Use of CNC technology in Cylinder Valve machining

My first visit to the UK in 2002 involved a meeting with a UK tool supplier in a small English town about 130 miles South East of London. We used to procure cutting tools like chasers and taps from the UK suppliers known for their precision and long life. Good quality cutting tools were critical to the productivity and accuracy of the threads manufactured on manual capstan lathe machines, which we were using for the last thirty years.

Computerised Numerical Control (CNC) machines had arrived in India in the mid-1990s, but they were expensive, programming was considered a challenge, and there were not many people trained to set the machine. A few self-proclaimed machining experts discouraged us from buying CNC’s, citing the involvement of significant investments; feeding them would be a challenge. It was speculated, even projected, that the lack of return on investment would sink our company if the machines were not properly utilised.

For the first 30+ years, our machine shop featured a series of capstan lathe machines. Despite using the best quality cutting tools, the machining technology could be described as rudimentary at best, as both productivity and quality were dependent on the operator’s skill.

With some apprehension, we decided to invest in a CNC turning centre in October 2003. We hired a CNC consultant who helped us shortlist three suppliers before deciding on Ace Designers, Bangalore. Our first CNC turning machine, tooled up for two of our high running models, arrived in May 2004.

The doomsday scenario did not unfold as we started getting consistent quality parts after our engineers fine-tuned the fixtures and tweaked the tooling received. The learning curve on how to use the CNC machine had well and truly started. We spent a lot of time optimising the cutting oil and selecting appropriate single point carbide tools for turning, boring and threading to reduce the cycle time for different operations.

Our production increased 2.5-3.5 times in comparison with manual capstan lathe machines. We decided not to utilise our capstan operators to work on the CNC machines as they were not conditioned to challenge the status quo. It was likely that they would be satisfied with an incremental (and not exponential) increase in productivity, hindering our machine utilisation.

We soon placed our second CNC turning machine within three months of starting the first machine. We had a fleet of eight CNC turning machines in three years, and it was now time for our technical director to doubt if we had invested too fast and whether market growth would be sustainable to support the investments. Each machine was compared to an elephant needing a lot of food every day, so feeding them day in day out was considered a challenge.

All apprehensions have been put to rest, and now we have a fleet of 45 CNC machines, including the world’s top brands. Most of our earlier purchased two-axis machines have been replaced in recent years by multitasking machines with up to eight axis for simultaneous turning and milling operations, offering unparalleled quality in a single set-up.

Our growth and reputation as India’s leading cylinder valve manufacturer have been mainly possible due to the CNC machining technology we initially flirted with at the start of the millennium, engaged a few years later and married before the end of the decade.

As our capstan operators retired, we slowly but surely phased out our capstan machines. We have managed to retain one, and even if it is no longer in use, it stands proudly as a relic from the past and just got a fresh coat of paint. The new breed of CNC machine operators have no idea how to operate the capstan lathe, and most have not seen it running in its glory days.

Our chaser cabinet still houses the hundreds of unused thread chasers we had procured from the UK. In no hurry to be used.

Reach me at rb@teknovalves.com