Inca Geometric helps improve Margate's sea front

The company was called in to supply and machine a batch of Ekki hardwood seats and fabricate and machine the stainless steel support frames as part of the project. It used its Mazak VMC to machine and drill key location holes for special self-tapping screws, which secured the blocks to the stainless steel frame. The batch of 144 individual seat blocks that when assembled made up six sections of 3 m bench had to be precisely aligned to prevent any edge or corner protrusions, and had to be flush with the concrete base. This involved the positioning of holes in the frame over its entire length, which were drilled and countersunk on Inca's horizontal borer. Said Tony Clifford, workshop manager: "First we had to source the Ekki wood to meet the design specification and then found this material was so hard and difficult to drill that any wood or standard tooling just failed, clogged or broke, so we called upon Sumitomo Electric Hardmetal to provide a solution." Ekki wood (red ironwood) is found in sub-tropical South Africa, where its trees grow up to 50 m high and 2 m in diameter. The highly dense timber, more often used in marine applications such as lock gates on rivers and canals, weighs some 30 kg per cub ft. It is both maintenance-free and, due to its hardness, presents an extremely low risk of being vandalised. Each seat block was some 150 mm wide by 125 mm thick and 380 mm in length. When assembled, each block was mounted and secured on the stainless steel fabricated frame. The frame was then located on pegs set into concrete beds on the seafront. All locations of seat blocks and frame had to be hidden and such were the positional allowances for machining the holes in the blocks and frame that, as the 24 blocks were located and secured with the special self-tapping screws, any out of position and even tolerance build up, would immediately be exposed. The seat blocks were held in fixtures to the table of Mazak VTC 300 C-ll in sets of four. The holes were drilled 5 mm diameter by 40 mm deep to accept the special quick helix self-tapping screws. The Sumitomo MDW HGS type Super Multi-Drill, a solid carbide drill with DEX (TiAlCr/TiS) coating, normally used on hardened and stainless steels, cast iron, titanium and Inconel, overcame the tooling problem and enabled the exact positioning to be achieved. In particular, due to the combination of the curved flute design, 30°helix and 135° point angle, all tooling problems were eliminated, including any clogging of the flutes. Concludes Mr Clifford: "The material was totally different to any ordinary application and we never believed we would have a problem drilling wood. Without the Sumitomo solution, we would have spent a disproportionate amount of time to overcome the problem, wasted spindle time on the machine and struggled to meet the job specification."