The demand for manufactured or machined parts, both standard and non-standard, is increasing in various industries, and CNC machining is the most preferred method for performing various techniques to achieve the desired shape and size. It has a high level of efficiency and can perform difficult tasks with the utmost precision. It can even perform repetitive and mundane tasks with the same accuracy and detail, regardless of the scale of complexity. The tool path is essentially its planning mode, which helps to complete the machined object as needed.
What about technologies such as CAD and CAM?
With CAD technology, or CAM software, CNC machining workshops can create the programs discussed in the article, which then transform complex designs into desired physical parts. If you are new to CNC machining, the term "tool path" may be confusing. The software provides a series of coordinates that the device follows to meet the exact requirements of the machined material. This is the trajectory that the cutting machine follows to achieve the appropriate geometry of the processed object. Currently, almost all CNC machining techniques use this, and CNC milling is no exception. Want to learn more about this topic? What is the tool path mode? What factors affect patterns in CNC milling? If so, this article will answer all these questions in detail. After reading it, you will be up to date.
Short overview of tool path mode and feed rate
As mentioned earlier, tool paths operate as separate programs during machining. CAD and CAM technologies stimulate them, creating coordinated positions. Cutting tools follow these coordinates during work, which in turn allows to detect the tool holder's gearing and alignment of the machined object, calculate the speed of the operation and learn the details of other important parameters. There is no single milling path. Currently, CNC milling paths are in 2D, 3D, 4-axis or 5-axis configurations, depending on the number of machine axes and how it moves. The terminology related to axes can be confused with the term 2D, as in the case of the former there is a value in the form of the Z axis. However, it is worth mentioning that it only represents the tool's position at a certain depth and is constant during work. Therefore, 2D labels make sense, as the cutting operation takes place only on the x and y axes.
Factors affecting the tool path mode in CNC milling
Below is a list of some typical factors that influence the tool path patterns in CNC milling. Let's take a closer look at them. The first and most important one to consider before starting work is the material of the item being processed, as it determines the machine's operating mode. The material being processed does not directly affect the feed, but it will have a very significant impact on the choice of tool size, material, processing method, etc. The geometry of the object, such as shape and size, reflects on the uniformity of the distribution of surplus for processing the required part. Similarly, details with optional semi-finished products affect the distribution of development strategies and fastening methods. This will result in a different way of feeding the tool, and consequently also has an indirect impact on the tool's operating mode. This may include adding additional forces to the cutting method, variability of vibrations, etc. Another important point is the choice of the tool or tools itself. This may include very different parameters, such as the material used, tool length, number of teeth on it, etc. These technical specifications determine the contact surface and frequency between the processed item and the machine. This in turn helps to determine the volume per unit of finished material, degree of wear, load on machine tools, etc. Routing determines the optimal sequence of operations to achieve the set cutting goals. In addition, it determines the rough machining lines, the order of machining areas, and the partitions or dividing lines between semi-finishing and finishing. The desired intent can be achieved using different process paths, which determine the choice of CNC machine tool program mode. Proper working procedures are extremely important to obtain clean and precise parts during the performance of various CNC milling operations. Depending on the application requirements, different tool path strategies can be chosen. This will increase the machine's durability, overall cost efficiency, and cycle time. Today, almost every CNC shop/workshop offers very precise machining, as well as diverse, modern tool solutions. One of them is BDE (BDE) production technology. Thanks to many years of market experience and a qualified team, the company meets the needs of customers from various industries through efficient CAD/CAM programming of complex parts.
Practice and methods of choosing feed
When choosing the method of administration, two points should be considered: the length of processing time and whether the allowance for processing is set evenly. The round cutting mode based on the shape and allowance of the processed item is generally considered a relatively uniform cutting method. A characteristic feature of row cutting method is that the allowance for processing is relatively uneven. To ensure a larger clearance, increase the length of the tool path to make a round cut around the boundary. The sizes of straight cutting tool paths are often short, and this happens if the requirements for material heterogeneity are not met. In the case of considering uneven margins to increase the length of the circular cutting path, when the boundary of the processing area is large, the circular tool path around the boundary has a greater impact on the total processing time. Horizontal cutting paths are generally more efficient than those circular. It is easier to calculate the position of the tool by arranging the tools and what is also a big plus it takes less memory. However, it should be added that in such a case the tool must be used multiple times. If you use a circular tool path, you will often have to move the boundary of the ring and remove it from the self-intersection line.
Selection according to appearance features in CNC
The way of processing an object depends on its shape. Using various processing projects, details can be divided into flat surfaces with grooves or of any shape. Row cuts are used to create grooves with a flat shell. Such details have large allowances, as they are usually formed by rough machining and turning, such as bases, for example. Linear processing is an excellent way to improve the progress of the machine tool. Row cutting is faster, more efficient, and provides a better working surface than round ones. Peripheral cuts are suitable for any surface shape. This is because the area is usually cast from solid material, and the edges are not evenly distributed. In such cases, there are also higher requirements for precision. The surface can be closer to its true form than when it has good processing properties.
Select a CNC machining strategy
Part machining is usually divided into three stages: roughing, semi-finishing, and finishing. Sometimes there is also a final stage. To ensure the accuracy of cutting, it is important to divide the steps into reasonable segments. Traditional techniques are limited to just one machine function. Therefore, the boundaries of individual stages are displayed along the route. However, in the case of CNC milling processes, these are blurred and can be mixed. The main purpose of roughing is to reduce the amount of material removed in a given unit of time and to prepare the geometry of the workpiece for semi-finishing. Layering is often done by cutting rows and mixing. The main purpose of semi-finishing is to smooth the contour of the material and unify the surplus of surface finish. The so-called trimming method is commonly used. The geometric characteristic of the developed texture requires the use of an internal cutting method, while the peripheral cutting method is used for edges and joints.
Select a CNC programming strategy
You should be able to achieve the desired processing in terms of precision and surface roughness, as well as reduce downtime and minimize the complexity of numerical calculations by choosing the right strategy. It is worth considering minimizing the amount of work we have to put into its preparation and programming. Below are a few valuable remarks that we must remember when planning activities. If you have additional suggestions - share them with us! Nevertheless, we indicate the most practical factors that affect the feed rate and may be significant:
- The row cutting method reduces tool lifting,
- In case of flat-shaped defects, a given area can be divided by the row cutting method,
- The freeform milling method approximates the shape,
- Programming options depend on the size of the cutout,
- The semi-finished product can be enlarged to facilitate its mounting. Alternatively, you can transform any shape surface created by circular cutting into linear cutting.
- To improve processing efficiency, semi-finished products can be largely cut out.
The durability of the tool can be improved through proper tool engagement during milling. The feed rate over time may vary during machining.