Loughborough University
Leicestershire, UK
LE11 3TU
+44 (0)1509 263171
Loughborough University

Loughborough University Institutional Repository

Please use this identifier to cite or link to this item: https://dspace.lboro.ac.uk/2134/11770

Title: Accuracy testing of coordinate measuring machines
Authors: Singh, Jagpal
Issue Date: 2006
Publisher: © J. Singh
Abstract: The proliferation of the bridge type Coordinate Measuring Machine (CMM) within the manufacturing environment has resulted in it being a core and important tool in the manufacturing cycle. In many circumstances, CMM's provide excellent measurement services, but when manufacturing tolerances are small, then detailed understanding of CMM error sources is ideally required, to maximise the confidence in the measurement data Multi-axis measurement arms (MMAs) are a unique subset of Coordinate Measuring Machines (CMMs). They incorporate a large number of degrees of freedom and compact design based on multi-element arm construction, which provides tremendous versatility of movement and access around an object being measured. The consequences of the flexibility of MMAs is that the volumetric accuracy and repeatability specifications can be substantially inferior to those of more traditionally designed CMMs. Various CMM error sources have been previously identified, evaluated and quantified, on a machine by machine basis. Many of these sources (parametric errors for instance) are systematic and considered to be minimised from the measurement system via verification procedures and the generation of software based error maps (applying compensations). However a number of error elements still occur which need to be considered. The research reported here has considered variation between manual and automatic probe tip qualification and the influence on the confidence of the measurement data for a bridge type CMM. A range of probe orientation angles were examined, and the results presented focused on the orientations most readily used. For the MMA the manufacturers four probe tip calibration techniques recommended were executed and the repeatability tested with the arm in different resolves. The investigation was extended further to test the volumetric performance of a multi-axis measurement arm, with repeated systematic measurements of a calibrated reference sphere. The research has examined the influence of various styli on the confidence of the measurement data on a bridge type CMM. Taking into account a number of existing texts which consider different styli length, this work has extended the analysis to consider the influence of stylus design and stylus material. Specifically, styli from two different manufacturers were tested under the same conditions. Varying lengths of stylus were examined, manufactured from stainless steel, tungsten carbide, ceramic and carbon fibre. Further effects as a function of solid or hollow cross sectional geometry and styli made up of extension joints were considered and are presented here.
Description: A Master's Thesis. Submitted in partial fulfilment of the requirements for the award of Master of Philosophy of Loughborough University.
URI: https://dspace.lboro.ac.uk/2134/11770
Appears in Collections:MPhil Theses (Mechanical, Electrical and Manufacturing Engineering)

Files associated with this item:

File Description SizeFormat
MPhil-2006-Singh.pdf67.18 MBAdobe PDFView/Open
Form-2006-Singh.pdf64.7 kBAdobe PDFView/Open


SFX Query

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.