ACP Fusion (DFM) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Volumetric energy density

A comparative index equal to laser power divided by the product of scan speed, hatch spacing, and layer thickness. It ranks parameter sets but is not a material property and does not alone predict defects.

Self-supporting overhang angle

The surface angle above which a powder-bed part prints without added support. It is commonly around 45 degrees from horizontal, but the exact value depends on machine and material and should be verified by test.

Inherent strain method

A fast distortion simulation approach that replaces the full transient thermal history with an equivalent anisotropic strain applied per deposited layer. It is used for full-part predictions where a coupled thermal solve is too expensive.

STL format limitation

STL stores only triangulated surface geometry with no units, material, color, or build orientation. Downstream systems must be told the units, and metadata must be carried separately.

3MF format advantage

A mesh-based build format that carries units, material, color, and metadata along with geometry. It supports a richer data chain than STL and reduces ambiguity at handoffs.

Build traveler

The job record that accompanies a build and lists part ID, material lot, powder reuse count, machine, operator, parameters, and post-processing steps. It provides traceability from feedstock to finished part.

Trapped powder escape path

A designed drain or vent hole, typically one to two millimeters or larger, that lets unused powder or liquid exit a hollow volume. Without it, hollow parts cannot be cleaned and may fail inspection.

Anisotropy in AM parts

Direction-dependent mechanical properties caused by layer-wise building. FDM parts are weakest along the layer axis, so load paths and build orientation must be designed together.

Stair-stepping error

Surface roughness caused by approximating a sloped surface with flat layers. The step height equals layer thickness divided by the tangent of the surface angle from horizontal.

Lack-of-fusion porosity

Internal voids that form when energy density is too low to fully melt powder between tracks or layers. Simulation shows unfused regions, and inspection detects them as irregular voids.

Keyhole porosity

Voids formed when energy density is too high and the melt pool becomes deep and unstable, trapping gas at its base. It appears in simulation as deep, narrow pools with voids.

Support contact marks

Surface defects left where supports touch the part. They are avoided by placing contact points on non-critical faces or by adding machining stock that is removed later.

Stress relief before plate removal

A heat treatment performed while the part is still attached to the build plate for thin or crack-sensitive geometries. It reduces residual stress before the constraint is released.

HIP processing

Hot isostatic pressing applies high temperature and pressure to close internal porosity. It changes mechanical properties and must be included in the qualified parameter set and build record.

Powder reuse tracking

Recording how many times a powder lot has been recycled and monitoring oxygen content and particle size. These metrics determine whether the powder still meets acceptance criteria.

Thermo-mechanical simulation

A coupled analysis that solves transient heat transfer with a moving heat source and then computes stress and distortion from the resulting temperature field. It predicts warpage and residual stress.

Distortion pre-compensation

The process of inverting a predicted distortion field, applying it to the nominal geometry, and re-slicing. It is iterated until residual error falls within tolerance and is verified by a physical build.

Thermal contact conductance

A boundary property describing heat flow between the part and build plate. Modeling it as a perfect bond overpredicts conduction unless the plate is flat and preheated.

Mesh convergence check

Refining element size until predicted peak temperature or distortion changes by less than a chosen threshold, often about five percent. It separates numerical error from model error.

Goldak heat source

A volumetric moving heat source model with a double-ellipsoid shape. It represents melt pool geometry more accurately than a point source for conduction and keyhole regimes.

Digital thread in AM

The linked record connecting as-designed CAD, simulation inputs and results, build parameters, and inspection data by a common part and serial number. It enables traceability and feedback.

Build file checksum

A hash computed on a released build file so the file used on the machine can be verified against the approved version. It detects unauthorized or accidental changes.

Released versus working data

A repository separation that keeps approved files distinct from draft files. It prevents production use of unapproved geometry or parameters and supports audit requirements.

First-article inspection

A full measurement of the first production part against the nominal model, documenting deviations. It is the gate that must pass before a build is released to production.

Conformal cooling channel

A channel that follows the part surface to improve heat removal. It must be designed support-free with drain paths, and channel spacing must preserve structural integrity.

Teardrop channel cross-section

A channel shape with an inclined roof that allows internal horizontal passages to print without internal support. It is a standard design rule for powder-bed cooling and fluid channels.

Lattice relative density

The fraction of the lattice volume occupied by struts. Stiffness scales with relative density, and the exponent depends on whether the cell is bending or stretch dominated.

Minimum resolvable feature

The smallest feature a process can produce reliably, set by beam diameter and layer thickness. Features below this limit must be redesigned or assigned to a different process.

Process window

The parameter region, spanning power, speed, hatch spacing, and layer thickness, that yields acceptable density and properties. Operating near its edge raises defect risk.

Design of experiments for parameters

A structured set of builds varying key process parameters to map responses such as density, porosity, and mechanical properties. It produces the data behind a qualified parameter set.

In-process monitoring record

Layer-by-layer imaging or melt pool data captured during a build and linked to the part serial number. Acceptance thresholds must be defined before the build starts.

Change management for build files

The rule that a parameter or orientation change is a design change requiring a new revision and re-validation. Released build files are never overwritten in place.