Nontraditional and Additive Manufacturing

Introduction and Context

Conventional manufacturing processes remove material with a mechanically harder tool, deform a workpiece, or cast liquid material into a mould. These methods remain fundamental, but they become less effective when a component has very high hardness, complex internal passages, fragile features, or a geometry that would require many setups and special tools. Nontraditional manufacturing processes address these limitations by using electrical, chemical, thermal, mechanical-wave, or high-velocity fluid energy. Additive manufacturing (AM) takes a different approach: it builds a component layer by layer from digital geometry.

The contemporary engineer must therefore select among processes rather than assume that one process is universally superior. Selection depends on material, geometry, tolerances, surface integrity, production volume, cost, energy use, safety, and qualification requirements. A small aerospace bracket, a hardened die, and a polymer prototype may all require different process chains.

Learning Objectives

By the end of this chapter, students should be able to:

1. Explain the operating principles and applications of EDM, ECM, laser, plasma, waterjet, ultrasonic, and chemical machining.
2. Compare major additive-manufacturing process families: material extrusion, vat photopolymerization, powder-bed fusion, and directed-energy deposition.
3. Relate process capability to material properties, geometry, accuracy, surface finish, productivity, and cost.
4. Apply design rules for nontraditional and additive processes.
5. Explain post-processing, inspection, qualification, and traceability requirements.
6. Evaluate sustainability, safety, and professional implications in process selection.

1. Process Selection: A Common Engineering Framework

A process should be selected through a structured comparison of requirements:

• Material: electrical conductivity, hardness, melting point, chemical reactivity, thermal sensitivity, and moisture sensitivity.
• Geometry: minimum feature size, aspect ratio, enclosed cavities, overhangs, internal channels, and access for tooling.
• Quality: dimensional tolerance, roughness, residual stress, heat-affected zone, porosity, and mechanical properties.
• Production: prototype or mass production, batch size, cycle time, machine availability, and repeatability.
• Economics: equipment, tooling, consumables, labor, energy, inspection, and post-processing.
• Risk and compliance: operator exposure, fire and explosion risk, waste disposal, intellectual-property protection, and industry standards.

A useful distinction is between shape generation and property generation. A process may produce the desired shape but still require heat treatment, infiltration, machining, polishing, or coating to achieve the required properties. The complete manufacturing route—not only the primary process—must be evaluated.

2. Nontraditional Subtractive and Shaping Processes

2.1 Electrical Discharge Machining

Electrical discharge machining (EDM) removes electrically conductive material through controlled sparks between an electrode and the workpiece. The workpiece and tool are separated by a small dielectric-filled gap. A pulsed voltage causes dielectric breakdown; the resulting plasma channel produces intense local heating, melting and sometimes vaporizing a small volume. Dielectric flushing removes debris and restores the gap.

Two principal forms are:

• Die-sinking EDM: a shaped electrode creates a cavity.
• Wire EDM: a continuously moving wire cuts a contour, usually through a workpiece.

EDM does not require the tool to be harder than the workpiece in the conventional cutting sense. It is especially useful for hardened steels, carbide, and intricate dies. Its limitations include electrical-conductivity requirements, relatively low material-removal rates, electrode wear, recast layers, heat-affected zones, and possible microcracking.

A simplified energy relation for one discharge is:

where E_d is discharge energy in joules, V is discharge voltage in volts, I is discharge current in amperes, and t_on is pulse-on time in seconds. This relation assumes approximately constant voltage and current during the pulse. Actual energy transferred to the workpiece is lower because of losses in the plasma, electrode, dielectric, and machine circuit. Increasing pulse energy generally increases crater size and removal rate but may worsen roughness and surface damage.

Important EDM variables include pulse-on time, pulse-off time, current, voltage, polarity, dielectric flow, electrode material, and flushing pressure. Roughing uses higher energy; finishing uses shorter, lower-energy pulses. EDM design should provide adequate flushing paths and avoid unnecessarily deep, narrow cavities.

2.2 Electrochemical Machining

Electrochemical machining (ECM) removes conductive workpiece material by anodic dissolution. The workpiece is the anode, the shaped tool is the cathode, and an electrolyte flows through the interelectrode gap. Unlike EDM, ECM does not depend on sparks or melting, so there is no conventional tool-workpiece contact and little thermal damage.

Faraday’s law provides the theoretical mass-removal relationship:

where m is dissolved mass in kilograms, M is molar mass in kilograms per mole, I is current in amperes, t is time in seconds, η is current efficiency, z is the number of electrons transferred per ion, and F is Faraday’s constant, approximately 96485 C·mol⁻¹. The equation assumes uniform current efficiency and a known electrochemical reaction. It predicts removal, not necessarily final dimensional accuracy, because electrolyte flow, stray current, and gap geometry affect the actual shape.

ECM is suitable for turbine blades, dies, deburring, and complex cavities in conductive alloys. It produces no burrs and little residual stress, but it requires conductive material, substantial electrolyte handling, careful tooling compensation, and environmental controls for contaminated electrolyte.

2.3 Laser Beam Machining

Laser machining uses a focused coherent light beam to heat, melt, vaporize, or ablate material. It can drill small holes, cut sheet, mark surfaces, weld, texture, and support additive deposition. The process is noncontact and can be automated with CNC or robotic motion.

The approximate intensity at a circular spot is:

where I_L is average laser intensity in watts per square metre, P is laser power in watts, A is spot area in square metres, and d is spot diameter in metres. The estimate assumes a uniform beam over a circular spot; real beams have spatial intensity distributions and optical losses.

Higher intensity may increase penetration or enable vaporization, but excessive energy can enlarge the heat-affected zone, cause dross, induce residual stress, or damage optics. Laser cutting requires attention to assist-gas type and pressure, focal position, sheet thickness, absorptivity, and travel speed.

2.4 Plasma Arc Machining

Plasma arc machining constricts an electric arc through a gas nozzle. The gas becomes ionized plasma and reaches temperatures sufficient to melt material; a high-velocity jet ejects the molten metal. It is mainly used for conductive metals and is productive for plate and sheet cutting.

Advantages include high cutting speed, suitability for thick plate, and automation. Limitations include a heat-affected zone, kerf taper, dross, noise, ultraviolet radiation, fumes, and poorer precision than fine laser or waterjet cutting. Process choice depends on thickness and the required edge quality. Plasma cutting is often followed by grinding or machining when close tolerances are required.

2.5 Abrasive Waterjet Machining

Waterjet machining forces water through a small orifice at high pressure. Pure waterjets cut soft materials such as rubber, foam, and food products. Abrasive waterjets entrain garnet or another abrasive to cut metals, ceramics, stone, glass, and composites.

The process has a small thermal effect and can cut heat-sensitive materials. It also produces relatively low mechanical distortion. However, it may suffer from taper, striations, slower cuts in thick material, abrasive consumption, and slurry disposal. Nozzle wear and abrasive quality strongly affect cut consistency. Operators must control pressure, abrasive flow, standoff distance, traverse speed, and pierce strategy.

2.6 Ultrasonic Machining

Ultrasonic machining (USM) uses a tool vibrating at ultrasonic frequency, commonly around 20–40 kHz, with abrasive slurry between the tool and workpiece. Abrasive grains impact and fracture brittle materials. Material removal is primarily mechanical rather than thermal.

USM is valuable for glass, ceramics, carbides, and semiconductor materials. It creates little thermal damage and can form holes or cavities in hard brittle materials. It is less effective for ductile materials, has relatively low removal rates, and involves tool wear and slurry management. Tool shape, amplitude, abrasive size, concentration, and static load influence performance.

2.7 Chemical Machining

Chemical machining removes material through controlled chemical dissolution. Areas not intended for removal are protected by a maskant, while exposed regions are etched by an appropriate chemical reagent. Variants include chemical milling, photochemical machining, and chemical blanking.

The process is useful for thin sheets, weight reduction pockets, shallow contours, and complex profiles without mechanical forces. It can process large areas and delicate parts, but it has undercutting, maskant adhesion, etchant control, waste-treatment, and operator-safety challenges. Dimensional control depends on etch rate, exposure time, temperature, agitation, and chemical uniformity.

3. Additive Manufacturing: Principles and Process Families

Additive manufacturing creates a part from a three-dimensional digital model by depositing or selectively solidifying material in successive layers. A typical workflow is: computer-aided design, model repair, build-orientation selection, slicing, process planning, fabrication, support removal, post-processing, inspection, and qualification.

The layer concept introduces anisotropy. Properties may differ in the build direction because of incomplete bonding, thermal gradients, raster orientation, or layer interfaces. Consequently, a printed part is not automatically equivalent to a machined or wrought part made from the same nominal material.

3.1 Material Extrusion

Material extrusion forces a thermoplastic filament or pellet through a heated nozzle. The deposited road cools and bonds to adjacent roads and layers. The process is commonly known by the commercial term fused-filament fabrication, although material extrusion is the broader process-family name.

Advantages are low equipment cost, rapid design iteration, and a wide range of polymers. Limitations include visible layer lines, warpage, anisotropic strength, nozzle-size restrictions, and support requirements. Design should consider bead width, layer height, bridge length, shrinkage, and thermal contraction. A thin wall should normally be designed with a thickness compatible with one or more deposited roads rather than an arbitrary fraction of a nozzle diameter.

For fiber-reinforced extrusion, fiber direction is important. A component loaded along a principal direction should, where possible, align continuous or highly oriented reinforcement with that load. Short-fiber composites improve stiffness but do not eliminate interlayer weakness.

3.2 Vat Photopolymerization

Vat photopolymerization selectively cures liquid photopolymer resin using a laser, projected image, or other patterned light source. Stereolithography and digital light processing are common variants. The process produces fine features and smooth surfaces, but uncured resin must be removed and the part usually requires post-cure exposure.

Photopolymers may be brittle, sensitive to ultraviolet aging, and less stable at elevated temperature than engineering thermoplastics. Design must include drainage holes for hollow parts, adequate support for overhangs, and allowance for resin removal. Parts intended for functional service require data on long-term aging, moisture, temperature, and chemical exposure.

3.3 Powder-Bed Fusion

Powder-bed fusion selectively fuses regions of a powder layer using a laser or electron beam. Polymer systems may use selective laser sintering; metal systems commonly use laser powder-bed fusion or electron-beam powder-bed fusion. Unfused powder can sometimes support overhangs, reducing the need for separate supports, although thermal distortion may still require them.

Critical variables include powder size distribution, powder flowability, energy input, scan speed, hatch spacing, layer thickness, preheat, atmosphere, and scan strategy. A useful process-screening ratio is volumetric energy density:

where E_v is nominal energy density in joules per cubic millimetre, P is power in watts, v is scan speed in millimetres per second, h is hatch spacing in millimetres, and t is layer thickness in millimetres. This is a comparative process parameter, not a universal physical law. It neglects absorptivity, beam shape, heat conduction, evaporation, and scan interruptions; equal values do not guarantee equal part quality.

Insufficient energy may cause lack-of-fusion porosity, while excessive energy may cause keyholing, evaporation, spatter, and distortion. Powder handling requires control of contamination, oxygen, moisture, recycling history, and combustible-dust hazards.

3.4 Directed-Energy Deposition

Directed-energy deposition (DED) feeds powder or wire into a melt pool created by a laser, electron beam, or arc. The deposition head moves along programmed paths and can build, repair, or add material to an existing component. DED has a higher deposition rate and larger feature size than many powder-bed systems, but it generally requires machining to achieve final dimensions.

DED is valuable for repair of high-value components, large near-net-shape parts, compositionally graded structures, and adding features to forgings or castings. Major concerns are thermal distortion, residual stress, dilution with the substrate, variable bead geometry, and process-monitoring requirements. Wire-based systems may have high material efficiency; powder-based systems offer more flexibility in material delivery but may have unused powder and capture losses.

4. Design Rules for Additive Manufacturing

Design for additive manufacturing (DfAM) is not merely the removal of machining constraints. It uses process freedom while respecting process limitations.

1. Choose orientation deliberately. Orientation affects support volume, surface quality, build time, thermal distortion, and mechanical anisotropy.
2. Avoid unsupported overhangs. The allowable angle depends on material, layer thickness, thermal conditions, and machine. Use a validated process-specific limit rather than a universal angle.
3. Provide powder or resin escape paths. Enclosed cavities must include openings large enough for cleaning, inspection, and safe removal of trapped material.
4. Respect minimum features. Holes, thin walls, text, and channels must exceed the process capability and include compensation for shrinkage or stair-stepping.
5. Use self-supporting geometry where practical. Chamfers, arches, teardrop holes, and blended transitions may reduce supports.
6. Control stress concentration. Smooth fillets, gradual section changes, and suitable scan strategies reduce distortion and crack risk.
7. Design for post-processing. Include machining stock, datum surfaces, fixturing features, access for tools, and allowance for coating or heat treatment.
8. Consider inspection. Internal channels and hidden surfaces may be difficult to measure; include reference surfaces or witness coupons.
9. Minimize unnecessary material. Topology optimization and lattice structures can reduce mass, but their performance must be validated for fatigue, cleaning, and manufacturability.

5. Post-Processing and Quality Assurance

Post-processing converts a fabricated near-net-shape part into a usable engineering component. Typical operations include support removal, depowdering, solvent cleaning, washing, thermal debinding, sintering, heat treatment, hot isostatic pressing, infiltration, machining, grinding, blasting, polishing, coating, and sterilization.

For metal AM, heat treatment may reduce residual stress and alter microstructure. Hot isostatic pressing can close internal pores under elevated temperature and gas pressure, but it does not correct every defect and may change dimensions. Machining establishes precision datums and critical fits. For photopolymers, washing and post-curing control residual resin and final conversion. For extrusion polymers, annealing may reduce stress but can also cause dimensional change.

Quality assurance should distinguish:

• Process qualification: demonstrating that the machine, material, software, parameters, and environment can repeatedly produce acceptable results.
• Part acceptance: verifying that a particular part meets drawing and performance requirements.
• Material qualification: establishing chemical composition, powder or feedstock condition, density, strength, fatigue behavior, and environmental performance.

Inspection methods include dimensional metrology, optical scanning, surface-roughness measurement, radiography, computed tomography, ultrasonic testing, dye penetrant inspection, metallography, density measurement, and mechanical testing. The method must be sensitive to the defect types that matter. For example, visual inspection cannot reliably detect internal lack-of-fusion defects.

Traceability should include machine identity, software version, material lot, powder reuse history, environmental conditions, build orientation, parameter set, operator, calibration status, in-process records, post-processing cycle, and inspection results. Qualification is especially important in aerospace, medical, energy, and automotive applications, where a process change may require revalidation.

6. Comparative Evaluation

7. Worked Example: Selecting a Process for a Hardened Die Insert

An illustrative manufacturer must produce a hardened steel die insert containing a deep cavity, sharp internal detail, and a small production quantity. Conventional milling would require specialized cutters and multiple setups. Wire EDM can create the external profile accurately, but it cannot directly generate a blind three-dimensional cavity. Die-sinking EDM is therefore a strong candidate because the electrode can reproduce the cavity geometry.

The engineering team compares three alternatives:

• Milling: flexible, but tool wear and cutting forces are substantial in hardened steel.
• Die-sinking EDM: suitable for hardened conductive steel and complex blind cavities; requires an electrode and may leave a recast layer.
• ECM: low thermal damage and no tool contact, but electrolyte flow and tooling compensation are difficult for a small, deep cavity.

The selected route is rough milling before hardening, heat treatment, die-sinking EDM for the hardened cavity, polishing of functional surfaces, and dimensional inspection. Low-energy finishing EDM is specified where surface integrity is critical. The decision illustrates an important principle: a hybrid route often outperforms a single process. Roughing and finishing need not use the same technology.

8. Applied Case: Additively Manufactured Cooling Manifold

This is an illustrative industrial case. A company needs a compact metal cooling manifold with internal channels that cannot be drilled and assembled economically. The initial design uses laser powder-bed fusion in a nickel alloy.

Problem. The manifold must withstand pressure, maintain leak tightness, and fit within a restricted envelope. The first prototype develops distortion near unsupported channels and retains powder in several dead-end passages.

Analysis. The team identifies three causes: insufficient drainage openings, an orientation that creates long unsupported overhangs, and inadequate compensation for thermal distortion. Computed tomography reveals partially fused powder and a small lack-of-fusion region near a thick section.

Approach. Engineers reorient the part, replace circular dead-end channels with accessible passages, add cleaning ports that will later be sealed, and blend thick-to-thin transitions. They validate a parameter set using witness coupons, apply stress-relief heat treatment, machine datum surfaces, remove cleaning ports by machining, and perform pressure testing and CT inspection.

Outcome. The redesigned manifold meets dimensional and leak requirements after one additional iteration. Although the printed component has a higher unit fabrication cost than a simple machined block, it eliminates multiple assembled parts and reduces the final assembly envelope.

Learning points. Geometric freedom creates value only when the design supports powder removal, inspection, post-processing, and qualification. Process selection must include the entire manufacturing and verification chain.

9. Sustainability, Safety, and Professional Practice

Nontraditional and additive processes can reduce tooling, material waste, and assembly count, but environmental benefit is not automatic. Energy-intensive lasers, inert gases, compressed air, resin waste, abrasive slurry, electrolytes, and metal powders impose impacts. Life-cycle comparison should include feedstock production, machine energy, scrap, post-processing, transport, service life, and end-of-life recovery.

Safety controls include guarding and interlocks for lasers and plasma systems; ventilation for fumes and photopolymer vapors; respiratory and combustible-dust controls for powders; high-pressure protection for waterjets; chemical-resistant equipment for ECM and chemical machining; and electrical isolation for EDM. Safety data sheets, exposure assessments, lockout procedures, and waste-management rules are professional responsibilities rather than optional administrative tasks.

Digital manufacturing also creates governance concerns. Build files, process parameters, inspection data, and machine logs may be proprietary. Access control, revision management, cybersecurity, and authenticated software are necessary where unauthorized modification could affect safety. Artificial intelligence can assist defect detection, parameter optimization, and predictive maintenance, but an AI recommendation must be validated against physical evidence and approved engineering procedures. It should not replace accountability, calibration, or qualified judgment.

10. Contemporary Developments and Best Practices

Current development emphasizes multi-material deposition, in-process monitoring, closed-loop control, high-speed metal deposition, recycled feedstocks, lattice structures, digital twins, and hybrid additive-subtractive machines. Sensors may monitor melt-pool emission, layer images, acoustic signals, temperature, or machine vibration. The challenge is converting sensor data into validated acceptance criteria rather than merely collecting large data sets.

Best practice is to:

1. Define functional requirements before choosing a process.
2. Compare the full process chain, including finishing and inspection.
3. Use qualified material and parameter data rather than nominal machine settings alone.
4. Design orientation, supports, escape paths, datums, and inspection features together.
5. Use coupons or representative test artifacts when properties are critical.
6. Record complete digital and physical traceability.
7. Validate changes in material lot, software, machine, orientation, or post-processing.
8. Treat sustainability and operator safety as design requirements.
9. Use hybrid processes when each technology is strongest at a different stage.
10. Communicate process limitations honestly in drawings, specifications, and technical reports.

Chapter Summary

Nontraditional manufacturing uses electrical, electrochemical, optical, plasma, fluid, abrasive, or chemical energy to process materials that may be difficult to machine conventionally. EDM is effective for conductive hardened materials and intricate cavities; ECM provides burr-free electrochemical removal; lasers offer concentrated noncontact energy; plasma provides productive thermal cutting; waterjets minimize thermal damage; ultrasonic machining serves hard brittle materials; and chemical machining produces delicate thin-sheet features with low mechanical force.

Additive manufacturing builds parts from digital models through material extrusion, vat photopolymerization, powder-bed fusion, or directed-energy deposition. Each family has characteristic materials, defects, geometric freedoms, and post-processing requirements. DfAM must consider orientation, overhangs, escape paths, minimum features, anisotropy, thermal distortion, and inspection access. Post-processing and qualification are essential because shape generation alone does not establish final performance.

Effective process selection evaluates material, geometry, quality, volume, cost, safety, sustainability, and regulatory risk. Qualification requires control of machine, material, parameters, environment, post-processing, inspection, and traceability. The most practical contemporary solution is often a hybrid route that combines additive or nontraditional shaping with conventional finishing and rigorous verification.

Key Terms

Electrical discharge machining (EDM): Material removal by controlled electrical discharges.

Electrochemical machining (ECM): Anodic dissolution of conductive material using an electrolyte.

Dielectric: Electrically insulating fluid used in EDM to control discharge behavior and flush debris.

Recast layer: Rapidly resolidified material remaining after thermal removal.

Heat-affected zone: Material altered thermally without necessarily being melted.

Laser beam machining: Removal or modification using a focused laser beam.

Plasma arc machining: Thermal cutting using a constricted ionized-gas arc.

Waterjet machining: Cutting with high-pressure water, with or without abrasive.

Ultrasonic machining: Abrasive impact machining driven by ultrasonic tool vibration.

Chemical machining: Controlled chemical dissolution through protected and exposed regions.

Additive manufacturing: Layerwise production of a component from digital data.

Material extrusion: Additive deposition of softened material through a nozzle.

Vat photopolymerization: Layerwise curing of liquid resin with patterned light.

Powder-bed fusion: Selective fusion of regions in a powder layer.

Directed-energy deposition: Feeding material into a melt pool generated by a focused energy source.

Design for additive manufacturing: Designing parts to exploit additive capability and accommodate its constraints.

Volumetric energy density: A comparative ratio of power to scan speed, hatch spacing, and layer thickness.

Qualification: Demonstration that a process or part consistently satisfies specified requirements.

Traceability: Documented linkage among materials, equipment, parameters, processing, and inspection.

Review Questions

5 Short Answer Questions

1. Why must EDM workpieces generally be electrically conductive?
2. State one important difference between EDM and ECM.
3. What is the main purpose of support structures in additive manufacturing?
4. Why can equal nominal volumetric energy densities produce different powder-bed fusion results?
5. Name two records needed for additive-manufacturing traceability.

5 Long Answer Questions

1. Explain the operating principle, applications, advantages, and limitations of EDM, ECM, and laser machining.
2. Compare material extrusion, vat photopolymerization, powder-bed fusion, and directed-energy deposition.
3. Discuss how orientation, overhangs, escape paths, anisotropy, and post-processing affect additive part design.
4. Explain why qualification must include material, machine, parameters, post-processing, and inspection rather than only the CAD model.
5. Evaluate the safety and sustainability issues associated with nontraditional and additive manufacturing.

3 Analytical / Application Questions

1. A hardened steel die requires a deep blind cavity in a small production batch. Select a suitable primary process and propose a finishing and inspection route, justifying each decision.
2. A metal powder-bed-fusion part contains internal channels, distortion, and trapped powder. Diagnose likely causes and recommend design, process, and post-processing changes.
3. Develop a process-selection matrix for a thin aerospace panel comparing laser, plasma, abrasive waterjet, and chemical machining. Identify the criteria and explain which process would be preferred under tight thermal-distortion limits.

Multiple Choice Questions with Answers

Question 1

Which property is generally required of a workpiece for EDM?

A. High electrical conductivity

B. High optical transparency

C. Low melting temperature only

D. Strong chemical reactivity with water

Correct Answer: A. High electrical conductivity

Question 2

In ECM, the workpiece normally functions as the:

A. Cathode

B. Anode

C. Dielectric

D. Electrolyte nozzle

Correct Answer: B. Anode

Question 3

What is a principal advantage of abrasive waterjet machining?

A. It always produces a mirror finish

B. It eliminates abrasive consumption

C. It causes minimal thermal damage

D. It requires the workpiece to be conductive

Correct Answer: C. It causes minimal thermal damage

Question 4

Which additive process cures liquid resin using patterned light?

A. Material extrusion

B. Vat photopolymerization

C. Directed-energy deposition

D. Plasma arc machining

Correct Answer: B. Vat photopolymerization

Question 5

In powder-bed fusion, insufficient energy input can commonly produce:

A. Lack-of-fusion porosity

B. Electrolyte contamination

C. Tool-electrode contact

D. Ultrasonic cavitation only

Correct Answer: A. Lack-of-fusion porosity

Question 6

Which process feeds wire or powder into a melt pool to build or repair a component?

A. Chemical machining

B. Ultrasonic machining

C. Directed-energy deposition

D. Vat photopolymerization

Correct Answer: C. Directed-energy deposition

Question 7

For the relation E_v = P ÷ (v h t), which variable represents hatch spacing?

A. P

B. v

C. h

D. t

Correct Answer: C. h

Question 8

Why are drainage or escape openings important in enclosed additive-manufactured cavities?

A. They increase laser wavelength

B. They permit removal of trapped powder or resin

C. They make every material conductive

D. They eliminate the need for inspection

Correct Answer: B. They permit removal of trapped powder or resin

Question 9

Which activity primarily establishes whether a particular finished part meets its drawing requirements?

A. Part acceptance inspection

B. Changing the CAD color

C. Selecting a new nozzle brand

D. Estimating theoretical energy only

Correct Answer: A. Part acceptance inspection

Question 10

Which statement best describes a major limitation of material extrusion?

A. It cannot process polymers

B. It always requires an electrolyte

C. It commonly exhibits layer anisotropy and warpage

D. It can only produce conductive parts

Correct Answer: C. It commonly exhibits layer anisotropy and warpage