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When to use rotary hammer drill bits

For light-duty tasks that require drilling a few small holes into concrete, a hammer drill driver fitted with a regular drill bit may do the job. But when you need a lot of holes, or larger or deeper holes in concrete and reinforced concrete, you’ll need a rotary hammer fitted with a rotary hammer drill bit.

These bits are specially engineered for maximum performance in concrete. Quality bits of this type provide optimal energy transmission from the tool into the concrete. Their head geometry and helix design also offer ideal demolition behavior and remove hazardous construction dust more efficiently so you can work longer, faster and more safely.

That makes rotary hammer drill bits the right solution for jobs like drilling precise holes for the setting of chemical and mechanical anchors and post-installed rebar in line with approvals. They are also your go-to option for jobs like drilling through-holes for cables, pipes, conduits and gas lines.

SDS-Plus drill bits versus SDS-Max drill bits

Most rotary hammer bits are designed to work with either SDS-Plus or SDS-Max rotary hammers. SDS-Plus and SDS-Max are industry standard shank sizes but note that Hilti has different names for them – “TE-C” for SDS-Plus and “TE-Y” for SDS-Max.

As a general rule of thumb, bits for SDS-Plus bits are for drilling smaller holes, while SDS-Max bits are used for making larger holes. But for mid-sized holes there is some crossover.

Whatever the size of hole you’re drilling, it’s important to note that SDS-Plus bits only work with SDS-Plus rotary hammers while SDS-Max bits are only compatible with SDS-Max rotary hammers. The bits are not interchangeable.

It's also possible to use Hilti rotary hammer bits with rotary hammers from other manufacturers but you'll get better results by using our tools with our bits as they are designed to work together. 

2-cutter bits versus multi-cutter drill bits

When choosing your drill bit, you’ll also need to look at the number of cutting edges. Most rotary hammer drill bits have one of two main head geometries – either two cutting edges (2-cutter) or four cutting edges (4-cutter). A 4-cutter has and ‘X’ shaped head. There are also 6-cutter bits, and these have a star-shaped head.

For concrete drilling when you don’t expect to hit rebar, a 2-cutter drill bit is usually the preferred option. With the Hilti TE-C (SDS-Plus) 2-cutter, for example, side hits on rebar are possible but drilling through rebar is not recommended.

For reinforced concrete, you should choose a 4-cutter – or even 6-cutter for the largest diameter holes. These multi-cutter bits are designed for optimal drilling through a mixture of brittle and tough material. You’ll experience less jamming and your bits will last longer. 

Why helix design counts for drill bits

Another important factor when you're choosing a rotary hammer bit is helix design. The helix supports the cutting edges of the drill bit by providing faster and smoother transport of dust out of the hole.

Improved dust removal makes a drill bit more robust as it helps reduce the risk of overheating. It also helps boost your productivity. That’s because the less dust there is in the hole, the less often you have to remove the drill bit from the drilled hole, and the less likely it is the bit will jam.

With our smaller rotary drill bits up to 18mm in diameter, we’ve designed them so that there is no obstacle between the head and the 4-flute helix. The helix goes directly into the cutting edge meaning you get optimal dust removal over the lifetime over the bit. For bits above 18mm in diameter, the technology we use allows us to twist the steel in our drill bits so you get the optimal pitch for removing dust.  

Minimize construction dust when drilling

Drilling into concrete creates hazardous dust which can negatively impact health and safety and productivity. However, you can get virtually dust-free drilling if you use a Hilti hollow drill bit fitted to one of our approved vacuum cleaners. Normal rotary hammer bits can be used in combination with an on-tool dust collector to remove up to 97% of dust. 

When to replace your concrete drill bit

You should replace your drill bit if the indicator mark for anchor setting is no longer visible. You should also replace the bit if you experience significantly reduced drilling performance, in the event of breakages or extreme wear on the drill bit head or helix, or when the connection end is worn out.

Tips for extending drill bit lifetime

You can help maintain the drilling performance of your bit and extend its lifetime by taking the following measures:

• Only apply normal contact pressure when drilling – let the tool do the work for you. Pushing down on the drill can actually slow down drilling.
• During heavy applications, give the drill bit regular breaks. This can help prevent possible drill bit breakage caused by overheating.
• Pull the drill bit all the way out of the hole you are drilling from time to time. The deeper the hole, the more important it is to clean it so that your drill bit doesn’t get stuck.
• Make sure there is concrete dust in the drilled hole. Add dust manually if you need to.
• Always lubricate the connection end of the drill bit

Why pay more for rotary hammer drill bits?

No matter what the requirements of your job or budget, we have a high-performing rotary hammer bit for your drilling applications.

All our SDS-Plus and SDS-Max bits beat standard rotary drill bits when it comes to drilling speed over lifetime in concrete, drilling speed in rebar, the total amount of anchor holes you can drill, and robustness in rebar and concrete.

To give you more control over costs, you can choose between our premium (TE-C and TE-Y) bits and ultimate (TE-CX and TE-YX) bits. Our ultimate drill bits can have a significantly higher up-front price tag. However, they are generally longer lasting, meaning the final cost-per-hole can be similar, or even lower, than with our premium bits.

Utimate class drill bits also help you do the job much more rapidly. For example, a 4-cutter TE-CX bit is designed to drill through reinforced concrete a lot faster than a TE-C, which helps bring down labor costs.

At the same time, choosing ultimate class bits can help extend the working life of your tool by allowing you to drill more quickly. Because a key factor in the life of any tool is how long it’s used for, finishing your job sooner means you’re using your tool less and helping prolong its working life.

Your drill bit warranty

Whether you choose our premium or ultimate class bits, you’ll be able to take advantage of our warranty. We stand 100% behind our German-made rotary hammer drill bits. If your bit breaks, bends, or becomes unusable and the wear mark is still visible, we’ll consider replacing it for free.