AM PARAMETER OPTIMIZATION

The ability to serially manufacture precision metal parts via additive manufacturing depends on successfully Designing For Additive Manufacturing (DFAM). Optimizing for the AM process is a difficult task given the numerous parameters involved throughout the entire metal additive manufacturing life cycle.

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Sintavia is able to work with its customers to identify the right parameters that will allow for quality, high speed production of parts.  With unparalleled on-site capabilities—including design, powder analysis, printer correlation, CT scanning, metallurgical analysis, and mechanical testing—Sintavia is the global independent leader in DFAM for critical industries.

 

Metallurgical Services for AM

Sintavia possesses one of the most advanced and sophisticated metallurgical analysis laboratories in the world. The company is capable of performing many highly technical tests and procedures in-house, allowing it to validate not only its own design and production within additive manufacturing, but also that of third parties. This in-house capability is critical for material and parameter development.

Metallographic Examination

Metallography is the microscopic study of the structure of metals. Sintavia offers the full range of metallographic preparation capabilities including sectioning, mounting, grinding, polishing and etching.

Per the ISO 17025 scope, Sintavia’s metallography testing includes the following ASTMs:

Preparation ASTM E3
Grain Size ASTM E112, E930, E1181, E1382
Micro Exam (including Alpha Case) ASTM E407
Macro Exam ASTM E340, E381, A604

Scanning Electron Microscopy

Sintavia uses a scanning electron microscope (SEM) with an energy dispersive spectrum (EDS) with magnification capabilities to 300,000x for micro analysis as well as analyzing small areas of interest on samples.

Types of analyses include:

  • Fracture Analysis – Fatigue Striations
  • Fatigue Analysis – Low and High Cycle
  • Corrosion Analysis – Sulfur and Chlorine Induced
  • Semi Quantitative Chemical EDS Analysis
  • Elemental Mapping and Scanning
  • Particle Identification
  • Reverse Engineering

Hardness Testing

Sintavia performs the following hardness tests: Rockwell (ASTM E18), Superficial Rockwell (ASTM E18), Micro-hardness via Vickers and Knoop (ASTM E384), and Shore (ASTM E2240).

Rockwell Hardness Test

For each Rockwell test, a minor load is applied to either a diamond cone or a steel ball indenter positioned on the test material’s surface to establish a zero reference position. Next, a major load is applied for a specified amount of time, leaving the minor load applied upon release. The Rockwell hardness number will be the difference in depth between the zero reference position and the indent due to the major load.

The choice of indenter is dependent upon the characteristics of the test material. The Rockwell Hardness Test applies larger minor and major load values than the Superficial Rockwell, yet both tests offer three different major load options. More than thirty different scales are used between Rockwell and Superficial Rockwell hardness testing due to the various choices and combinations of tests, indenters and major loads.

Knoop Hardness Test

This microhardness test is used on very small parts and material features that are unable to be tested by the other methods and employs a test load of 1000 grams or less. The Knoop test is performed like Brinell hardness by applying controlled force for a specific amount of time to an indenter in a rhombus-shape. The impression is measured microscopically and is used along with the test load to calculate the hardness value on the Knoop scale.

Vickers Hardness Test

A Vickers hardness test can be performed on both the micro and macro scales (some Vickers testers have a maximum test load of up to 50 kilograms). This type of hardness test is also performed by applying controlled force for a specific amount of time to an indenter, which in this case is a square-based diamond pyramid. The impression measurement and test load are used in the appropriate formula to calculate the Vickers hardness value. Like Brinell and Knoop, this method has one scale that covers its entire hardness range.

Inductively Coupled Plasma Mass Spectrometry (ICP)

Sintavia performs accurate and fast sub-ppm elemental analysis of metals using an Inductively Coupled Plasma (ICP) mass spectrometer. By testing samples pre and post build, Sintavia is able to determine the chemical composition of the powder and verify the finished part meets or exceeds industry specifications.

Failure Analysis Testing

Sintavia performs failure analysis testing, including the determination of origin of failure, failure mode and type of corrosive attack, root cause determination / contributing factors, material anomalies / features, mechanical damage, geometric influence, and remaining life assessment.

Below are the various types of failure analyses in which Sintavia has expertise.

  • Fatigue – Low or High Cycle
  • Rotating Bending Fatigue
  • Torsional Bending Fatigue
  • Unidirectional Bending Fatigue
  • Mechanical Overload
  • Corrosion Fatigue
  • Microbiologically Influenced Corrosion
  • Stress Corrosion Cracking – Chloride or Sulfur Induced
  • Electrical Arc Inspection
  • Wire Rope or Cable Failures
  • Material Inclusion Failure
  • Weld Failures – Lack of Fusion, Stress Risers, Toe of the Weld
  • High Velocity Erosion-Corrosion
  • Threaded Fastener Failures
  • Preferential Corrosion of Ferrite
  • Shaft Keyway Failures
  • Detrimental Phase Identification (Sigma)
  • Excessive Thermal Overheating
  • Transgranular and Intergranular Failures
  • Corrosion Pitting Cells – Stress Riser
  • Material Heat Treat Failures – Insufficient Thermal Conditioning
  • Intergranular Decohesion and Corrosion
  • Pitting Corrosion
  • Sheer Overloading
  • Quench Cracking
  • Shaft Misalignment Failures
  • Bearing Failures
  • Reverse Bending Fatigue
  • Fracture Analysis – Intergranular Verses Transgranular
  • Hydrogen Induced Cracking
  • Thread Root Examination – Rolled Verses Machined
  • High Temperature Thermal Creep and Fatigue Failure

 

Precision Scanning

CT Scanning

Sintavia utilizes a 225kV and 320kV x-ray source in a single scanning platform.  This system allows adjustments to spot size detection, penetrating power, scanning speeds and resolution for different materials used within the AM industry.

Common analysis used in CT scanning include:

  • Porosity Analysis to determine density, void size and distribution of the AM parts
  • Wall Thickness
  • Part to CAD Comparison
  • Part to Part Comparison
  • First Article Inspection

 

CT scanning provides an excellent resource to complement Sintavia’s metallurgical analysis, AM in-situation monitoring and metrology expertise.

 

Blue Light 3D Scanning

Sintavia uses a non-contact blue light 3D scanner to accurately measure millions of points on a part to capture part sizes, surfaces, finishes and geometries for dimensional inspection and reverse engineering.

Blue Light 3D Scanning allows for fast and accurate measurement and inspection.

Powder Analysis

Sintavia’s powder analysis services include:

  • Particle Size Distribution by Laser Size Diffraction per ASTM B 822
  • SEM Morphology
  • Hall Flow Rate per ASTM B 213
  • ICP (Inductively Coupled Plasma Mass Spectrometry)
  • Oxygen, Nitrogen and Carbon Content
  • Element Characterization by EDS
  • Tap Density per ASTM B 822

Mechanical Testing

As part of its Material Characterization lab, Sintavia offers comprehensive Mechanical testing capabilities using some of the most advanced equipment available.

Mechanical Testing provides validation and confirmation to additive and traditional manufacturing processes as they relate to forces applied in static or dynamic applications. A mechanical test can validate newly developed material and process technologies as well as provide a method of controlling quality. Typical mechanical testing properties include elasticity, tensile strength, elongation, hardness, fracture toughness, impact resistance, creep, stress rupture and the substantiation of fatigue limits.

Creep and Stress Rupture Testing

Creep is high temperature progressive deformation at constant stress. “High temperature” is a relative term dependent upon the materials involved. Creep rates are used in evaluating materials for boilers, gas turbines, jet engines, ovens, or any application that involves high temperatures under load. Understanding high temperature behavior of metals is useful in designing failure resistant systems. A creep test involves a tensile specimen under a constant load maintained at a constant temperature.

Sintavia uses a creep testing system to perform high temperature progressive deformation and constant stress tests, a critical metric for the A&D industry.

Fatigue Testing

Sintavia conducts a variety of fatigue tests onsite measuring the ability of materials to withstand the application of repeated load cycles. Sintavia is equipped to conduct a variety fatigue tests including:

  • Component Fatigue Testing
  • Fatigue Crack Growth Rate
  • Fatigue Toughness Testing
  • Fracture Toughness
  • Low Cycle and High Cycle Fatigue Testing

These tests can all be performed in high temperature chambers, simulating the real word environment of each underlying part’s end use.

Tensile Testing

Sintavia also performs tensile testing on-site, and is able to measure both ultimate tensile strength and yield strength, or the point at which plastic deformation begins.

As part of this process, Sintavia conducts elevated temperature tensile tests as a proven method of evaluating the behavior of materials under a combination of heat and tension.

Creep And Stress Rupture Testing

In addition to fatigue and tensile testing, Sintavia also performs creep testing on-site, allowing the company to measure the tendency of a material, after being subjected to high temperatures, to change its form in relation to time.

Creep is high temperature progressive deformation at constant stress. Similar to fatigue and tensile testing, creep data is used in evaluating materials for jet engines, boilers, gas turbines, ovens, and other applications that involve high temperatures under load.

Charpy Impact Testing

Finally, Sintavia performs Charpy Impact testing on-site.  This test is used to determine a material’s toughness or impact strength in the presence of a flaw or notch under fast loading conditions.  The Charpy impact test is a destructive test that involves striking notched specimens with a swinging weight or pendulum at a series of temperatures to show the relationship of ductile to brittle transition and measuring the amount of energy absorbed by the material during fracture.