Abstract: Mechanical properties of materials fabricated with additive manufacturing process are determined through optical monitoring in real time. A plasma generated in a zone where a laser interacts with deposited material is monitored using optical emission spectroscopy to generate one or more plasma spectral lines. The emission lines are analyzed to determine the hardness, micro-hardness, yield/residual stress, tensile strength, or other mechanical characteristics of the material. The composition may be an alloy such as an aluminum-magnesium alloy, including 7000 series aluminum alloys. The mechanical property may be derived from a change in a ratio of the plasma spectral lines, including a change in a ratio of ionic and neutral magnesium (Mg) associated with a 7000 series aluminum alloy. The apparatus and methods are extendable to other alloys and compositions.

Abstract: Direct metal deposition (DMD) is used to fabricate knife edges with extended service life. A metal alloy powder is deposited along a blank and melted with a laser beam so that the powder solidifies into a strip of material having a hardness and/or wear resistance greater than that of the starting material. The piece is then finished to produce a sharp edge in the solidified material. The powder may be melted while it is being deposited, or it may be melted after being deposited. A slot or groove may be formed in the blank with the metal alloy powder being deposited into the slot or groove. A hardened steel alloy powder is deposited onto a mild steel blank. For example, a tool steel or vanadium steel powder may be deposited onto a 1018 steel blank. An invention line-beam nozzle may be used for deposition and/or powder melting.

Abstract: An additive manufacturing process is monitored, in situ, using optical emission spectroscopy to analyze the composition, phase transformation or manufacturing defects. The system or method may include an analysis of contours of the plasma line intensity, or pre-processing of the plasma spectral line including signal-to-noise ratio analysis, baseline removal, line identification, line de-convolution and fitting. Improvements may additionally involve consideration of plasma parameters such as plasma spectral line intensity, line ratio, plasma temperature and electron density using high-resolution optical emission spectroscopy in both visible and ultraviolet regions. Parameters of the plasma may be determined using an intensity ratio of the ions or atoms emission lines, a FWHM of the line profile for electron density estimation, or a Boltzmann plot for plasma temperature estimation. One or more techniques may be used to monitor when there is a lack of deposition.

Abstract: An additive manufacturing process is monitored, in situ, using optical emission spectroscopy to analyze the composition, phase transformation or manufacturing defects. The system or method may include an analysis of contours of the plasma line intensity, or pre-processing of the plasma spectral line including signal-to-noise ratio analysis, baseline removal, line identification, line de-convolution and fitting. Improvements may additionally involve consideration of plasma parameters such as plasma spectral line intensity, line ratio, plasma temperature and electron density using high-resolution optical emission spectroscopy in both visible and ultraviolet regions. Parameters of the plasma may be determined using an intensity ratio of the ions or atoms emission lines, a FWHM of the line profile for electron density estimation, or a Boltzmann plot for plasma temperature estimation. One or more techniques may be used to monitor when there is a lack of deposition.

Abstract: A direct metal deposition (DMD) process is stabilized by monitoring the temperature and the shape of the melt pool during deposition, applying a recursive least square (RLS) model estimation algorithm to adaptively identify process characteristics in accordance with the temperature and the shape of the melt pool, and delivering the process characteristics to a generalized predictive controller with input constraints to control the process. The process may be controlled by adjusting laser power or by adjusting the speed of the movement of the laser. In the preferred embodiment the temperature is monitored using a two-color pyrometer, and the shape of the melt pool is monitored by detecting the edge of the melt pool with a camera and/or photodetector.

Abstract: A method of monitoring a welding process, comprising detecting a selected portion of a light spectrum of plasma plume of a fusion welding process with a photo detector, processing the detected portion of the spectrum, comparing the detected portion of the spectrum with an expected spectra to determine whether a weld is acceptable, providing a signal to a welder control, and adjusting the weld process based on the signal.

Abstract: Direct metal deposition (DMD) is used to fabricate knife edges with extended service life. A metal alloy powder is deposited along a blank and melted with a laser beam so that the powder solidifies into a strip of material having a hardness and/or wear resistance greater than that of the starting material. The piece is then finished to produce a sharp edge in the solidified material. The powder may be melted while it is being deposited, or it may be melted after being deposited. A slot or groove may be formed in the blank with the metal alloy powder being deposited into the slot or groove. A hardened steel alloy powder is deposited onto a mild steel blank. For example, a tool steel or vanadium steel powder may be deposited onto a 1018 steel blank. An invention line-beam nozzle may be used for deposition and/or powder melting.

Abstract: A direct-metal deposition (DMD) processing stage and a 5DOF (degree of freedom) dry micro-EDM (mEDM) stage are integrated to provide the submicron scale resolution necessary for the ultra-precision processing of work pieces. The DMD processing stage includes optical feedback for dimensional control utilizing a high-power, fiber-coupled diode laser with fast response time and small beam parameter product. The electrical discharge machining (EDM) stage is a dry EDM stage using an inert gas with appropriate dielectric properties to perform the surface finishing operations. The system further includes one or more surface treatment operations to obtain a desired level of surface hardness or wear resistance and/or to minimize the distortion induced in treating the surface.

Abstract: Disclosed is the design and working principle of a welding monitoring system that can monitor the spectra of zinc and iron in the plasma generated during a welding process involving zinc-coated steel. The monitoring system is capable of monitoring multiple parameters, including spectral line intensity, electron temperature, and ratio of zinc and iron composition in the plasma. The results can then be used individually or in combination to predict resulting weld quality and generate appropriate feedback control signals.

Abstract: Direct metal deposition (DMD) is used to fabricate knife edges with extended service life. A metal alloy powder is deposited along a blank and melted with a laser beam so that the powder solidifies into a strip of material having a hardness and/or wear resistance greater than that of the starting material. The piece is then finished to produce a sharp edge in the solidified material. The powder may be melted while it is being deposited, or it may be melted after being deposited. A slot or groove may be formed in the blank with the metal alloy powder being deposited into the slot or groove. A hardened steel alloy powder is deposited onto a mild steel blank. For example, a tool steel or vanadium steel powder may be deposited onto a 1018 steel blank. An invention line-beam nozzle may be used for deposition and/or powder melting.

Abstract: The present invention incorporates one or more diode lasers for the high-power CO2 or Nd-YAG lasers currently used in closed-loop DMD systems. Being semiconductor-based, such devices are almost instantaneously responsive to the electrical input. As such, a DMD system driven by a diode laser according to the invention provides a much faster response compared to other sources. The faster response time, in turn, provides for enhanced dimensional control and capability to produce intricate components with better dimensional accuracy.

Abstract: A method of monitoring a welding process, comprising detecting a selected portion of a light spectrum of plasma plume of a fusion welding process with a photo detector, processing the detected portion of the spectrum, comparing the detected portion of the spectrum with an expected spectra to determine whether a weld is acceptable, providing a signal to a welder control, and adjusting the weld process based on the signal.

Abstract: A direct metal deposition (DMD) process is stabilized by monitoring the temperature and the shape of the melt pool during deposition, applying a recursive least square (RLS) model estimation algorithm to adaptively identify process characteristics in accordance with the temperature and the shape of the melt pool, and delivering the process characteristics to a generalized predictive controller with input constraints to control the process. The process may be controlled by adjusting laser power or by adjusting the speed of the movement of the laser. In the preferred embodiment the temperature is monitored using a two-color pyrometer, and the shape of the melt pool is monitored by detecting the edge of the melt pool with a camera and/or photodetector.

Abstract: A thermally conductive, wear-resistant alloy is particularly suited to cladding aluminum engine head valve seats. In the preferred embodiments, the alloys are metallurgically compatible with the cast Al—Si alloy used for the engine head. Three alternative embodiments are disclosed, namely, copper-based alloys; aluminum silicon-based alloys; and two-layer systems.

Abstract: A linear model based generalized predictive control system controls the molten pool temperature during a Direct Metal Deposition (DMD) process. The molten pool temperature is monitored by a two-color pyrometer. A single-input single-output linear system that describes the dynamics between the molten pool temperature and the laser power is identified and validated. The incremental generalized predictive control algorithm with Kalman filter estimation is used to control the molten pool temperature.

Abstract: Disclosed is the design and working principle of a welding monitoring system that can monitor the spectra of zinc and iron in the plasma generated during a welding process involving zinc-coated steel. The monitoring system is capable of monitoring multiple parameters, including spectral line intensity, electron temperature, and ratio of zinc and iron composition in the plasma. The results can then be used individually or in combination to predict resulting weld quality and generate appropriate feedback control signals.

Abstract: In a direct-metal deposition (DMD) process used to deposit successive layers in accordance with instructions from a CAD/CAM program, the laser beam, or an additional beam, is deployed as a localized heat treatment tool instead of a deposition tool. The use of laser energy during the process can minimize, if not eliminate, the periodic heat treatments now required for stress alleviation, thereby compressing the DMD fabrication cycle. In the preferred embodiment, every deposition run may be followed by a dry (i.e., without powder) run of one or more intensities to manipulate the stress magnitude and location. Since it is well known that residual stress is a function of cooling rate, a plurality of laser beams may alternatively be used to control the cooling rate of the deposited layer. Examples of stress reduction using H13 tool steel are provided.

Abstract: A direct-metal deposition (DMD) processing stage and a 5DOF (degree of freedom) dry micro-EDM (mEDM) stage are integrated to provide the submicron scale resolution necessary for the ultra-precision processing of work pieces. The DMD processing stage includes optical feedback for dimensional control utilizing a high-power, fiber-coupled diode laser with fast response time and small beam parameter product. The electrical discharge machining (EDM) stage is a dry EDM stage using an inert gas with appropriate dielectric properties to perform the surface finishing operations. The system further includes one or more surface treatment operations to obtain a desired level of surface hardness or wear resistance and/or to minimize the distortion induced in treating the surface.

Abstract: Manufacturing tools having a base and a working surface, such as trim steels, flange steels and die inserts, are formed by fabricating or casting a substrate out of a relatively ductile, low wear-resistant metal and forming the working surfaces such as cutting edges, flanging surfaces, die surfaces and die inserts by depositing layers of relatively hard, wear-resistant materials to the substrate by closed-loop direct-metal deposition or laser cladding. A multi-axis numerically controlled robot may be used to position and move a beam and deposition material over large substrates in forming such tooling.

Abstract: A laser-aided, direct metal deposition (DMD) fabrication process is used for dies and molds having integrated sensors for monitoring and controlling characteristics that determine the quality of an article being processed. A method of fabricating such devices, as well as the “smart” devices themselves are disclosed. A system of manufacturing articles uses smart dies or smart molds so that various characteristics that affect the quality of the finished article are monitored during the die-forming or injection-molding process. The sensors, which are an integral part of the product-shaping devices, include simple thermocouples for measuring the temperature in various locations, as well as piezoelectric sensors and strain gages to monitor the build-up of stress and strain history caused by fluctuations in temperature during the fabrication process.