At first, understand the difference between CNC turning and milling machines. Simply speaking, CNC turning machines make round components. While numerically controlled CNC milling machines produce parts on a flat surface. During CNC turning, the work piece is held in a chunk and rotated, but the single point cutting tool does not move. But in the milling operations, the tool rotates, and the milled parts keep still. Below, we introduce turning and milling respectively.
What is CNC milling and turning?
CNC turning process
CNC turning features
At first, it is easy to ensure the position accuracy of each machining face of CNC turning parts. For example, it is easy to ensure the coaxiality requirements. If using the chunk to install the work piece, the rotary axis is the spindle of computer numerical control CNC lathe. And when using front and rear centers to mount the work piece to remove material, the center line of them is the axis of rotation. Besides, it’s also easy to ensure the verticality of the end face and the axis.
Secondly, the processing of CNC turning machines is relatively stable. It avoids inertial force and impact force, allows a larger amount of cutting. High speeds turning operations are conducive to improving productivity and get short lead times.
Thirdly, it’s suitable for precision CNC machining services of non-ferrous metal parts. If they have large surface roughness and smaller Ra values, we’d better not use grinding, but CNC milling and CNC turning. And using diamond cutting tools for precision turning can get high quality CNC machining parts.
Finally, the single point cutting tool is simple. And it’s convenient to manufacture, sharpen and install the cutter.
CNC turning application
Using different turning tools or other tools in the CNC turning center can process a wide range of rotating surfaces. Such as inner and outer cylindrical surfaces, conical surfaces, threads, grooves, end surfaces and forming surfaces. The processing precision can reach IT8-IT7, and the surface roughness Ra value is 1.6～0.8. Usually, the CNC machine shop uses turning operations to produce parts with a single axis, such as straight shafts, general discs, and sleeve parts. If we change the position of the work piece or suitably modify the CNC lathe, it can also process multi axis parts or disc cams.
During rapid prototype and small batch production, we make a wide range of shafts, disks, sleeves and other custom CNC parts. And they are usually processed by horizontal lathes or CNC turning machines with wide adaptability. For parts with large diameters and short lengths ( length-to-diameter ratio: 0.3- 0.8 ), CNC turning and CNC milling parts suppliers often use vertical lathes. When mass producing small parts with less complex shapes such as screws, nuts, and pipe joints, we mostly use semi-automatic and automatic CNC machines. Its productivity is high but its accuracy is low.
CNC milling process
First of all, it has a high productivity. During milling processes, the cutting tool rotates continuously and allows high speeds. Therefore, the CNC milling machine has high productivity.
Secondly, cutting is intermittent. During milling, each tooth is cutting intermittently, especially in end milling. The milling force fluctuates greatly, so vibration is inevitable. And when its vibration frequency is the same as or multiple of the natural rate of CNC machines, the wave is the most serious. Besides, in high-speed milling, the cutter teeth are also subject to periodic cold and thermal shocks. Thus, cracks and chipping are prone to occur, which reduces the durability of the tool.
Thirdly, it’s the multi knife and multi blade cutting. Cutting tools in a multi axis machine have many teeth, and the total length of the cutting edge is large. So, it’s conducive to improving tool durability and productivity. There are many advantages, also some problems. First, the cutter teeth are prone to radial runout, which will cause the different loads of cutter teeth, uneven wear and tear. As a result, it affects the quality of the processed surface. Second, the chip space of the cutter teeth must be sufficient, otherwise, they will be damaged.
Finally, there are different milling methods. According to different processing conditions, we can choose different milling methods to improve tool durability and productivity. For example, reverse milling, down milling or symmetric milling, asymmetric milling.
For other more features and applications, please refer to CNC milling service.
Difference between milling and turning conclusion
Both CNC turning and CNC milling operations can be used to produce complex parts. The main difference is the shape of the final components. For cylindrical parts, we select turning. And for most other components, adopting CNC milling. MLS Mold will be your friendly partner if you need high quality products, short lead times and cost effective solutions. We provide services including CNC machining, mold parts manufacturing, sheet metal fabrication and so on.