Galling mechanisms in lubricated systems: A study of sheet metal forming

Schedin, Erik; Lehtinen, B.

doi:10.1016/0043-1648(93)90358-s

Cited by 56 publications

(24 citation statements)

References 8 publications

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“…These minor scratches were mainly in the form of ploughing wear as no major fracture was observed at the edges. These minor scratches observed at the edges indicate the initiation of galling wear on the tool and lump growth on the tool [26]. With the increase in number of stamped parts, the severity of the ploughing wear mode on the stamped parts increases (Figure 11c).…”

Section: Profilometry Study Of Stamped Partsmentioning

confidence: 99%

Investigation of Galling Wear Using Acoustic Emission Frequency Characteristics

2020

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In the sheet metal stamping process, during sliding contact between the tool and sheet, it is expected that severe events such as tool wear or fracture on the sheet generate acoustic emission (AE) burst waveforms. Attempts have been made in the literature to correlate the AE burst waveform with the wear mechanisms. However, there is a need for additional studies to understand the frequency characteristics of the AE burst waveform due to the severity and progression of the galling wear. This paper will determine the AE frequency characteristics that can be used to monitor galling wear, independent of the experimental process examined. The AE burst waveforms generated during the stamping and scratch tests are analysed in this paper to understand the change in the AE frequency characteristics with the galling severity. These AE burst waveforms were investigated using the Hilbert Huang Transform (HHT) time-frequency technique, band power, and mean-frequency. Subsequently, these AE frequency features are correlated with the wear behaviour observed via high-resolution profilometer images of the stamped parts and scratch surfaces. Initially, the HHT technique is applied to the AE burst waveform to understand the influence of wear severity in the power distribution over the wide AE frequency range. Later, the AE bandpower feature is used to quantitatively analyse the power in each frequency interval during the unworn and worn tool conditions. Finally, the mean-frequency of AE signal is identified to be able to determine the onset of galling wear. The new knowledge defined in this paper is the AE frequency features and wear measurement feature that can be used to indicate the onset of galling wear, irrespective of the processes examined. Highlights •AE burst waveform can be used to investigate galling. • AE mean-frequency can indicate galling wear initiation at industrial and tribological condition. • Profile depth wear feature can be used quantitatively to correlate with AE frequency features. • Frequency-magnitude and bandpower increased with increase in galling severity.

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Section: Profilometry Study Of Stamped Partsmentioning

confidence: 99%

Investigation of Galling Wear Using Acoustic Emission Frequency Characteristics

2020

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“…Galling wear in sheet metal stamping is a localised multistage sliding wear mechanism, where material transfer occurs at initiation sites and accumulates with progressive contact. The accumulated material ploughs the opposing surface and eventually the continual accumulation of galled material can result in fracture [3][4][5]. Galling wear damage is characterised by macroscopic localised roughening of the surface, and the creation of protrusions above the original surface due to plastic flow of the material and material transfer [6].…”

Section: Galling Wear Measurementmentioning

confidence: 99%

A new methodology for measuring galling wear severity in high strength steels

Voss

Pereira

Rolfe

et al. 2017

Wear

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A new methodology for measuring galling wear severity in high strength steels, Wear, http://dx. AbstractWith the increased usage of Advanced High Strength Steels, galling wear has become a significant challenge for sheet metal stamping industries. Galling, in particular, can have a large economic impact due to the high costs and lost productivity associated with manual monitoring, refinishing/resurfacing damaged tooling and formed parts, and the need to apply expensive treatments or coatings to tool surfaces. This has led to a push for automated galling wear detection systems. However, developing such systems requires an accurate measurement of galling wear severity that can be easily implemented in industrial situations. Parameters used for measuring galling wear are often difficult to collect in large industrial style trials, and can be inaccurate as they are not targeted towards characterising the localised features associated with galling wear damage. In this study, a new galling wear characterisation and measurement methodology is introduced that accurately measures galling wear severity by targeting the localised features on sheet metal parts. This methodology involves calculating Discrete Wavelet Transform detail coefficients of 2D surface profiles. A case study on a series of deep drawn channel parts demonstrates the accuracy of the Discrete Wavelet Transform methodology when compared to visual assessment of galling wear severity. Based on comparison to visual assessment the presented Discrete Wavelet Transform galling wear measurement methodology outperforms other commonly used wear measures. The methodology provides a targeted, repeatable and non-subjective measure of galling wear severity. The specific outcome of this work provides an important tool for research into galling wear monitoring and detection systems in sheet metal forming, and the study of galling wear and its prevention in general.

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“…Karlsson and Gåård et al [11] summarized that the galling process was gradually developed in many stages and its final stage was often characterized with coarse scratching on the slid sheets and lumps of adhered material on the surface of forming tools. Although there are many different initiation mechanisms been propounded, these mechanisms are closely related to the combination of one, some or all of the effects of adhesion, surface defects, microstructure, efficiency of lubrication, and temperature [17][18][19][20]. With the increasing use of galvanized AHSS sheet in automotive industry, exploring and understanding the different aspects of galling like friction behavior, dynamic evolution and wear mechanism under friction coupling plastic bending deformation are certainly beneficial to proper design and application of the sheet.…”

Section: Introductionmentioning

confidence: 99%