For what it's worth - I was asked a couple of years ago, to do a technical survey on a range of Chinese manufactured mma & Tig inverters for a reputable wholesaler of welding equipment. Like most of the reputable importers/wholesalers in the UK, they said that they had an 'agent' working on their behalf within the manufacturer, so quality was controlled by them. Whether this is factual, I'm not sure but it seemed to be working.
I had worked on a lot of the early Chinese equipment and did not expect to see good quality kit, however, most of the stuff (about 15 different models) exceeded my expectations. They performed well and mostly exceeded their rated duty cycles. Most components looked as if they were from well known manufacturers, with a few wound components (small transformers etc) obviously from within China. I suggested that they were good value and this company has been supplying them for quite a while now and I have even sold a few with no comebacks.
After testing these machines, I was given the job of fixing any machines that were returned under warranty. I think I saw about 40 machines in 18 months and you have to bear in mind that these people were selling to distributors throughout the country, including Ireland, so this was probably a tiny percentage.
Most of the problems were either user error, pcb failures, cooling fan or switch failures. Pcb failures were generally in the autoswitching machines (110/240V) where the switching relays were not man enough to cope with 30/40Amps @110V (a problem lots of manufacturers face). Surprisingly, most other (quality) inverters I fix, mostly fail when the main transistors (IGBTs) fail - these Chinese sets never had this problem when I was deeply involved. The other major problem was that the on/off switch that is rated at 16A, would fail if the machine was used heavily (all the supply goes through this switch on most of them) This is a design fault without a doubt but other manufacturers do the same.
More recent machines from this importer have been improved but I have no real experience of these yet.
Bottom line is, buy from a reputable UK agent, then you'll get a warranty and 1st year problems should be sorted for free. But remember, some distributors are now working on silly low margins. If they only make £20/30 on a mchine, they are likely to be unwilling to repair them if they fail. My distributor had a deal with the manufacturer in that they got a load of free spares each time the placed a large order for machines, so they could afford to pay me to fix them. Others do not have this luxury.
Also, I would recommend that you buy from a UK agent, not over the internet direct from China - It's tough enough to get service in the UK but impossible to get if you buy direct.
My 2ds worth but I hope it helps somebody.
Dave
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