Additive Manufacturing Processes Overview

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the first step in the Generalized Additive Manufacturing Process Chain?

Conceptualization and CAD (correct)

Build

Post-processing of part

Machine setup

STL stands for Stereolithography.

True

Name one application area for Additive Manufacturing that does not involve conventional CAD modeling.

Medical modeling

The process of converting a CAD model to STL involves approximating the surface of the model with a series of __________.

triangular facets Signup and view all the answers

Match the different AM systems with their characteristics:

Photopolymer based systems = Use light to cure resin Powder-based systems = Utilize powdered material to build parts Molten material systems = Extrude melted material to create objects Solid sheets = Build layers from solid sheets of material Signup and view all the answers

Which of the following is NOT a step in the AM process chain?

Material quality assessment Signup and view all the answers

Additive Manufacturing is only applicable to metal systems.

False Signup and view all the answers

What is a key consideration in Design for AM when creating a part?

Part orientation Signup and view all the answers

Which process automatically generates supports for molten material systems?

Thermojet process Signup and view all the answers

Solid sheets used in lamination methods require supports for their production.

False Signup and view all the answers

What should be avoided when using material handling systems in additive manufacturing?

Moisture and excess light Signup and view all the answers

In additive manufacturing design, features that prevent parts from being easily removed are called __________ features.

interlocking Signup and view all the answers

Match the application areas with their respective imaging techniques:

Medical modeling = 3D ultrasound Metal systems = Subtractive manufacturing Signup and view all the answers

What is one of the key considerations when working with metal systems?

Maintenance of equipment Signup and view all the answers

What is a laborious process required after using lamination methods?

Cleaning up the parts Signup and view all the answers

In the extrusion process, supports must always be generated automatically.

False Signup and view all the answers

What is a possible issue that can arise from poor technique in support removal during additive manufacturing?

Low product quality Signup and view all the answers

Post-processing is exclusively done using manual techniques.

False Signup and view all the answers

What is the term used to describe the part that should be separated from the build platform in additive manufacturing?

part Signup and view all the answers

Some additive manufacturing machines require __________ to prevent parts from collapsing during the building process.

support structures Signup and view all the answers

Match the following terms with their descriptions:

Post-processing = Manual finishing of parts for application purposes Anisotropic properties = Different properties in different directions Support structures = Stabilization during building Additive manufacturing (AM) = Process of creating objects layer by layer Signup and view all the answers

What characteristic do AM parts often exhibit due to the manufacturing process?

Trapped voids or bubbles Signup and view all the answers

The properties of parts created through additive manufacturing are often isotropic.

False Signup and view all the answers

Name one advantage of advancements in AM materials and processes.

Increased number of applications for components Signup and view all the answers

What is one benefit of reverse engineering data using laser scanning technology?

Creates architectural models with textures and colors Signup and view all the answers

The STL file format is effective for all additive manufacturing technologies.

False Signup and view all the answers

What future trend is expected in additive manufacturing regarding materials?

Color and multiple material systems becoming more common. Signup and view all the answers

Additive manufacturing technologies may integrate ______ processing elements as they evolve.

subtractive Signup and view all the answers

Match the following topics with their corresponding descriptions:

Direct digital manufacturing = Increases the need for standardized software processes Software optimization = Enhances additive manufacturing processing efficiency Hybrid technologies = Combine additive and subtractive manufacturing methods Post-processing techniques = Refine and enhance printed models after creation Signup and view all the answers

What is the nominal layer thickness for most FDM Dimension machines?

0.254 mm Signup and view all the answers

Thicker layers in additive manufacturing lead to more precise builds.

False Signup and view all the answers

What common issue do fine details in a design cause for some AM technologies?

Problems with wall thickness. Signup and view all the answers

In powder-based systems, there is no need to use __________.

supports Signup and view all the answers

Match the following AM machine types with their characteristics:

Photopolymer-Based Systems = Good accuracy with thin layers but poor mechanical properties FDM Machines = Nominal layer thickness of 0.254 mm Powder-Based Systems = No supports needed for builds Zcorp Parts = Can be colored using binder material Signup and view all the answers

What is a requirement for post-processing that involves heat?

Knowledge of the melting temperature of the material Signup and view all the answers

With droplet deposition systems, support material cannot be modified as it comes out of the print head.

False Signup and view all the answers

What type of systems primarily use a vat of liquid photopolymer?

Photopolymer-Based Systems Signup and view all the answers

Which type of radiation is primarily used in photopolymerization processes?

Ultraviolet (UV) radiation Signup and view all the answers

Photopolymers were developed in the 1980s.

False Signup and view all the answers

Who conducted experiments with UV curable materials and contributed to sl technology?

Charles Hull Signup and view all the answers

Photo-curable resins are commonly used in __________ to seal dental surfaces.

dentistry Signup and view all the answers

Match the following types of radiation to their usage in curing photopolymers:

Gamma rays = Used in medical imaging X-rays = Applications in treatment and inspection Ultraviolet (UV) = Curing photo-curable resins Visible light = Used in some photopolymer systems Signup and view all the answers

What is one type of technology discussed in vat photopolymerization processes?

Two-Photon Vat Photopolymerization Signup and view all the answers

Laser-resin interaction is an important factor in photopolymerization process modeling.

True Signup and view all the answers

Name one component of the photopolymerization materials used in vat photopolymerization.

UV curable photopolymers Signup and view all the answers

In photopolymerization, the formation of a three-dimensional structure occurs through the process of __________.

polymerization Signup and view all the answers

Match the following scan patterns with their descriptions:

WEAVE = A scan pattern characterized by back-and-forth motion STAR-WEAVE = A scan pattern that resembles a star shape ACES = A scan pattern designed to reduce build errors Layer-based = A technique focusing on building one layer at a time Signup and view all the answers

Which photopolymerization approach uses a large patterned radiation beam?

Mask projection Signup and view all the answers

In dentistry, UV radiation is predominantly used for photopolymerization.

False Signup and view all the answers

Name one advantage of the two-photon photopolymerization approach.

It does not require recoating. Signup and view all the answers

The ______ approach involves scanning laser beams in photopolymerization.

vector scan Signup and view all the answers

Match the photopolymerization processes to their primary configurations:

Vector scan = Point-wise approach Mask projection = Layer-wise approach Two-photon = High resolution point-by-point Visible light = Used predominantly in dentistry Signup and view all the answers

What is the primary role of photoinitiators in photopolymer materials?

To convert light energy into chemical energy Signup and view all the answers

UV curable photopolymers are mainly used in the food packaging industry.

False Signup and view all the answers

Name one type of polymerization used in photopolymer chemistry.

Free radical polymerization or Cationic polymerization Signup and view all the answers

The laser scan vat photopolymerization creates solid parts by selectively solidifying a liquid photopolymer resin using a __________ laser.

UV Signup and view all the answers

Match the following types of radiation used for curing photopolymers with their characteristics:

Gamma rays = High penetration capabilities X-rays = Used in medical applications UV = Most prevalent in commercial use Electron beams = Effective for surface curing Signup and view all the answers

Which of the following is NOT a component of the machine subsystem hierarchy in Vector Scan VP machines?

Cooling system Signup and view all the answers

Interpenetrating polymer networks are formed primarily by the cationic polymerization of acrylates.

False Signup and view all the answers

What is the function of the recoater blade in the Vector Scan VP process?

To deposit a new layer of resin and smooth the surface of the vat Signup and view all the answers

What is the position accuracy in the x-y directions for the atypical point-wise Microsterolithography process?

0.25 µm Signup and view all the answers

Two-photon VAT photopolymerization has no notable speed advantage over laser scan SLA.

False Signup and view all the answers

What is one main drawback of using photopolymer materials in additive manufacturing?

Limited impact strength and durability compared to thermoplastics. Signup and view all the answers

The minimum size of the unit of hardened polymer in atypical Microsterolithography is ______.

5 µm x 5 µm x 3 µm Signup and view all the answers

Match the following characteristics with their respective advantages or drawbacks in Additive Manufacturing:

Accuracy = Advantage of SLA-250 Surface finish = Submicron Ra for upfacing surfaces Flexibility = Supports many different configurations Aging of materials = Drawback of photopolymers Signup and view all the answers

What is the maximum size of the fabrication structure in the atypical Microsterolithography process?

10 mm x 10 mm x 10 mm Signup and view all the answers

Surface finishes for slanted angles in SLA can be better than for upfacing surfaces.

False Signup and view all the answers

What is the spot size of the UV beam in the specifications for atypical point-wise Microsterolithography?

5 µm Signup and view all the answers

Study Notes

Generalized AM Process Chain

The generalized AM process chain includes eight steps: conceptualization and CAD, conversion to STL, transfer and manipulation of STL file on AM machine, machine setup, build, part removal and cleanup, post-processing of part, and application.
There are variations in the AM process depending on the machine, material, and desired application.
Photopolymer-based systems are easy to set up, but have poor mechanical properties compared to other AM materials.
Powder-based systems do not require supports, while molten material systems do.
Solid sheet systems require waste material removal, which can be a laborious process.
Metal systems require careful attention to substrate usage, energy density, weight, accuracy, and speed.

Maintenance of Equipment

AM machines may use fragile laser or printer technology, requiring careful monitoring and a clean, low-noise environment.

Materials Handling Issues

Moisture and excess light should be avoided when handling AM materials.
Material loading is typically done offline using software systems.
Recycling of unused material from builds is sometimes possible.

Design for AM

Consider part orientation, support removal, hollowing out, undercuts, interlocking features, part count reduction, and identification markings when designing parts for AM.

Application Areas

Applications that do not involve conventional CAD modeling include medical modeling (using CT, MRI, and 3D ultrasound), reverse engineering data (using laser scanning technology), and architectural modeling.
Future developments in AM include thicker layers, processing regions rather than layers, and more complex processes within a single machine.
Color and multi-material systems will become more common in the future.
Software is increasingly being optimized for AM processing, including dedicated software for converting designs into printable formats.
As direct digital manufacturing becomes more common, standardized software processes based around AM will be needed.

Vat Photopolymerization Processes

Vat Photopolymerization processes are used to cure liquid photopolymers using radiation to create 3D structures.
Photopolymers materials are primarily used for coating and printing industries and were developed in 1960.
Radiation sources for curing photopolymers include gamma rays, x-rays, electron beams, UV, and visible light.
UV and visible light are primarily used for SL systems.

Photopolymerization Materials

UV curable photopolymers are used as photoresists in the microelectronics industry.
Photopolymer chemistry includes free radical polymerization (acrylates) and cationic polymerization (epoxies and vinylether).
Resin formulations use multifunctional monomers (MFM) along with photoinitiator system, monomer formulation, and interpenetrating polymer network formation.

Laser Scan Vat Photopolymerization

Processes creates solid parts using an UV laser to selectively solidify liquid photopolymer resin.
Part building involves creating cross-sectional contours or slices, one on top of another.
Post-curing includes cleaning, post-curing, and finishing (removing support structures, sanding, and filing for desired surface finishes).

Vector Scan VP Machines

Five main subsystems: recoating system, platform system, vat system, laser and optics systems, and control system.
Process: after a layer is cured, the platform dips down by a layer thickness, then the recoater blade deposits a new layer of resin and smooths the surface of the vat.

SL Scan Patterns

Layer-based build phenomena and errors: discretization causes "stair steps".
WEAVE scan pattern: a back-and-forth zigzag pattern reduces staircase artifacts.
STAR-WEAVE scan pattern: reduces stair-stepping by alternating the direction of the laser beam.
ACES scan pattern: a complex pattern featuring serpentine and star-like patterns that reduces contour errors and increases fabrication efficiency.

Vector Scan Micro-Vat Photopolymerization

Microfabrication applications: using lasers and X-rays as energy sources.
Atypical point-wise Microsterolithography process: 5-µm spot size of the UV beam, position accuracy of 0.25 µm in x-y directions and 1 µm in z-direction, minimum size of hardened polymer of 5 µm x 5 µm x 3 µm, maximum size of fabrication structure of 10 mm x 10 mm x 10 mm.

Mask Projection VP Technologies and Processes

Mask Projection VP technology: uses a large radiation beam patterned by a device like a Digital Micromirror Device to irradiate entire layers at one time.

Two-Photon VP

High resolution point-by-point approach: using the intersection of two scanning laser beams.

Process Benefits and Drawbacks

Advantages of vat photopolymerization: accuracy (0.002 in/in for SLA-250), surface finish (ranging from submicron Ra for upfacing surfaces to over 100 um Ra for slanted angles), and flexibility.
Drawbacks of vat photopolymerization: limited chemistries (acrylates and epoxies), low impact strength and durability compared to injection molded thermoplastics, material aging resulting in degraded mechanical properties, limitations for production applications.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the generalized additive manufacturing (AM) process chain, covering key steps from conceptualization to application. It also delves into maintenance considerations for AM equipment and material handling issues. Test your knowledge on the nuances and variations of different AM systems.