Wednesday, 8 January 2020

Continuous Flight Augers with Removable Cutting Heads

We recently delivered a custom drilling solution for one of our customers, who uses a piling process called Sheet Piling. For this particular application, Digga developed and provided CFA style augers with a removable cutting-head-design and varying lengths.  

What are traditional CFA augers?

Here is some background information: Continuous Flight Augers (CFA) are mainly used for drilling water-bearing sandy soil, sludge, clay, muddy sub clay, sandy gravel, cobble, and weathered soft to hard formation (rock). 

CFA piles are a type of drilled foundation in which the pile is drilled to a final depth in one continuous process, using a continuous flighted auger (CFA). Concrete or grout is then pumped under pressure down the hollow stem of the auger to the bottom of the bore. Once pumping starts the auger is progressively withdrawn bringing the soil with it to the surface, leaving the Concrete/Grout in the pile. Reinforcement (Reo) is then added to the concrete pile for additional strength. 

Variations to the hollow stem style CFA augers, are CFA augers with solid coupling (non-hollow core). They are used to achieve depth in one continuous motion - just like hollow stem - but simply without the concrete/grout injection. It is traditionally used in more stable grounds or over the more traditional methods like rotary piling or utility piling, where the operator drills to top of the flight and removes the auger and spoil from the hole, shakes it off and returns the auger to the hole to drill deeper. This process is repeated over and over, until depth is achieved (tube extensions might be added to drill deeper than the OAL of the auger). This method is slower and more cumbersome and can cause the pile to collapse in unstable softer ground.
Continuous flight augers
So, what was our customer after?

With that in mind, a client who uses a piling process called Sheet Piling (used for excavation support and soil retention), came to Digga for a solution to an issue they faced with pile run-off, meaning the sheet pile was deflecting when hitting hard ground as the sheet was unable to achieve penetration.  

The client requested augers for pre-drilling to loosen the ground before sheet piling. Pre-drilling enables the sheet pile to be driven to depth without deflection. So, our customer challenged us to come up with a cost effective and versatile solution to their drilling needs.

Wanting to drill to a depth of 12m and everything in-between but minimising the logistics of material handling on site of multiple 6m long augers and the versatility of being able to drill all ground conditions from Earth to Rock.

Our solution

Digga developed a CFA style auger using solid hex drive hubs and shafts. Utilising the CFA-design, it provides the ability to reach depth in a continuous process. The package Digga provided to the customer consisted of two 3-metre long and one 6-metre long CFA sections, which allows for greater depth flexibility.
Continuous flight augers
This means that the customer has the capability of various depth options from 3m, 6m, 9m up to 12m, coupled with Pin-On or Removable heads (REM). This way, the client can change from an Earth Auger (A series) to a Rock Combo (RC Series) to a Dedicated Rock (DR Series) within minutes.

Not only do we have the advantage of being able to change cutting styles quickly, it also means that there is no need to fit, remove or refit the auger sections from the host machine, when requiring a change to the cutting head style to meet the varying ground conditions.
Continuous flight augers
Overall, this resulted in saving manual labour charge and safer material handling on site.

This multipurpose auger package was coupled to a Digga PD50 two-speed drive complementing the total cost effective, cost saving and flexibility of the package. 

Find out more about our custom solutions here.

Got questions or a similar application yourself?  Give us a call at 1300 2 DIGGA or visit

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