Corpus N2

As part of my studies, I was on a work placement at ... in ..., an industrial boiler making factory of about fifty employees.

They don’t produce in mass but mainly on demand as bridges parts, mostly heavy machines parts as crane parts (clamps, chassis …)

To ensure a good production rhythm and quality of welds (as customers require a precise work (ISO 9002) ), the portable welding machines must regularly be checked to prevent failures and their precision is validated at least once a year to be sure to provide the best welding quality possible.

Both calibration and parts are checked regularly even if the welding stations which don’t pass the calibration test can still be used for work which requires a lower quality of welding.

As a preventive task, I was asked to check these machines and replace the parts which were too worn-out to prevent failure before the next scheduled control and I had to validate their precision level in some cases.

The calibration checking procedure consist on control if both the measure of the voltage and current delivered by the welding station and displayed by it’s screen display are in accordance of the value table provided by the manufacturer.

To be certified these values must be on 5% range of the value table.The calibration test require two people: as the values must be measured while the welding station is in use (soldering), one is taking the measures and the second uses the welding station on metal scrap parts (second could be a non-technician as the machine operator for example).

The values are measured with a voltmeter for the voltage and an ampermetric clamp for the current.

As I was taking the measures with the machine open and while it was working, I had for evident security reasons to wear protective equipment as insulated gloves and eyeshade glass to be protected from electric arc.

Before taking the measurements I had to ensure that the welding station was ready to simulate work operation. To do that I inserted the soldering wire coil inside the automatic dispenser. Then I connected the welding post to gaz supply and adjusted the manometer to adjust the gas pressure at a level of 0,3 bar, and the plugged in the machine.

Once done I put the voltage and current selectors on the required values, linked the scrap part to the ground and switched it on. Then I asked my colleague to start some soldering action and took my measurement.

I compared the values I took to the ones displayed by the post and the ones required by the table. If the values are I accordance then the machine pass the certification and I add a sticker that show it’s certified with the date of next planned control, if the machine is used only for work that require less precision. Another option is to replace the electronic card of the machine but this option is used only if the company is lacking of certified machines as this card are expensives.

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