Vasantha Tool Crafts Pvt. Ltd. established a plant at Coimbatore in 1989 to manufacture injection moulded parts. From its inception, the company has provided complete solutions to its customers, from product design to manufacturing. With the help of Renishaw’s RMP600 touch trigger probe and TS27R tool setting technology, Vasantha Tool Crafts has successfully increased the utilisation of every one of its machine tools by 20%, and reduced part setting process time from one hour to just three minutes.

Productivity solutions

According to Mr. R. V. Rao (General Manager): “In order to manufacture precision components it is vital to follow the right process, from initial design to the final quality check. Precision and quality are the company’s hallmarks, and in this respect the decision to utilise Renishaw systems has been very beneficial, as they not only encompass the best productivity solutions but are also highly reliable. These solutions are used with various product mixes, reducing breakdowns and increasing value.”

The company initially employed manual part and tool setting methods using dial gauges and a ‘tools via block’ method. Setting using these methods took hours to complete as everything was dependent on individual operator skill
and experience. After replacing these time consuming manual processes with automated Renishaw probing systems, Vasantha Tool Crafts has been able to optimise cycle times, thereby reducing costs and achieving significant improvements in quality and reliability.

Solutions implemented

Vasantha Tool Crafts installed the Renishaw RMP600 – a compact, high‐accuracy‐touch trigger spindle probe with radio signal transmission – to enable automated job set up. The company also installed the TS27R contact tool setting probe to enable broken tool detection and rapid tool length/diameter measurement.

As well as the significant reduction in part set‐up time enabled by the RMP600, the implementation of the TS27R has also benefitted the company. It has reduced the time taken to set tool offsets by 80% and significantly decreased human error, leading to a reduction in scrap. Setting parts and tooling using Renishaw probes has increased productivity, throughput and machine up time, giving Vasantha Tool

Crafts a competitive edge. The company has now decided to install Renishaw probing systems on all of its machines as part of its quality control policy.

Mr. A. Dayanand Reddy (Managing Director) says: “Renishaw probing systems have been beneficial as they encompass the best productivity solutions, which are impeccable and highly dependable. These solutions are also extremely versatile, ensuring that the company is on the right track. Renishaw has been a trustworthy partner in providing a complete solution and transforming our manufacturing process.”

“REVO® has reduced inspection times by up to 80% per part.” Mecanizados Escribano has reduced bottlenecks while maintaining rigorous part inspection.

A Madrid, Spain-based precision engineering business specialising in complex parts for aerospace and defence applications has invested in a Renishaw REVO® five-axis measuring head and probe system. The change has resulted in a reduction in inspection time by as much as a factor of 5, ensuring quality control and inspection keep up with its high-productivity CNC machine tools.

It’s true that in many ways making things is getting easier, at least as far as the technology is concerned. For example, machine tools are simpler to program and operate, rapid prototyping means that product development is faster and cheaper than ever, and user-friendly CAD software may even negate the need for physical prototypes entirely. All of this assumes that what you are actually making, or trying to make, is relatively uncomplicated. It’s a different matter, however, if you are building complex multi-million dollar aerospace systems, like those engineered by Mecanizados Escribano.

“When we buy a machine tool we specify all the options,” says company project manager Juan A. Humanes. “But, having the best machines is only part of the equation. Our customers demand very rigorous part inspection, which means there’s always the chance that the metrology department can become a bottleneck, especially when the parts are complex and machined to very tight tolerances.”

He continues, “Depending on what the customer requests, we inspect between 10% and 100% of machined parts. The Renishaw REVO system, recently fitted to a Metris CMM, measures non-prismatic surfaces very quickly, many of which would be difficult or impossible to measure with touch trigger systems. In some cases, such as a complex avionics chassis for the Typhoon, the REVO has increased our inspection throughput by a factor of 5; typically, up to 80% reduction in time per part.”

Exceptional scanning speed and accuracy
The key attribute of the REVO five-axis head is its ability to overcome the limitations of three-axis scanning methods, where any attempt to rapidly move the large mass of a CMM results in inertial errors caused by accelerations and decelerations. Therefore, the only possible way to maintain acceptable accuracy in three-axis scanning has been at the expense of measuring speed. However, REVO uses synchronised head and machine motion when scanning, rapidly following changes in part geometry without introducing its own dynamic errors. The CMM is able to move at a constant velocity whilst measurements are being taken, without impacting accuracy.

REVO also benefits CMM users with infinite head positioning and innovative tip-sensing probe technology, which further improves measurement accuracy by sensing close to the measured surface. This combination of speed, flexibility and accuracy has proven to give exceptional performance in a wide range of scanning measurement applications, including circle, helix, sweep and gasket scanning, plus, if required, rapid single-touch routines.

Expanding to meet increased demand
Any visitor lucky enough to tour the Escribano factory can see the size and significance of the investment required for such production. Juan A. Humanes (pictured right) reveals it to be between €1million and €1.5million a year, and most of the company’s CNC machines are top-end, Japanese or Swiss-built multi-pallet and multi-axis: Makino, Matsuura, Mazak; Sodick wire EDMs and CNC precision grinders from Jung.  All of them are the latest models, meticulously maintained and configured to minimise set-up and non-machining time, mostly using Renishaw OMP40 spindle-mounted touch probes and NC4 non-contact laser tool setting systems.

Escribano has outgrown its current building and has designed and built a new facility, where it will relocate in the next few weeks. Until then, the two small rooms adjacent to the main workshop that house the company’s inspection equipment will remain crowded. In the larger of the two rooms, three DEA Global Advance co-ordinate measuring machines (CMMs) with Renishaw probes check samples of parts for everything from thermal imaging cameras to components destined for the Joint Strike Fighter. Alongside the main metrology lab’ is a smaller room housing the company’s largest CMM: a Metris LKV CMM equipped with the Renishaw REVO five-axis measuring head and probe system; part of a recent investment in inspection equipment that totalled around €300,000.

For most precision engineering businesses, the Metris and Renishaw REVO combination would be enough to cater for their metrology needs. But Escribano isn’t your typical workshop and its customers are somewhat more demanding, leading to further investments in other advanced metrology systems such as a white light interferometer microscope for measuring roughness, and a contact profile meter capable of assessing the size and texture of a part’s surface.

Sophisticated expertise and technology
The Madrid-based company is a rarity; privately owned engineering workshops with the expertise and the technology to deliver components and systems for such sophisticated applications are few and far between. No one at Escribano can or will talk about its customers or their products, but Humanes is happy to discuss what the company is equipped to do and how it does it.

“We specialise in machining complex, 5-axis parts in aircraft-grade aluminium, stainless steel, nickel alloys, copper and titanium,” he says. “The only way to be good at this kind of work is to make the necessary investments in technology and people. Our customers can choose between some of the best equipped suppliers in the world, so we have to make sure we can deliver exactly what they want, when they want it.”

A large proportion of Escribano’s production is for the US defence sector, which probably has more small, privately owned precision engineering companies than any other country on Earth so the question is; why would a US defence contractor choose to outsource some of its most complicated, quality-critical parts to a company in Spain, instead of one closer to home?

“Some people might assume that we win business because Spanish labour costs are lower than they would be at a similar, US company,’ says Humanes. “But they would be wrong. If that were the case the work would simply migrate to Asia. The truth is we are competitive because we invest in the best technology and we train people to high levels. We don’t just benchmark ourselves with competitors in Spain or Europe, we aspire to be the best in the world.”

General precision engineering may, thanks to the technology, be getting easier, but Escribano’s willingness to meet almost any standard of engineering precision means that even during the worst recession in living memory – and the Spanish economy is suffering the effects as acutely as any country – this family-owned company is still busy 20 hours a day.

With negative headlines often surrounding the Western car industry, it is easy to forget that major manufacturers continue to operate world-class volume vehicle production facilities in Western markets. The Nissan plant in Sunderland is demonstrating how it is possible to significantly reduce costs to compete against manufacturers based in emerging lower-cost economies. Within their engine plant, the introduction of Renishaw probes onto four CNC twin turret lathes has led to an initial saving of £250,000 ($400,000).

The Nissan plant at Sunderland was set up in 1986, with two dedicated camshaft production lines following in 1991. Nissan’s continual development of new car models and wide variation in engines meant that a completely fresh approach had to be taken in 2001 to meet future production needs.

Simon Edwards, the engineer responsible, explains;”It was clear that the current lines could not manage the complexity of the new generation of camshafts so we defined a new camshaft process that replaced two dedicated camshaft lines to form one flexible line. The new line occupies half the floor space of the two originals whilst maintaining the same output. In 2002 we were juggling 14 variants of camshaft through the new line; currently, we produce 6 variants.”

Probing meets resistance
Nissan’s Sunderland plantMr Edwards joined Nissan after working at Michell Bearings, where he had used Renishaw’s spindle probe systems on machining centres, and knew that introducing probes was easily the best way to achieve the objectives. “I had to use the existing machines where possible to produce the new camshafts in order to reduce investment, so I selected four Okuma lathes – two were 14 years old and two were eight years old. I looked at using the existing dedicated machining techniques, requiring us to maintain good quality on these machines, and checking finished camshafts on dedicated post process gauges. The initial quote for a stand alone flexible gauge to cope with the vast differences was $400,000, so I considered a turret mounted probe that would utilise the lathes’ flexibility to manage the number of variants, working out at a total of $40,000 for the 4 facilities.”

According to Mr Edwards, there was significant initial resistance from the machine operators and other engineers, as they did not want machine time spent on what they saw as measuring operations. The common feedback was that ‘machines are there to cut metal, not measure!’

However, Simon Edwards was determined to make the changes. “It all comes down to the fact that we needed to hit a certain cycle time to get the throughput, so I did everything I could to shave the machining time and add in the probe operations. This was mainly through smart use of the twin turrets. In the end, with the probe operations included, the whole cycle time is now less than the previous machining-only process”, he explained.

The initial anti-probe attitudes have now reversed, as he described. “If I go down there now and suggest we remove the probes and the software, the lads wouldn’t let me near the machines!”

Zero scrap after almost 2 million parts
So how have probe systems made such a dramatic impact and won friends at Nissan? The key areas reported are part set-up and post-machining inspection, where new processes have had a dramatic impact on scrap levels.

The camshaft castings arrive at the lathe cell with the front face qualified, and each one is manually loaded. After approximate positioning, the machine tailstock clamps the casting in place and, on every component, uses the turret-mounted Renishaw probe to find the front face in a matter of seconds. The 2 turret offsets for the subsequent machining program are immediately updated by comparing the measured position to the nominal value, with any variation subtracted or added. The machine then cuts multiple surfaces on the shaft referencing all machine positioning to this compensated zero point – total cycle time 90 seconds.

Simon Edwards is quite happy to make a bold statement at this point – “To my knowledge there has never been a scrap component on these machines as a result of this process. That’s out of 550,000 camshafts a year. In fact we are now nearing something of a milestone; this year we will reach two million good parts. This process of redefining the datum has had implications for the processes upstream from the lathes and this is where the scrap has disappeared completely. We now have general tolerances for key features at these operations where very tight tolerances used to exist. This has also increased facility efficiency with minimal downtime experienced on these operations through addressing historic quality concerns.

Inspection of finished camshafts to update tool offsets
The other application of the Renishaw turret-mounted probes is sample inspection of finished components after machining. The positioning required on most features is not tight, typically ± 0.2 mm, but it is vital that it is closely controlled, otherwise it will tend to drift. Typically the probe takes about 40 seconds (or up to 60 seconds for a few longer shafts) to check the 17 defined features, automatically updating tool offsets with any variation as it goes. Originally, this check was done after every 10 shafts, but experience of actual tool wear has reduced this to a check after every 20 parts.

Productivity transformed through “hands-on” engineering and cost-effective probing
Mr. Edwards spends a lot of time on the camshaft line, because as he says, “All these gains are made by production engineers working directly with the process and being aware of concerns as they happen. These old machines have been given a new lease of life because they now have intelligence via the probe and can therefore react to issues as they rise. New machines won’t get through the door now without probes. So far, as value for money goes, they are easily the best bit of kit we’ve got on the camshaft line.”

Process traceability
The whole system is calibrated on the CNC lathe in just a few minutes using an automatic cycle with a master part. This is the standard by which traceable quality is guaranteed.

Probe use becomes standard practice
Each CNC lathe has a document permanently attached that details the use of the measurement system within the manufacturing process, acting as a constant reference for every operator. The document lists the four key reasons to trigger post process measurement using the Renishaw probe:

1. Maintain general quality i.e. measure key features at a set frequency (20 parts).
2. Tool change. The tool management system on the lathe is interrogated every cycle to determine a full change or a single change. A full tool change will result in the measurement of all features whereas a single tool change will only measure the relative feature machined by that tool.
3. Variant change.
4. Start of shift or first off part. The part counters on the lathe are monitored every cycle. This is particularly important when the machine is started from cold on a Sunday night.

With the dramatic improvements in Nissan’s manufacturing capability, and the integration of probing as standard practice, any initial resistance now seems a distant memory.

Nissan’s Sunderland site and the camshaft line
The vast Sunderland site encompasses most of the manufacturing processes necessary to build and assemble all the piece parts for Nissan cars, whether within Nissan itself or through the multiple independent parts suppliers located around the perimeter.

Visitors are immediately struck by the high standards of cleanliness and positive enthusiastic attitude of the operators and engineers. Maybe other manufacturers have something to learn.