CRACK! There goes the new PHD auger...

[Tollster]

Looking at the coarse grain structure, it appears to be a casting, many times if there is any impurities, slag, or laminations in the material it will reduce the tensile strength considerably, I can see a change in the material in the first image between 9 and 11 o団lock, this could be from use after the failure or where the indication propagated from, additionally, and I cannot tell from the photo's, if there are any hair line cracks or perhaps when they turned the threads, they could have left a ridge or some sort of stress riser, in this case it would more than likely be concaved indication, leading to the shearing indication seen hear. It is very common on bolting.

 

[daugen]

thanks, I sure am no metallurgist, but perhaps have watched too much CSI...
I'm wondering, speculating that the ear of the bit got hung up on one side of a rock that was big enough to stop it "dead" because the ear hooked around the rock in just the right way. And therefore due to the rotational force, also pulled the bit away from the shaft, perhaps popping off its head? I don't have the experience here but I expected more damage to the surface at the break
than even what you point out.

Does it "look different" when you break a common stove bolt, a grade 5? grade 8? Iron vs steel? Hardened vs. non-hardened? It's funny, when I first looked at this broken bit my reaction was it looked like iron breaking with all that texture. But if you say this is common, ok. Can't imagine anything but hardened steel in this application, plus any optional carbide or ceramic cutting edges.

 

[Tollster]

thanks, I sure am no metallurgist, but perhaps have watched too much CSI...
I'm wondering, speculating that the ear of the bit got hung up on one side of a rock that was big enough to stop it "dead" because the ear hooked around the rock in just the right way. And therefore due to the rotational force, also pulled the bit away from the shaft, perhaps popping off its head? I don't have the experience here but I expected more damage to the surface at the break
than even what you point out.

Does it "look different" when you break a common stove bolt, a grade 5? grade 8? Iron vs steel? Hardened vs. non-hardened? It's funny, when I first looked at this broken bit my reaction was it looked like iron breaking with all that texture. But if you say this is common, ok. Can't imagine anything but hardened steel in this application, plus any optional carbide or ceramic cutting edges.

Actually it looks the same. Most of the failures we see are from operational stresses, combined with reuse. We typically visually inspect all the threads for any stress cracks prior to reuse, we also inspect all new bolting for thread tears and impurity's. These are required visuals inspections we do on the major components in the nuclear plants. I still feel there is an issue with the material as the grain in not uniform in the first picture, it looks between 7 and 11 o'clock. The other side is very uniform grain.
In bolting we do not see grain with the naked eye, only under magnification when one it fails, but we use grade 8 in many instances and failures are very few do the quality standards, inspections, and scheduled replacement.

 

[daugen]

I looked at the broken off bit piece and didn't see any other cracking. I'll look again and be careful this time, though I don't have one of those nifty lights or testers that find cracks. If I find something, I'll post more pics. Thanks.

 

[Creamer]

As a degreed and licensed engineer this is a pure junk material issue. It is a cast part that has either contamination or way to much silicon and lead in the mix. A part for this application should be a cast steel not nodular iron and the mix and process should be controlled to not allow this type of grain growth. IF this isn't warranted, I would raise he-- to put it mildly. This is why we should not buy the cheap Chinese junk - obviously you did not get what you paid for!

 

[daugen]

maybe these will help, but yes, I think this is just a weak link in a good machine.

 

[Creamer]

In looking at the break it is not a twist failure or crack propagation. It is an all-at-once due to impact on a metal that is not made to take impact.

 

[daugen]

scheduled replacement.

I spent some time away from my core career in insurance, including one dabbling with a good friend who asked me to help grow his business, was putting in Schlumberger measuring instrumentation for predictive maintenance purposes, mostly on rotational equipment and much of that GE gas turbines. My friend was the engineer, I was the gopher, but I learned about critical mission maintenance and found it fascinating. Not if it will break, but only when... And if the vibration stays under a certain level, all is well. But over time wear sets in, temperature change, operational stress, and I guess what I can only call metal fatigue sets in. Big business out there trying to figure out just when that expensive part will break and how to change it only on the prior shift change...

So when you say "scheduled replacement" in the same context as tractor equipment, it brings up a whole range of interesting questions. Should those grade 5 bolts I installed ten years ago in my hitch or plow be changed out? Maybe not if they were grade 8? I sure don't know, and my assumption is that in normal operation grade bolts don't wear out, other than from being physically worn which we can inspect and see. But what about what we can't see? None of us are paranoid enough to expect moon mission fail safe stuff on our tractors, but, for example, I'd sure like the pins in my ROPS to work, in just about any situation... Anyone who sails an older boat knows they have to inspect their metal lines (halyards?) carefully, whatever they are called.

The most fascinating place I ever visited was one of the hydro electric plants, I believe Conowingo, where the machinery was, I think, about a hundred years old. Huge old brass gauges, next to strip recorders and sensors, and a joy to see. Truly machinery made to last a long long time. Just like the older tractors. And perhaps the new, but time will tell.

So somewhere between my half hour life on my auger bit and a hundred years on giant gears in a dam, is the reasonable life of the product. And not knowing what was reasonable was why I posted this. If it's common to break these things, then I want to make sure I tone down my expectations in dealing with the dealer, who may or may not eat some cost here. But likely not, I hope. I also bought a 12 inch auger from the same company, but I couldn't imagine trying to dig with that thing in this rocky soil. It was bought to plant small trees elsewhere.

 

[gengine]

Is it possible this is a cast iron guide point? My leinbach PHD has a bolt on cast iron point. Like this: CountyLine Auger Bolt-In Tip - 2100301 | Tractor Supply Company I broke one last year, and had to replace it. Tractor Supply also has the screw in type.

 

[rsewill]

Where I used to work (a trucking company) we had a chart on the wall from Rockwell. Rows and rows of photographs of busted rear end gears. All were broken due to end user action and the chart was to show what the damage would look like due to particular end user action. Not one photograph of a bad casting, therefore no broken gear was ever due to a manufacturer's defect.

Good luck on getting a replacement.