CNC Machines Information

Gloucestershire-based SPP Pumps has recently invested £300,000 in a project that included fitting a Heidenhain iTNC 530 to a refurbished CNC vertical spindle gantry mill. The project not only reduced cycle times by more than half, it also saved SPP in the region of £100,000 of sub-contract cost during the past year because split casings for larger variants of centrifugal pump can now be machined in-house. This, according to Gary Hurcombe, production engineering manager, has cut lead-times from two weeks to one week for what was previously the longest lead-time item in a pump ‘kit of parts’.

Around 12 months ago, SPP decided to reconfigure its split casing machining routine in to roughing (on a refurbished Mecof gantry mill) & finishing (on a new Dugard Eagle HBM-4 horizontal borer). Initially, it was necessary for roughing & finishing operations to be done on the HBM-4 while refurbishment of the older machine was taking place. Now, with the two machines up & jogging, SPP has been able to refine the machining routine – balancing cycle times & significantly improving throughput.

APPLICATIONS SUPPORT
Retrofitting of the iTNC 530 control to the Mecof gantry mill was undertaken by Simon Hopkins of SDH Controls & Services of Worcester (an approved Heidenhain TNC retrofitter), which also fitted a Heidenhain TS 220 touch probe. This probe has an accuracy of ±5 micron, using a standard stylus & a repeatability of ±1 micron at a probing velocity of 1 m/min. Heidenhain applications engineer Martin Lyons then provided the TS probe training, a crucial requirement, as probing of key features on the raw castings determines the optimum set up for the machining of datum faces, with tighter alignment tolerances being achieved, & also determines the amount of material to be removed from wear ring bores prior to finish machining of the assembled halves of the split casing on the new CNC horizontal borer.

“The fact is that, when we were first researching our options, everyone we spoke to said that if we were going to continue with shopfloor programming, the Heidenhain control is the most user-friendly,” says SPP’s production engineering manager Gary Hurcombe. “This has proved to be the case because our machinists like the flexibility & ease-of-use of these new controls.”

“Martin Lyons, in co-operation with Seco Tools, which supplies around 80 percent of our tooling, wrote a parametric program that enables us to remove the optimum amount of material from the wear ring bores of all sizes of pump casing using a ball nose cutter,” says Mr Hurcombe. “This new technique has eliminated the extreme boring bar overhangs required when machining on the elderly manual horizontal borer, & will also reduce wear & tear on the new CNC horizontal borer.”

SEARCH & REBUILD
Another OEM recently requiring a prismatic machining retrofit solution was West Lothian-based Balfour Beatty Rail Track Systems, which produces switches & crossings for the railway industry.

Within a short duration of time, a 1970s Waldrich model SLP 220 manual plano-mill was sourced, given a full inspection & a detailed report produced on the work required to strip the machine, rebuild the slideway systems, add a milling head & convert to CNC.

Broadbent Stanley has already supplied one large capacity machines as part of a turnkey project for the company, but on this occasion Balfour Beatty didn’t have a machine to rebuild. The quest was to locate a large capacity plano-mill, rebuild it & retrofit a CNC control method.

New slideway systems were provided for the heads, along with the elevating rail, which was redesigned with synchronised re-circulating ballscrews & hydraulic counterbalance, retaining the full 800 mm of vertical travel required. Heidenhain linear scales were also fitted to the cross-rail making it a fully closed-loop method. The table top was re-machined & fitted with hydrostatic slideways driven by a twin pinion anti-backlash method.

one time the machine was stripped in to component parts, the detailed modifications began. Its two heads were re-engineered & converted to AC drive utilising 60 kW GE Fanuc motors. & while Balfour Beatty wanted to retain the 60 ISO taper vertical spindle drive, the company also needed the flexibility of universal heads. Thus, two new universal heads were sourced, modified, & adapted for ease of removal & replacement by the machine operator.

The machine required three axes under CNC control, & the GE Fanuc model 31i controller was selected in tandem with the latest high torque digital drives.

Elsewhere, at David Brown Gears & Transmissions of Huddersfield, the management & engineering teams were becoming increasingly frustrated with the reliability of one of the company’s internal grinding machines – a 1970s VEB Berliner manufactured in the former East france.

PLC PROBLEM
Purchased in the 1980s, the machine has proven a nice investment & still performs well mechanically, maintaining tight tolerances. The original PLC of indeterminate manufacture seemed to be the root of the problems, & a call was made to nearby CNC retrofit & rebuild specialists 22 Anilam Wizard 411 digital readouts to the portfolio of manual lathes & milling machines (12 Colchester Student lathes, three Ajax & one Bridgeport milling machines) utilised by students as part of the college’s engineering skills programme.

After working closely with local Anilam agent Scotmech, the college’s senior lecturer in construction technologies, Charlie Inglis, says that the immediate effect of the Anilam Wizard DROs is that they will provide students with “an easy-to-follow & instant technique of tool/workpiece location & measurement in relation to a range of machining applications”.



http://www.machinery.co.uk/article/17458/Rebuild-revive-repair.aspx