Slugging it out!

Jul 15, 2020 2:46 PM

Two new wire EDM technology innovations from GF Machining Solutions make true uninterrupted and unmanned operations a reality.

Wire EDM manufacturing specialists face a unique challenge when it comes to fully embracing and adopting unmanned and lights-out operations in their facilities. The problem concerns slug removal.

Even as machine tool manufacturers transform more conventional metal cutting operations with state-of-the-art automation, operators of wire EDM machines must deal with slugs in the old-fashioned way. And, despite decades of effort, custom and practice dictates that stopping the machine and manually removing slugs, is still the norm

That was until a recently-developed slug management/removal system developed by GF Machining Solutions, and available on its latest wire cut machines, made its way onto the market

This system - called Automatic Slug Management (ASM) - ensures that manufacturers are able to run their EDM machines in true, lights-out style and benefit from reduced cycle times with no operator intervention.

Left to their own devices slugs will fall onto the lower head of a EDM machine. This can cause a crash or trigger alerts that cause the machine to stop. To help prevent this CAM programs include ‘tabs’ to keep the slug connected to the workpiece during machining operations. Once completed, operators remove the tabs and slugs.

Such manual intervention prevents true unmanned operation from being realised. At best manufacturers can achieve rough cutting of parts overnight - but will need to wait until operators are available to remove the slugs and to run trim and finishing passes.

Lights out process

With Automatic Slug Management manufacturers can machine parts (roughing and finishing) overnight. The system is particularly well suited to die-stamping applications and other small cavity operations.

The process begins with a complete roughing pass leaving no welds or tabs. Instead the GF Machining Solutions’ wire EDM machines ‘ lower head catches the slug before it can fall into the tank. A device retro-fitted to the upper head is lowered and blows high pressure air over the slug, which creates suction and pulls the slug from the part.

The slug is the deposited away from the machining zone by the upper head (moving along the U-and V-axes).

ASM is slower than the manual alternative. However, the fact that it requires no human intervention, means that manufacturers can load up machines at night with raw material and return the next morning to completed parts.

Some limitations

Because suction is used an obvious limitation is the slug’s size and weight. (In these instances it is possible to remove slugs using a pocketing strategy (where EDM wire is used like a milling cutter) to machine the slug away.

Applications involving/producing heavy slugs and large cavities are more likely to adopt ASW (Automatic Slug Welding) as the technology process of choice. Although ASW doesn’t enable true uninterrupted, lights-out operations to occur, it does significantly reduce cycle times.

ASW makes use of an unwelcome EDM condition when using brass wire: the creation of a brass residual build-up that could re-attach the slug to the workpiece.

Using brass accumulation

The slug welding process uses G-code commands to manipulate brass accumulation. It prevents top-to-bottom welds from occurring but does enable welds between the surface of the workpiece and the slug. The end result is a slug that can be (gently) knocked out of the workpiece with a hammer. (The brass residue that remains does not interfere with or compromise skimming passes or other finishing operations).

Summary

Although ASW does not facilitate true lights out automation - it does eliminate the need to cut slug tabs and does shorten EDM process times.

ASM and ASW, available on GF Machining Solutions’ latest wire EDM machines are, along with automatic threading and rethreading, SMART consumables’ technology and remote monitoring, helping manufacturers fully automate their EDM processes.

img-edm-technology-1With Automatic Slug Management manufacturers can machine parts (roughing and finishing) overnight. The system is particularly well suited to die-stamping applications and other small cavity operations.
img-edm-technology-2ASW eliminates the need to cut slug tabs and shortens EDM process times.

For further information

Martin Spencer
Managing Director
GF Machining Solutions Ltd
North View
CV2 2SJ Coventry
West Midlands
United Kingdom

martin dot spencer #at# georgfischer dot com

Profile of GF Machining Solutions
GF Machining Solutions is the world’s leading provider of machine tools, diverse technical solutions and services to manufacturers of precision molds and tooling and of tight-tolerance, precision-machined components. The key segments we serve include the aerospace, automotive, medical, energy, information and communications technology (ICT) and electronics industries. Our extensive portfolio ranges from Electrical Discharge Machining (EDM) solutions, three- and five-axis Milling machines and Spindles, 3D Laser texturing machines, Additive Manufacturing and machines for Laser micromachining to solutions for Tooling, Automation, Software and Digitalization—all backed by unrivaled Customer Services and support. GF Machining Solutions is a globally acting Division of the Georg Fischer Group (Switzerland) and maintains a presence at 50 locations worldwide. Its 3,394 employees generated sales of CHF 1,066 million in 2018. More information can be found at www.gfms.com

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For further information

Martin Spencer
Managing Director
GF Machining Solutions Ltd
North View
CV2 2SJ Coventry
West Midlands
United Kingdom

martin dot spencer #at# georgfischer dot com

About GF Machining Solutions