CNC cutting tools, hard material technology!

In the mold manufacturing process, the use of hard material milling technology can replace some of the most expensive and most time-consuming processing steps, which can eliminate or greatly reduce the work of electrode milling, EDM processing, grinding, polishing, and point by point dressing on press.
Processing in “walnut shell”
Hard material milling technology is a branch of high speed machining technology. The core of high speed machining technology is to carry out multiple minor cutting processes with close steps, thus leaving only very tiny machining traces on the machined surface. The goal is to greatly reduce the requirement for subsequent processing. For the tool, in order to achieve effective chip load, the tool feed speed and spindle speed must be greatly improved to exceed the normal processing speed used in the traditional processing technology, so the process is named “high speed machining”. High speed feed also greatly improves the cutting speed of cutting tools, so the speed of machining workpiece is faster than that of traditional methods.
The technology of hard material milling is a step further than the concept of high speed machining. The combination of high speed light cutting and high speed spindle can effectively process hardened steel, so that the original properties of materials can be maintained. At the same time, a small diameter round end end milling cutter is used for high speed machining with close interval interval. The surface finish of the machine is close to the level of hand grinding and polishing.  Because steel is processed under hardened condition, there is no need for subsequent heat treatment, stress relief or grinding. More importantly, this process can also replace many EDM processes with high processing cost.
Another advantage of hard material milling technology is that it can guarantee very precise tolerance size (10mm), which is precious to die processing. The moulds after processing do not need to be trimmed by manual work, and the shape of the die is completely consistent with the CAD design model because of the degree of no manual finishing after processing. Moreover, the processing of mould mating surface has reached the level without any dressing. The concept is to follow the parting line, usually at one end of the die cavity, to make a little bit more precise, so that it is slightly lower than the nominal size. In this way, when the half of the die is closed, a little gap between the contact surface of the die can be left, but the gap is very small (usually only 0.2mm), so that a part of the plastic can be flow out in the injection molding, but the die can still keep the closed state effectively. Moreover, when molten plastic is injected into the mold, this gap also allows air to be removed from the gaps without prior ventilation. The small contact pad on the corner keeps the gap, otherwise the contact between the closed surfaces will not be able to touch each other. Generally speaking, the interference between these mating surfaces must be solved in the process of point by point dressing and matching. There is no such problem now. When the core and die cavity are closed, the interaction between the surfaces is eliminated because of the clearance, so the surface is completely protected and the parts produced will not appear to be flying.
Improve efficiency from the tip of the knife
Mastering the technology of hard material milling may be a challenge.  The way to understand hard milling technology is to know how to protect the tool tip. Concentrate on making cutting tools safe and effective. If all of these are managed in an orderly way, the tip of the end milling cutter can be integrated with the processed materials and be machined freely. If any part of the system is neglected or interrupted, the tool tip will suffer and the whole process will fail.
Taking the problem of end milling as an example, the following factors should be noted:
1. Cutting tools
Generally, round end end mills are used for rough machining, semi finishing and finishing. The round end milling cutter with two chip grooves is specially used for finishing. In the hard material milling process, these finishing tools are very important. A round end end milling cutter for finishing must meet two key requirements: the tool must have a near perfect radius and a virtually flawless cutting edge. The precision of the radius of the blade must be very high, so that both the high or low chip grooves will not cause the unaverage state of the metal scrap, so as not to affect the geometric shape, reduce the surface quality and the tool life, the precision of the end milling cutter used in the workshop should be at least 10mm. The circular end milling cutter with a diameter of 0.3mm is also used occasionally, with a radius accuracy of + 5 mm.
The cutting edges of chip removal grooves will inevitably have some trace chips, breakage or other irregular shapes. These defects show that they accelerate wear when touching workpiece. This situation will lead to rough roughness and shorten the service life of the tool. The service life of a tool is a very critical factor, because when the machine is unmanned, the workshop is entirely dependent on the End miller to work to the desired time limit.
Suppliers such as OSG and NS tools can provide tools that meet the above specifications, but their prices are much higher than those of standard tools. It is absolutely necessary to use this quality grade tool, and the cost should not be a problem. These tools are the basis of die processing, which can save the polishing process and the point by point trimming process of the mold. In the hard material milling process, it is a very important investment to add these tools.