HSS VS Carbide

[Heavy D]

Where and when would you use HSS & Carbide?? What types of materials would you use it on? I know carbide is harder then HSS but what considerations do you take into account when choosing which one to use.. for the purpose of this discussion, lets use drills as an example...

thanx


dan

[pauluk]

Wow that’s a big question and I bet you will get loads of different answers. From my point of view I would normally use HSS due to the lower cost, the most I normally make of anything is about 6 to 10 off’s. However if you are cutting hardened steel or some of the more exotic materials then carbide is the only answer. I also use carbide where cutter rigidity is required, maybe because of the length of cutter relative to the diameter. On the other hand if there is any question over the rigidity of the job or the clamping of it HSS is better, since carbide will not flex at all it will break. In short there is no right answer as to which one is better, you have to judge each job and then chose the best tool for the job.

The simplest things confuse the cleverest minds

[Caprirs]

For milling aluminum, my experience has been that carbide is always worth the extra cost. The tools last so much longer than HSS that I haven't bothered trying to save money on the tools. I've made thousands of these parts using the same tool bits: http://evlgt85.com/gallery/MC_Machine_Samples

In addition to the long life, the carbide does not get dull as quickly as HSS. This means I spend less time chasing tool wear issues that cause dimensional changes on the parts. By producing parts that are all consistent with each other, time is saved in the long run. Also, speeds and feeds can be increased significantly reducing cycle times.

[HuFlungDung]

I still like using HSS for general purpose small hole drilling. This is because HSS is tougher than carbide, and can stand a bit of incidental shock loading. But for larger holes, carbide insert drills are really nice, if your machine has the horsepower to run them at their design speed and feed rates. When you run out of horsepower, then you are back to HSS and spade drills.

Part of what is taken into consideration in a small shop is the ease of resharpening, drill bits especially. To sharpen a carbide drill properly requires expert technique to regrind the point properly. HSS is more forgiving, and grinds easier by hand on typical tool room grinding wheels.

For milling, HSS used to have quite an advantage pricewise. On a manual machine, HSS is still likely the best choice for small endmilling, due to inadequate coolant, spindle hp or feedrate capability of the machine power feeds (if present). Carbide insert facemills do work well on manual machines.

Carbide works very well with smooth controlled entry into the cut, with high, steady feedrate in proportion to spindle rpm. Without those factors being at their best, the carbide is likely to fail prematurely due to chip recutting, built up edge, and of course, the tendency to workharden the material is greater because of the greater speed capability of carbide, if the tool dwells on the part while the operator struggles to control what is going on.

[ViperTX]

Hu....have you heard of Randomat....or something like that....used to make tools from.....M3 steel....I should look that up.....

[Mcgyver]

dan your question is a little bit like asking how long is a piece of string, in that there is not usually a hard and fast stop on one or the other, a lot depends on your priorities. Also,the relative merits depend on so making factors answering it fully would required writing a book, what a sec, its been done; Machinery’s Handbook

the biggies imo are: 1) commercial or hobby - if you are trying to cover an overhead its a different world than a weekend warrior (me), 2) can your machines handle the removal rates and speeds - these are the paybacks for the higher price of carbide, if you don't have the horsepower, spindle speed and rigidity, you may not be able to take full advantage of them 3) your sharpening capabilities - I sharpen my endmills so hss is much more economical, the list goes on and on and on

both have a place in the shop, imo hss more than carbide in the home shop but depends on your priorities

[gibbsman]

Your question is a good one, I was even asked the same thing in a job interview once. I believe that 'huflungdung' answered it perfectly. If your on a manual machine without power feed don't waste yor time with carbide, if not, it's really up to # of parts and material.

[dertsap]

cabide all the way the only times that ive ever wanted to use high speed is on plastics because they are sharper than carbide and for long series cutting where carbides will snap under the load or deflection , even then i'll break one or two carbides before resorting to hss , high speed under normal cercumstances cannot possibly keep up in speeds and feeds especially on steal

[kalmah]

Use HSS when you have a little workshop and you machine a lot of different part on material easy to machine (aluminium, brass, low alloyed steel,...).
Of course, tapping with carbide tool is very difficult.

Carbide tool has better chip removal, tool life than HSS tool if the stability is good. The carbide don't like heavy vibration and flexion. It's not the case with HSS tool.

[Traceycnc300]

The company I work for cuts alot of exotic matrials Hastaloy,Wasploy and Inconel and we use alot of hss on these metals.Granted at very very low rpm's and they last long after carbide bites the dust.That said I love carbide on most aplacations.

[ScoobRS]

Are we talking automated or manual machining operations???


At our work carbide inserts is the go for the automated cnc lathes etc, indexable inserts easy to change and set back up, for intricute shapes when cutting we will sometimes grind our own HSS toolsteel on a tool and cutter grinder, for drilling its always HSS and HSS coated drills, very rarely use solid carbide drills...

Manual Milling: I prefer my slab cutter with carbide inserts, I go hammer and tong and the cutter loves it.... Small slots etc HSS end mills but always have to be careful with them, I hate the smaller diameter ones I have a habit of breaking them

Manual turning on the lathe, depending on surface finish required, I will rough down and taking whopping cuts with the carbide then finish with a nicely sharpened and honed hss tool... Drilling I just use my HSS same with the centre drills etc with a bit of cutting oil on them...

[big_mak]

Good Question.

I think alot of people struggle with this question.

There are even more materials to consider as well, powdered metals is another one to consider. OSG makes HSS, Powdered Metal and Carbide Endmills. They are all priced differently.

Some peeps swear by HSS for Stainless, but I've used TiAlN coated solid carbide quite sucessfully. So you can't just say carbide sucks for stainless or exotics.

I've used Carbide insert drills from Seco with great sucess on stuff like cast Inconel, just make sure you have the right grade and geometry. What's important when selecting cutters, is GEOMETRY. Stainless likes to be cut, not lobbed off, so your tooling needs to be sharp!!!!

Hu's got a good perspective on the issue.

I think it all comes down to each individual application. You need to consider:

Machine Rigidity,
Fixture Rigidity,
Material being cut
Spindle Capability
Finished geometry of the work itself.

If your finished work has thin walls, you'll need to balance the tool geometry so that the tool will still cut without grabbing the material. You'll also need to focus on your machining strategy, using waterline techniques.

Hope this helps you out.