Additive Manufacturing and Rapid Tooling

Introduction and context

Additive manufacturing (AM) produces a component by adding material layer by layer from a digital model. Unlike conventional machining, which removes material, or casting, which fills a mould, AM creates geometry directly from computer-aided design (CAD) data. The technology has developed from rapid prototyping into a manufacturing family capable of producing functional polymer, metal, ceramic, and composite parts.

AM is particularly valuable when geometry is complex, production volume is low or moderate, customization is important, or tooling lead time is a major constraint. However, “3D printing” is not a single process. Material deposition, energy input, powder behaviour, thermal history, support strategy, dimensional accuracy, and post-processing differ substantially among process families.

Rapid tooling applies AM to manufacture production aids such as moulds, dies, patterns, jigs, fixtures, conformal cooling channels, and sacrificial cores. It can shorten development cycles, but its engineering success depends on design rules, process planning, inspection, qualification, and an understanding of total life-cycle cost.

Learning objectives

After completing this chapter, the student should be able to:

1. Explain the operating principles of the principal AM process families.
2. Compare material extrusion, vat photopolymerization, powder-bed fusion, directed-energy deposition, binder jetting, and sheet lamination.
3. Apply design-for-additive-manufacturing principles to part orientation, support reduction, lattices, and consolidation.
4. Describe process planning, common defects, post-processing, inspection, and qualification.
5. Select an appropriate AM process for a specified engineering application.
6. Explain the role, benefits, limitations, and economics of rapid tooling.

1. Additive manufacturing as an engineering system

An AM system comprises more than a printer. The engineering chain normally includes requirements definition, CAD modelling, design review, tessellation into a surface file, build preparation, machine operation, part removal, post-processing, inspection, and documentation. Errors introduced early in the chain can remain invisible until manufacture.

A typical workflow is:

Requirement → CAD model → design-for-AM review → build orientation and supports → slicing or toolpath generation → fabrication → post-processing → inspection → qualification and release.

The digital model must describe a closed, valid volume. Tessellation quality influences curved-surface accuracy; coarse triangular facets can produce visible or dimensional errors. Build-preparation software assigns orientation, supports, scan paths or deposition paths, and process parameters. These decisions influence strength, surface finish, residual stress, build time, and material consumption.

Important terminology includes:

• Layer thickness: nominal height of one deposited, cured, bonded, or fused layer.
• Build orientation: position of the part relative to the machine axes and layer plane.
• Build envelope: maximum manufacturable volume.
• Support structure: temporary material that supports overhangs, dissipates heat, or anchors a part.
• Anisotropy: dependence of properties on direction, often caused by layerwise bonding or thermal history.
• Scan or deposition strategy: programmed path used to expose, melt, spray, extrude, or bond material.
• Digital thread: traceable flow of design, process, inspection, and production data.

The basic material balance for an AM part can be stated as:

where m_feed is feedstock consumed, m_part is material retained in the component, m_support is support material removed after fabrication, and m_waste includes powder loss, purge material, machining allowance, and rejected material. This identity is a mass-accounting relationship, not a prediction of material efficiency. Its terms must be measured or estimated using consistent boundaries.

2. Principal AM process families

2.1 Material extrusion

Material extrusion forces a material through a nozzle or orifice and deposits it along a programmed path. The most widespread form is fused filament fabrication (FFF), in which a thermoplastic filament is heated above its processing temperature and deposited onto a build platform. Other variants extrude pellets, thermosets, ceramics, concrete, or metal-filled feedstock.

The deposited roads bond through contact, wetting, diffusion, and cooling. Part strength is therefore affected by nozzle temperature, chamber temperature, layer time, raster direction, air flow, and the thermal state of the previous layer. Polymer extrusion commonly produces anisotropic properties: strength within a road can exceed strength across interlayer boundaries.

Advantages include relatively low equipment cost, broad polymer availability, easy design iteration, and suitability for large parts. Limitations include stair-stepping, visible raster patterns, support requirements, warpage, porosity, and relatively slow production for small detailed parts. Filled filaments containing carbon fibre, glass fibre, or metal powder improve selected properties but may increase nozzle wear and complicate recycling.

2.2 Vat photopolymerization

Vat photopolymerization selectively cures liquid photopolymer resin using ultraviolet light, a laser, or a projected image. Stereolithography (SLA) scans a laser, while digital light processing (DLP) exposes an entire image or pixel array. The resin undergoes photoinitiated polymerization, changing from liquid to solid.

These processes offer high resolution, smooth surfaces, and fine features. They are used for patterns, dental models, medical devices, investment-casting patterns, and visual prototypes. Limitations include resin cost, limited long-term environmental stability for some materials, brittleness, oxygen inhibition or incomplete cure, resin handling, and the need for washing and post-curing. Supports must often be removed manually and can leave marks.

Dimensional accuracy is influenced by optical spot size or pixel size, resin shrinkage, cure depth, recoating, vat temperature, and orientation. A nominally small pixel does not guarantee equivalent functional accuracy because exposure spreads beyond the intended boundary.

2.3 Powder-bed fusion

Powder-bed fusion (PBF) selectively fuses regions of a powder layer using thermal energy. The major variants are laser powder-bed fusion (LPBF) for metals and selective laser sintering (SLS) for polymers; electron-beam powder-bed fusion (EB-PBF) uses an electron beam in a controlled vacuum or low-pressure environment.

A recoater spreads a powder layer, the energy source selectively processes the layer, and the platform indexes before the next layer is spread. In metal LPBF, the material is generally melted locally, producing a rapidly solidified microstructure. In polymer SLS, particles are heated near their softening or melting range and bonded thermally.

PBF can produce internal channels, lattices, and complex shapes without the extensive support structures required by some other metal processes. Metal PBF supports aerospace, medical implants, tooling inserts, and high-performance components. Important limitations are high equipment and powder-handling cost, residual stress, thermal distortion, surface roughness, powder refresh requirements, trapped powder, and the need for extensive inspection.

Typical defects include lack-of-fusion pores from inadequate energy or poor overlap, keyhole pores from excessive local energy, balling, spatter-related defects, recoater interference, and distortion. A useful, dimensionally consistent process indicator is volumetric energy density:

where E_v is nominal volumetric energy density in J/mm³, P is beam power in W (J/s), v is scan speed in mm/s, h is hatch spacing in mm, and t is layer thickness in mm. This relationship assumes a simplified uniform distribution and does not replace experimentally validated parameter sets. It omits absorptivity, beam shape, thermal conduction, evaporation, and scan-vector effects; therefore equal E_v values do not necessarily produce equal quality.

2.4 Directed-energy deposition

Directed-energy deposition (DED) delivers powder or wire into a melt pool created by a laser, electron beam, or arc. The deposition head and workpiece move relative to each other, allowing material to be added to a substrate or an existing component.

DED is attractive for large parts, repair, feature addition, compositionally graded structures, and near-net-shape preforms. Wire-arc additive manufacturing is particularly productive for large metal structures. DED generally has lower geometric resolution and rougher surfaces than PBF, but it offers high deposition rates and a relatively large build envelope.

Process control must manage melt-pool size, interpass temperature, dilution with the substrate, bead geometry, shielding gas, and thermal distortion. Machining is commonly required. Metallurgical defects may include lack of fusion, porosity, cracking, excessive dilution, and nonuniform microstructure.

2.5 Binder jetting

Binder jetting selectively deposits a liquid binder onto a powder bed. The printed “green” part is fragile and normally undergoes curing, depowdering, and sintering. The binder does not itself melt the powder during printing.

Binder jetting can achieve high productivity because an entire layer may be printed rapidly, and it avoids the intense local thermal gradients of laser melting. It can process metals, ceramics, sand, and other powders. The principal engineering challenge is dimensional change and distortion during drying and sintering. The final part shrinks according to powder packing, binder distribution, furnace cycle, geometry, and atmosphere.

Binder jetting is widely used for sand moulds and cores, metal prototypes, and batch production of relatively small components. Dimensional compensation must be validated rather than assumed to be a simple uniform scale factor.

2.6 Sheet lamination

Sheet lamination builds parts by bonding sheets or foils and cutting each layer to shape. Processes include laminated object manufacturing and ultrasonic additive manufacturing. Bonding may use adhesive, heat, pressure, or ultrasonic energy. Unwanted material can be removed during or after lamination.

The process can be fast and can combine dissimilar metal foils in some systems. Ultrasonic methods can embed sensors or create metal laminates with low bulk heating. Limitations include stair-stepping, sheet-stock constraints, interlayer bonding defects, and difficulty producing enclosed cavities unless the process includes a suitable removal strategy.

3. Comparison and process selection

A rational process-selection decision considers material, required properties, size, accuracy, surface finish, geometry, production volume, inspection requirements, post-processing, health and safety, and total cost. No process is universally superior. For example, a metal conformal-cooling insert may favour LPBF, a large repaired die may favour DED, and a sand casting core may favour binder jetting.

4. Design for additive manufacturing

Design for additive manufacturing (DfAM) changes the design process from merely reproducing a conventional part to exploiting additive capability while respecting process constraints.

4.1 Geometry and part consolidation

AM permits channels, topology-optimized structures, internal lattices, and organic forms that may be difficult or impossible to machine. Several conventionally assembled parts may be consolidated into one part, reducing fasteners, joints, leakage paths, and assembly labour. Consolidation must not remove necessary inspection access, repairability, or safe failure modes.

Topology optimization mathematically distributes material within a design domain subject to loads, constraints, and an objective such as minimum mass or compliance. The optimized shape must then be redesigned for manufacturing, surface quality, fatigue, cleaning, and inspection. A mathematically efficient shape is not automatically a reliable product.

4.2 Orientation and support strategy

Orientation affects build time, supports, surface quality, dimensional accuracy, heat flow, and mechanical anisotropy. A practical orientation balances competing objectives rather than optimizing only one. For metal PBF, orienting critical surfaces and long axes appropriately can reduce support contact and residual stress. For vat processes, orientation influences suction forces, peel loads, drainage, and support marks.

Support structures may anchor a part, conduct heat, prevent warping, and support overhangs. Their design should allow removal, avoid inaccessible trapped regions, and minimize damage to critical surfaces. In polymer extrusion, bridge length and overhang angle depend on material, cooling, speed, and nozzle geometry; a universal angle limit is therefore unreliable.

4.3 Tolerances, clearances, and features

AM tolerances are process- and size-dependent. Designers should specify functional datums, allow machining stock on critical interfaces, and validate small holes, thin walls, threads, and snap fits experimentally. Powder removal paths are essential for enclosed cavities. Drain holes may be needed for liquid resin, uncured powder, or binder.

Lattices reduce mass and can tune stiffness, energy absorption, filtration, or heat transfer. Their performance depends on unit-cell geometry, relative density, manufacturing resolution, surface roughness, and defects. Lattice design should include cleaning and inspection provisions.

4.4 A simple cost and time model

For early comparison, total manufacturing cost can be represented as:

where the terms represent setup, machine time, material, post-processing, inspection, and expected failure or rework cost. This is an estimating framework, not an accounting standard. Each term must use the same currency and production boundary. In low-volume production, setup and tooling savings may dominate; in high-volume production, cycle time, automation, and repeatability often dominate.

5. Process planning and control

Process planning begins with identifying critical-to-quality characteristics: dimensions, surface finish, density, strength, fatigue performance, leak tightness, and material condition. The planner then selects material, orientation, layer thickness, supports, scan or deposition strategy, and post-processing route.

For metal processes, thermal management is central. Scan-vector rotation between layers can distribute directional effects. Preheating may reduce thermal gradients, while controlled cooling can influence microstructure. For polymers, chamber temperature, bed adhesion, and cooling rate strongly affect warpage. For binder jetting, powder packing and furnace atmosphere are critical.

Process monitoring may include optical melt-pool sensing, layer imaging, acoustic monitoring, temperature measurement, chamber oxygen measurement, recoater-force monitoring, and machine-log analysis. Monitoring is useful only when linked to validated acceptance criteria. A camera image is not by itself proof that a part is acceptable.

Statistical process control can track variables such as layer thickness or melt-pool intensity. If a process characteristic has mean μ and standard deviation σ, a common capability index is:

where USL and LSL are upper and lower specification limits. C_p describes potential spread relative to the specification width under the assumptions of a stable, approximately normal process and a centered interpretation. It does not prove capability when the process is unstable or the mean is off-center. A centered process is often assessed with:

These indices require independent observations or an appropriate model and should not replace engineering inspection.

6. Defects, causes, and corrective action

Defects should be classified by mechanism rather than by appearance alone.

Root-cause analysis should connect defect location and morphology to process history. Corrective actions may include changing orientation, adjusting energy or temperature, modifying scan paths, improving powder condition, changing supports, or redesigning the geometry. Increasing energy indiscriminately can convert lack-of-fusion defects into keyhole porosity or excessive evaporation.

7. Post-processing, inspection, and qualification

Post-processing may include support removal, depowdering, washing, UV post-curing, heat treatment, stress relief, hot isostatic pressing, machining, grinding, blasting, tumbling, coating, infiltration, and surface polishing. The chosen route must be specified as part of the manufacturing process, not treated as an afterthought.

Heat treatment can relieve residual stress and alter strength, ductility, hardness, and microstructure. Hot isostatic pressing can reduce internal porosity in suitable metal parts, but it cannot correct every geometric error and may change dimensions. Machining provides accurate datums and interfaces, while chemical or abrasive finishing can improve surfaces that are inaccessible to cutting tools.

Inspection methods include coordinate measurement, optical scanning, profilometry, visual inspection, density measurement, microscopy, hardness testing, tensile testing, fatigue testing, ultrasonic testing, radiography, and computed tomography. CT is especially valuable for internal channels and porosity, but resolution, artefacts, and measurement uncertainty must be considered.

Qualification establishes documented evidence that a process repeatedly produces conforming parts. It may include:

1. Material qualification: powder or resin identity, cleanliness, moisture, particle-size distribution, storage, and reuse limits.
2. Machine qualification: calibration, environmental control, beam or nozzle condition, platform temperature, and software revision.
3. Process qualification: validated parameter sets, build orientation, support design, and post-processing.
4. Part qualification: dimensions, density, mechanical properties, surface condition, and functional tests.
5. Production control: traceability, operator competence, maintenance, nonconformance handling, and change control.

Qualification is application-dependent. A decorative prototype does not require the same evidence as an aircraft bracket, pressure-containing component, implant, or safety-critical tooling insert. Standards and specifications from organizations such as ASTM International, ISO, SAE, and sector regulators provide useful frameworks, but the applicable requirements must be identified for the industry and jurisdiction.

8. Rapid tooling

Rapid tooling uses AM to produce moulds, dies, patterns, cores, inserts, fixtures, and other manufacturing aids more quickly than conventional tooling routes. It may be classified as:

• Direct tooling: the AM-produced item functions directly as the mould, die, or insert.
• Indirect tooling: AM produces a pattern or master from which a conventional tool is made.
• Soft tooling: relatively short-life materials or processes are used for prototypes and limited batches.
• Hard tooling: durable materials and treatments support longer production life.

A major benefit is conformal cooling. Conventional drilled cooling channels are usually straight and constrained by tool access. AM can produce channels that follow the cavity surface, potentially improving temperature uniformity and reducing cycle time. Nevertheless, channels require adequate wall thickness, leak testing, powder removal, and consideration of thermal fatigue and corrosion.

Other applications include vacuum-forming tools, investment-casting patterns, sand-casting cores, injection-mould inserts, trim fixtures, assembly aids, and low-volume composite moulds. Tooling selection should compare lead time, life, thermal and mechanical loading, surface requirements, maintenance, and total cost rather than considering printing time alone.

Illustrative case: conformal-cooling injection-mould insert

Background. A manufacturer produces a polymer housing in moderate batches. The conventionally drilled mould insert creates a hot region near a thick boss, causing warpage and a long cooling cycle.

Problem. Extending straight cooling holes would require a larger insert and still leave the hot region poorly cooled. The product requires dimensional stability, and the batch volume does not justify a completely new high-volume mould system.

Analysis. Engineers map the cavity surface and identify the hot zone using thermal simulation and mould trials. An LPBF stainless-steel insert is considered because it can create channels that follow the cavity contour. The design includes powder evacuation openings, minimum wall thickness, support-access regions, machining stock on the parting surface, and inspection datums.

Approach. The insert is printed with a validated metal parameter set, stress-relieved, removed from the build plate, machined at sealing and locating surfaces, and polished on the cavity face. The conformal channels are leak-tested and inspected by CT or another suitable internal method. A controlled mould trial compares cycle time, cavity temperature, and part warpage with the conventional insert.

Outcome. The AM insert may reduce thermal nonuniformity and shorten cooling time, but the result must be demonstrated experimentally. If the insert life is insufficient, a hybrid strategy may be preferable: AM for the complex cooling region and conventional steel for structural backing and interfaces.

Learning points. The value is created by improved mould performance, not by printing alone. Design, simulation, machining, sealing, inspection, and life testing are integral to the solution. A conformal channel that cannot be cleaned, inspected, or connected reliably is not an engineering improvement.

9. Challenges, sustainability, safety, and emerging directions

AM can reduce buy-to-fly ratio and enable lightweighting, but sustainability is not automatic. Electricity use, inert gas, powder production, resin disposal, failed builds, support removal, and post-processing affect life-cycle impact. Recycling must account for contamination, thermal history, and property changes. A lightweight part may have a higher embodied impact if it requires energy-intensive processing and frequent rejection.

Safety hazards include combustible powders, inhalable particles, laser or ultraviolet radiation, high voltage, hot surfaces, solvents, reactive chemicals, and oxygen-deficient atmospheres. Risk controls include enclosure, ventilation, housekeeping, grounding, appropriate personal protective equipment, safe powder handling, interlocks, training, and documented emergency procedures.

Intellectual-property and cybersecurity issues arise because a digital build file can reproduce a product and can be altered without obvious visual evidence. Access control, version management, encrypted transfer, digital signatures, and traceable build records support governance. AI can assist with topology optimization, parameter recommendation, defect-image classification, predictive maintenance, and adaptive process control. However, AI-generated settings require physical validation, explainable acceptance criteria, representative training data, and control of model changes.

Contemporary development is moving toward multi-laser PBF, higher-rate wire deposition, automated support generation, closed-loop monitoring, hybrid additive-subtractive machines, graded materials, improved recyclability, and distributed production. These developments increase capability but also increase the need for metrology, data standards, qualification methods, and skilled personnel.

Best-practice checklist

Before releasing an AM design, the engineer should confirm that:

• functional requirements and critical characteristics are defined;
• the process and material are appropriate for the environment and loading;
• orientation, supports, overhangs, clearances, and removal paths are reviewed;
• critical surfaces include suitable machining or finishing allowance;
• shrinkage, distortion, anisotropy, and residual stress are considered;
• feedstock condition and reuse policy are documented;
• post-processing and inspection are specified;
• qualification evidence matches the consequence of failure;
• digital files, parameters, operators, and machine status are traceable; and
• total cost, safety, sustainability, repairability, and end-of-life are evaluated.

Chapter Summary

Additive manufacturing is a family of layerwise processes rather than a single technology. Material extrusion is accessible and economical but often anisotropic; vat photopolymerization provides detail and smooth surfaces; powder-bed fusion enables complex polymer and metal parts but requires careful thermal and powder control; directed-energy deposition suits large parts and repair; binder jetting offers productive powder processing but introduces sintering shrinkage; and sheet lamination bonds foils or sheets with distinctive material and integration advantages.

Design for additive manufacturing considers orientation, supports, feature resolution, powder or resin removal, lattices, part consolidation, inspection access, and post-processing. Process planning and qualification are essential because build parameters, thermal history, feedstock, and finishing determine final performance. Defects such as porosity, distortion, cracking, delamination, and dimensional error require mechanism-based diagnosis.

Rapid tooling creates value through shortened lead times, design iteration, part consolidation, and conformal cooling. Its success depends on tool life, thermal performance, inspectability, sealing, machining, and total life-cycle economics. Safe and responsible adoption also requires control of powders and chemicals, digital security, environmental assessment, and validated use of monitoring and AI.

Key Terms

Additive manufacturing: Layerwise production of a component by adding material from digital model data.

Material extrusion: AM process that deposits material through a nozzle or orifice.

Vat photopolymerization: Selective curing of liquid photopolymer in a vat.

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

Directed-energy deposition: Addition of powder or wire into an externally generated melt pool.

Binder jetting: Selective deposition of binder into a powder bed followed by post-processing.

Sheet lamination: Fabrication by bonding and cutting sheets or foils layer by layer.

DfAM: Design for additive manufacturing; design practice that exploits AM capabilities and constraints.

Build orientation: Position of a part relative to the machine and layer directions.

Support structure: Temporary or sacrificial material that stabilizes or thermally manages a build.

Anisotropy: Direction-dependent material or geometric properties.

Residual stress: Locked-in stress caused by nonuniform heating, cooling, deformation, or transformation.

Volumetric energy density: Simplified energy-per-volume process indicator in powder-bed fusion.

Post-processing: Operations performed after building, such as heat treatment, machining, or polishing.

Qualification: Documented evidence that a material, machine, process, and part meet requirements.

Rapid tooling: Use of AM to produce moulds, dies, patterns, inserts, jigs, or fixtures quickly.

Conformal cooling: Cooling channels shaped to follow a tool or cavity surface.

Powder refresh: Addition or replacement of unused powder to control feedstock condition.

Digital thread: Traceable connection among design, process, inspection, and production data.

Review Questions

Short Answer Questions

1. What distinguishes additive manufacturing from subtractive manufacturing?
2. State two advantages and two limitations of powder-bed fusion.
3. Why does build orientation affect AM part performance?
4. What is the purpose of stress relief in metal AM?
5. Define conformal cooling and identify one rapid-tooling benefit.

Long Answer Questions

1. Compare material extrusion, vat photopolymerization, and powder-bed fusion in terms of feedstock, operating principle, accuracy, defects, and applications.
2. Explain the major stages of an AM process plan from CAD model to qualified part.
3. Discuss the design principles required for supports, internal cavities, lattices, and consolidated assemblies.
4. Explain how defects in metal powder-bed fusion arise and how inspection and corrective action can address them.
5. Evaluate the technical and economic advantages and limitations of AM rapid tooling compared with conventional tooling.

Analytical / Application Questions

1. A manufacturer needs a large repaired steel die with moderate dimensional accuracy and substantial deposited volume. Select an AM process and justify the choice against at least two alternatives.
2. A polymer extrusion part repeatedly warps at its corners. Develop a root-cause investigation covering material, temperature, bed adhesion, orientation, geometry, and cooling.
3. An injection-mould insert has a localized hot spot and a moderate production volume. Propose a hybrid rapid-tooling solution, including design, process, post-processing, inspection, and validation steps.

Multiple Choice Questions with Answers

Question 1

Which AM process selectively cures liquid photopolymer using light?

A. Vat photopolymerization

B. Directed-energy deposition

C. Binder jetting

D. Sheet lamination

Correct Answer: A. Vat photopolymerization

Question 2

In directed-energy deposition, material is generally delivered into a:

A. Powder recoater

B. Laser-cut sheet stack

C. Melt pool

D. Liquid resin vat

Correct Answer: C. Melt pool

Question 3

Which process commonly requires a sintering cycle after printing a fragile green part?

A. Material extrusion

B. Binder jetting

C. Vat photopolymerization

D. Sheet lamination

Correct Answer: B. Binder jetting

Question 4

In the simplified powder-bed-fusion relation E_v = P/(v h t), increasing scan speed while all other variables remain constant will:

A. Increase nominal energy density

B. Decrease nominal energy density

C. Leave nominal energy density unchanged

D. Reverse the energy flow

Correct Answer: B. Decrease nominal energy density

Question 5

Which feature is a principal advantage of conformal cooling in a mould insert?

A. Channels must be straight and drilled from an external face

B. Cooling channels can follow the cavity surface more closely

C. The insert requires no inspection

D. The insert cannot be machined after printing

Correct Answer: B. Cooling channels can follow the cavity surface more closely

Question 6

Which defect is commonly associated with inadequate overlap or insufficient energy in metal powder-bed fusion?

A. Lack-of-fusion porosity

B. Photopolymer yellowing

C. Adhesive delamination in sheet stock only

D. Binder drying shrinkage only

Correct Answer: A. Lack-of-fusion porosity

Question 7

Which factor is especially important when designing an enclosed powder-bed-fusion cavity?

A. Providing a route for removal of trapped powder

B. Eliminating all inspection requirements

C. Using liquid resin as the support material

D. Preventing any post-processing

Correct Answer: A. Providing a route for removal of trapped powder

Question 8

Which process is generally most suitable for repairing or adding material to a large existing metal component?

A. Vat photopolymerization

B. Directed-energy deposition

C. Binder jetting

D. Sheet lamination of paper

Correct Answer: B. Directed-energy deposition

Question 9

What is the primary purpose of part qualification?

A. To maximize file size

B. To provide documented evidence that requirements are consistently met

C. To eliminate all post-processing

D. To guarantee zero manufacturing cost

Correct Answer: B. To provide documented evidence that requirements are consistently met

Question 10

Which statement about C_p is correct under its stated assumptions?

A. It measures specification width relative to six standard deviations

B. It proves that a process is stable regardless of data behaviour

C. It is calculated only from the process mean

D. It replaces dimensional inspection

Correct Answer: A. It measures specification width relative to six standard deviations