Bosch Impact Tough Titanium Nitride Coated Drill Bit Set

A compact titanium-coated set for everyday drilling

I keep a small drill index in my go-bag for quick installs, repairs, and the odd piece of metalwork on site. The Bosch titanium set has been riding along for a few weeks now, and I’ve run it through wood, plastics, aluminum, and a mix of light- to medium-duty steel tasks to see where it shines and where it falls short. In short, it’s a convenient, general-purpose set with a coating that helps in certain materials, but it’s not a cure‑all—especially if your day involves a lot of steel.

What’s in the box

Bosch sells two configurations:

• TI5IM (5-piece): 3/32, 1/8, 5/32, 3/16, 1/4 inch
• TI9IM (9-piece): 1/16, 3/32, 1/8, 5/32, 3/16, 7/32, 1/4, 5/16, 3/8 inch

Coverage is smart for everyday jobs: pilot holes, clearance holes, and common anchor sizes are here, and the 9-piece reaches up to 3/8 inch, which is about as large as I expect to drill with a handheld driver in typical site materials. This is strictly a fractional set; no letter or number sizes. For furniture hardware or tap-drilling, you’ll still want a fuller index.

Build and coating

These are standard twist drills with a titanium nitride (TiN) coating. TiN increases surface hardness and reduces friction, which can lower cutting temperatures in the right conditions. It’s a thin, surface-level coating, so two realities apply:

• The base steel still matters. This is a general-purpose HSS-style set, not cobalt or carbide.
• Once you wear or resharpen past the coated zone, the performance advantage fades.

The coating on my set was even and consistent at the cutting lips and flutes. Edges were clean from the factory with no visible burrs. Shanks gripped securely in my keyless chuck; I had no slippage issues.

Performance in wood and plastics

In softwood and hardwood, the titanium set is a straightforward performer. I used the 1/8, 3/16, and 1/4 inch sizes to run pilot holes for screws and through-holes for hardware in pine, poplar, and white oak. At typical drill speeds, chip evacuation was good, holes stayed on line, and I didn’t see burning—even when I intentionally leaned on the bit in oak. Tear-out on exit in plywood was about average for a standard twist drill; backing the work or slowing down at the break-through helped.

Plastics (PVC and acrylic) were uneventful in a good way. TiN’s lower friction seems to help avoid melting when you keep the speed moderate and the feed steady. Pecking the bit to clear chips every few seconds keeps the flutes from clogging.

Aluminum and non‑ferrous metals

Aluminum is where this set feels happiest in metal. I drilled a handful of 1/8 to 5/16 inch holes in 6061 plate and extrusions with a dab of cutting wax. The bits cut cleanly with a consistent chip, and the coating seemed to reduce the tendency to stick and gall. After several dozen holes, the cutting edges still felt crisp, and the gold finish at the lips showed only light polishing.

Brass behaved similarly—clean, controllable cuts with minimal grab as long as I avoided high RPMs.

Mild steel and the limits of TiN

Steel is a more mixed story. On thin mild steel sheet and light angle (up to about 1/8 inch thick), the Bosch titanium set handled small to mid sizes (1/8, 5/32, 3/16) reasonably well with proper technique: slow speed, steady feed, pecking to clear chips, and a touch of oil. I could feel the bits warm up fast if I got impatient; slowing the drill made a noticeable difference.

On thicker mild steel plate and structural shapes, performance dropped off. The 1/4 and 5/16 inch sizes dulled more quickly than I’d like when I attempted multiple holes without strictly managing heat. Once the edges lost their bite, the coating couldn’t compensate—the bits started to skate, work-harden the surface, and generate heat that accelerates wear.

For stainless, I don’t recommend this set. I tested the 1/8 and 3/16 bits on 304 sheet and received the expected pushback: slow progress, edge wear, and heat build-up even with cutting fluid. Cobalt (M35/M42) or carbide is a better match there.

Accuracy and control

Starting a hole in metal benefits from a center punch; that’s standard practice, and it helped keep the smaller sizes from wandering. In wood, I found minimal walking—keeping the drill square and starting at low RPM brought the bit on center reliably. Hole roundness and size were on target for typical jobber-style bits. I measured 1/4 inch holes in pine and aluminum within a couple thousandths of nominal with a clean wall finish.

I didn’t experience noticeable runout from the bits themselves; where I saw wobble, it traced back to the chuck or operator error rather than the tool.

Durability across materials

After a few weeks, the story on wear lines up with what I’d expect from TiN-coated general-purpose bits:

• Wood/plastics: Edge life is long. The 1/8 and 3/16 bits still cut aggressively after dozens of pilot holes.
• Aluminum/brass: Light polishing of the coating at the lips but good retention of sharpness.
• Mild steel: Small sizes held up for occasional holes with proper technique; larger sizes showed visible edge rounding sooner, especially if I got the speed wrong.
• Stainless/harder steels: Not a good match.

One note on maintenance: resharpening these bits will remove the coating at the cutting edge. You can absolutely bring them back on a bench grinder or a sharpening jig, but post‑sharpen they’ll behave like uncoated HSS at the lips.

Coverage and convenience

Between the 5-piece and 9-piece, the 9-piece (TI9IM) is the better “do most things” kit. The jump from 1/4 to 5/16 to 3/8 inches covers common bolt clearances and many hardware installs. The smaller 5-piece (TI5IM) is fine if your work rarely exceeds 1/4 inch or you just want a compact set for carpentry and general maintenance.

What’s missing? This is a fixed-size, fractional selection. There are no duplicates of high-use sizes (like 1/8 or 3/16), and there aren’t the in‑between letter/number sizes you’d want for tapping or precision fits. For shop work, I’d keep a fuller index nearby and treat this as the portable, jobsite-friendly set.

Best practices to get good results

• Use slower speeds in metal. If you see blue chips or smell hot oil, you’re too fast.
• Apply steady pressure. Let the bit cut; rubbing creates heat and dulls edges.
• Peck-drill to clear chips, especially in deep holes and aluminum.
• Use cutting fluid on metals. A tiny amount goes a long way.
• Center punch steel to prevent walking and work-hardening at the surface.
• Back the workpiece in wood and laminate to reduce tear-out on exit.

Following those basics materially improved edge life and hole quality for me, especially in mild steel.

Who this set suits—and who should look elsewhere

The Bosch titanium set makes sense for:

• General carpentry and installation work where wood and plastics dominate
• Maintenance tasks with occasional aluminum or mild steel
• A compact, go-to kit that covers the most-used fractional sizes

If you routinely drill steel, stainless, or hardened fasteners, you’ll be happier with a cobalt set for HSS-speed work or carbide for higher productivity and abrasive materials. Likewise, if you need tight hole-size control for tapping, a numbered/lettered index is the right tool.

Recommendation

I recommend the Bosch titanium set as a handy, general-purpose kit for wood, plastics, and non‑ferrous metals, with occasional mild steel duty when you use proper technique. The TiN coating helps reduce friction and wear in those friendlier materials, and the size selection in the 9-piece set covers most everyday needs without weighing down your bag. I wouldn’t choose it for regular steel or stainless work; in those scenarios, the bits dull too quickly and the coating can’t bridge the gap. For broad, everyday use and a compact footprint, though, it earns a spot in my carry.