I wonder if anyone has ever tried to make fair comparisons by use?
For a start, carbide inserts are designed with remarkably short lives in mind; but when used on the materials they are intended for and at their maximum machining rates.
A Sandvik catalogue I have quotes figures like 20 minutes – but this is for the professional production-planner and machine-setter equipping very rigid machines removing a lot of metal in very short times. The tip costs might be factored into the individual piece cost or spread among the overheads.
Really a fair comparison for any given tip between such industrial use and our use is how much metal it cuts to a good finish; but importantly, of similar metal and irrespective of speed.
There is a common belief that because the industrial user can work carbide tips at enormous speeds, usually under a much coolant / lubricant, these tips can only work at such speeds. I am sure some users obtain better results with higher surface speeds, but I would suggest it is very much more than mere speed, and have not noticed any loss in quality with using inserts at quite low speeds, especially on self-acting feed.
After all, brazed-on carbide tools with very simple tip geometry were being used industrially, on conventional lathes, decades before the advent of high-speed, NC-controlled machine-tools.
If I obtain a poor finish I first suspect a worn insert.
Then my setting and driving of the machine. Was the tip true to centre-height or a tiny fraction of a mm out? Did the work-piece chatter? Sometimes I have noticed chatter nodes depending on the length and diameter at the time, possibly too the material; and overcome by changing the speed – often downwards.
If I cannot see a fault there, I ask myself, is it the right tool for the material? As that Sandvik book shows, inserts are made for narrow ranges of materials under very particular production conditions.
If the tip I have used is blunt, I do not know if I have given it a good life and it has expired of old-age, or if I have blunted it by using it on its wrong material and/or inappropriate feeds and depths of cut (not surface speed).
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The hobby's traders know our machine-tools, operating conditions and budgets may not match aerospace QA standards, and we don't usually machine exotic metals to microns anyway, so offer us sensible-quality inserts and some advice on the applications. I trust them. If nothing else it would be bad for them to sell us either poor-quality tools or top-rate ones far fewer of us could afford and too narrowly-specified anyway.
Now, I don't know about you but like many who at the exhibitions, I rarely buy complete packs of 10 tips at a time, at £4 – £5 a tip. This leaves the traders with assorted partially-empty boxes, so what they put in the box to hand to you may not be by the name on the box – not by deceit but by convenience, though possibly negating the trade-standard type-code also on the label. However, the names on my boxes of tips and the holders, almost all from one supplier at the shows, include Taegutec, Kenametal, Sandvik, Vandurit, Walter and APT. All probably selected by the retailer for general-purpose machining of common metals on ordinary machine-tools. I have noticed no special differences between any, but would I notice any such differences in my workshop, on my materials and fairly old, conventional machines operated by fairly old, conventional me? I have not investigated, but I very much doubt it.
To summarise:
Buying anything from on-line generalists will always be a gamble.
We can trust the retailers to the hobby.
We are using industrial-pattern tools often outside of the narrow conditions for which they are designed, so we cannot criticise them if they don't always work for us. That includes saying that because carbide inserts can work at very high speeds, such speeds are necessary; but the high-speed is intended to be accompanied by precise, consistent cutting rates and usually under coolant / lubricant floods.
These inserts from major manufacturers are also designed with quite specific lives cutting particular ranges of materials at a maximum designed rate.
How do we know if they have the same, longer, or shorter, lives in our hands? If shorter, why is it shorter?
And if the finish is not always a beautiful mirror… what is the real reason?