Additive Manufacturing (3D Printing) Inspection Applications and Light Microscopy Techniques

Introduction

The Additive Manufacturing (AM) industry has been exploding over the last several years with new materials and processes to produce more complex and reliable parts for critical applications. Due to this rapidly growing field with new developments and needs, it becomes extremely important to be able to understand the materials characteristics along with the process variations which can impact the final product.

From incoming inspection of raw materials to final inspection of the product, there are several points along the way for Light Microscopy to be a valuable tool in understanding how the process is working. Additionally, Light Microscopy is also extremely useful in the development of new processes or in failure analysis investigation.

This document explores several applications in Light Microscopy for use in Powder Bed Fusion, a process widely used in metals. This method provides some challenges but also some distinct advantages. Motic Compound light microscopes and Stereo microscopes can provide the tools to improve the end AM product from start to finish.

Fundamentally, the AM process known as Powder Bed Fusion, discussed here, consists of several insertion points along the way from powder to the final product where microscopy can provide valuable insight.

[Image: A Motic microscope is shown.]

Insertion Points

#1 Powder Material Analysis

For the metal powder bed fusion process, incoming powders of various metals and exotic alloys need to be inspected for size, shape, density, and defects. Size distribution(s) must be checked to ensure proper operation of equipment.

The shape is considered best when spherical, which leads to maximum powder bed density and flowability. Bed density refers to how well particles fit tightly together. If all powder particles are of the same size, there will be gaps between them.

Oftentimes, two or three-size particles (bimodal or trimodal) are used to fill gaps during melting, creating flows to fill the smallest gaps for fully dense material.

• Light microscopy can provide powder size distribution and shape (sphericity/roundness) through image analysis. This is typically used for powder sizes >= 5 microns (ISO/ASTM 52907) in brightfield transmitted light. Transmitted light is blocked by the particles, producing a high-contrast shadow-like image for analysis.
• Brightfield reflected light allows observation of powder particle surfaces for inspection of powder defects such as surface voids and contaminants.

[Image: Fig.1: Metallic powder imaged in Brightfield transmitted light microscopy.]

[Image: Fig.2: Metallic powder imaged in Brightfield reflected light microscopy.]

#2 Process Analysis

Additive Manufacturing for metals is performing real-time metallurgy, melting and solidifying layer by layer, a process not seen in traditional machining. Each part is unique, and problems can arise. To produce highly critical parts, significant time and money are spent ensuring proper and consistent processes.

More complex metallurgy is available where metal characteristics can be designed to function differently in various areas of the same part.

To ensure high levels of dependable parts production, several inspection methods are required, some of which may include destructive testing of a part per build.

• Metallographic microscope techniques can be used to view and size grain structures and layering effects of cross-sectioned polished parts using reflected Brightfield or Crossed Polarized light.
• Voids can be viewed and analyzed. Shapes or the voids/pores can indicate process problems, such as unmelted powder, oxides, or moisture.
• Contaminants can enter the process and cause various problems. Understanding and tracing these unwanted particles to their source is important, and light microscopy is used for visualization and identification.
• Delamination (layer separation), fatigue cracks, and micro-cracks can be observed in reflected light microscopy of polished cross-sections, pointing to process issues and potential solutions.

[Image: Fig.3: Brightfield reflected light image of longitudinal cross-section laser tracks.]

[Image: Fig.4: SLM (Selective Laser Melting) spherical voids in aluminum alloy caused by moisture.]

[Image: Fig.5: Contaminant (magenta color) in reflected light polarization.]

#3 External Defect Analysis

During production, parts undergo steps like heat treatment, removal, surface modification, and cleaning, which can cause defects. External critical areas can be inspected visually using a stereomicroscope to identify damaged areas such as voids, pits, or edge deformation.

#4 Surface Analysis

The surface of parts directly after production often exhibits some degree of roughness. This may require further processes such as sandblasting, shot peening, electropolishing, or vibratory techniques to achieve the required surface finish for proper functionality.

Using stereomicroscopy with various illumination types, the effects of surface finishing methods can be visualized and compared to a known good surface. It can also be used to check for damage caused by the surface finishing technique.

Many other Additive Manufacturing methods and materials exist, but they all share a common need for analysis and inspection using Light Microscopy.

[Image: Close-up of a microscope focusing knob.]

SM7 Series

The First Motic Stereo Plan-Apochromat: Enjoy and Be Surprised.

Power in any Aspect

The SM7 features optical performance with true color reproduction, high resolution, and low distortion. A stand with Incident/Transmitted LED light supplies variable illumination.

Stand Design

Ultra-flat stand bases provide relaxed positioning for hands and forearms, facilitating lengthy preparation work. The advanced ergonomic design maximizes efficient usage and minimizes fatigue.

Flexibility for Individual Demands

A variety of objectives and eyepieces allow tailoring a personal SM7. Upgrade your workplace with ergonomic stands and powerful optics, whether Apochromatic color fidelity or improved resolution power is the focus.

[Image: A Motic SM7 microscope.]

SM7 Series

Motic SM7: High-Precision Galilean Optics

Galilean Optical System

The SM7's Galilean Optics feature a 7:1 Zoom system, offering a standard magnification range of 8X-56X. A 10-Position Click-Stop aids in setting precise magnifications for repeatable measurements. The standard optical setup can be varied by exchanging objectives and/or eyepieces.

Superior Optics

For the best possible image results, a 1X Plan-Apochromatic objective with a Working Distance of 81mm is available. True-color reproduction combined with improved Field Flatness and minimized image defects covers both living specimens and technical samples with the SM7 stereomicroscope.

Resolution Power for Tiny Details

Beyond minimized chromatic and spherical aberrations, the resolution of the 1X Apochromatic objective makes the SM7 particularly interesting for technical applications, offering 36% more resolution power.

[Image: Close-up of a microscope focusing knob.]

SM7 Series

Powerful visualization for both eyes and camera

Eyepieces

The High eyepoint eyepieces 10X/22 suit spectacle wearers and offer a diopter adjustment range within +5/-8 dpt. Easy use of reticles is a standard feature on Motic's top models.

Observation Tubes

The Trinocular head is supplied with a 100:0/20:80 2-position beam split, providing sufficient light to the camera port even under low-light conditions. C-Mount cameras are adapted to the respective camera sensors. Besides the standard Binocular tube, a 60° inclination tube is available for special OEM demands.

[Image: Images of microscope eyepieces, a trinocular head, and a microscope.]

SM7 Series

Illumination is the Second Key for the Safe of Information

Illumination

For years, LEDs have been replacing Halogen light sources in business and private life due to their low energy consumption, long lifetime, and low heat production, especially beneficial for living samples.

Transmitted / Incident Light Stands

The SM7 Stand for transparent and opaque specimens incorporates 3W LEDs for both illumination types, with separate controls for mixed samples. An optional 4-segment ring illuminator is available for the standard stand. Surface topographies can be visualized by activating different illumination angles. The SM7 features significantly flat stand bases for ergonomic positioning of hands and forearms, allowing long preparation work without fatigue. For ESD-sensitive work, Motic's ESD and surge protection system complies with UL and CL standards and regulations, making it essential for electronic and electric quality control environments.

[Image: Image of a microscope with LED illumination. Images include Chinese text and a pagoda graphic.]

Moticam S-Line

Scientific-Grade Microscope Cameras

The new Moticam S-line represents a further step in Motic's digital microscopy. Utilizing the latest sCMOS sensors, proprietary PCB design, and on-board image management, each Moticam S series camera promises professional digital results at an affordable price. Designed and manufactured entirely in-house under strict German quality guidelines, this Moticam S-line is suitable for Clinical, Research, and Industrial applications. Motic aims to make high-level digital microscopy affordable for everyone.

Key Features

• Super-Fast Frame Rates [Icon: FPS]
• sCMOS Sensor [Icon: sCMOS]
• USB 3.1 Data Transfer [Icon: USB 3.1]
• Up to 20MP Resolution [Icon: 20 MP]
• True color reproduction
• Rolling and Global shutter models

[Image: Image of a Motic microscope with a laptop displaying a circuit board.]

SM7 Series Dimensions

Detailed technical drawings showing the dimensions of the SM7 microscope are provided, including measurements for height, width, depth, and various component placements. Key dimensions indicated include overall height of 371.6mm, base dimensions, and arm lengths.

[Image: Technical drawings with dimensions.]

SM7 Series System Overview

This section outlines the modular system of the SM7 Series microscopes, detailing various compatible components. It illustrates how eyepieces (e.g., 10X/22, 20X/13), reticles, binocular and trinocular tubes, and the 7:1 Zoom Microscope Body can be combined. Various objective lenses (ACH 0.5X, 1X, 2X; PL APO 1X) and C-Mount adapters (0.5X, 1X) are shown. Different stand options are presented, including the Standard Large Stand, LED Incident/Transmitted Illumination Large Stand, and various boom stands (articulating, ball bearing, special universal, industrial). Illumination options like the 4 Split LED Ring Light and head holders are also depicted.

[Image: System overview diagram showing components and connections.]

SM7 Series Technical Specifications

A comprehensive table details the technical specifications for various SM7 Series models, including Sku, Name, Optical System (Galilean infinity optical design, Plan Achromat, Plan Apochromat), Observation Tube (Binocular, Trinocular), Inclination (30° inclined), Trinocular Light Split (100:0/20:80), Interpupillary Distance (55-75mm), Diopter Adjustment (+5/-8 diopter on eyepieces), Eyepieces (Widefield WF10X/22mm), Objectives System (Zoom ratio 7:1), Objectives Classification (Plan Achromat, Plan Apochromat), Objectives (0.8X-5.6X, 1X), Working Distance (90mm, 81mm), Stand Type (Fixed-arm stand), Head Holder (For Ø76mm head), Focus Mechanism (Coarse focusing system with tension adjustment), Focusing Stroke (120mm), Incident Illumination (LED 3W with intensity control or reflector), Transmitted Illumination (LED 3W), Transformer (External, 110-240V CE), Power Supply, Accessories Included (Dust cover, Glass plate Ø160mm), Dimensions (LxWxH), Base, Column/Arm, Net weight (ranging from 6.9 Kg to 7.5 Kg), and Contrast Techniques (Brightfield).

See the SM7 in action

Motic offers demonstrations and quotes for the SM7 series.

• Free Demo
• Request a Quote
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Contact Information

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General Contact

Tel: 1-877-977-4717

Email: sales@motic-america.com

Website: www.moticmicroscopes.com

Motic locations include Canada, China, Germany, Spain, USA.

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