Anthony and Michael Pateman, the brothers that run zinc and aluminium high-pressure die casting specialist RD Castings, have invested in two new Brother high-speed machining centres
The company has used the Japanese-built high-speed, twin-pallet machining centres since 1989 and currently has nine of in two machine shops in Mildenhall, Suffolk.
Since the mid-90s, the 30-taper machines have replaced manual milling, drilling and tapping, which was both labour intensive and subject to quality variation.
The first machine ordered was a Speedio R650X1 with Nikken rotary 4th axis and another identical machine was ordered within six months.
The machines are articularly applicable to machining light castings because of the speed. Workpiece changeover is completed entirely within the 3.4-second rotation of the twin-pallet Quick Table, as the 21-pocket magazine’s 0.9 second tool change time, 50 m/min rapids in X Y and Z, and rotation of the 4th CNC axis are carried out simultaneously.
The first tool is ready to cut the next component immediately it arrives in the machining area and little time is wasted on each subsequent exchange of the cutter due to the rapid tool-to-tool time and spindle acceleration from zero to 16,000 rpm in 150 milliseconds, with similarly fast stop time.
Anthony Pateman said: “There is a trend towards larger castings these days and we have just installed a 500-tonne casting machine to meet the requirement. In order to machine them, the ability of the R650X1 to swing our 400 mm diameter parts in the rotary axis means that we are often able to finish these bigger castings in one hit and save on a second set-up operation, which hugely decreases cost of production.”
For example, a larger part that used to need a second operation but is now machined in one 4-axis process, saving 70 pence per part.
Simon Hale, CNC machine shop manager, stated that productivity of another part – an aluminium die cast housing for the rail industry – has been nearly doubled using the larger machine compared with the other Brother models with similar tool carousels. 17 castings per hour were drilled and tapped using 12 tools on the latter machines, whereas using a trunnion fixture on an R650X1, 32 parts per hour come off the machine after each pallet rotation and just eight tools are needed.
The increase in output is partly because, by routing coolant at the uprated 30-bar pressure on RD Castings’ latest machines through an indexable-insert drill rather than employing a twist drill, it is possible to produce larger holes above 18 mm diameter in one spindle movement, rather than having to spot and then peck drill the holes multiple times.
Michael Pateman says that manufacturing costs are increasing in Asia while the lower pre-Brexit value of the pound is helping UK competitiveness.
He said: “By employing ultra-high-speed machining techniques on 30-taper rather than 40-taper machines, with extensive use of polycrystalline diamond inserts clamped in dynamically balanced tool holders, the cost of producing a casting is now about the same in Mildenhall as it is in China – and we are winning back business as a result.
“The latest Brother Speedios with their larger working envelope have added considerable versatility to our shop floor, as they can economically machine anything from the simplest, smallest casting up to the largest and most complex. Productivity is also up due to the faster control and by allowing more flexible production planning.”