Position Accuracy of Drilled Holes

Kaminski, Jacek K; Crafoord, R; Mårtensson, N.

doi:10.1016/s0007-8506(07)62040-x

Cited by 13 publications

(5 citation statements)

References 1 publication

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“…Once the entire drill tip is engaged in the cutting and both the margins and outer cutting edge corners guide the drill, the hole's location is finally determined. In the case of the drill still being bent, it is very likely for the tool and, therefore, the hole to run out considerably, resulting in a substantial location error at the bottom/exit of the hole [3,4]. Small-diameter drills in particular are prone to run-out, firstly because of their slenderness and, secondly, because their web in proportion to their nominal diameter is much larger than in the case of large-diameter drills [5,6].…”

Section: Introduction and Scope Of This Workmentioning

confidence: 99%

The effect of starting hole geometry on borehole quality and tool life of twist drills

Heinemann

2011

Int J Adv Manuf Technol

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This paper reports about the relationship between starting hole geometry and twist drill performance, which is determined by the location error and diameter of the drilled borehole as well as the tool life of the employed twist drills. The experimental results lead towards the conclusion that the type of starting hole has a significant effect on borehole quality. This, however, is not as commonly assumed attributed to a variation in the location error of the different starting holes themselves, but to how a starting hole allows the subsequent twist drill to engage in the cutting process. Although twist drills that drill straight into the workpiece material achieved the longest tool life due to a gentle engagement, a deep starting hole ('pilot hole') results in the most satisfying overall twist drill performance.

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Section: Introduction and Scope Of This Workmentioning

confidence: 99%

The effect of starting hole geometry on borehole quality and tool life of twist drills

Heinemann

2011

Int J Adv Manuf Technol

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“…Industrial practice has, on the other hand, revealed that statistically D and Á are satisfactorily represented by the normal distribution (Kirschling 1988, Kaminski and Crafoord 1991, Morrison 2001. The two variables can also be assumed, within the frame of the present approach, as statistically independent.…”

Section: Theoretical Analysismentioning

confidence: 99%

Maximum material condition in process planning

Diplaris

Sfantsikopoulos

2006

Production Planning & Control

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Appropriate and cost effective assignment and interpretation of dimensional and geometrical tolerances, in conjunction with tolerancing principles such as the maximum material condition (MMC), constitute a major area of concern for manufacturing SMEs. This is particularly true for the process planning stage, where production operations and parameter values establish the final product quality and cost. A frequently used geometrical tolerance is the position tolerance. It allows at least 57% more space for feature allocation without affecting product quality and is very useful for accurate specification of multiple-hole assemblies. Feature allocation becomes further relaxed in case a position tolerance is assigned to the MMC. This assignment is mainly exploited during inspection, because it permits fewer rejections. In terms of cost, it is advantageous to systematically integrate the MMC tolerance bonus into the position tolerance at the process planning stage. A methodology that allows a new MMC-adapted position tolerance to be calculated is presented in this paper. The new, increased, position tolerance can then be taken into consideration early in the process planning stage, in order to achieve lower production cost, without affecting the quality.

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“…These results, however, are in general experimental or analytic in nature and are not formulated in terms of uncertainties. Kaminski and Crafoord [7] state that drilling operations give rise to forces in the X, Y and Z directions as well as torque. They found that the tool deflects more under dynamic cutting conditions than under static simulated force loads.…”

Section: Related Researchmentioning

confidence: 99%

Comparative statistical analysis of test parts manufactured in production environments

Gilsinn

Ling

2002

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Estimating error uncertainties arising in parts produced on machine tools in production machine shops is not a well understood process. The current study details a process of estimating these error uncertainties. A part with significant features was defined and a vertical turning center was selected in a production shop to make multiple copies of the part. Machine tool error components were measured using a laser ball bar instrument. Twenty-one copies of the part were produced and measured on a coordinate measuring machine. A machine tool error model based on the measurements of the vertical turning center machine tool errors was developed. Uncertainty estimates of the errors in the working volume were calculated. From coordinate measuring machine data error uncertainties at points on the part were developed. Distances between hole centers were computed and uncertainty estimates of these lengths generated. Many of the hole centers were designed to fall along orthogonal lines. Uncertainty estimates were computed of the orthogonality of these lines. All of these estimated uncertainties were compared against uncertainties computed from the measured parts. The main conclusion of the work is that the Law of Propagation of Uncertainties can be used to estimate machining uncertainties and that predicted uncertainties can be related to actual part error uncertainties. Keywords: coordinate measuring machine, drilling, error uncertainties, laser ball bar, machine tools, machine tool errors, milling, Monte Carlo, propagation of uncertainty, vertical turning center. 5. 1 Hole Center Location Uncertainties for Manufactured Part 40 5.2 Estimating the Uncertainty of a Machined Length Feature from CMM Measurements 46 5.3 Estimating the Uncertainty of Machined Part Orthogonality from CMM Measurements 48 5.4 Estimating the Uncertainty of a Machined Part Circularity from CMM Measurements 49 6.0 Comparative Results 6. 1 Comparison of Hole Location Errors and Uncertainties 6.2 Comparison of Length Uncertainties 6.3 Comparison of Orthogonality Uncertainties 6.4 Comparison of Circularity Uncertainties 7.0 Conclusions 8.0 Acknowledgements 9.0 References APPENDIX A: Model Based Estimates of Point Error Variances and Confidence Intervals 57 APPENDIX B: Uncertainty Estimates for Hole Centers Based on CMM Measurements of Parts APPENDIX C: Analysis of Variance for Selected Hole Centers 71 APPENDIX D: Derivation of the Variance of Length Equation 83

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Position Accuracy of Drilled Holes

Cited by 13 publications

References 1 publication

The effect of starting hole geometry on borehole quality and tool life of twist drills

The effect of starting hole geometry on borehole quality and tool life of twist drills

Maximum material condition in process planning

Comparative statistical analysis of test parts manufactured in production environments

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