The machine was one of Pennine's on-going programme of re-engineering large capacity CNC machine tools, which includes vertical & horizontal borers, centre lathes, milling machines and machining centres.

John Ginley (Pennine's MD) describes the process and requirements:

'We have found, even in difficult times, that there is a demand for CNC vertical borers to meet the needs of the Aerospace and turbine sector. Typical parts are large rings with complex profiles to tight tolerances from exotic materials, such as titanium and nimonic alloys. A significant priority is placed on accuracy, machine rigidity and high torque & power at relatively low cutting feeds & speeds. Re-engineering a sturdy carcass machine, such as the Schiess variants, provides an excellent base to achieve these priorities. '

A re-engineering programme starts with a complete assessment of the machine condition, followed by dismantling of the machine for examination, logging and a quality audit of all the major sub assemblies. At this stage, depending on the examination results, a decision is taken on which aspects of the machine will be retained and which will be re-engineered.

Typical areas that will be re-engineered are:

• Replace the existing axis drive arrangement with the latest digital servo motors.
• Replace an existing multi-speed table drive gearbox & fixed speed motor with a 2 speed, electric change unit and modern digital spindle motor.
• Fit a table encoder to provide screw cutting and feed per rev. operation.
• Replace the axis lubrication system (pump, distributors, piping, etc.) and enhance monitoring to aid precise positioning and to minimise wear.
• Replace the original hydraulic installation with a new compact system to reduce oil capacity, lower power consumption and allow greater monitoring (levels, pressures etc).
• Fit an enhanced guarding system to meet current health & safety requirements and provide improved coolant & swarf control.
• Replace existing wiring with new to meet CE requirements.
• Select a new CNC control to suit machine type with digital control, to provide latest features at the machine and with enhanced communication capabilities to allow connection to customer networks.
• Add direct axis measurement, particular to the X (diameter) axis, for enhanced accuracy and improved repeatability.
• Upgrade the toolholding arrangement to incorporate modern systems, such as Sandvik's Capto.
• Take advantage of modern compact electrical & electronic equipment to reduce the size of the electrical panels., which are then normally mounted on the machine carcass to ease maintenance and reduce floor space.
• Decide on operator station type & position to provide flexible viewing and operation available with new compact CNC controls. Fixed or portable handwheel arrangements can be incorporated to aid machine setting.
• Consider the fitment of tool setting and/or workpiece inspection probing systems.

The same care and attention to detail is applied to the elements of the machine that are being retained.

After a thorough cleaning of all parts, the slideways are re-ground or, where necessary, replaced. PTFE-based anti-friction material is fitted to the moving elements to reduce stiction and aid positioning accuracy and repeatability. This is scraped & re-bedded to return the machine alignments to British Standards, with new improved oil ways added to ensure best performance and long life.

Gearboxes (e.g. elevating rail and retained table drive components) are stripped and all bearings and any worn gearing replaced.

Table bearings are inspected and, if required, replaced with new.

The table bearing and gearbox lubrication system is overhauled and, where possible, improved and then checked for correct operation.

Tool holding systems (turrets or toolchangers) are completely overhauled.

Ballscrews are refurbished or, if necessary, replaced with new. New support bearings are fitted.

Telescopic steel slideway covers are refurbished, with the fibre bellows type being replaced with steel telescopic units.

A more powerful coolant system with new piping, distributors and holding tank is fitted, along with new hydraulic hoses and piping to connect to the replacement pump unit.

The machine's moving elements are precisely aligned and adjusted using calibrated granite artifacts, and finally checked with Pennine's Renishaw laser interferometer.

The re-assembled machine is now completely rewired using appropriate wiring, conduits and drag-chains and with due regard to CE requirements.

Sensors and solenoid valves on the machine are wired directly to the CNC's distributed I/O, which allows a comprehensive software interface to be written to control the machine and provide the necessary safety interlocking and enhanced diagnostic support.

Finally, a suitable enclosed & interlocked guarding system is designed, manufactured & fitted.

At the end of the exhaustive Pennine re-engineering process, the machine is now ready to meet the customer's 2005 production demands.

Mr Steve Russell at Steelcraft - says :

'We purchased our first Schiess VTL from Pennine's Re-engineering program in 2000 and a further machine in 2005. Steelcraft specialise in the machining of complex components up to 1600mm diameter and we are considering what Pennine can provide as we are looking to make further strategic purchases of plant.

Picture shows both machines, with the latest delivery in the foreground.

Pennine's programme of Re-engineered machines continues, with the next large Schiess VTL Lathe 1600mm chuck Fanuc 21-IT Control more details contact sales@pennineuk.com