Zinc and aluminium high-pressure die casting specialist RD Castings has used Japanese-built high-speed twin-pallet CNC machining centres from Brother since 1989 and currently has nine of them in its two machine shops in Mildenhall.

Since the mid-90s, these 30-taper machines have replaced manual milling, drilling and tapping, which was both labour-intensive and subject to quality variation.

The company is run by brothers Anthony and Michael Pateman, who were interested when Brother’s UK agent — Whitehouse Machine Tools Ltd (www.wmtcnc.com) — suggested they see a demonstration of the machine manufacturer’s new ISO control with 12in colour LCD screen as fitted to its latest machines, saying the CNC-C00 is a significantly faster and more user-friendly CNC system compared with the previous one.

After visiting Whitehouse’s Kenilworth showroom and technical centre at the end of 2016, the brothers came away with not only up-to-date information on the new control’s capabilities, but also an order receipt for another Brother machining centre — a Speedio R650X1 with a Nikken rotary fourth axis.

Before the visit, they had not intended to buy this machine, but it was so productive and such a good fit for RD Castings’ needs that an order was placed that day.

Moreover, the brothers bought a second identical model within six months.

A number of factors make the machine particularly applicable to machining light castings, including its high speed: the twin-pallet Quick Table indexes in just 3.4sec, the 21-pocket magazine offers a 0.9sec tool-change time, and the rapid-traverse rate for the X, Y and Z axes is 50m/min.

All this adds up to the first tool being ready to cut the next component as soon as it arrives in the machining area; and little time is wasted on each subsequent cutter exchange of the cutter thanks to a spindle acceleration time from zero to 16,000rev/min of 150 milliseconds — and a similarly fast stop time.

Michael Pateman said: “The speed of tool change on the R650X1 mirrors that of our Brother 324N and R2A machine models, where the tool carousel encircles the spindle and travels with it.

The spindle does not have to move to a carousel to pick up a new cutter, as on the Brother TC32A and 32B machining centres that we also have on-site.

“Furthermore, the machine’s productivity is enhanced by the faster processing of existing programs in the new CNC-C00 control. For example, we recently reduced a 3.5min cycle by 20sec with no change to the original program. For parts that we machine in quantities of 20,000 annually, the savings run into thousands of pounds.”

Working volume

Anthony Pateman highlights another advantage of the R650X1 — namely, its axis travels of 650 x 400 x 305mm in X, Y and Z.

Furthermore, the table accepts RD Castings’ 500 x 350mm base plates on the trunnions fitted to both machines, allowing multiple components to be fixtured for two- and three-axis machining, relieving the load on the 324Ns and R2As which are always filled with work.

He added: “There is a trend towards larger castings these days, and we have just installed a 500-tonne casting machine to meet this requirement. The ability of the R650X1 to swing 400mm-diameter parts in the rotary axis means that we are often able to finish these bigger castings in one hit and save on second set-up operations — hugely reducing the cost of production.”

CNC machine shop manager Simon Hale says 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).

“We had been drilling and tapping 17 castings per hour using 12 tools on the 324Ns and R2As, but using the R650X1 with its trunnion, we are producing 32 parts per hour — and just eight tools are needed.”

Also contributing to greater productivity is the 30-bar coolant system on RD Castings’ latest machines. When using this in conjunction with though-coolant indexable-insert drills, rather that a conventional twist drill, it is possible to produce holes greater than 18mm in diameter in one spindle movement, instead of having to spot- and then peck-drill the holes.

In conclusion, Michael Pateman said: “By using ultra-high-speed machining techniques on 30-taper rather than 40-taper machines, along with extensive use of poly-crystalline 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 shopfloor, as they can economically machine anything from our simplest and smallest casting up to the largest and most complex.

“All our Brother machines work ‘flat out’ 8hr a day, and their speed, accuracy and reliability are invaluable.”