Laine Mears Clemson University, Clemson, SC 29634 John T. Roth Penn State Erie, Erie, PA 16563 Dragan Djurdjanovic University of Texas, Austin, TX 78713 Xiaoping Yang Cummins Inc., Columbus, IN 47202 Thomas Kurfess Clemson University, Clemson, SC 29634 Quality and Inspection of Machining Operations: CMM Integration to the Machine Tool Dimensional measurement feedback in manufacturing systems is critical in order to con- sistently produce quality parts. Considering this, methods and techniques by which to accomplish this feedback have been the focus of numerous studies in recent years. More- over, with the rapid advances in computing technology, the complexity and computational overhead that can be feasibly incorporated in any developed technique have dramatically improved. Thus, techniques that would have been impractical for implementation just a few years ago can now be realistically applied. This rapid growth has resulted in a wealth of new capabilities for improving part and process quality and reliability. In this paper, overviews of recent advances that apply to machining are presented. More spe- cifically, research publications pertaining to the use of coordinate measurement machines to improve the machining process are discussed. DOI: 10.1115/1.3184085 1 Introduction Dimensional measurement as a feedback method to the manu- facturing enterprise has traditionally lain in the realm of the long term, as metrology activities on thermally stabilized parts are car- ried out in a controlled temperature environment away from the manufacturing activity. Incorporating true dimensional feedback to the manufacturing process has necessitated a transition of the metrology activity from a highly controlled remote function to an environmentally robust measurement function tightly integrated to the manufacturing activity itself. Since measurement systems and their integration with machin- ing systems have evolved dramatically in recent years, the pri- mary focus of this paper is on the use of coordinate measuring machines CMMs in conjunction with machining. The primary research barriers to enabling this integration are highlighted in Fig. 1. These activities establish a framework of research progress that allows the identification of needs for the near future that will enable a transition of the metrology function to a more tightly integrated feedback solution for reducing manufacturing variation and improving process control. Recent work in these areas is cov- ered in this paper, leading to commentary and recommendations for future research needs. The remaining sections of this paper are subdivided into the following: • off-line CMM use • integration of the CMM with the machine tool • advances in sensing technology • inspection planning and efficiency • advanced controller feedback schemes • machine error compensation • on-line calibration • the use of simulation in measurement system planning Finally, conclusions are made with recommendations regarding immediate and long-term research needs with respect to address- ing issues of integration of the disparate measurement and ma- chining functions. 2 Measurement Assessments for the Quality Control of Machining Systems In their comprehensive review paper on machining process monitoring and control, Liang et al. address a number of part measurement systems for monitoring and process feedback. To that end, it is noted that vision systems and advanced image pro- cessing techniques, enabled by improved software capability, have become viable options for surface measurement metrology 1. In addition, specialized types of in-process gauging allow for dimen- sional measurement at the micron level. However, generalized di- mensional metrology, integrated to the machine tool, still needs to be addressed. While not initially integrated to the machine tool, the coordi- nate measuring machine has been in use for decades as a versatile high-precision offline measurement device. As such, the CMM has the capability of generating multiple types of measures using a single sensor head. Moreover, a multitude of measures can be made on a single program without manual intervention, making the CMM highly efficient and allowing for the evaluation of a greater percentage, or even 100%, of manufactured parts. Though “inspecting in” of quality is not condoned in this paper, research into approaches for maximum inspection ability is important. However, as stated by DeStefani 2, the benefits of measurement and machining integration must be well understood before we “invade the process.” The CMM’s versatility and efficiency has led to its more recent use as an on-line measurement device, particularly as an advanced feedback sensor for machining processes and their tooling. Con- sidering the number of advances that have recently been made in this area, this section will only present a brief review of some notable accomplishments. 2.1 Coordinate Measuring Machines. In general, the coor- dinate measuring machine is used to digitize a measured part for the purpose of inspection or model creation as in the reverse engineering process. A CMM has the capability of measuring in three dimensions, but is also widely used for two-dimensional planar or one-dimensional linear evaluations. The classical configuration of the machine is the Cartesian movable bridge de- Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received April 1, 2008; final manuscript received May 29, 2009; published online September 8, 2009. Review conducted by Kourosh Danai. Paper presented at the 2007 Interna- tional Conference on Manufacturing Science and Engineering MSEC 2007, At- lanta, GA, October 15–17, 2007. Journal of Manufacturing Science and Engineering OCTOBER 2009, Vol. 131 / 051006-1 Copyright © 2009 by ASME Downloaded 29 Jun 2012 to 146.6.84.42. Redistribution subject to ASME license or copyright; see http://www.asme.org/terms/Terms_Use.cfm