Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Assessment of Arc Stability Features for Selected Gas metal Arc Welding Conditions
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
2021 (English)Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

Stability is a key indicator of the efficiency of the gas metal arc welding (GMAW) operation,and it is linked to other quality indicators like spattering and weld formation. This thesis work describes methods of assessing arc stability for selected GMAW conditions. It focuses on stability characterisation and defines the relationships between process stability and influencing factors.

Welding tests were performed using two selected transfer modes being the spray and the pulse transfer modes to characterize stability and develop processes further for better overall performance. Short circuit was not included because it exceeds the scope of thesis even though it is also of interest for ESAB to characterize stability using this mode. For the spray transfer, stability characterization was carried out by analyzing voltage disturbances (explosions) in the form of voltage peaks (negative and positive) since the explosions occurring in the arc corresponded to the voltage fluctuations during welding. These tests were performed on a sandblasted carbon steel plate, using carbon steel wire in diameter 1,0 mm, gas mixture of 82%CO22/18%Ar, and with three different voltage values (29V, 31,5V and 32,5V) and inductance control settings (0, 60 and 95). This scope of parameters was selected in order to simulate certain range of stability behavior, so it was possible to analyze the factors correlated to stability, their relevance in influencing stability, and consequently to define a calculation algorithm for the determination of stability.Also, stability was calculated and scored based on two scoring indices. The first was stability scoring based on performance character (spatter presence, hardness of arc, smoothness of process) The other was stability scoring based on regularity of the process (repeatability and steadiness of electrical parameters, variations of process disturbances, uniformity of the process). These two different stability characteristics are recognized in industry within ESAB applications, and the process regularity represents the major proportion of this characterisation.

For the pulse transfer, stability characterization was carried out by analyzing and comparing two different current waveforms in terms of evaluating effects on stability. The linear waveform, which is the conventional type of waveform, was compared to an exponential waveform (with optimised droplet detachment). Results obtained from spray arc analyses showed that stability has certain indicators that are measurable by signal and image processing, and these were further analysed. Voltage disturbances were correlated to explosions observable during the process. Actual values of positive and negative voltage peaks, voltage amplitudes, and their average values and standard deviations in selected analysed time showed to be relevant indicators to characterise stability of the process. Variations of indicated voltage signals related to explosions showed to have complex patterns in terms of their waveforms. So, all these were analysed step by step and consequently selected for characterisation (calculation of stability) in the welding conditions that were selected in the scope of this project. Exact determination of stability formula was established, and this can be further developed in ESAB conditions in terms of automating the calculation with possibility of variable setting of calculated factors and ranges for specific analysed welding conditions.

The results for the pulse arc confirmed that the exponential waveform when compared to the linear waveform showed better stability conditions. It also showed that an important factor is the duration of the base current time and its standard deviation over selected analysed time, which optimised the droplet detachment mechanism.I

n conclusion, this approach of characterizing stability has been shown to be successful in terms of having a reasonable capacity to evaluate distinct elements that are acting in the process and determining overall stability.

Place, publisher, year, edition, pages
2021. , p. 89
Keywords [en]
Gas metal arc welding, Arc stability, Metal transfer, shielding gas, power source synergy, adaptive control.
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
URN: urn:nbn:se:hv:diva-17716Local ID: EXP800OAI: oai:DiVA.org:hv-17716DiVA, id: diva2:1609693
Subject / course
Mechanical engineering
Educational program
Masterprogram i tillverkningsteknik
Supervisors
Examiners
Available from: 2021-12-03 Created: 2021-11-09 Last updated: 2021-12-03Bibliographically approved

Open Access in DiVA

No full text in DiVA

By organisation
Division of Subtractive and Additive Manufacturing
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 232 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf