Process optimisation and process security: a journey not a destination

Manufacturing companies invest considerable time, effort and resources designing, developing and refining their machining processes. The goal, ultimately, is process optimisation – effectively striking an acceptable and appropriate balance between manufacturing costs, quality and productivity.

But, whilst optimising a machining process in the first instance is clearly a desirable position, ensuring that the process has longevity, remains reliable and predictable, and continues to deliver the expected results day-in, day-out is also critically important. To achieve such process security requires vigilance and constant monitoring.

This need for process security can result in manufacturers investing in the latest automated condition monitoring technologies to enable them to intervene, in real time, in their processes, preventing in advance any deviation from preset process parameters. Or, restoring them as soon as possible, if and when any deviation has occurred.

In June 2017 VSMPO Tirus, a leading supplier of titanium stock and semi-finished titanium components to the aerospace sector, took the decision to invest in an Oracle fluid management system, supplied by Jemtech UK, to help improve process security and ensure a failsafe method of delivering ‘right first time, every time’ parts to its customers.

Majoring in aerospace

VSMPO Tirus Ltd., the UK-based sales, distribution and service centre of the global giant and vertically integrated VSMPO - Avisma Corporation (headquartered in Russia), supplies titanium stock and pre-machined/semi-finished products in a variety of sizes, forms and quantities to a diverse and growing range of UK customers operating primarily in the aerospace sector.

The company’s operations in Redditch provide warehousing and stock management (over three months of stock is held at any given time) for major customers that include Rolls-Royce, Airbus, Bombardier and GKN.

VSMPO Tirus has long-term agreements (LTAs) with many of its customers that ensure security of supply of titanium stock and an increasing number of them also rely on the company’s added value machining services - i.e. supplying them with cut-to-size and part-machined titanium components.

Initially these added value services mainly concerned sawing, profiling and shearing titanium ingots, bar, plate and sheet, using the company’s suite of bandsaws as well as a large-capacity dual-head waterjet machine and a high-speed shearing machine.

In recent years the company has invested in three CNC machining centres which are used for first machining operations – high stock removal from primary forms, and the machining of fixture points and clamping holes/bores on titanium components – prior to delivery to customers.

VSMPO Tirus’ managing director, Colin Whitehouse explains: “Customers rely on our added value machining services. By supplying them with high-precision, pre-machined parts, the pressure is taken off their own machining operations. Our services help customers save production time by freeing-up their machines to perform more intricate machining and finishing operations.”

Machining titanium

Titanium is a popular and proven material for the aerospace, marine, and medical industries. Titanium parts are stronger than their steel counterparts but only weigh half as much. Furthermore, titanium components have twice the elasticity of steel parts, which makes them ideal for applications that require flexible components that do not crack or disintegrate under extreme forces.

Titanium components also resist corrosion better than those manufactured from stainless steels, and, like steel, titanium offers manufacturing flexibility because it can be readily cast or forged into various shapes.

But while the material offers advantages compared to other materials, it does pose several manufacturing challenges.

Because it’s a poor thermal conductor, heat generated during the cutting process does not dissipate. Instead, the heat intensifies in the cutting zone, sometimes reaching 2,000 °F, which can quickly dull cutting tools – and using dull cutting edges can generate even more heat, further shortening tool life.

Titanium’s elasticity also creates additional manufacturing challenges. Under cutting pressure, the material springs away from the cutting tool, which causes edges to rub together (instead of cut), increasing friction and further raising temperatures in the cutting zone.

Faced with these challenges VSMPO Tirus, having decided to offer CNC part-machined components to customers, invested in ‘best-in-class’ and proven machining technologies.

The investments included rigidly-built 3-axis machining centres, high-quality tooling and high-performance metalworking fluids. The company also began developing effective, efficient and repeatable machining processes to (a) machine consistent high-quality parts and (b) meet customers’ stringent delivery schedules.

The company currently has three machining centres at its disposal that include two large-capacity, box guideway Doosan Mynx 7500/50 machines equipped with powerful, high torque spindles ideal for heavy-duty cutting operations and high material removal rates.

Fluid of choice

All three machining centres use Blaser Swisslube metalworking fluids supplied by Jemtech with the fluid of choice being Blaser Vasco 7000 – a vegetable ester oil-based micro-emulsion designed specifically for the processing of difficult-to-machine materials.

“High-performance cutting fluids are a critical element in our machining processes,” says Ray Flynn, VSMPO Tirus’ production Manager. “Vasco 7000 delivers improved tool life, longer sump life and reduced fluid consumption which all help us achieve high quality and reduce our overall manufacturing costs.

“Furthermore, by using the coolant under high pressure, we have been able to increase cutting data – speeds, feeds and depth of cut – to improve cycle times and reduce lead-times.”

Never a company to rest on its laurels, VSMPO Tirus, having optimised its machining processes, began to investigate methods to help maintain their reliability. As part of this search the company attended Jemtech’s launch of its new automated Oracle fluid management systems in August 2016 at the MTC in Coventry, and liked what they heard and saw.

In fact, it was so impressed with the potential of what an Oracle system could do when integrated into machining processes, that the company began discussions with Jemtech about installing Oracle technology at its Redditch facility.

Mr Whitehouse elaborates: “We ultimately decided to invest in a multi-sump Oracle system and to interface it with our two Doosan machining centres. The system automatically monitors, in real-time, the condition of metalworking fluids in the sumps of these two machine tools and adjusts the fluid’s volume, concentration and pH levels where and when required.”

Time for a top-up

When a machine tool needs topping up with metalworking fluid, a probe located in the sump sends an alert message to the Oracle unit signalling that more fluid is required. The Oracle system then measures current fluid concentration levels in the sump and, operating within pre-defined fluid volume and concentration parameters, first calculates and then fills the sump to the required levels.

Simultaneously the Oracle unit also monitors and records existing pH levels adjusting, by automatically adding pH correction fluid if required, as well as capturing and recording current fluid conductivity and temperature data which can be acted on immediately or reviewed at a later date.

“Oracle removes the human dimension from metalworking fluid management,” Mr Whitehouse adds. “This delivers an obvious cost saving and, just as importantly, ensures that fluid management actually does occur.

“We operate tight production schedules and simply cannot afford machine tool downtime – something that can occur if machine tool sump levels are not topped up regularly. A particular strength of the Oracle system is that our processes are monitored in real-time by Jemtech engineers. If our processes move out of tolerance we are notified straight away, and if required, Jemtech can undertake remote diagnostics and rectify the issue.

“Our investment in Oracle has helped us improve process reliability. And that’s good news for us and for our customers.”

Jemtech www.jemtech.co.uk

VSMPO Tirus www.vsmpo-tirus.co.uk