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Single set-up machining

The ability to undertake milling, turning and drilling in a single setting boosts productivity

Posted on 12 Nov 2019 and read 1525 times
Single set-up machiningKOSO KentIntrol’s latest investment in a Starrag Group 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 multi-tasking machining (milling, turning and drilling) has eliminated the need for two separate machines, along with all the associated re-setting and queuing times previously required to produce finished workpieces.

The DBF machine complements the company’s other Starrag-brand machines, including a Scharmann Ecoforce HT2 with integrated P600 facing head that undertakes the single set-up machining (milling, boring and turning) of larger workpieces at the Brighouse (West Yorkshire) site.

Richard Addy, KOSO KentIntrol’s machine shop manager, said: “In addition to replacing separate machining operations, the Heckert DBF has ‘simplified’ the production process by allowing us to load once with raw material, undertake complete machining, then unload a finished part ready for inspection.

“This means that we are effectively getting more parts per week from that machine than we were when using separate machines.

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

Established in 1967 (as Introl) and now a leading global supplier of a wide range of valves (including choke, control and butterfly types, as well as actuators and instruments) to industry sectors such as oil and gas, petrochemical and power generation, KOSO KentIntrol purchased the Heckert DBF — from Birmingham-based Starrag UK Ltd (www.starrag.com) — to increase its capacity for the machining of valve and globe bodies in the 1-6in range (flange outlet bore size).

These are produced from a variety of materials, including carbon steels, super duplex stainless steel and Inconel.

Single machine

Mr Addy said: “We were previously using two machines to complete the bodies — a lathe to produce the flange and plug-way in three operations, followed by drilling operations on a separate machine.

“When we needed to increase capacity, we had no hesitation in selecting the Heckert 630 DBF, as it offers a machining capability that more than meets our needs for valve body machining.

“Its specification includes: 630 x 630mm pallets; a work envelope of 1,070 x 870 x 1,200mm; traverse speeds of 40m/min in X and Y and 60m/min in Z; ±35mm in the U (turning) axis; and a 45kW (1,700Nm of torque) spindle.

“It enables us to complete body machining in one or two operations, depending on casting type and size.

“Angle bodies require a single set-up and are produced in one hit, while globe bodies require two set-ups.

“The first is for machining the plug-way and includes drilling; the second is for machining the flanges and also includes drilling.

“That said, this has replaced the comparatively longer and laborious process of: loading to a lathe; setting up and machining the first flange; re-setting to machine the second flange; re-setting to machine the plug-way; moving the body to the drilling cell; and setting the part for drilling operations.”

KentIntrolKOSO KentIntrol’s association with Starrag stretches back over many years.

Indeed, its heavy machine shop exclusively features Starrag-brand machines — a Solon 4 machining centre, a Dorries vertical turning lathe and the Scharmann Ecoforce HT2 machining centre.

This accommodates workpieces of 10,000kg and features a 63kW spindle that produces 4,000Nm of torque. Furthermore, the facing head can undertake in-process turning at up 300rev/min.

Single source

Mr Addy said: “We have proven the reliability of — and consistently high-quality machining results from — our Starrag machines.

“Coupled with the fact that we’ve always received excellent after-market backup and support from the company, we decided to continue that single-source association when we needed to address the throughput needs of our smaller valve bodies.

“We also knew that significant gains would be made by the multi-tasking single set-up capabilities offered by Heckert’s DBF head.

“This features an integral U axis that can undertake a wide range of internal and external machining operations.”

The DBF spindle head comprises a faceplate with an integrated work spindle and a CNC radial facing slide.

For turning on a fixed workpiece, the rotating turning tool (with an axial run-out of just 5µm) can be radially adjusted by a total of 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.

For milling and drilling, the work spindle is located in its central position.

Mr Addy says that KOSO KentIntrol makes good use of the machine’s 45kW 3,500rev/min (1,700Nm of torque) spindle by, for example, often applying a high-feed Capto milling cutter to machine WCB carbon steel at a speed of 850rev/min and a feed rate of 3,000mm/min.

“The machine is particularly rigid, and we are taking cuts 2-3mm deep on softer materials.

“On duplex stainless bodies — for example — we are taking 3mm cuts at speeds and feeds of 60m/min and 0.25mm/rev.

“However, it is necessary to carefully balance cutting depths, 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, as this operation can be particularly onerous on the wear of the ‘slitting saws’ used.

“We worked closely with Starrag on the initial fixturing.

“Starrag engineers also helped us to establish the DBF processes and programming, which meant that the machine was immediately into production and saving us money.”