Measurement Science for Optimized Machining Processes

This project provides measurement science development and standardization to meet industry need for optimized machining of technology-intensive complex products made with non-conventional materials. NIST will combine industrially-practical sensor technologies with high-speed multispectral optical sensing for validation and implementation of process measurement methods in a practical manufacturing environment. Through the establishment of a public private consortium, NIST will ensure (1) alignment of results with industrial need, (2) dissemination of results to industry, and (3) completion of NIST contributions to achieve end-user impact.

To develop and deploy measurement science to enable optimized machining of technology-intensive complex products made of non-conventional materials through combined application of validated process models, verified practical in-process measurement methods, and advanced optimization methods by 2014.

To enable optimized machining of technology-intensive complex products made of non-conventional materials, U.S. manufacturers need current machining processes to evolve into smart machining processes that can know, communicate, and optimize their performance.  Current practice at small, medium, and large manufacturers explores machining process performance through costly and time-consuming empirical development of process recipes based on specially designed experiments as well as post-process product inspection and process data analysis. Current standards for machining performance provide methods to empirically determine conservative processing windows that yield acceptable performance for a single combination of cutting tool and product material, where a process window consists of allowable ranges of controllable process variables. To progress from the current state of practice, manufacturers need the capability to (1) predict process windows based on generalized physics-based models, (2) assess process performance in-process to monitor and adapt process variables in response to changing processing conditions, and (3) optimize process performance by dynamically adjusting allowable process windows in response to practical in-process measurements of processing conditions. Measurement science developed and disseminated through this project will enable industry partners to overcome barriers to optimized smart machining processes by improving: (1) the fundamental basis for physics-based modeling of machining through measurement methods and reference data sets for machining tool temperature distributions and mechanical material response to cutting, (2) the practical basis for in-process measurement of process performance through correlation of practical measurements to fundamental measurements, and (3) standardized methods for process performance optimization.

This project will provide the measurement science to enable smart machining systems to know, communicate, and optimize their process performance.  A consortium will be formed with industry participants from small and large manufacturers who specialize in using non-conventional materials, equipment, and processes to ensure alignment with industrial smart machining process needs.  Using existing unique NIST facilities, the project will develop and disseminate a combination of state-of-the-art and practical measurement methods and reference data sets to the consortium and to broader audiences through technical publications.  These measurement methods and reference data sets will include (a) precise tool temperature and material flow for high-priority non-conventional materials (e.g., new titanium alloys, nickel-based superalloys, and composites) using unique NIST capabilities in combination with (b) practical methods for measuring machining process behavior.  NIST will develop and disseminate practical methods and systems for optimization of machining process performance based on these measurement methods and reference data sets. The optimization and measurement methods and systems will be (1) developed at NIST with consortium-provided input, (2) documented in draft form at NIST and released to the consortium, (3) revised based on consortium feedback and approved by the consortium, (4) implemented at NIST and validated based on unique NIST capabilities, and (5) verified through implementation at consortium facilities. The measurement methods, data sets, optimization methods and algorithms and optimized smart machining process systems will be disseminated as technical publications and provided to appropriate standards bodies as technical contributions.

• [Output] NIST has documented and demonstrated a measurement method for tool temperature using the MADMACS system in comparison to a practical embedded thermocouple measurement with matching results and quantifiable measurement uncertainty (NISTIR 7650).  The thermal measurements have been favorably compared to machining simulations using measured dynamic material response from the unique NIST pulse-heated Kolsky bar apparatus.
  
• [Outcome] NIST has demonstrated the feasibility of measuring mechanical material response during machining using digital image correlation of visible spectrum imaging in conjunction with an industrially practical dynamometer measurement.
  
• [Impact] In addition to technical publications documenting the above accomplishments, results have been disseminated through a website with downloadable videos that more fully capture the technical results. In the past 5 months alone (Jan 2011 to May 2011) the page has been viewed over 325 times and videos have been downloaded over 310 times.

This project’s technical area draws extensively from standards focused on other technical areas, including materials, equipment, tooling, quality, and control systems. The project team will contribute fundamental and practical measurement methods for machining process performance and corresponding in-process monitoring and optimization methods through ASME B5 TC94 (Cutting Tools) and through the US TAG to ISO/TC29/SC2 (High Speed Steel Cutting Tools and Their Attachments).    NIST is well positioned to play a leading role in these activities.