Excessive Wear on Rock Augers

Customers often ask us about excessive wear on rock augers. As rock augers are designed to drill through very tough ground and hard rock, we’d like to outline what kind of wear should be expected, why rock augers wear and how this can be avoided to keep your augers operating at maximum performance.

First of all, what types of rock augers are there?

At Digga we offer three variations of rock augers.

The Digga Earth/Rock Combo Rock Auger features tapered tungsten taperloc teeth and is designed for drilling in earth, shale, permafrost and some fracturable rock.

Dedicated Rock Augers on the other hand, come in a standard and Tapered Rock variation, both featuring rotating picks and used to drill in fracturable to hard rock. The design with short flighting and rotating pick pilot encourages regular spoil removal, allowing cool air to enter the hole, and facilitate regular tooth inspection. Additionally, a hard-faced finish is applied to the flight edges and pockets of the dedicated rock augers to insure a longer life.

The advantage of the rotating pick pilot is the ability to build up or maintain body of the pilot while also having the ability to replace worn teeth in an effort to maintain a longer serviceable life.

If conventional augers aren’t getting through the rock, we would recommend trying a dedicated rock auger. If that doesn’t work, the next step would be a tapered rock auger and if the rock is still too hard then a core barrel should be used.

So, why do rock augers show more wear than e.g. general-purpose augers?

Rock augers face a lot of extreme conditions in very tough ground, so naturally you’re going to get a lot of wear. To achieve penetration into the rock, the rock needs to fracture or break into chip. For this to happen the point of critical pressure must be reached and exceed to burst through that hard material. If your machine doesn’t have enough down pressure to push the augers into the ground, the auger starts grinding – if that is the case you are going to experience a lot of wear.

You’re going to see wear on your teeth, flight edging and especially on your pilot. The pilot sits in its own hole at the tip of your auger at about 150mm to 200mm, so a lot of spoil sits around that pilot acting like sandpaper due to the rocks abrasive nature. Because the pilot has teeth, doesn’t mean it will never wear out – it is still a replacement part. The advantage is that you can replace the teeth, or you can rebuild the pockets to get a bit more life out of it.

Another important factor to be considered when drilling in rock for extended periods of time is, that air is trapped in the hole creating an “oven”, which can cause the face of the rock to “glaze over” and become even harder. Drilling in rock for extended periods of time will therefore cause the wearparts and pilot to heat up to an extreme temperature potentially making them melt or fuse in the pocket.

Overall, when drilling in extreme rock, you should generally expect that you are going to get some wear – it needs to be priced into your job. Make sure your customers know that you drill into really hard rock, this comes with tooth replacements, extra wear or maybe some rebuild work on your auger.

How can I tell that my auger has worn?

The images below indicate wear on rotating picks and the pilot.

ROTATING PICKS WEAR

The tungsten tip and tooth should always be evenly pointed looking like it has been in a pencil sharpener and teeth need to rotate while drilling in order to maintain an efficient cutting tip. A flat spot on the tooth and teeth being locked in, indicates they have stopped rotating. Side wear exposes the carbide, meaning that the carbide tip will eventually drop off. If the tungsten tip has been worn down and flattened, we recommend replacing the tooth. Poorly maintained teeth reduce cutting efficiency and wear out faster costing time and money.

PILOT WEAR

On the pilot you will notice worn rotating picks as well as worn tooth sockets. 

How do I avoid excessive wear?

We’ve summarized the most important rules to help you maintain your rock auger at maximum performance:

1. Do not use a dedicated rock auger (DR) to drill through earth or clay. This ground prevents the teeth from rotating, causing flat spots and premature wearing of the teeth.
2. Control your temperature when drilling: Try putting some water down the hole to cool it down and to make the spoil easier to remove. You should stop drilling every 5 minutes, bring the auger to surface and allow air back down the hole. Once spoil has been removed, we recommend a visual inspection of your auger and teeth. 
3. Use a soft copper or dead blow hammer to tap all teeth ensuring they are rotating freely in their pockets. This will encourage even wear around the tooth. Tip: Don’t touch the picks with your bare hands after drilling, as they’re going to be extremely hot.
4. Check for slightest signs of flat spots on the teeth every time the auger is removed from the hole. Flat spots indicate a non-rotating tooth.
5. Regularly remove the teeth and clean pockets with a wire brush. Ideally after each day’s use. Especially if storing for an extended period of time.
6. Do not use grease or lubricants on the tooth. Mixed with dirt, lubricants form a paste which prevents teeth from rotating in the pockets.
7. Always clean the drilling head prior to storage. Dirt will solidify overtime making it harder for the teeth to rotate. Rock augers are not a ‘set and forget’. Just like a sportscar – it needs a little bit more maintenance than your family car.
8. The outside teeth will wear the fastest as they are travelling the greatest distance, so they will need replacing more often. Try swapping the outer tooth for an inner tooth to keep the wear even. Always use your best teeth on the outside pockets.
9. Replace worn teeth immediately.

For additional information watch this video with Anthony, explaining excessive wear on dedicated rock augers.

Should you have any further question feel free to contact us at 1300 2 DIGGA or get in touch with our service department for any replacement parts at www.masr.com.au