AGP’s key elements of successful wet diamond core drilling

Published 23/12, 2024 at 11:39

Wet diamond core drilling is seen as the fastest and most economical way to drill precise cylindrical openings in reinforced concrete. Drilling reinforced concrete is challenging because of the combination of the hardness of the concrete material, and the difficulty of cutting the steel reinforcing bars which are embedded in it. The cutting tools required are diamond segment tipped core bits, since they perform best on hard concrete, but steel rebar is difficult to cut with diamond segments. It takes a powerful motor to drive the core bits, and it needs to deliver the correct speed with the required torque to complete the job. AGP states that its line of wet diamond core drilling machines have been designed to satisfy all of these requirements.

Applications

Diamond core drilling is useful for a wide range of applications, from creating openings for pipes, conduit, or ducts, to stitch drilling massive openings. They can also be used for taking core samples. However, the skill of the equipment operator is also paramount as there is no substitute for an operator who understands the machinery and the principles of how to operate it at its peak potential. The operator must also understand how to deal with workpiece and field conditions. 

 

Criteria for choosing a diamond coring motor

The key point of choosing a coring motor must be based on the sizes of holes needed to be drilled. Since a larger hole requires each diamond segment to travel further with each revolution, the larger the bit, the slower the rotation speed must be. Any given motor will have an optimum diameter range for each of its gear ratios. Most diamond coring motors have multiple gears to cover a broader range of sizes. The gear ratios and the motor power are key criteria. A motor with less power, even if the RPM is correct, will tend to work less efficiently and the bits will go dull easily. 

Wet diamond coring is one of the most stressful applications for an electric motor, with motors being worked to their limits most of the time. Additional features for the motor, such as an LED load indicator, help the operator to optimise the drilling process. An effective electronic motor protection suite and heavy duty features, such as all metal construction and oil bath gearbox, are vitally important. It is essential to choose a motor with high quality, durability and optimised design, which AGP states are found with its diamond core drilling line. 

 

Types of diamond core bits

Broadly speaking, there are two main types of bits, wet and dry. Dry bits are usually used for softer materials such as brick, while wet bits are used for hard concrete and reinforced concrete. The diamond segments of the bit also vary in their composition to apply to different work materials. The aggregate in the concrete affects the hardness of the material and it varies by region. The bond which holds the diamonds in the segment needs to be of a certain hardness to keep the segments sharp. 

In other words, as the segment wears away, new diamonds are exposed. If it wears too slowly, the segment will polish smooth. If it wears too quickly, the segments will be wasted unnecessarily. It’s a bit counterintuitive, but the harder the material, the softer the bond in the diamond segments needs to be, and the softer the material, the harder the bond should be. Choosing the correct type of diamond segment will allow drilling to be more economical and effective. 

Drill stands are also of importance, as although some coring motors can be used hand held, this should be limited to diameters below about 80mm for safety reasons. The gear ratio for drilling anything larger than 80mm has far too much output torque to be held by hand and absolutely requires a drill stand to be used. 

The key characteristic of a drill stand is its stability. It needs to hold the motor steadily as it plunges into the workpiece and to resist the torque created by the motor. Excessive vibration and backlash will lead to poor drilling performance, shortened core drill life and possible danger to the operator. A good drill stand will have features which make it easier to use such as quick release cradles, convenient adjustments, and integrated spirit levels. AGP recommends its own line of drill stands as the company says that all save time for the operator and enable better work efficiency. 

 

Water feed

Naturally wet drilling requires a supply of water. The water acts as a coolant to keep the diamond segments cool whilst also helping to flush away the ground down concrete as it drills, mixing to become a slurry. This water also eliminates dust in the air. Water can be taken straight from the tap, or if that is not available on the job site, water can be delivered by a portable pressure tank. In freezing conditions, antifreeze can be added to the water in a pressure tank. 

 

Conclusion

A successful wet drilling operation requires five main elements: a skilled operator, a good quality and powerful motor with the correct speed, a suitable bit which is sharp, a stable, properly fixed drill stand, and sufficient water supply.  If any one of these elements is lacking, then the wet drilling operation will be sub optimal. AGP states that it believes that it provides the best equipment possible, but it’s still up to the end user to ensure that every element of successful wet drilling is in place.

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