With Loran technology, it is now possible to machine the sides of the workpiece cleanly without subjecting the electrode to wear.
And we can now achieve positional control in 1-micrometer increments using NC units developed and manufactured by Sodick.
Our next goal is to further improve the precision
of the machines themselves.
This means creating heads and tables that are impervious to changes in the ambient environment…
Until now, the mainstream has been to use reinforced plastic materials as insulation between the head and the electrode and between the table and the workpiece.
But because these types of material expand as the temperature increases, problem arise such as changes in the position of the center of the wire when workpieces are machined using wire-cut EDM and loss of spark stability in die-sinker EDM.
So at Sodick, we concluded that we needed a new material to replace reinforced plastic and steel in order to achieve truly accurate machining.
As a result of exhaustive research, we found that the material we need is ceramics.
So we are now manufacturing our own original ceramics for Sodick electrical discharge machines.
So, what are ceramics anyway?
“Ceramics” refers to a wide range of “(non-metallic, inorganic) substances hardened through firing.”
Familiar items made of ceramics are pottery and bricks.
There are also what we call “fine ceramics,” in which the raw materials are chemically bonded to give them new and superior characteristics that allow their maximum performance.
A typical example of fine ceramics is “alumina ceramics”, which are used in many Sodick ceramic products.
These alumina ceramics contain aluminum oxide as their main ingredient and are extremely strong materials.
Where alumina forms a single crystal, it becomes a jewel of sapphire or ruby.
Where are ceramics used?
We use them primarily in electrical discharge machines.
They are fitted at key locations on the head and table units in die-sinker and wire-cut EDMs.
Why are ceramics necessary?
If insufficient insulation is used in electrical discharge machining that uses sparking, the discharge energy is scattered to areas other than the electrode and workpiece, resulting in unstable discharge.
Maintaining a state of complete insulation is vital to achieving stable electrical discharge machining.
On the first electrical discharge machines, insulating reinforced plastic (glass epoxy) was used only in the head unit.
But this resulted in problems of temperature-induced changes in structure size and insufficient strength in long-term use.
On the one hand, the tables used at the time were made of steel and had insufficient insulating capacity.
For this reason, we tried using stone tables. But there were problems such as inconsistent quality depending on where the stone was sourced and the areas in which it was used, as well as insufficient strength due to the tendency of the stone to crack.
Given these problems, we needed to find a way to produce more precise, better quality electrical discharging in more tightly controlled areas.
At Sodick, we tested a range of materials, including resin + iron, stone, and ceramics, for their suitability for use in electrical discharge machines.
The results showed that ceramics were the ideal in that they resolved the problems encountered thus far and had the properties demanded by electro-discharge machines. In particular, ceramics provided the most complete insulation.
The length of a 1-meter piece of iron increases by 10 micrometers for every 1°C rise in the temperature. In a wire-cut EDM, this means that the position of the center of the wire changes.
With ceramics, the thermal displacement is limited to half that amount or less.
Ceramics are also the ideal material for accurate electrical discharge machining as they prevent current from flowing to areas other than the wire electrode and workpiece, as with die-sinker EDM.
Furthermore, ceramics also have excellent corrosion resistance, which makes them ideally suited for wire-cut EDMs where the wire electrode is constantly bathed in water or oil.
Why did Sodick develop its own ceramics?
As the photo shows, the tables in electrical discharge machines are very large.
The larger the table size, the higher the cost and the more difficult the table is to make. We had a lot of trouble finding someone who could make them for us.
So we decided to do the R&D ourselves and manufacture our own tables.
Initially, we were only manufacturing the materials needed for Sodick products. However our ability to produce large-scale ceramics to high levels of precision has generated considerable demand from other sectors. So now, as well as supplying ceramics for Sodick products, we also supply to companies who manufacture products such as measuring instruments and semiconductor fabrication equipment.
The Features of Sodick Ceramics
- Because the ceramics are developed and manufactured by Sodick, they can be used for any of the parts, including spindle sliders, work stands, and pulleys.
- The fact that we develop and manufacture the ceramics in-house means that we can make the world’s largest ceramic products, such as tables for machining very large products (LCD panels, etc.).
- We develop and manufacture the ceramics ourselves, so we can tailor our products to the customer’s requirements, including using ceramics other than alumina.