Machine Tools - EDM Machine

Basic Machining Technology of Molybdenum Wire Cut EDM

a@b.com (admin) — Thu, 01 Jul 2010 18:32:02 +0800

Molybdenum wire cut EDM is original in China, and widely used in molds, precision parts making, here are some basic knowledge of molybdenum wire cut EDM machining.

...

Reasons and solution for wire broken of CNC wire cut EDM machine-Reason 6

a@b.com (admin) — Mon, 21 Jun 2010 00:26:29 +0800

There is some dielectric material inside of workpiece, everything looks normal from outside, but suddenly, short circuit happens; It doesn’t work no matter whatever we try. It is likely some impurities in the workpiece while forging or stamping, these impurities is not conductive, and make short circuit happen, and break the wire finally. It is advised to use good quality material, or enlarge cooling liquid to flush impurities.
...

Reasons and solution for solving wire broken of CNC molybdenum wire cut EDM machine-Reason 5

a@b.com (admin) — Wed, 16 Jun 2010 01:50:58 +0800

Reason 5, Molybdenum wire is easy to break when cut workpiece with large thickness.

Normally, for CNC wire cut EDM machine, workpieces with thickness larger than 100mm are called large thickness workpiece. Wire broken may happen at the moment that spark appears, during cutting process, and when cutting is about to finish.

...

Reasons and solution for solving wire broken of CNC molybdenum wire cut EDM machine-Reason 4

a@b.com (admin) — Mon, 14 Jun 2010 20:50:44 +0800

Reasons relative to workpiece.

Molybdenum wire is easy to break when machine thin workpiece。 When talking about thin workpiece, it means workpiece with thickness less than 3mm. Reason of wire broken under this situation: the distance between up and down guide pulley is fixed, regularly around 70mm, while cutting thin workpiece with high wire running speed, wire is easy to vibrate. Solution: adjust machining voltage to around 50V; adjust machining electric current to around 0.3A, adjust frequency width to less than 10μm; reduce vibration of molybdenum wire, for example drive wire drum with DC motor, lower RPM of motor; if drive by AC motor, lower phase voltage by connecting resistance in random two phases in series, nowadays, wire drum is controlled by inverter, it can change direction smoothly with low speed; increase the thickness of workpiece by cutting many workpiece together or cushioning other parts.The last method is easy to do and no need to adjust parameters.

...

Reasons and solution for solving wire broken of CNC molybdenum wire cut EDM machine-Reason 3

a@b.com (admin) — Fri, 11 Jun 2010 23:07:10 +0800

Reason 3 new wire

New molybdenum wire and self-broken of molybdenum wire. There is a layer of black oxide cover on molybdenum wire, the would be dark black while cutting with fast speed, for this case, big power will cause broken of wire. For new wire, it is better to use lower power(low electric current), when molybdenum wire goes white, then start to cut with regular parameters. Thinking about wear of molybdenum wire, after long term use,it is suggested to measure the diameter of wire, then according to required tolerance, choose to change the wire or not, if there is no strict requirement upon tolerance,no need to change the wire until broken. If wire cut EDM machine haven't been used for a long period, but wire is broken,such kind situation is caused by expansion and contraction of material due to temperature difference. So it is advised to remove molybdenum if don't use machine in a long time.
...

Reasons and solution for solving wire broken of CNC molybdenum wire cut EDM machine-Reason 2

a@b.com (admin) — Thu, 10 Jun 2010 22:38:25 +0800

Reason 2 the choice of electrode wire

Choice of electrode wire is consist of diameter and type. Normally, material used for electrical discharging should have good conductivity, strong tensile strength, good electric corrosion resistance. The wire won't bend and knot. Regular used wires are molybdenum wire, tungsten wire, tungsten-molybdenum wire,brass wire, copper-tungsten wire and etc.., Among the, especially molybdenum wire and brass wire are widely used.
...

Reasons and solution for solving wire broken of CNC molybdenum wire cut EDM machine-Reason 1

a@b.com (admin) — Wed, 09 Jun 2010 20:47:08 +0800

Reason 1, Tension and running speed of wire.

To CNC molybdenum wire cut EDM machining, regular diameter of molybdenum wire range from 0.09 to 0.25mm, as its ability of resistance to wear,good tensile strength, and wire is not easy to turn fragile and break. For increasing wire tension will reduce impact from vibration of wire, thereby, increase accuracy and cutting speed. Fluctuation of wire tension have great effect upon stability of working situation. Reasons of fluctuation: the tensions of running wire on the wire drum in positive and negative direction are different; Length of wire will extend after long time work, it makes wire tension go down, regularly, ideal tension would be 12-15N, when wire tension goes down, vibration is getting worse, and wire is easy to break.

...

How to improve CNC wire cut EDM machining surface quality

a@b.com (admin) — Mon, 07 Jun 2010 19:59:04 +0800

The reasons that influence surface quality of wire cut EDM machining: instability of machining process and unclean working solution. Here are some measures to improve this situation:
...

Cut Helical Gear with CNC Molybdenum Wire Cut EDM Machine-big taper type

a@b.com (admin) — Mon, 07 Jun 2010 17:54:38 +0800

Steps of helical gear programming sample

Main parameters of helical gear

Number of teeth: 35

Thickness: 20 mm

Helix angle: 30 degrees

Pressure angle: 20 degrees

Modules: 2 mm

...

General introduction of Wire Cut EDM machine

a@b.com (admin) — Fri, 15 Jan 2010 00:11:00 +0800

CNC Wire Cut EDM Machine refers to wire EDM. It uses a wire electrode(brass, molybdenum etc.) that travels through the conductive workpiece. The electrically charged wire is controlled by a comp