Efficient milling tool with many performances


The most common milling process currently in the shop is square shoulder milling, which means that this special prismatic metal cutting strategy has great potential for improvement in productivity, availability and product quality.

In many end milling applications where end faces, perimeters and grooves are required, square shoulder milling is often seen. The cutting performance of square shoulder milling can be improved from two main aspects, namely achieving a higher metal removal rate and a single pass machining to produce an excellent surface quality. With the continuous development of milling technology, Sandvik Coromant can now combine these necessary processing capabilities with the introduction of a unique new milling tool concept, the CoroMill 490.

Combination ability is crucial
When developing the concept of a new square shoulder milling cutter, it is critical to combine the high quality plane with the square shoulder surface. Some milling tools are capable of cutting high-level end faces or square shoulders, but no tool can combine both high precision and high surface quality. In addition, in order to achieve higher production efficiency, it is necessary to combine excellent end face and square shoulder finishing milling with a roughing process with high metal removal rate, and sometimes it can be processed in one pass.

For many users, the tool cost is the same as the tool inventory and is placed in a prominent position. The square insert provides four cutting edges and also provides the optimum cutting edge for each insert. In order to achieve the goal of combining roughing and finishing tools (whether or not a square blade is used), it is necessary to provide a new cutting edge that can simultaneously produce end faces and square shoulders.

In any multi-tooth milling tool, parallel forging of the cutting edge is a decisive factor in the generation of the end faces. Parallel forging must be longer than the feed per revolution of the tool to ensure a good surface quality. One of the problems with parallel forging is that the cutting edge is too long to increase the cutting force and is therefore prone to vibration. How to have the most suitable parallel forging without inherent disadvantages is the main challenge.

Based on a sufficiently large axial rake angle and a sharp cutting edge in the insert, the solution was further developed with this lightweight cutting tool design. The shearing of the basic tool geometry also indicates that the blade will enter the material at a negative lead angle, which ensures smoothness and increased strength. The unique new parallel insert forging and tooling features successfully developed is a key factor in ensuring CoroMill 490's processing capabilities. This tool achieves the best metal removal rate per unit of power consumption.

Optimize in many ways
1. Wiper (wiping edge) technology
This is the core part of the solution. Developed by Sandvik Coromant for turning, and further developed for CoroMill 490 parallel forging and insert cutting edges for square shoulder cutting. When cutting, tools with multiple inserts can easily cause some tooling errors through the transitions produced by each blade forging. In addition, there is also the problem of tool skewing, which causes a certain program to skew during cutting, and the use of conventional parallel forging often has a negative impact on the surface quality due to the sharp transition edge.

The CoroMill 490 blade parallel forged multi-curved Wiper design compensates for tolerances and angular misalignments during cutting. This not only minimizes any tooling errors, but also eliminates the need for subsequent finishing.

2. Optimize with blade grades
A sharp cutting edge with a positive rake geometry is a key feature of lightweight cutting, especially with a large number of parallel forgings, which allows for high productivity, high surface quality and true 90° square shoulders with square inserts. In order to achieve this characteristic at high feed rates and high cutting speeds, the blades must have high strength and durability.

For CoroMill 490, the new PVD coated grade GC1030 is the answer, especially for small diameter applications, unstable conditions, large tool overhangs, and demanding tool cuts and cuts.

The CoroMill 490 is available in a wide range of insert grades including CVD coatings and PVD coated grades. Blades made with CVD grades are not as sharp as those made with PVD grades, but are still used in CoroMill 490, which provides higher cutting speeds and longer tool life. For example, GC4230 (CVD) is a general-purpose insert grade with wear resistance that optimizes cutting speed for end mill applications, while GC4240 (PVD) is a tough steel grade with cutting edge toughness for this grade. It is its decisive parameter.

3. Optimized with blade geometry
The square shoulder milling process usually uses a very moderate feed rate. Recent studies have shown that the vast majority of feed rates per tooth are below 0.12 mm. These feed values ​​are acceptable for the finishing process, but they are somewhat inadequate for cost-effective general and roughing processes.

The CoroMill 490 is a highly efficient tool with high metal removal rates (up to 0.22 mm per tooth feed) and high precision milling (feedrates down to 0.05 mm per tooth). To optimize its wide range of applications, three different insert geometries are now available: L, M and H.

The H-slot shape is suitable for a large range of feed per tooth, while the L-slot blade transforms the CoroMill 490 into a powerful finishing tool. The per-tooth feed range of the M-blade geometry covers the central general range.

4. Depth no longer needs
Now, small depth of cut is preferred in the workshop, as is the case with small machine tools. Power limiting is also one of the factors, especially for ISO taper 30 and 40 machining centers and for deploying most turning and milling machines and turning centers.

This helps to clarify the direction of the new generation of square face milling cutters. Test results show that the maximum depth of cut for the CoroMill 490 is 5.5 mm and the recommended value is 4 mm. It offers the possibility of a new concept tool with a square insert, which also lays the foundation for high blade stability and good tool economy through precise and safe blade positioning.

5. Choose the right square shoulder milling cutter
Tool selection depends on the existing cutting process, but when they match the high performance of the CoroMill 490, it must be preferred for optimum performance, results and predictability. With the first tool CoroMill 490 based on the new square shoulder milling platform, milling has taken a big step forward.

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