Oversizing Thread Diagnosis in Tapping Operation

Alain Gil Del Val,Mariluz Penalva,Fernando Veiga,Miguel Arizmendi

doi:10.3390/met11040537

Abstract

Automotive, railway and aerospace sectors require a high level of quality on the thread profiles in their manufacturing systems knowing that the tapping process is a complex manufacturing process and the last operation in a manufacturing cell. Therefore, a multivariate statistical process control chart, for each tap, is presented based on the principal components of the torque signal directly measured from spindle motor drive to diagnosis the thread profile quality. This on-line multivariate control chart has implemented an alarm to avoid defected screw threads (oversized). Therefore, it could work automatically without any operator intervention assessing the thread quality and the safety is guaranteed during the tapping process.

Highlights

Internal thread manufacturing is a widespread operation in automotive, railway, and aerospace sectors
All the GV values are lower than upper control limit (UCL) value and, the tapping process is in control and the process safety is guaranteed with these cutting conditions
The manufacturing users assumes this penalty over the tap tools knowing without diminishing the process competitiveness because the tapping process is in control and the operation safety is guaranteed

Summary

Introduction

Internal thread manufacturing is a widespread operation in automotive, railway, and aerospace sectors. In addition to this, tapping and threading can be applied after new ways of joining dissimilar alloys, as it was developed by Urbikain et al [1]. These sectors require high quality in the manufacturing systems. Before defining the thread quality, the tapping is described. The tapping requirements are challenging because a need of high synchronism between rotational and vertical movements is required [2] and the tool has many teeth while mating the thread during the tapping operation. Coatings are a prime concern about threading [3], PVD ones must be carefully eliminated of droplets to achieve a good performance [4]

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Conclusion