HSS and carbide tooling

[PixMan]

I thought it would be a good idea to for me to start out this section with a discussion regarding the application of HSS (high speed steel) tooling, brazed carbide tools and indexable carbide insert tooling.

IMO, I believe there is a place in most (not all) shops for both. There are many factors which come into play when driving down the decision path as to which is best for you. Here's a few variables that need to be weighed in making choices:

Knowledge of the options
Budget
Spindle speeds
Tool holder system
Machine rigidity
Grinding skills

When it comes to knowledge of the options, it may surprise you to learn there are many different types of HSS cutting tools, many different materials used in making them.

The same is true of both brazed carbide and especially indexable carbide insert tooling. HSS tools have varying levels of cobalt, vanadium, titanium, manganese, and more, all of which lend certain cutting characteristics that may or may not be desirable for your particular application. The same is true of brazed and indexable carbide insert tooling. Add to that the enormous range of coatings available on indexable carbide inserts and you start to see how it can be overwhelming.

It doesn't have to be. You have ME to ping for questions and comments. I have extensive training and experience (over 30 years of making chips), and that includes a lot of training from major carbide insert manufacturers. As I have on other websites, I offer my help in any cutting tool related questions. Just be prepared to get an overly-verbose response. ;)

Fire away.

[EdK]

Ken,

Here's a general question that I think a lot of hobby machinists would like to know the answer to. Assuming the average lathe size for a hobbyist metalworker is 12x36 with a weight of about 1100lbs, does it make any sense to use carbide insert tooling on such a lathe. Assuming the materials being worked with would be aluminum and mild steel. Yes, nasty 1018 steel. It's cheap and it's very weldable. I happen to use it a lot because of those traits. Let's forget about leaded steel for this conversation. That stuff is so easy to machine you could do it with a Popsicle stick (exaggeration of course).

Thanks,
Ed

[ETC57]

Ok Ken,

along the lines and thinking with Ed my machine is a granite 1340 from
smithy, yes a 3in1 so taking into account the inherent weaknesses of the machine and the fact it only weighs about 1000lbs with the 8" rt on it.

What would you suggest for tooling both lathe and mill keep in mind money is a factor. ( one of the reasons for a 3in1 )

Thank's

Jerry.

P.S. I do push it hard stainless,ar plate and what ever come's up.

[PixMan]

Good question. No single answer to suit everyone.

The age of a lathe that size can affect it's maximum speed. SOme older ones max out at well-under 1000 rpm, so with those carbide insert tooling doesn't really make much sense. Newer ones with higher speeds can definitely benefit from the right application of carbide insert tooling, with some caveats.

First and foremost, there is much benefit from learning cutting tool geometry and how it affects cutting of various materials. The best way for that is of course to start with grinding your own HSS tools to see what works and what doesn't. You learn quickly what you can do to cut with ease, have chip control or not, and get good finishes.

Once you learn that, apply the knowledge to brazed carbide tooling for a time. There you'll see quantum leaps in tool life and cutting speeds. Then when you really want or need higher productivity and time grinding tools isn't easy to find, indexable carbide insert tooling can be the answer.

Specific to your question Ed, yes the average lathe can use the indexable carbide tooling, and do it well. Just which style you might choose depends upon the specific machine, the available speeds and the available funds. I think any machine with 3HP or more can use some negative rake insert tooling, as well as screw-down positive rake tools. Machines with less power are better-off with the screw-down positive rake tooling.

Jerry,

Your machine would do well with screw-down positive rake tooling. What size shanks does you machine accept, and do you have a specific task in mind?

[Highpower]

My problem is 90% of the time I don't know what grade of material I am working with. Most of the metal suppliers I buy from don't you an exact alloy as to what "mild steel" or aluminum you are buying. And anything out of the scrap bin is :huh:

Getting a decent finish is pure luck most of the time after trying several different tools in both HSS and carbide. :(

[ETC57]

Ken,

Thank's for your time and thought, as for your questions about my machine.

The mill is r8 and the lathe tool holder will accept 1/2" shank tools,

the machine is 110 single phase 2hp with variable speed control 50rpm up to 28000 rpm.

Jerry.

[PixMan]

Jerry,

With that much speed you can run either HSS or carbide, whichever makes the most sense for the application and your budget. Id the toolholder on your lathe one of the 4-way turret posts, a "lantern" (rocker style) post or a Quick Change Tool Post (QCTP)?

The single phase motors can sometimes restrict one from getting the very best finishes with the turning tools, but that can be overcome with a bit of emery cloth. For reasons that I suck at explaining, the phase does seem to impart wavy finishes, some sort of frequency resonance going on. I'm sure that someone more electrically knowledgeable than me can queue up that that one. It's cutting tools I best know.

Willie,

Materials from the metals suppliers' scrap bin is commonly referred to as "scrapbinium".

HSS tooling can usually take care of it at slower speeds and it's a really tough tool that can take some abuse and costs "fractions of pennies" per edge because you can resharpen them so many times. Carbide insert tooling can also take care of the material easily if you find a tougher grade that can take some abuse. Your machine would do well with screw-down positive rake inserts such as CCMT/CCGT or the less-common (read:often more expensive) WCMT/WCGT styles. The advantage to using those inserts is that once you get a holder with a couple of inserts and establish what works for you, it's such a pleasure to use. The right carbide (not $1.50 apiece Chinese "gold coated) inserts can last months per edge. When you do have to change them, the tool center height doesn't change and you can go right back to work.

Often the total time required to use and maintain HSS tooling is dismissed in favor of its extremely low cost. I can't argue that and won't. I'll just say unabashedly that I have a higher value on my limited time in the shop (and on this earth) to be spending much of it grinding tools as I did in the 1970's when I was in school for this trade. I have more FUN finding inserts that peel metal off at incredible rates and look no worse for the wear. Do what's right for your own shop, you own situation.

[DaveH]

(02-19-2012, 02:19 AM)ETC57 Wrote: Ken,
the machine is 110 single phase 2hp with variable speed control 50rpm up to 28000 rpm.

Jerry.

Jerry,

Wow 28000 rpm, errrr ...... may be a slight error with the last zero
:)
DaveH

[ETC57]

OOOOOOOOPs!!!!! ya it was late.:s

2800 rpm

Good morning Dave

Jerry.

[DaveH]

Jerry

And a good morning to you too.:)

DaveH