HSS-R Vs HSS-G Drill

Your problem sounds like a lack of lubrication and excessive feed rate, not choice of drills.

Try some of the more costly drills using your present methods and then you will know.

Are you using lubricants, as in cutting oil/fluid?

Try a tungsten carbide drill. It can drill small holes with ease. Regret I do not more specific information immediatley available as I am away from all of my data/information at my 'vacation' location.

You still need to use cutting oil/fluid.

Rate of feed, pressure and lubrication plays a critical roles in drilling. Normal drill bit HSS can drill very efficiently.

The problem you shared seems related to one or more of following reasons:

1) Drilling speed is very high, check the cutting speed needed

2) Drills are not sharp enough. Blunt edge drill bits gets damaged very soon.

3) If material to be drilled, is very hard, re-check the cutting speed required before changing the drill bit type.

4) Similarly if very soft material is to be drilled at low speed and high feed, drill bit may brake and get embeded in the work piece.

All of the above, definatelt sounds like you are doing something wrong though, speed?, feed?, lack of lubrication? Or a combination of the three combined with the metal you are cutting being super hard/unique (it was not specified in the original post).

Cobalt drill bits are a good option to, they are a little more expensive, but if they are treated with care, they will outlast most others.

Good luck.

You have told us the hole diameter, but not hole depth or the grade of steel being drilled.

Does '4mm or less' extend down to 3mm or 0.5mm?

What do you define as frequently? Is this in a production situation?

A 4mm drill in a pedestal drill should not buckle unless the spindle bearings are shot or the work piece moves. How is the work piece held? Is it firmly clamped?

If you are using a hand held drill, changing to a pedestal drill, running at the correct speed, lubricated, and with a firmly clamped work piece, will dramatically improve bit life.

Are you drilling thin sheet? Have you considered punching the holes?

Are you drilling more than 10mm deep? Have you considered milling the holes?

You need to provide more information for us to advise what is most suitable in your case.

Since you did not provide all the pertinent details of the task such as depth and grade of metal I will give some generic info that I learned from what we call a big hole shop. (they drill large numbers of holes in all kinds of materials professionally. Check with your drill supplier or manufacturer as to speed and rate of feed for that particular material to be drilled. You may have to change the angle of the cutting surface of the drill for some applications. Here is the hot tip---try using WD40 as a cutting fluid. Several of the big hole shops tried it with great success, one even claimed drill life extended to 4 times. Others reported similar results also the WD40 is very inexpensive compared to some wonder fluids that do not perform to this level. I have had similar experiences with this product as a drill and tapping fluid.

Lyn, Muckhergee and Mukesh0861 have all mentioned feed rate. This is important. A HSS drill at 4mm diam should be run fast, with coolant and a feed rate that produces ribbons of swarf.

Ideally the swarf should be in chips but it is too hard to ascertain whether the chips are being formed by just the right feed rate or too much.

It is also important to remove the drill from the hole during the process to both cool and remove chips/swarf. A drill can be broken by a buildup of chips regardless of material being drilled ( even wood ).

Jim

You may be drilling a metal that work hardens quickly. This can be discouraging because the drill starts normally and then just stops drilling. Replacing the drill with a new one will help but won't solve the problem because the metal in the hole is harder than it was before you started to drill it. Lower speed. lubricant, and constant feed are your friends. Also, a harder drill like carbide, will help. Carbide tipped drills are less costly than solid carbide. Drills are not polished to sharpen, they are ground. See http://www.drilldoctor.com/. They make low cost sharpening equipment.

(1) Use a center drill to start the location of the hole (2.) Try using a 135 degree split point drill with a high cobalt content, (available at machinery supply businesses like Rutland Tool Supply) and use a cutting lubricant. (3) Use recommended speeds and feeds for the materials you are drilling. (sounds like your drill RPM might be too high) Solid carbide drills are an option but much more expensive.

"Solid carbide drills are an option but much more expensive."

Where can you purchase "Solid carbide drills..."? I checked LynDoor™ and KrisDel™.

I'm always on the lookout to spend some of the company money.

Maybe it's time to roll out our "guarenteed-for-life" drills made from our proprietary super-metal, LynDoor™ Cargonite®SuperDuponol© triplex-metallic-hybrid-composite material that is hard as a diamond:tough as a nail.

You can throw away those old concrete drills, cause they are now obsolete.

I'm still working on the saw blades, but the drills are ready to go. Can't find anything hard enough to sharpen the teeth properly.

"Can't find anything hard enough to sharpen the teeth properly."

I remember something that might work. We talked about it here at CR4... Let me see if I can find it... where in the... Yeah, here it is.

We should contact drbobwoolery and see about that stuff that is harder than a whore's heart. That should do it!

^{Man this place is a lot of fun!}

Man,
I'd forgotten all about "Dr". Bob. That guy was a real crack-up.

I think he finally went to work driving one of KrisDel's fork lift, after we fired him.

I remember that last day, when he came in with a snoot full and wanted to fork the secretary. Wow, that was a close one.

I bought quite a few new ones of various diameters on E-bay, very reasonably priced. If you need to sharpen carbide drills, whether solid carbide or carbide tipped you have to use a diamond impregnated wheel with coolant. Carbide drills chip VERY easy because of it's hardness (brittle) so caution is encouraged when engaging the surface being drilled. ~~~DON'T BUMP IT INTO WORK PIECE~~~~

There are various grades of carbide drills, and before purchasing any drills, it would be a good idea to consult with a drill manufacturer and explain the specifics of your project, type of material, hardness, depth, etc. Let the drill manufacturer (Chicago Latrobe is a large one) give you some recommendations on type of drill to use, spindle speeds and feeds, recommended coolant, etc. They are the "experts" Personally, I think a drill with a high cobalt content would suffice for most projects and are considerably cheaper than solid carbide. They also can be sharpened on a standard grinding wheel. (Value engineering)

My main application for carbide has been machining fiberglass and FRP, (extremely abrasive) and drilling out broken drills and taps, (extremely hard) The only production application I had for carbide drills was drilling attachment holes in armor plating.

Another factor is how the material is being held in place: in a vice?? What type of machine: Drill press?? Milling machine?? Hand Drill?? All will play a role.

If you plan on doing a lot of manufacturing or machine shop projects, a book called Machinery's Handbook is a virtual cornucopia of valuable information for a machinist or engineer. Mine is a 'Nineteenth Edition" and is over 42 years old, and it's still a great book for reference and math formulas, speeds and feeds, etc.

If you're using a set of "Harbor Freight" drill bits, you're doomed from the start!!!!! They do not run true and are poorly sharpened even when new. (That 8 year old in China hasn't got the hang of it yet!!!)

Hope this helps???

It is impossible to answer your question without more information. What type of steel; what drilling speed; what rate of feed; what type of drill bit, 118° or 135° angle; Are you using a drill press or a hand held drill; Are you center punching before drilling? One bit of advise is do not use solid carbide drill bits. They are brittle and can snap easily; they are expensive. Use HSS, Tin or cobalt.

P.S. What does the "R" and "G" mean after HSS?