The limitations that determine success

    ConstraintWhy it mattersTypical mitigation
    Heat input and accumulationChanges bead shape, microstructure, distortion and interpass stabilityInterpass temperature control, dwell time, active cooling, path planning and process monitoring
    Residual stress and distortionLarge thermal cycles can move the part during and after depositionBalanced paths, fixturing, rolling, heat treatment, simulation and machining allowance
    Surface roughness and wavinessAs-deposited beads are not final engineering surfacesNear-net-shape design followed by machining or finishing
    Dimensional accuracyBead geometry varies with torch angle, wire position, travel speed and heat stateClosed-loop sensing, calibrated tool-center point, adaptive paths and probing
    Anisotropy and microstructureLayered thermal history can produce directional properties and local variationQualified parameters, interpass control, heat treatment and representative testing
    DefectsLack of fusion, porosity, inclusions, oxidation and cracking can occurStable transfer, shielding, cleaning, parameter control, monitoring and NDT
    Access and collision riskTorch, robot, fixture and growing part can interfereMulti-axis simulation, staged deposition and integrated machining planning

    Material considerations

    Commercial and research WAAM routes cover low-alloy and stainless steels, aluminum alloys, titanium alloys and nickel-based alloys. Printability is alloy-specific. Wire quality, surface cleanliness, cast and helix, chemistry, shielding gas and storage conditions all influence stability.

    Reactive alloys such as titanium require strict shielding beyond the immediate arc region. Aluminum demands attention to oxide control, wire feeding and heat accumulation. Nickel alloys may face hot cracking, segregation or heat-treatment challenges. A weldable alloy is not automatically qualified for an additively manufactured structural application.

    Design rules for WAAM

    • Design near-net shape: include machining stock on critical surfaces and interfaces.
    • Use accessible geometry: the torch, shielding arrangement and cutting tool need clear approach paths.
    • Avoid abrupt mass changes: they destabilize heat flow and bead geometry.
    • Plan starts, stops and intersections: these locations can concentrate defects and geometric variation.
    • Control slender features: tall walls and thin sections can distort or vibrate.
    • Use modular deposition: dividing a complex part into stable zones can improve access and thermal control.
    • Define datums and fixtures early: the part must remain locatable after deposition and heat treatment.

    A realistic WAAM production workflow

    1. Define the final part requirements and choose the substrate or preform strategy.
    2. Select alloy, wire specification, arc process, shielding and motion platform.
    3. Develop bead geometry and layer-height control on representative coupons.
    4. Create a deposition model with machining allowance, tool access and inspection zones.
    5. Simulate toolpaths, robot reach, collision risk and thermal distortion where appropriate.
    6. Qualify the procedure, equipment, operator responsibilities and monitoring plan.
    7. Deposit with controlled interpass temperature and traceable process data.
    8. Apply stress relief or other heat treatment as required.
    9. Machine the component to final dimensions.
    10. Inspect material, geometry and critical defect modes against defined acceptance criteria.

    Process monitoring and closed-loop control

    Useful sensing can include arc voltage and current, wire-feed speed, travel speed, interpass temperature, melt-pool or bead imaging, laser profiling, acoustic signals and in-process probing. Monitoring is valuable only when signals are linked to known failure modes and response limits.

    Closed-loop systems may adjust travel speed, wire feed, torch position or layer height. They reduce variation but do not remove the need for qualified procedures, calibration, material control and final inspection.

    WAAM economics: calculate the complete route

    A credible cost model includes wire, substrate, deposition time, shielding gas, labor, fixtures, heat treatment, machining, tooling, inspection, scrap risk and machine utilization. Compare the WAAM route with the actual alternative — billet machining, forging, casting, fabrication or repair — using total lead time and accepted-part yield.

    WAAM tends to be strongest where conventional material removal is high, lead times are long, geometry is large and the final machining envelope remains practical.

    Standards and qualification

    ISO/ASTM 52943-2:2024 establishes aerospace process-characteristic and performance requirements for directed energy deposition using wire and arc. ISO/ASTM 52926-5:2023 addresses operator qualification for DED-Arc/M. These standards reflect the transition of WAAM from laboratory demonstrations toward controlled industrial production.

    Conclusion

    WAAM is a powerful route for large near-net-shape metal components, repair and hybrid manufacturing. Its success depends on welding metallurgy, thermal management, robot accuracy, path planning, machining and inspection working as one system. The right question is not how quickly material can be deposited, but how reliably the route produces an accepted finished component.

    Related Addithive resources: Metal AM Process Selection · Metal AM vs Casting and Forging

    References and further reading