The appearance quality and dimensional accuracy of the copper electrode not only affect the cavity accuracy grade and dimensional stability of the Electrical discharge machining, but also affect the speed of the Electrical discharge machining, therefore, the copper electrode plays a vital role in the quality of the mold cavity.

1.Reason and harm of burr on Red Copper electrode

Due to the good plasticity of Red Copper, it is easy to produce burr in the process of processing. At the same time, the factors such as not sharp enough cutting tool and unreasonable machining reserve will also aggravate the Burr. The presence of copper electrode burrs can cause the following hazards:

(1) It affects the accuracy of the electrode dimension test result and the dimension precision of the workpiece. 

(2)Reduce The workpiece shape and appearance quality. 

(3)Because of the high and low burr of the electrode, it may affect the size consistency of the machined workpiece. 

(4)In the Electrical discharge machining process, if the electrode burrs fall off in the cavity, it will cause carbon deposition, resulting in the cavity size and poor appearance. In the process of precision mold manufacturing, the mold cavity processing precision and appearance quality requirements are high, the above hazards are very deadly, so the electrode on the burr must be removed.

2.Method of removing burr of Red Copper electrode

At present, the most common and traditional deburring method in die and mould industry is manual deburring after electrode processing. This method not only has high labor intensity, high technical requirements for workers, but also wastes working hours, low production efficiency and unstable deburring quality. In the electrode processing process, often replace the new knife, can improve the burr problem, but the cost is too high, and not easy to establish a strict standard, not easy to manage. Precision die manufacturing is a multi-variety, single-piece or small batch production, and the cavity shape, size accuracy has very high requirements, so special mechanical, electrolytic, electrochemical deburring methods are not suitable for electrode processing.

3.How to remove electrode BURR IN NC milling

Programming is one of the most demanding tasks in electrode machining. The emphasis of the programmer is to determine the electrode machining process reasonably, which is very important to realize high quality, high efficiency and economic electrode machining. Process analysis is a flexible part of electrode programming, which is influenced by many factors, such as machine tool, cutting tool, machining object (geometry, material, etc. . To some extent, it can be considered that process analysis is basically the embodiment of machining experience, so it requires programmers to sum up and accumulate experience in their work, so that process analysis can meet the actual needs of electrode machining. After many tests, a better effect can be achieved by adding the deburring step to the electrode processing. However, the following points should be noted:

(1)Control the direction of the Burr

3-axis vertical machining center is usually used in electrode machining. The direction of Burr should be controlled as far as possible (see Fig. 1(a)) , which is perpendicular to the rotating plane of the tool, that is, to the cutting direction. Try to avoid burrs left on the side of the electrode, parallel to the tool rotation plane (see figure 1(b)) .

The vertical burr is more convenient to remove than the one parallel to the rotating plane of the tool. Therefore, in the electrode finishing, should first process the top surface, and then process the side surface, in order to achieve fast, convenient to remove electrode burr.

(2)Direction of cutting tool

The deburring effect is better when the cutting direction is from the outside of the electrode to the inside (see Fig. 2(a)) , whereas when the cutting direction is from the inside of the electrode to the outside, the deburring is squeezed to the adjacent side and the deburring effect is not good (see Fig. 2(b)) .

The reason is that in the process of cutting from the inside to the outside of the electrode, there is plastic deformation space for the Burr, while cutting from the outside to the inside of the electrode, the burr has no plastic deformation space and can only be cut off.

(3) Forward and backward milling

For deburring, the forward milling (see Fig. 3(a)) should be used to cut the electrode from the outside to the inside, whereas the reverse milling (see Fig. 3(b)) will produce the effect of cutting from the inside to the outside.

(4)deburring

Fig. 4 and Fig. 5 are two kinds of deburring tool paths. Among them, Fig. 4 is plane deburring tool path and Fig. 5 is curved deburring tool path. The specific method is: 1. Plane deburring can be done by plane milling, and the top profile of electrode can be machined by flat-bottomed cutter. 2. Surface deburring select area milling (areamilling) projection milling method, cutting surface (cutting area) select electrode top surface, machining method setting and variable step setting should be reasonable, otherwise there will be knife marks on electrode surface. This method can remove the burr on 80% copper electrode (some special shape electrodes need manual deburring) and reduce the work load of electrode polishing (manual deburring is usually in the charge of polishing personnel) , reduce the difficulty of processing, improve the quality of electrode processing, and will not increase a lot of processing time. 

Source: Die Industry, Original Text Author: Wang Yi, Yan Lili, Gao Jutao

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