New Mitsubishi EDM delivers lights-out machining

The new Mitsibushi wire EDM at Bellcliffe

With more than 40 years of manufacturing tube and roll forming machinery, equipment and consumables, West Bromwich-based Bellcliffe Engineering Ltd is a specialist in extending the service life and uptime of rolling mills and extrusion plant. To enhance its service to its longstanding customer base, the manufacturer has added an advanced Mitsubishi MV 2400S wire EDM supplied by Engineering Technology Group (ETG).

Installed in September last year, the new Mitsubishi MV 2400S was purchased to replace an ageing EDM machine on the shopfloor. The sub-contractor serves customers in the automotive, offshore, energy, and agricultural sectors among others. With a wide portfolio of high-end machine tools, Bellcliffe Engineering made its first foray into wire EDM cutting around eight years ago.

Recalling why the company initially invested in EDM technology, John Sutcliffe, Bellcliffe Engineering’s manufacturing director, said: “We were manufacturing a lot of roll tooling for cold forming and extrusion dies and the electricity generation sector and the parts we were machining required keyway cutting. With a lot of the parts machined from H13, D2, and Inconel, we were using a lot of indexable inserts and solid carbide tools to machine the parts. The cost of inserts was £55 per part, and we tried several different tooling solutions without tangible benefits. As this cost was unsustainable, we looked at ‘dipping our toe’ in the water with EDM. My wife lent the business £4,000, and we bought a secondhand EDM machine.”

With limited experience and an old EDM machine, the company managed to machine the external profiles and then finish the parts on a wire machine, reducing cycle times from 2.25hr for machining to 1.75hr as well as reducing the tooling bill. With the benefits apparent, the company invested in an additional secondhand wire EDM five years ago. However, as the business has evolved, the requirement for EDM has exponentially increased.

Mr Sutcliffe explained: “The extrusion die tools incorporate an aperture and a sweep and these are consumable items that we are now producing in quantities of more than 100 per month. Our ageing EDM machines can process six apertures and four sweeps in a single setup. However, with old machines that have reliability issues as well as no automatic wire re-threading facility, we were losing a lot of lights-out production hours.”

Pictured right: some of the billets clamped and ready for lights out machining at Bellcliffe

With the parts requiring pre-EDM block and face machining, when transferred to the EDM machines, an aperture would take 1hr 10min to wire cut while the sweep parts would take over 2hr 45min of wire cutting. With the potential for up to 18-plus hours of unmanned wire cutting, Bellcliffe was losing significant machine hours due to the reliability of its machines and the lack of automatic wire re-threading. A new solution was required and the Mitsubishi MV2400S fitted the bill perfectly.

Discussing why the company opted for the Mitsubishi MV2400S from ETG, Mr Sutcliffe continued: “We are a sub-contract machine shop with expertise in machining — not EDM. So, when it came to finding a suitable solution, we investigated the market and spoke with all the major manufacturers and found a lot of high-end technology with all the ’bells and whistles’, but we needed a reliable, productive, precision EDM solution that would meet our needs The Mitsubishi MV2400S was the perfect machine.

“We were sold on Mitsubishi due to two main factors. Firstly, it was the discussions with ETG’s Andrew Dolan and Scott Elsmere — they were extremely knowledgeable, discussing the comprehensive training packages and how ETG would be at our side from the installation, training, and through to the daily operation of the machine. As EDM novices, this was of critical importance to us. Secondly, it was the performance of the machine. With automatic wire re-threading, automatic clocking-up and datum setting of the jobs, and a programming suite with remarkable ease of use, we were confident we could hit the ground running — which we did.”

Looking at some of the productivity benefits of the Mitsubishi machine over the existing EDM technology at Bellcliffe, EDM machinist Conor Deakin said: “The cutting speed of the Mistubishi MV2400S is 10 to 20% faster than our existing machines. On jobs upward of 200mm thick, we are cutting through D2 at more than 0.4mm/min compared to 0.2mm/min on our other machine — giving us a 50% cycle time improvement.

Pictured. left: the ability to clamp multiple components provides efficient lights-out production

He continued: “Another major benefit is the ability to set more parts on the machine. The Mitsubishi can accommodate 15 apertures and eight sweeps, which is a major improvement on the six apertures and four sweeps on the other machine. This means that we can now run for more than 18 hours unmanned. We are also about to introduce new fixturing that will allow us to clamp up to 30 plates — this will give us an unmanned running time of 60-plus hours. This means we can set the machine at the end of the week and it will run most of the weekend unmanned. Considering we cannot leave our other EDM machine unattended without the concern of a wire breakage, tank refill time-out or a paddle breaking, having over 60 hours of unmanned production is fantastic.”

Mr Deakin added: “We have a lot more to come from this machine, as we are still in the early stages. For example, when we fully understand how to optimise the flushing cups, we expect to increase productivity by an additional 20%. There are benefits everywhere with this machine. We have reduced clocking up jobs from 20-plus min to 2-3min due to the Mitsubishi’s ability to set the datum points automatically. Furthermore, the CNC system is easy to operate and navigate and this further streamlines programming and setting up.”

Mr Sutcliffe concluded: “Overall, we are delighted with the Mitsubishi machine and while it was purchased for a specific type of work, we are now applying it to other components. This is absorbing capacity from some of our other machine tools by giving us unmanned lights-out machining while reducing the costs of cutting tools and machining. We are also being asked by new and existing customers to quote for additional work that is perfectly tailored to EDM cutting. As word spreads regarding our EDM capacity, we are generating more new business and having a reliable, precise and efficient machine to accommodate this is helping our EDM department to expand.”