Steinbeis experts develop new welding device for diamond wires
To cut hard brittle materials such as silicon, hard metals, sapphires, or even composite materials like circuit boards, it is common to use diamond wire saws. The surfaces of the cutting wires – attached in the form of diamond wire spools – are coated with diamonds, which have to be held in position by a nickel layer. The Steinbeis Innovation Center for Development Technology in Oberndorf am Neckar has been working on diamond wire technology since it was founded in 2009, and has already developed numerous diamond wire saws for its business partners. For one such project, DIASIP, the Steinbeis experts developed a connecting process that made it possible to connect wires with only 0.12 of a millimeter in diameter. The Steinbeis experts continued working on the process, even after project completion in 2015. Their aim was to develop a mobile welding device that would allow to connect wires in a multiwire saw so that you can use the exsiting wire web of a multi-wire saw. And it worked!
Sawing with diamond wire loops offers two key advantages over conventional wire saws based on winding technology: The cutting performance remains uniform, because the wire only moves in one direction, and much higher cutting speeds are possible – up to 50 m/s.
For the Steinbeis experts’ project, which aimed to develop a mobile welding device, joints in the wire web would need to deliver a strength of around 3,000 N/mm2 to be able to continue sawing with the existing wire web. The method makes it possible to use all wire in the wire web, paving the way for a full ROI after 80 days. This is based on a sales price of €100,000 per welding device.
The welding device developed by the Oberndorf Steinbeis experts for diamond wire connecting has nine NC axes and is controlled by a custom-built microprocessor controller unit via an Android tablet. To conduct preliminary testing, the experts controlled the welding device via a unit using programmable logic, but it very quickly became clear that with the extremely fast heat transfer through the thin wire, using this type of controller was too slow.
From an initial idea to a finished product
To launch its newly developed welding solution and hold its own against competitors, the Development Technology Steinbeis Innovation Center entered into a partnership with DIDRAS, a spin-off of the Steinbeis enterprise that works on the development and production of diamond wire loops. This partnership works very well for both teams and has already resulted in the development of a CNC diamond wire saw and a straight-cutting machine, both of which are used in a variety of industries, as well as the laboratory sector.
DIAMOND WIRE SAWS AT A GLANCE
Sawing with thin diamond wires is ideal for
- Extremely fragile workpieces that are highly vulnerable to clamping (feed and cutting force < 5N)
- Applications in which edge breakouts need to be avoided, such as tasks involving green compact
- Workpieces that need to be cut from simultaneously hard and soft materials
- Applications involving narrow kerf