Molybdenum Wire Breaking Introduction

In the practice of wire cutting, used metal wires often take place breaking. When operators process the workpieces, molybdenum wire breaking happens. Then in many cases, they can’t find the cause why wires always break in wire cut machines. So the the processing is delayed and wire cutting precision is greatly reduced in some ways. In this paper, take the molybdenum wire as an example, we analyse the common moly wire breakage during the wire edm machine cutting practice.

Keywords: Wire Cutting, Molybdenum Wire, Wire Breaking Analysis.

With the extensive application of wire electrical discharge machine cutting technology, the broken condition of molybdenum wire in the process is paid more and more attention. As to the DK77 series WEDM, the use of molybdenum wire is a case.

In EDM field, we currently use the wire diameter of 0.18mm molybdenum wire widely. But when internship operatots often practice, molybdenum wire can break out in a very short period of time. It just can not achieve the normal life of molybdenum wire, which will greatly increase the cost of wire cutting, waste of working time and make the processed workpiece being scrapped or the accuracy decline. Through the observation and analysis of the broken wire, we can conclude that molybdenum broken wire can be divided into the following cases:

Normal wire breaking

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In the course of common wire use, there will be the continuous loss of metal wire. In this case, molybdenum wire can complete the normal processing quite normally. The wire will gradually become thin, until it reaches the limit size and wire breaks. For the normal use of molybdenum wire on the cartridge, the color is silver. For the unused molybdenum wire which is retained by processing limiter device, the color is bright black.

Abnormal wire breaking

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Molybdenum wire tight wrap, coiling ways and other issues caused by wire breakage.

When producing molybdenum wire, if wire winds too tight, wire would be easy to be pulled  out. So this phenomenon notices us molybdenum wire winding can not be too tight and should tight and appropriate. Tighten wire after the completion of molybdenum wire. The tightness will reflect in the processing. If wrap too loose, molybdenum wire will vibrate sharply that makes workpiece is not enough. And large vibration amplitude will result in molybdenum wire discharge and cause molybdenum wire burnt. If wrap too tight, processing will exceed the tensile limit that molybdenum wire can withstand. Broken wire will also happen.

TAGUTI factory has specialized machines to wrap molybdenum wire well, so it assures the quality stability of molybdenum wires. Molybdenum wires are always our hot products. We can ensure the high quality, enough length and warm-hearted after-sale service!

2.2 The choice of coolant liquid on molybdenum wire broken wire

Coolant in the wire cutting process has an important impact on the wire breakage. Coolant materials have many types such as wire cut edm soap, concentrated ointment and coolant liquid. For example, the commonly used coolant is wire cut machine emulsion. When the emulsion is too thin, its ability to eliminate ionization will decline, and even frequently make molybdenum wire and parts short circuit which results in molybdenum wire breaking. When the emulsion concentration increases, its permeability and lubricity will be improved. But the concentration is too large, it will make cooling liquid difficult to enter the cutting part of workpiece, and make the chip processing hard removal which results in Molybdenum wire breaking.

In addition, to use coolant for a long period of time but do not replace will lead to increased impurities in the cutting fluid. During the processing, it will invoke molybdenum wire and parts from the secondary discharge which causes by molybdenum wire broken wire. So coolant needs to be replaced frequently when emulsion uses for a long time in the cutting fluid storage tank.

Our hot-sale product is JR-3A WEDM Super Concentrated Ointment Wire Cut Machine Coolant EDM Wire Gel with 9 bottles per box.

2.3 The impact on molybdenum wires caused by positive and negative electrode

In the workpiece processing, it often involves different pulse widths. When the pulse width is within 0.5-100μm, we tend to treat workpiece as positive electrode and molybdenum wires as negative electrode. We make use of negative effect to reduce the loss of molybdenum wire. Instead, when the pulse width is more than 300μm, we tend to treat workpiece as negative electrode and molybdenum wire as positive electrode to save the consumption of molybdenum wires. When the diameter of 0.18mm molybdenum wire in the processing of continuous wear and tear, every 0.01mm diameter of molybdenum wire processes 30000mm ~ 60000m and when its diameter is consumed to 0.11mm ~ 0.12mm, the molybdenum wire will be broken. Thus the choice of positive and negative electrodes can also be effective mitigation for molybdenum wire breakage.

2.4 The workpiece parts and the material itself resulting in broken wire

The material of workpiece will cause a very straightforward and vast impact on molybdenum wire breaking. If workpiece to process contains too much impurities or too rough surface, molybdenum wire is very prone to be broken, as well as when multiple parts overlap clamping, more attention should be paid on the tightness degree of EDM clamping in order to prevent the worlpiece displacement and cut off the molybdenum wire. Besides, too thin or too thick sheet metal parts will make molybdenum wire break. In the processing of parts too thin or a number of thin pieces of superposition, the pulse width can be increased appropriately so that molybdenum wire can stably discharge to reduce the occurrence of wire breakage. And when the workpiece is too thick, due to too long continuous discharge time of molybdenum per unit length, the internal cuttings is not easy to rule out. Therefore we need to increase the wire speed of molybdenum wire to reduce the molybdenum wire breakage.

Conclusion

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In the actual processing, the high speed wire-cutting machine faces more diverse as to the reasons for wire breakage. The above suggestions are just a few practical experience in the process of operation. Through continuous attempts and analysis , TAGUTI believe in the future processing, the application of high speed wire cut machine will be more extensive, molybdenum cutting wire life span will be further extended, the workpiece processing quality, processing speed and processing efficiency will be further improved.

Our TAGUTI factory produces high-quality molybdenum wires with a long history. TAGUTI molybdenum wires starting from 1997 initiate a new era of “Cold Drawing Molybdenum Wires” in Chinese EDM industry. We receive good feedbacks and do many OEM both in China and overseas. We have two versions for domestic package and exported packing, also blank packing which appeals to the market demand.

Welcome all feedbacks from partners or your technical suggestions!!!