Advanced Welding Processes: Technologies and Process Control

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Advanced welding processes
Table 11.2 Example of costing spreadsheet output showing the influence of £20000
investment in welding automation on the cost of making a butt weld in steel with
GMAW, 1.0-mm-diameter filler wire. The left-hand column shows the original cost
for manual GMAW, and the right-hand column shows the estimated effect of
automation on the capital cost, operating factor (arc on time) and weld quality
(rejection rate). The totals show the reduced cost per weld and increased
productivity to be expected.
Operational parameters Manual Automated
Deposition rate kg h –1 3.55 3.55
Cost for flux or gas per m 3 or kg £ 3.10 3.10
Cost per 1000 electrodes or kg wire £ 0.77 0.77
Labour cost (without equipment) per hour £ 14.08 14.08
Number of hours per annum h 1500.00 1500.00
Process arc – on time % 28.00 50.00
Amount of work under survey % 100.00 100.00
Rejection rate % 5.00 1.00
Total investments k£ 2.535 22.535
Interest % 8.00 8.00
Depreciation period yr 5.00 5.00
Total cost per annum k£ 28.788 36.500
Deposited weldmetal per annum kg 1416.45 2635.88
Weight per metre kg 0.33 0.33
Total cost per kg weldmetal £ 20.32 13.85
Cutting cost per metre £ 0.00 0.00
Cost for this process per metre £ 6.68 4.55
Cumulative cost for this weld £ 6.68 4.55
for the process (the ratio of effective to non-effective time) and the consequent
reduction in labour cost. For example, a manual GMAW operator may achieve
an operating factor of 15–20%, whereas, with a tractor-mounted system, an
operating factor of 30–40% may be possible and fully automated systems are
likely to achieve 80–90%. Secondary cost savings can also be expected from
improved control of weld size; which, in turn, saves time, reduces consumable
costs and improves control of operating technique; which produces more
consistent quality, reduces defect levels and decreases repair costs. A
preliminary evaluation of the economic factors associated with the automation
of a given application is straightforward, particularly if one of the many
commercial weld-costing software packages 8 is used. Examples of simple
cost comparisons made with the NIL COSTCOMP software are shown in
Table 11.2 and Fig. 11.10: a comparison of manual and mechanized welding
approaches to one of the most common weld configurations is shown in
Table 11.2. The cost of the simple tractor involved would be recovered after
8 For example, the UK Welding Institutes ‘WELDCOST’ programme, The Netherlands
Welding Institute’s ‘NIL COSTCOMP’ or any suitably configured spreadsheet software.