27-12-2017, 12:50 PM
Seems prudent David - thank you.
I have some time to sit and read (at last) and John Hopwood’s article on this very subject in the latest PWA7C Magazine caught my eye.
He makes reference to shrinkage cracks left on steering arms on cooling after forging. He details his method of magnetic particle crack-testing (my own kit employs this method) concluding that it is more effective than the dye kit ‘he’ had.
He found several surface cracks which he removed after grinding and polishing 40 thou of material away.
This is new information to me and raises the question as to the cause of cracks found to date? Are they in fact stress or perhaps manufacture related? Shrinkage cracks, if left, could cause future problems but appear to be easy enough to remove.
If anyone has a cracked arm I would be interested to receive it and undertake some tests as John did - then report the findings back here.
It may be that many (including me) have consigned arms to the scrap bin unnecessarily.
I have some time to sit and read (at last) and John Hopwood’s article on this very subject in the latest PWA7C Magazine caught my eye.
He makes reference to shrinkage cracks left on steering arms on cooling after forging. He details his method of magnetic particle crack-testing (my own kit employs this method) concluding that it is more effective than the dye kit ‘he’ had.
He found several surface cracks which he removed after grinding and polishing 40 thou of material away.
This is new information to me and raises the question as to the cause of cracks found to date? Are they in fact stress or perhaps manufacture related? Shrinkage cracks, if left, could cause future problems but appear to be easy enough to remove.
If anyone has a cracked arm I would be interested to receive it and undertake some tests as John did - then report the findings back here.
It may be that many (including me) have consigned arms to the scrap bin unnecessarily.