Mitsubishi Materials Cutting tools a key factor for unmanned lights-out production
UK – Mitsubishi Materials provided the tooling and expertise that enabled Formagrind, an ISO9001 company with 26 employees based the UK to fulfil a challenging automotive machining contract. Software and cutting tools were among the key factors for lights-out production.
Formagrind, which was established in 1983, has been operating from a 1,000 m² factory since October 2015. Its equipment includes two new Hurco VMX30Mi machines, in addition to its Mazak, Hardinge and Gildermeister turning centres, Hurco VMCs and Sodick EDMs. It also has three i-Machining CAM software seats.
Formagrind initially trialled Mitsubishi’s face mills, then implemented the Alimaster aluminium roughing end mill range on a long-term satellite project that had “brutal” material removal rates. The success of the face mills and the Alimaster cutters gave the company complete confidence in both Mitsubishi tools and the local engineer.
Machining hard-to-cut materials
The company machines molybdenum, titanium, Inconel and other hard-to-cut materials. It is now a consignment stock customer and has had an Autocrib vending system since April 2016. It has also made use of Mitsubishi’s expertise in setting of performance parameters and structures.
In February 2015 it received an order for over 100 complex titanium fixtures, each consisting of a carrier base and corresponding top plates that clamp electronic PCBs assemblies during their production and final assembly processes. They were required in a batch size of 105 bases and 160 cover plates. With over 14 hours of machining for each base and 110 minutes for each cover plate, Formagrind needed to run its new Hurco VMX30Mi machines 24 hours a day, seven days a week, for almost two months. With i-Machining optimising the process, the key factor for lights-out production was the cutting tools; Mitsubishi’s solid carbide end mills were selected.
Formagrind developed a fixture to clamp and process two 300 mm by 200 mm by 9.5 mm base plates at a time. The grade 2 titanium plates are first machined with an 8 mm diameter solid carbide four flute VQ Series end mill at 4.5 mm depth, with a 1.2 mm step-over and a feed rate of 1400 mm/min. After almost two hours, a 4 mm and a 3 mm diameter VQ end mill final details. Two, 3.5 and 4 mm diameter VQ end mills are used for rough and finish machining pockets that have already been waterjet cut. A 0.5 mm diameter MS2-SLB end mill handles fine details. Total machining time is nine hours for the top face. Formagrind changes the tools after each pair of bases; wear is hardly noticeable, even after 14 hours of machining.
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Tool life is an essential aspect of unmanned production runs
"We consulted with Mitsubishi at the very start of the project and they recommended the VQ end mills for the majority of base plate operations. For us, the ability to confidently run unmanned for prolonged periods was crucial," says Formagrind's shop floor manager, Mike John. "Tool life is an essential aspect of this."
Formagrind created a fixture to machine 10 of the smaller guide clamps in a single set-up. The first stage takes over 110 minutes with a 6 mm diameter VQ Series end mill at 4.5 mm depth and is followed by 3, 3.5 and 4 mm diameter VQ end mills for other machining and pocket milling. A 2 mm diameter VFH long neck series with 0.5 mm radius and variable helix provides detail finishing.
The 3.5 mm VQ end mill has a run-time of 55 minutes and hasn't been changed through the complete project, demonstrating life of 550 minutes, on titanium. The 6 mm roughing tool has conducted 4.5 mm deep roughing throughout the complete batch, returning over 20 hours of machining.
The final base plates and top plate covers have now been delivered, after total machining time of 2400 hours. The customer is moving to the next generation electrical assembly and Formagrind will again be providing the clamping bases and guides.