Rules Based Scan Strategy for Powder Bed Fusion

A computer-implemented method of laser powder bed fusion additive manufacturing of parts, the method comprising:

• using a number of processors to perform the steps of:
• converting a 3D geometry into 2D layers, wherein the 2D layers contain information about the 3D geometry, and wherein the 2D layers define at least one target melt pool characteristic for regions of the 2D layers;
• assigning laser scan parameters to achieve the target melt pool characteristic according to an algorithm derived from preexisting melt pool data for a specified build material;
• and
• controlling a laser and laser beam steering according to the assigned laser scan parameters to additively manufacture a part.

A computer-implemented method of certifying digital instructions for powder bed fusion additive manufacturing of a specified alloy, the method comprising:

• using a number of processors to perform the steps of:
• recording one or more digital or analog signals controlling an additive manufacturing system energy delivery and position;
• creating a digital file of a powder bed fusion component according to the digital or analog signals controlling the additive manufacturing system;
• comparing laser powers, position, time, and calculated velocity in the digital file to a melt pool database or number of specified rules for the alloy;
• and
• certifying, rejecting, or assigning a probability of flaw to each comparison of the laser powers, position, time, and calculated velocity in the digital file to the specified rules.

A method of generating a melt pool database for powder bed fusion, the method comprising:

• performing a number of melts on a metal alloy plate with a laser beam, wherein the number of melts is sufficient to determine:
• a minimum time between adjacent melts before melt pool area deviates by more than 5 percent;
• a maximum laser power reduction rate that results in end of vector depression less than 20 micrometers;
• a maximum shift in laser beam spot size before melt pool area deviates by more than 5 percent;
• a maximum laser scan speed before melt pools form discontinuous tracks of greater than 5 percent width variation;
• wherein the plate has a surface roughness arithmetic mean greater than 0.5 but less than 4 micrometers;
• sectioning the metal plate to interrogate melt pool cross section;
• and
• imaging a top surface of the metal plate at after melting.

A method to quantify the quality of a laser beam coupled to a laser beam steering apparatus, the method comprising:

• performing a laser melt pattern to include:
• a number of scans wherein energy is pulsed at a known frequency for a known duration and as a scanner is commanded to move at a constant velocity;
• and
• imaging a top surface of a metal alloy plate at 50× magnification or greater after melting.

A computer-implemented method of laser powder bed fusion additive manufacturing of parts, the method comprising:

• using a number of processors to perform the steps of:
• converting a 3D geometry for a part into a number of 2D layers, wherein the 2D layers contain information about the 3D geometry;
• specifying a number of laser scan parameters according to preexisting empirical melt pool data for a specified build material;
• specifying laser energy levels according to unique characteristics of a specific powder bed fusion machine;
• and
• controlling a laser and laser beam steering in the specific powder bed fusion machine according to the specified laser scan parameters and specified laser energy levels to additively manufacture the part from the specified build material.