Valve body machining in a single set-up

West Yorkshire-based Koso KentIntrol’s latest investment in the Starrag Group’s Heckert 630 DBF horizontal machining centre is paying big dividends in the machining of valve bodies, not least because the machine’s ability for single set-up and multi-task machining.

The acquisition of the new Starrag HMC has eliminated the need for two separate machines and all the associated re-setting and queuing times, to produce finished workpieces at valve specialist Koso KentIntrol.

The success of the DBF machine builds on the prowess of the company’s other Starrag brand machines – in particular, a Scharmann Ecoforce HT2 with integrated P600 facing head that has consistently and reliably proved its worth in the single set-up machining (milling, boring and turning) of larger workpieces at the company’s Brighouse-West Yorkshire site.

And the Heckert DBF’s record in increasing Koso KentIntrol’s machining capacity of smaller valve and globe bodies, and its ability to effectively transform the production process for such parts, is now similarly attracting praise.

“In addition to replacing separate machining operations, the Heckert DBF has effectively simplified the production process by allowing us to load once with raw material, undertake complete machining, then unload a finished part ready for inspection. That also means we’re effectively getting more parts per week from that machine than we were using separate machines by eliminating queuing times,” says Richard Addy, machine shop manager.

“The elimination of multiple set-ups on a lathe, plus the queuing and set-up times for drilling, has produced dramatic time savings,” he adds.

Sizes and steels

Established in 1967 (as Introl) and now a leading worldwide supplier of a wide range of valves (choke, control and butterfly), as well as actuators and instruments to a global customer base throughout industry sectors such as oil and gas, petrochemical and power generation, Koso KentIntrol purchased the Heckert DBF to increase capacity in the machining of valve and globe bodies in the 1-6 inch range (flange outlet bore size) and from a variety of materials, from carbon steels through to super duplex and Inconel.

“We were previously using two machines to complete the bodies,” continues Mr Addy. “A lathe to produce the flange and plug-way in three operations; then the part had to often queue for a separate operation (and additional set-up) on a drill, for the final operation.

“We needed to increase capacity and with a good working relationship with Starrag, we had no hesitation in selecting the Heckert 630 DBF, which offers a machining capability and specification that more than meets our needs for valve body machining: 630mm by 630mm pallets: X, Y and Z-axis travels of 1,070mm x 870mm x 1,200mm, respectively, and traverse speeds of 40, 40, 60m/minute in X, Y and Z; plus ±35mm in the U (turning) axis and a 45kW/1,700Nm spindle.

“The DBF machine enables the production of complete body machining in one or two operations depending on casting type and size,” explains Mr Addy.

The DBF strategy – for angle bodies in one-hit and for globe bodies in two operations of set-up for machining the plug-way (including drilling) then set-up and machine the flanges (including drilling) – has replaced a comparatively longer and laborious processes of: load to lathe; set-up and machining of the first flange; set-up and machining of the second flange; set-up and machining of plug away; moving the body to the drilling cell and set-up and drill.

Single brand loyalty

Koso KentIntrol’s association with Starrag stretches back many years. Its heavy machine shop exclusively features Starrag brand machines – a Solon 4 machining centre and a Dorries vertical turning lathe plus the Scharmann Ecoforce HT2 machining centre equipped with integrated P600 facing head.

With X-, Y- and Z-axis capacities of 2,000/2,500mm x 1,600/3,500mm x 2,200/3,650mm, respectively, and able to accommodate workpieces of 10,000kg, the Ecoforce not only offers the capacity for the company’s larger workpieces but also the power – a main spindle rated at up to 63kW that produces 4,000Nm of torque for even the heaviest of milling and boring cuts, and the facing head for in-process turning at up 300rpm.

“We’ve proven the reliability and consistently high-quality of machining from our Starrag machines and, coupled with the fact that we’ve always received excellent aftermarket back-up and support from the company, it made complete sense to continue that single-source association when we needed to address the throughput needs of our smaller valve bodies,” affirms Mr Addy. “We also knew that the multi-tasking, single set-up benefits we would gain by using Heckert’s DBF head made even more business sense.”

The Heckert DBF machine features an integral U-axis that carries Starrag’s innovative DBF multi-tasking head for a wide range of internal and external machining operations.

The DBF spindle head comprises a faceplate with integrated work spindle and CNC radial facing slide. For turning on a fixed workpiece, the rotating turning tool – which has an axial runout of just 5/6µm – can be radially adjusted by ±70mm. In addition to external, internal and face turning, the head also permits conical and contour turning courtesy of the radial facing slide’s NC-axis.

Central milling and drilling

Mr Addy confirms that Koso KentIntrol makes good use of the machine’s 45kW, 3,500rpm and 1,700Nm torque spindle by, for example, applying a high-feed Capto milling cutter on carbon steel (WCB) at speeds of 850rpm and feeds of 3,000mm/minute.

He continues: “The machine is really rigid and on softer materials we are taking cuts of 2-3mm deep. On Duplex bodies for example, we’re taking 3mm cuts at speeds and feeds of 60m/minute and 0.25mm/revolution. But it is a careful balance between cutting depths and speeds and tool wear; we aim to prolong tool life as much as we can. This is especially so when milling the rear of flanges – an operation that can be particularly onerous on the wear of the slitting saws used.

“In addition to working closely with Starrag on the initial fixturing, Starrag engineers also played a key role in helping us establish the DBF processes and programming,” Mr Addy concludes. “This meant the machine was immediately into production and saving us money.”

Starrag www.starrag.com