Introduction to Wet Diamond Core Drilling

Wet diamond core drilling is the fastest and most economical way to drill precise cylindrical openings in reinforced concrete. Drilling reinforced concrete is challenging because of the hardness of the concrete material on the one hand, and the difficulty of cutting the steel reinforcing bars which are embedded in it. The cutting tools are diamond segment-tipped core bits, since they perform best on hard concrete, but the steel rebar is difficult to cut with diamond segments. It takes a powerful motor to drive the core bits and they need to deliver the correct speed and the required torque to do the job.  AGP’s line of wet diamond core drilling machines are 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.

Equipment Operator

There is no substitute for an operator who understands his machine and the principles of how to operate it at its peak potential. The operator must also understand workpiece and field conditions.

How to Choose 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 are the first criteria, and the motor power is the second. 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. It is essential to choose a motor with high quality and optimized design such as the AGP diamond core drilling line.

Types of Bits

Broadly speaking, there are two main types of bits, wet and dry. Dry bits are usually used for softer materials like 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.

Drill Stands

Although some coring motors can be used hand-held, this should be limited to diameters below about 80mm for safety reasons. Anything larger than 80mm certainly requires a drill stand. The key characteristic of a drill stand is its stability. It needs to hold the motor steadily as it plunges into the workpiece. Excessive vibration and backlash will lead to poor drilling performance, shortened core drill life and possible danger to the operator. Choose from among AGP’s complete line of drill stands for your needs.

Water Feed

Naturally wet drilling requires a supply of water. The water acts as a coolant to keep the diamond segments cool and they also help to flush away the ground down concrete as it drills, and this 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 not succeed. At AGP we provide 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.