Other

The P.o.m. Group

University of Michigan

Dm3d Technology, LLC

Precision Optical Manufacturing (pom)

Mazumder, Jyoti

Jyoti Mazumder

Timothy Walter Skszek

Lijun Song

Joseph K Kelly

Dwight Morgan

Ashish K Dasgupta

Justin L Koch

Albert J Shih

Bhaskar Dutta

Jun Ni

Joohyun Choi

Mikhail Vasilyev

Harshad Natu

Michael Bembenek

Seung H Lee

W Swenson

Matthew Lowney

Frank A DiPietro

Justin Koch

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.

Method of manufacturing of cutting knives using direct metal deposition

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.

Smart additive manufacturing system (SAMS)

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.

Real-time implementation of generalized predictive algorithm for direct metal deposition (DMD) process control

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.

Monitoring of a welding process

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.

High-speed, ultra precision manufacturing station that combines direct metal deposition and EDM

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.

Optical sensor for quality monitoring of a welding process

The present invention incorporates one or more diode lasers for the high-power COor 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.

Direct metal deposition apparatus utilizing rapid-response diode laser source

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&#x2014;Si alloy used for the engine head. Three alternative embodiments are disclosed, namely, copper-based alloys; aluminum silicon-based alloys; and two-layer systems.

Wear-resistant alloys particularly suited to aluminum-engine head-valve seats

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.

Tailoring residual stress and hardness during direct metal deposition

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.

Method of fabricating composite tooling using closed-loop direct-metal deposition

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. This information is transmitted to a computer, where it is analyzed or compared with standardized histories obtained either through calibration experiments or through theoretical calculations.

Production of smart dies and molds using direct metal deposition

Multiple criteria are monitored and controlled to enhance the success of direct-metal deposition, including greater control over factors such as deposit layer height/thickness, sub-harmonic vibration, contour path shape, powder mass flow, and deposition speed, and stress accumulation. Sensors are used to monitor some or all of the following parameters during the deposition process: deposit height, width, temperature, and residual stress. A predetermined limit with respect to the yield strength of the material is preferably set. If the stress exceeds that limit sensors will automatically introduce one or more remedial measures, the priority of which is established using a look-up table generated in accordance with prior experimental knowledge. To control temperature induced distortion and stress, an infrared temperature detector may be used in conjunction with a controller to reduce temperature, increase speed and decreased power for purpose of stress management.

Closed-loop, rapid manufacturing of three-dimensional components using direct metal deposition

Direct metal deposition (DMD&trade;), preferably closed-loop DMD, is used to deposit machine-readable codes onto articles with high accuracy, directly from digital data. In different embodiments, the substrate/layer combination may be tailored for improved wear resistance, thermal conductivity, density/hardness, corrosion and/or resistance to corrosion, oxidation or other environmental conditions. Alternatively, the layer(s) of material may be tailored to have specific properties custom-tailored to suit the application. To enhance throughput, code features may be fabricated using a robotic closed-loop DMD arrangement. In concert with the improvements made possible through the tailored outer layer(s), the method may further include the step of incorporating a third dimension by controlling the height of the deposit line in addition to the width.

Machine-readable code generation using direct metal deposition

Continuously adjustable focusing optics for use in laser-assisted direct metal deposition (DMD&trade;) processes provide for adaptive deposition width to increase deposition rate while maintaining the dimensional tolerances. The focusing optics and method may be adapted for variable deposition road width under closed-loop feedback, so that complicated features may be fabricated with close tolerance, stress and microstructure control to improve the lead-time and design flexibility. The preferred embodiment uses adaptive mirror arrangements and beam movement for variable deposition width and geometry. Conceptually, an infinite number of mirror arrangements can be made to adapt to a particular deposit shape.

Focusing optics for adaptive deposition in rapid manufacturing

A system and method for remotely controlling the fabrication of a product at a local manufacturing site. The product is fabricated by depositing successive material layers through a local laser-aided, feedback-controlled, direct material deposition system. The system is equipped with strain gages, optical sensors and acoustic sensors generating signals which are processed in a local computer to determine the temperature, strain and residual stress of the product during fabrication. A feedback controller interfaces with the local computer and with a numerical controller and operates to control the material deposition process. The local numerical controller receives a file of a digitized description of the product from the remote computer, preferably via an Internet connection. The local computer sends temperature, strain and stress data to the remote computer, enabling a designer interfacing with the remote computer to monitor, control and modify the fabrication of the product in real time on line. The fabrication process is recorded by video or television camera and the shown in real-time on a screen display connected to the remote computer.

Growing community of inventors

Ann Arbor, MI, United States of America

Jyoti Mazumder