Process Description, Types and Applications of CNC Drilling Technology

Holes are an essential feature of almost any machined part or tool, whether for aesthetic or assembly purposes. In precision manufacturing, we need precise holes. This is exactly what CNC drilling technology is used for. It is a CNC machining process designed to machine precision holes in a variety of materials. It covers a wide range of tasks from simple single hole machining to complex multi-axis machining.This article provides an in-depth look at CNC drilling, its detailed process, tools, and types of drilling machines.

Description of CNC drilling process?

CNC drilling is a computer-controlled subtractive machining process in which a rotating drill bit creates circular holes in a fixed workpiece, which may be wood, metal, plastic or composite materials. To drill, the operator presses a rotating twist drill with multiple cutting edges into the workpiece to create a circular hole that matches the diameter of the drill bit. This hole is mainly used for assembly and is used to install bolts or screws. Traditionally, workers drilled holes manually, usually using a power drill on a drill press. They manually adjust the cutting tool movement and depth of cut. However, CNC drilling automates the entire process, with programming codes to control the drilling operations.

Universal step-by-step procedure for CNC drilling processes

CNC drilling may seem like a simple drilling operation, but achieving such high precision requires a lot of effort. Here’s a breakdown of the process:

Step 1 Create workpiece geometry: Design the workpiece geometry on CAD software such as SolidWorks or Fusion 360. The design includes all technical details including dimensions, location of holes, size and depth. It is like a blueprint that lists all the requirements precisely. CAD software is often paired with CAM software to convert the design into G-code, a programming language that CNC drilling machines can understand.

Step 2 Select a suitable drilling cycle: Next, in G-code programming, you can select any of the three drilling cycles as per your specific requirements. G73 (chip breaking cycle) is suitable for situations where the hole depth exceeds three times the diameter of the drill bit but is within the effective insert length of the drill bit. G81 (shallow hole cycle) is suitable for drilling center holes, chamfers and holes up to three times the diameter of the drill bit. Additionally, choosing to drill holes with internal coolant tools increases efficiency. G83 (deep hole cycle) is used to process deep holes.

Step 3 Choose the right tool and tool holder: The drill bit plays a key role in the drilling process. A twist drill is often used because it is so versatile. However, center drills and step drills are also options for specific applications. It is equally important to choose the tool holder that will hold the tool head in place. You need to consider taper type, toolholder compatibility and tool overhang before making your selection. Common choices for CNC drill bits include collet chucks, end mill shanks, and hydraulic chucks.

Step 4 Determine appropriate tool parameters: Enter the necessary tool parameters (such as length and diameter) into the CAM system. These parameters are critical to ensuring that the tool operates correctly within the predetermined specifications of the workpiece.

Step 5 Set up the CNC drilling machine: Place and clamp the workpiece securely on the machine tool. Make sure the cutter head is properly installed on the tool holder. For secure fixation, use mounting plates, clamps or magnetic chucks. Keep them close to the drilled area and do not over tighten.

Step 6 Programming a CNC Drill Machine Traditionally, operators manually write G-code. Today, advanced CAD and CAM software can automatically generate these codes. With only minor modifications, it can be fed into a CNC machine. This automation simplifies the setup process. You can do a test run to see if everything runs smoothly and if there are any program errors. In addition, please turn on the cooling system of the machine.

Step 7 Actual Drilling Process: Once operation begins, the CNC machine follows the programmed path exactly. The drill moves to the specified coordinates and drills the hole to the specified depth and diameter. The machine tool’s automation system manages speed and feed rates to ensure efficient and precise drilling.

Step 8 Quality inspection and post-processing: After drilling, check the accuracy and quality of the workpiece. Technicians take measurements to ensure tolerances are within specified limits. All necessary post-processing, such as deburring or additional finishing, is performed to ensure final specifications are achieved.

Advantages of CNC drilling technology

Automation and computer control make CNC drilling operations very convenient in industrial applications where precision, accuracy and efficiency are critical. Some advantages of this process include:

Precision and Accuracy of Drilling: CNC machine tools achieve extremely high precision with their CNC and programming technology. They are capable of drilling stably to tolerances up to ±0.005 inches (±0.127 mm). This makes CNC drilling a favored processing technology in all walks of life.

Improved efficiency and productivity: Compared with traditional drilling methods, the CNC drilling process significantly improves efficiency and productivity. This is mainly due to its degree of automation, which minimizes manual intervention and reduces the possibility of errors. It is also much faster than manual operation, thus reducing production time.

Ability to handle complex drilling tasks: CNC machine tools are versatile and capable of handling complex drilling tasks that are often challenging or even impossible to complete manually. With CNC machining, we can drill holes of various sizes and depths with precision and consistency.

Important Considerations for Accurate Drilling

In order to achieve the desired drilling results, the following additional information may be helpful.

Tip 1 Choose the right drill bit: The drill bit is a key component in the entire drilling process and needs to be chosen wisely based on your application. One classification of CNC drill bits is based on coating; including titanium carbonitride drill bits, aluminum nitride drill bits, oxide drill bits and diamond drill bits. Each drill bit differs in durability. A more common classification is based on the profile (shape) of the cutting tool.

Tip 2: Optimize spindle speed and feed rate: Feed rate and spindle speed are key parameters that need to be optimized. They depend on a variety of parameters, including material hardness, tool diameter, and often diameter depth. You can start with the settings recommended by the manufacturer and then try to optimize them through calculations. An online feed calculator may be able to help you.

Tip 3 Use a suitable coolant or lubricant: For metal drilling, it is usually recommended to use a mixture of water and soluble oil. The exact ratio depends on the metal type. For example, when drilling aluminum, the coolant is a soluble oil, of which 80-90% is water.

Tip 4 Clamp the workpiece securely: Use clamps and clamps that are appropriate for the size and shape of the workpiece. Make sure the workpiece is clamped securely to prevent movement during drilling. Correct clamping improves stability and safety.

Types of CNC Drilling Machines

There are many types of CNC machine tools depending on the machine configuration and the type of cutting tools. The following six types of CNC machine tools are common in the drilling field:

Multi-axis Drilling Machine: As the name suggests, this machine tool comes with multiple spindles that can hold drill bits simultaneously. It is ideal for machining parts with multiple holes or densely packed holes. It is an essential tool in batch production environments.

Mini Drill Press: This drill press is known for its precision. It comes with a small chuck designed for precision drilling. Ideal for applications that require high tolerances and precision, such as medical parts manufacturing.

Vertical CNC Drill Press: The most common drill press also comes in manual versions. It is rugged and designed for heavy-duty and oversized components. The machine has a gear-driven spindle and can drill holes in the thickest materials.

Radial CNC Drilling Machine: A radial drilling machine features a movable spindle that is located above the fixed workpiece. The drill’s mobility enables the machine to accurately handle parts of various sizes and shapes. It is ideally suited for use on CNC beam drilling production lines.

Turret Drilling Machine: The turret refers to the rotating tool holder. The machine features a turret that can accommodate multiple tools. It is ideal for operations that require regular tool changes. Ideal for complex tasks with diverse drilling requirements.

Row drilling machine: This drilling machine is equipped with multiple independent working heads for continuous operation on fixed workpieces. Its design simplifies the drilling process and is particularly suitable for tasks requiring a series of drilling operations.

Common six CNC drill bit types

Twist drill: A cylindrical shaft with spiral grooves. Versatile and can be used to drill holes in wood, walls and a variety of materials.

Center Drill: Short, stiff, with countersunk hole and pilot section. Creates a starting point or “point” for precision drilling.

Step drill: conical shape with stepped cutting edges. Drill holes of various diameters, especially in soft materials such as aluminum.

Jet Suction Drill: Tube-in-tube design with carbide tip. Drill deep holes with diameters ranging from 19-102 mm.

Indexable drill bits: carbide or ceramic, wear-resistant, with coolant channels. Efficiently cuts large holes approximately five times their diameter.

What are the main differences between CNC milling and CNC drilling?

CNC milling and drilling are two distinct processes. The main purpose of CNC drilling is to drill holes in the workpiece. The rotating cutter head moves in a single direction to achieve drilling. In CNC milling, the rotating cutting tool moves in multiple directions (horizontal + vertical) to cut and remove material and shape it into the desired shape. Milling comes in many forms; its use cases are machining and achieving complex shapes.

What are the main differences between CNC lathes and CNC drilling?

CNC lathes are used for CNC turning. During turning, the workpiece rotates while stationary cutting tools cut and shape the material. Its uses include profiling, threading and shaping of cylindrical or spherical objects. In contrast, CNC drilling is just drilling holes. In this case, the workpiece is stationary while the rotating drill bit is pressed into the workpiece to drill the hole.

How deep can CNC drilling be?

The depth a CNC drill can reach depends on the drill and machine tool specifications. Generally speaking, most CNC drill bits can easily handle depths of 5x diameter. If it is 5-10 times deeper, pecking drilling technique is required. Beyond this depth, you can employ custom drilling cycles and deep hole drilling techniques. It is estimated that in extreme cases, depths of nearly 400 times diameter can be reached.

Partner with Xtproto and start your CNC drilling project

Are you interested in custom drilling services? By choosing Xtproto, we are able to machine a wide range of complex, high-tolerance holes in a variety of materials from metals to plastics and composites. Our commitment to quality ensures every drilled component meets the highest standards. But our expertise doesn’t stop with CNC drilling. Xtproto offers comprehensive CNC machining services for all your precision manufacturing needs. To experience our convenient service, just send your design files directly to our backend. You’ll receive an immediate quote and enjoy a free Design for Manufacturability (DFM) analysis from our experienced engineers. Choose Xtproto for a fast, easy and reliable solution to start your CNC drilling project today.

In Conclusion

Part assembly is mainly done through fasteners such as nuts. The hole is the basis for fastening. CNC drilling is a precise and fast drilling method suitable for drilling holes in a variety of materials. Whether your project requires the machining of small, intricate holes, or large, sturdy holes, there is a CNC drilling solution to meet all your needs. Interested in custom drilling services? Contact the team at Xtproto today for professional help.

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