Machining with CNC turning
Turning is a well-known metal machining method used for various metals and plastics. This technique allows for the creation of symmetrical components with outstanding precision and impressive surface quality.
Turning is carried out on a lathe and can be adapted to a wide range of tasks. Depending on the type of lathe, it can be used for everything from manufacturing individual custom components to producing larger production runs.
What methods are used for turning?
Modern metal lathes and machining centers utilize CNC technology to produce metal components, and we are no exception. Computer Numerical Control (CNC) precisely controls tool movement through accurate code instructions. CNC control offers the significant advantage of increasing both efficiency and precision, resulting in a more cost-effective price for turned metal components compared to manual turning. In turning, the workpiece is securely clamped to the main spindle and rotated at high speed. Since it is the workpiece that rotates, not the tool, metal turning is particularly suitable for producing symmetrical components.
Profile turning differs from longitudinal turning by being a more complex process. In this technique, the feed motion of the tool still moves along the workpiece's axis, meaning that machining occurs on both the inside and outside of the workpiece. However, the difference lies in the fact that the tool "intrudes" into the workpiece to create a specific profile, such as a groove or narrowing. Profile turning involves greater variations in feed, depth of cut, and speed, adding a level of complexity to the process. This technique is suitable for creating unique workpiece profiles and is often customized to meet specific design requirements.
Facing is a relatively straightforward turning process where the tool moves radially inward toward the center of the workpiece. In other words, cutting is performed from the outside and inward. Depending on the task, different tools can be used in this process. Facing is primarily used for external machining of workpieces, while longitudinal turning or profile turning is used for internal machining.
Automatic turning, often used for large production runs, is a fully automated process. In this process, the material is fed into the automatic lathe at one end, and the finished component emerges at the other end, possibly on a conveyor belt. The automatic lathe clamps the workpiece by itself during the process, and multiple machining operations can be performed in the same setup. Different machines are available for various workpiece sizes and shapes. In general, automatic turning is an efficient process that can result in significant cost savings when large quantities of components need to be produced.
Longitudinal turning, also known as lengthwise turning, represents the most common form of turning. Here, the tool moves along the axis of the workpiece in a feed motion (also called cutting motion), which involves machining either on the outside or inside of the workpiece. Longitudinal turning is used to reduce the diameter of the workpiece and can be performed on both the inside and outside using various tools.
Taper turning represents a variation of longitudinal turning where the workpiece gradually increases or decreases in diameter. The term "taper" refers to a cone, and taper turning results in the creation of conical or tapered workpieces. Workpieces manufactured by taper turning have a wide range of applications in the machinery industry and include components like collets, chucks, milling and turning arbors, couplings, tapered gears, and more. Taper turning can be performed using various techniques and, in some cases, requires specialized lathes to achieve the desired result.
External and internal
Turning can be used to create both external and internal threads. External threads are typically generated using cutting tools or threading heads, while internal threads are usually achieved using a tap. The advantage of using turning for threading is that it allows for the correct thread profile to be created, and the surface roughness of the threads can be precisely controlled. Effective thread turning requires a smooth and precise turning process to achieve the desired thread pitch and profile. Therefore, it is a task that demands experience and expertise.
The turning process
Turning refers to a type of machining called "chip removal machining." This involves removing material or chips from the workpiece to shape it as desired.
The core of the turning process is the continuous rotational movement of the workpiece, which is attached to the main spindle. The feed motion is a linear (non-rotational) movement performed by the cutting tool, which pushes or cuts against the workpiece, removing chips in the process. The feed motion is the basis of material removal.
Since the workpiece material is typically softer than the tool material, the workpiece will yield and deform or break when it encounters the cutting tool.
The most significant factors affecting the outcome of the turning process are:
Cutting speed (how fast the workpiece moves for the cutting tool).
Depth of cut (how deep the tool goes into the workpiece to create chips).
Feed rate (how fast the tool moves through the workpiece).
These parameters are finely adjusted to achieve the desired machining result.
Materials that can undergo a turning process
A wide range of materials can undergo the turning process. When working with turning, it's important to consider the specific mechanical properties of the chosen material, including tool selection and method.
Some of the materials that can be processed by turning include:
Steel and Various Steel Alloys.
Super Alloys based on metals like nickel, iron, cobalt, and titanium.
The choice of material often depends on the intended application and the required mechanical properties of the finished product.
Different materials may require specific tooling and machining parameters to achieve the desired results.