scholarly journals Traceability on Machine Tool Metrology: A Review

2017 ◽  
Author(s):  
Unai Mutilba ◽  
Eneko Gomez-Acedo ◽  
Gorka Kortaberria ◽  
Aitor Olarra ◽  
José Antonio Yagüe-Fabra
Keyword(s):  
Machine Tool ◽  
Manufacturing Process ◽  
Machine Tools ◽  
Nuclear Power ◽  
Measurement Data ◽  
Coordinate Measuring Machine ◽  
Manufacturing Processes ◽  
Scientific Objective ◽  
Measuring Process ◽  
Measuring Machine

Errors during manufacture of high value components are not acceptable nowadays in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power manufacture complex and accurate components that demand close measurements and fast feedback into manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They shall provide the possibility to measure the workpiece during or after the manufacturing process, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable for process control or product validation. Due to the similarity between a coordinate measuring machine and a machine tool, some of the methods applied for a correct assessment of uncertainty in coordinate measuring machines are adapted to the challenges of a machine tool. The scientific objective is to determine the uncertainty on a machine tool measurement and, in this way, convert it into a machine integrated traceable measuring process. This paper reviews the fundamentals of machine tool metrology.

A Technique for Enhancing Machine Tool Accuracy by Transferring the Metrology Reference From the Machine Tool to the Workpiece

2006 ◽  
Vol 129 (3) ◽  
pp. 636-643 ◽  
Author(s):  
Bethany A. Woody ◽  
K. Scott Smith ◽  
Robert J. Hocken ◽  
Jimmie A. Miller
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
High Speed ◽  
Large Scale ◽  
Thermal Environment ◽  
Coordinate Measuring Machine ◽  
Shop Floor ◽  
Finished Part ◽  
Measuring Machine ◽  
Monolithic Components

High-speed machining (HSM) has had a large impact on the design and fabrication of aerospace parts and HSM techniques have been used to improve the quality of conventionally machined parts as well. Initially, the trend toward HSM of monolithic parts was focused on small parts, where existing machine tools have sufficient precision to machine the required features. But, as the technology continues to progress, the scale of monolithic parts has continued to grow. However, the growth of such parts has become limited by the inability of existing machines to achieve the tolerances required for assembly due to the long-range accuracy and the thermal environment of most machine tools. Increasing part size without decreasing the tolerances using existing technology requires very large and very accurate machines in a tightly controlled thermal environment. As a result, new techniques are needed to precisely and accurately manufacture large scale monolithic components. Previous work has established the fiducial calibration system (FCS), a technique, which, for the first time provides a method that allows for the accuracy of a coordinate measuring machine (CMM) to be transferred to the shop floor. This paper addresses the range of applicability of the FCS, and provides a method to answer two fundamental questions. First, given a set of machines and fiducials, how much improvement in precision of the finished part can be expected? And second, given a desired precision of the finished part, what machines and fiducials are required? The achievable improvement in precision using the FCS depends on a number of factors including, but not limited to: the type of fiducial, the probing system on the machine and CMM, the time required to make a measurement, and the frequency of measurement. In this paper, the sensitivity of the method to such items is evaluated through an uncertainty analysis, and examples are given indicating how this analysis can be used in a variety of cases.

scholarly journals Adjustment of Axis Offset Errors during Reaming

2018 ◽  
Vol 885 ◽  
pp. 267-275
Author(s):  
Andreas Bretz ◽  
Felix Geßner ◽  
Tugrul Öztürk ◽  
Christian Rinn ◽  
Eberhard Abele
Keyword(s):  
Machine Tool ◽  
Motion Control ◽  
Coordinate Measuring Machine ◽  
Measured Data ◽  
Manufacturing Processes ◽  
High Quality ◽  
Need To Evaluate ◽  
Measuring Machine ◽  
Axis Offset

The reaming process normally takes place at the end of manufacturing processes when a lot of value has already been added. Therefore, reaming plays an important role for the quality of the finished product. To achieve this high quality, the occurring process errors caused by the machine tool and the reamer or incorrect workpiece handling have to be minimised. Measured data of the reaming process allow the prediction of occurring process errors without the need to evaluate the bore with a coordinate measuring machine. However, manufacturing is already completed at this stage and the correction of errors is either no longer possible or very costly. This paper presents an approach to detect axis offsets within the entry phase of the reamer by analysing the process forces. The calculated offset is then compensated by adjusting the nominal value of the motion control.

A Method for Measuring the Systematic Errors of CNC-Machine Tools

2012 ◽  
Vol 271-272 ◽  
pp. 1770-1775
Author(s):  
Qi Gao
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Tool Path ◽  
Laser Interferometer ◽  
Coordinate Measuring Machine ◽  
Calibration Method ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Measuring Machine ◽  
Error Calibration

The method used for measurement and calibration of machine tool errors should be general and efficient. With this method, the machine tool status can be completely identified and its accuracy can be enhanced by software error compensation. The point compensation method can be used as a means for modifying the nominal tool path and on-machine inspection where the machine tool is used as a coordinate measuring machine. The validity of the error calibration method proposed in this' paper was shown using a vertical 3-axis CNC machine with a laser interferometer and a ball bar technique.

Measurement of Movement Error and its Compensation for 6-DOF Parallel Mechanism Worktable

2012 ◽  
Vol 523-524 ◽  
pp. 463-468 ◽  
Author(s):  
Yuan Rui Zhang ◽  
Jiang Zhu ◽  
Tomohisa Tanaka ◽  
Yoshio Saito
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Parallel Mechanism ◽  
Coordinate Measuring Machine ◽  
Geometric Error ◽  
Degree Of Freedom ◽  
Positioning Error ◽  
Uncertainty Factor ◽  
Movement Error ◽  
Measuring Machine

In this study, a small, 6-DOF (degree of freedom) parallel mechanism worktable for machine tool was developed. There are a lot of factors that affect the positioning error and the accuracy of the machine tools. The uncertainty in position is mainly due to the rigidity of the structure, the geometric error of parts and assembly errors. It is very difficult to estimate the assembly errors and the link parameter of each part. In this paper, the uncertainty factor in positioning of the worktable was investigated and compensated based on measurement of movement error by using coordinate measuring machine (CMM).

Accuracy Analysis of Machining Process Using a Spindle Probe and a CMM to Reduce the Scrap

2005 ◽  
Author(s):  
Yongjin Kwon
Keyword(s):  
Machine Tool ◽  
Measurement Data ◽  
Coordinate Measuring Machine ◽  
Machining Process ◽  
Inspection Time ◽  
Cnc Machine ◽  
Part Quality ◽  
Post Process ◽  
Measuring Machine ◽  
Touch Probe

In-process part inspection using a spindle touch probe has gained a significant importance, mainly because parts can remain on the machine without disrupting the machine setup while inspection is being conducted. This practice leads to a shorter inspection time, improved part accuracies, and reduction of scraps. Recently, intense domestic and international competition has put more importance on part quality in terms of producing parts right the first time and maintaining the consistent quality standards. A literature review revealed that a comparative analysis between in-process gauging using a touch probe and post-process inspection using a coordinate measuring machine (CMM) to ascertain part quality has not been adequately studied. Therefore, there is a need for a study to measure the characteristics of the two inspection techniques. To address the problem, cutting experiments were conducted and measurement data were analyzed using a state-of-the-art CNC machine, a CMM, a touch probe, and a high-precision ballbar system. The experimental data show that machined features and touch probe measurements are affected by the inherent shortcomings in machine tool structure, suggesting a machine tool capability analysis be undertaken in tune with the required tolerance specifications prior to machining operations, rather than solely relying on the touch probe inspection for part quality assessment.

scholarly journals Study of Machining of Gears with Regular and Modified Outline Using CNC Machine Tools

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2913
Author(s):  
Rafał Gołębski ◽  
Piotr Boral
Keyword(s):  
Machine Tools ◽  
Coordinate Measuring Machine ◽  
Optical Microscope ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Milling ◽  
Cnc Machine ◽  
Cylindrical Gears ◽  
Measuring Machine ◽  
Five Axis

Classic methods of machining cylindrical gears, such as hobbing or circumferential chiseling, require the use of expensive special machine tools and dedicated tools, which makes production unprofitable, especially in small and medium series. Today, special attention is paid to the technology of making gears using universal CNC (computer numerical control) machine tools with standard cheap tools. On the basis of the presented mathematical model, a software was developed to generate a code that controls a machine tool for machining cylindrical gears with straight and modified tooth line using the multipass method. Made of steel 16MnCr5, gear wheels with a straight tooth line and with a longitudinally modified convex-convex tooth line were machined on a five-axis CNC milling machine DMG MORI CMX50U, using solid carbide milling cutters (cylindrical and ball end) for processing. The manufactured gears were inspected on a ZEISS coordinate measuring machine, using the software Gear Pro Involute. The conformity of the outline, the tooth line, and the gear pitch were assessed. The side surfaces of the teeth after machining according to the planned strategy were also assessed; the tests were carried out using the optical microscope Alicona Infinite Focus G5 and the contact profilographometer Taylor Hobson, Talysurf 120. The presented method is able to provide a very good quality of machined gears in relation to competing methods. The great advantage of this method is the use of a tool that is not geometrically related to the shape of the machined gear profile, which allows the production of cylindrical gears with a tooth and profile line other than the standard.

Evaluation of Parts Produced by a Novel Additive Manufacturing Process

2013 ◽  
Vol 315 ◽  
pp. 63-67 ◽  
Author(s):  
Muhammad Fahad ◽  
Neil Hopkinson
Keyword(s):  
Additive Manufacturing ◽  
Rapid Prototyping ◽  
Manufacturing Process ◽  
High Speed ◽  
Three Dimensional ◽  
Coordinate Measuring Machine ◽  
Layer By Layer ◽  
Nylon 12 ◽  
Measuring Machine ◽  
End Use

Rapid prototyping refers to building three dimensional parts in a tool-less, layer by layer manner using the CAD geometry of the part. Additive Manufacturing (AM) is the name given to the application of rapid prototyping technologies to produce functional, end use items. Since AM is relatively new area of manufacturing processes, various processes are being developed and analyzed for their performance (mainly speed and accuracy). This paper deals with the design of a new benchmark part to analyze the flatness of parts produced on High Speed Sintering (HSS) which is a novel Additive Manufacturing process and is currently being developed at Loughborough University. The designed benchmark part comprised of various features such as cubes, holes, cylinders, spheres and cones on a flat base and the build material used for these parts was nylon 12 powder. Flatness and curvature of the base of these parts were measured using a coordinate measuring machine (CMM) and the results are discussed in relation to the operating parameters of the process.The result show changes in the flatness of part with the depth of part in the bed which is attributed to the thermal gradient within the build envelope during build.

Table-Based Volumetric Error Compensation of Large Five-Axis Machine Tools

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Jennifer Creamer ◽  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers ◽  
Philip L. Freeman ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Machine Tools ◽  
Data Gathering ◽  
Measurement Data ◽  
Geometric Error ◽  
Compensation Method ◽  
Geometric Errors ◽  
Simultaneous Generation ◽  
Five Axis

This paper presents a geometric error compensation method for large five-axis machine tools. Compared to smaller machine tools, the longer axis travels and bigger structures of a large machine tool make them more susceptible to complicated, position-dependent geometric errors. The compensation method presented in this paper uses tool tip measurements recorded throughout the axis space to construct an explicit model of a machine tool's geometric errors from which a corresponding set of compensation tables are constructed. The measurements are taken using a laser tracker, permitting rapid error data gathering at most locations in the axis space. Two position-dependent geometric error models are considered in this paper. The first model utilizes a six degree-of-freedom kinematic error description at each axis. The second model is motivated by the structure of table compensation solutions and describes geometric errors as small perturbations to the axis commands. The parameters of both models are identified from the measurement data using a maximum likelihood estimator. Compensation tables are generated by projecting the error model onto the compensation space created by the compensation tables available in the machine tool controller. The first model provides a more intuitive accounting of simple geometric errors than the second; however, it also increases the complexity of projecting the errors onto compensation tables. Experimental results on a commercial five-axis machine tool are presented and analyzed. Despite significant differences in the machine tool error descriptions, both methods produce similar results, within the repeatability of the machine tool. Reasons for this result are discussed. Analysis of the models and compensation tables reveals significant complicated, and unexpected kinematic behavior in the experimental machine tool. A particular strength of the proposed methodology is the simultaneous generation of a complete set of compensation tables that accurately captures complicated kinematic errors independent of whether they arise from expected and unexpected sources.

Evaluation of Actual Geometric Tolerances Using Coordinate Measuring Machine Data

1989 ◽  
Author(s):  
W. H. ElMaraghy ◽  
Z. Wu ◽  
H. A. ElMaraghy
Keyword(s):  
Three Dimensional ◽  
Measurement Data ◽  
Simulated Data ◽  
Coordinate Measuring Machine ◽  
Optimization Techniques ◽  
Test Cases ◽  
Tolerance Zone ◽  
Geometric Tolerances ◽  
Measuring Machine

Abstract This paper focuses on the development of a procedure and algorithms for the systematic comparison of geometric variations of measured features with their specified geometric tolerances. To automate the inspection of mechanical parts, it is necessary to analyze the measurement data captured by coordinate measuring machines (CMM) in order to detect out-of-tolerance conditions. A procedure for determining the geometric tolerances from the measured three dimensional coordinates on the surface of a cylindrical feature is presented. This procedure follows the definitions of the geometric tolerances used in the current Standards, and is capable of determining the value of each geometric tolerance from the composite 3-D data. The developed algorithms adopt the minimum tolerance zone criterion. Nonlinear numerical optimization techniques are used to fit the data to the minimum tolerance zone. Two test cases are given in the paper which demonstrate the successful determination of geometric tolerances from given simulated data.

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