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.

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.

Predicting the Effect of Vibration on Machining Distortion in High-Speed Milling Aerospace Monolithic Components

2010 ◽  
Author(s):  
Q. H. Song ◽  
X. Ai ◽  
Z. Q. Liu
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Coordinate Measuring Machine ◽  
Stable Case ◽  
Machining Distortion ◽  
Stable Conditions ◽  
Unstable Case ◽  
Measuring Machine ◽  
The Stability ◽  
Monolithic Components

Based on the stability lobe diagram of two degrees of freedom milling system obtained by using the numerical method, two kinds of cutting conditions (stable and unstable) are selected to perform the cutting tests of aeronautical monolithic components. Cutting distortion and secular distortion are measured and analyzed by using the MISTRAL 775 coordinate measuring machine (CMM), respectively. Influences of chatter on machining distortion are investigated. It is shown that, both machining distortion and secular distortion are smaller in stable case; in unstable case, machining distortion is also smaller, while secular distortion is very large, and torsion occurs in the workpiece end with larger box. Therefore, workpiece need be machined in stable conditions for subsequent assembly work, especially aeronautical monolithic components.

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.

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).

Study on Generation and Optimization Methodology of On-Machine Measurement Schemes for Multi-Axis CNC Machine Tool

2017 ◽  
Author(s):  
Zhao Bohan ◽  
Gao Feng ◽  
Li Yan ◽  
Zhang Dongya ◽  
Zhang Wanli ◽  
...  
Keyword(s):  
Machine Tool ◽  
Large Scale ◽  
Coordinate Measuring Machine ◽  
Measuring Error ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Real Time Control ◽  
Position Detection ◽  
Volumetric Errors ◽  
Measuring Machine

Quality Control (QC) is one of the most important phases in the production process. In tradition, the workpiece must be inspected for dimension and shape errors in the QC lab or Coordinate Measuring Machine (CMM) after being machined, which is time-consuming and labor-intensive, especially for large scale parts. Thus the only practical way to do that is to migrate the critical primary inspection operations upstream from the QC lab or CMM to the production floor, and that’s what On-Machine Measurement (OMM) does. OMM technology can inspect the workpiece on its operating station by motion control and the position detection function of CNC machine tool, by which the measuring error caused by the misalignment between measuring datum and manufacturing datum can be avoided accurately. Therefore, it is a feasible way to achieve the real-time control of the manufacturing process and improve the manufacturing accuracy and efficiency. The servo axes of multi-axis CNC machine tool might be redundant for being used in OMM, which will result in that one measurement task could be done by different servo motion schemes. In addition, the map between the machine accuracy and measuring accuracy has not been found out previously. Thus, how to determine metering schemes to measure a workpiece with high accuracy and efficiency is one of the most important problems and also a hotspot for everybody. To solve this problem, a generation method of task-oriented OMM scheme is proposed. Utilizing multi-body system theory and transformation of homogeneous coordinates, a function relationship between the geometrical characteristic of workpiece as independent variables and motions of machine tool as dependent variables is established. All possible metering schemes are obtained by analyzing the solution of functional equation. Then the performance of measurement scheme can be evaluated by comparing the measuring errors of each scheme after building a mapping relationship between the machine tool volumetric errors and measuring errors. In the end, a case study was accomplished, and the correctness and efficiency of the methodology has been verified.

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.

scholarly journals A “Double Accuracy Theory” and Experimental Research on Precision Grinding

2020 ◽  
Vol 10 (6) ◽  
pp. 2030
Author(s):  
Lai Hu ◽  
Yipeng Li ◽  
Jun Zha ◽  
Yaolong Chen
Keyword(s):  
High Speed ◽  
Coordinate Measuring Machine ◽  
Precision Grinding ◽  
Machined Parts ◽  
Accuracy Theory ◽  
Machine Theory ◽  
Ultra Precision ◽  
Measuring Machine ◽  
Grinding Machine ◽  
Multi Body

In the global machining industry, ultra-precision/ultra-high-speed machining has become a challenge, and its requirements are getting higher and higher. The challenge of precision grinding lies in the difficulty in ensuring the various dimensions and geometric accuracy of the final machined parts. This paper mainly uses the theory of a multi-body system to propose a “double accuracy” theory of manufacturing and measurement. Firstly, the grinding theory with an accuracy of 0.1 μm and the precision three-coordinate measuring machine theory with an accuracy of 0.3 μm are deduced. Secondly, the two theories are analyzed. Aiming to better explain the practicability of the “double accuracy” theory, a batch of motorized spindle parts is processed by a grinding machine. Then the precision three-coordinate measuring machine is used to measure the shape and position tolerances such as the roundness, the squareness, the flatness, and the coaxiality. The results show that the reached roundness of part A and B is 5 μm and 0.5 μm, the squareness is 3 μm and 4.5 μm, and the coaxiality tolerance is 1.2 μm, respectively.

On a Methodology for Establishing the Machine Tool System Requirements for High-Speed/High-Throughput Machining

1985 ◽  
Vol 107 (4) ◽  
pp. 316-324 ◽  
Author(s):  
R. Komanduri ◽  
J. McGee ◽  
R. A. Thompson ◽  
J. P. Covy ◽  
F. J. Truncale ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Machine Tool ◽  
High Throughput ◽  
Machine Tools ◽  
High Speed ◽  
Cutting Speed ◽  
Tool Material ◽  
Higher Power ◽  
Increase Productivity ◽  
System Requirements

This paper presents a methodology for determining the machine tool system requirements for high-speed machining (HSM)/high-throughput machining (HTM). Both technological and economic factors should be considered in the formulation of the model for determining machine tool system requirements. The HSM function model is given here in the form of ICAM-defined (IDEFo) charts with corresponding text. For machining most aluminum alloys, the maximum cutting speed is not limited by tool life, and the technology for high-speed machine tools (spindles, table drives, controls, chip management, and other features) exists today. Therefore, HSM of aluminum alloys can be implemented. Selection of a suitable HSM system involves detailed technological analysis and economic justification for a given part-family production configuration. The recent introduction of Si3N4 based tool materials has enabled significantly higher cutting speeds (up to 1524 mpm or 5000 sfpm) in the machining of gray cast iron. However, the machine tools using this type of tool material should be more rigid and capable of higher power, higher speed, and faster feed in order to increase productivity and reduce manufacturing costs. In the machining of the difficult-to-machine materials (e.g., superalloys), the cutting speed is still limited by tool wear. Nevertheless, a high-throughput machining (HTM) strategy is pertinent for this application.

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