Uncertainty evaluation for twist drilling stability model

• Published in: Precision engineering Vol. 66; pp. 324 - 332
• Main Authors: Schmitz, Tony, Gomez, Michael, Honeycutt, Andrew, Karandikar, Jaydeep, Shim, Jongyoup, Ro, Seung-Kook, Hwang, Jooho
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-11-2020; Elsevier
• Subjects: Chatter; Drilling; ENGINEERING; Monte Carlo; Uncertainty; Drilling; Uncertainty; Monte Carlo; Chatter
• ISSN: 0141-6359; 1873-2372
• DOI: 10.1016/j.precisioneng.2020.08.007

This paper describes the first uncertainty analysis for drilling stability using a frequency-domain drilling stability model. The stability model inputs include: the modal parameters for the torsional-axial vibration mode from the twist drill-holder-spindle axial frequency response function; and the mechanistic coefficients that relate the torque and thrust force to chip area for the selected drill-workpiece material combination. Monte Carlo simulation is applied to propagate the input uncertainties to output uncertainty in the predicted stability map, which separates stable from unstable (chatter) zones in the spindle speed-chip width parameter space. The mean stability boundary and its 95% confidence intervals are determined for five cases: varying all four inputs simultaneously and varying them individually. This enables the individual sensitivities to be compared. Experimental results from drilling tests are included for comparison to the prediction. Additionally, Matlab code is provided to implement the stability model and Monte Carlo uncertainty analysis.
•A first uncertainty analysis for drilling stability is presented.•Inputs for the drilling stability model include the torsional-axial frequency response and force model coefficients.•Uncertainties are assigned to inputs and are propagated through the stability model to evaluate the stability uncertainty.•Experiments are completed and results presented for comparison to the predicted stability boundary.