The Link Between CNC Process Control and Powertrain Warranties

During a brief period in the mid-1960s, the Big Three automakers — locked in fierce competition — extended their engine and powertrain warranties to a then-unheard-of five years or 50,000 miles. It proved to be a reckless decision. Within just a few years, consumer claims on these warranties were so overwhelming and expensive that the automakers reverted to one-year warranties by the early 1970s.

Today, five-year powertrain warranties are nearly standard, with some automakers bumping that coverage up to 10 years or 100,000 miles. What has changed between then and now, of course, is that automotive manufacturers have achieved higher levels of accuracy in their design and manufacturing. Precision-manufactured parts are now achievable at scale, and product performance, efficiency and reliability all have increased because of it.

This month’s cover features the original 1972 touch-trigger probe invented by Sir David McMurtry and patented by Rolls-Royce, where McMurtry worked as a young deputy chief designer. Known for his keen analytical mind and problem-solving skills, McMurtry was tasked with addressing a problem the company was having with measuring the instrumentation pipe of a Concord jet engine.

The probe that Rolls-Royce used at the time was rigid and kept pushing the part away each time it made contact. After studying the issue, McMurtry designed and built the first touch-trigger probe over the course of a weekend using a lathe that he kept in his garage. Soon after, McMurtry and his then-colleague at Rolls-Royce, John Deer, quit Rolls-Royce and went on to form the company Renishaw in 1973. McMurtry was able to buy the patent from Rolls-Royce (the original U.S. patent is featured as the background of our cover image), and the probe served as Renishaw’s central focus during the company’s early days.

McMurtry (often referred to as “Sir David” after he was knighted by the Queen several years ago), still serves as chairman and chief executive at Renishaw. McMurtry has been quoted as saying that most cars and aircraft that exist in the world today have at least one component that has been measured by a Renishaw probe. It is a claim that, given the ubiquity of the product at manufacturing facilities around the globe, hardly feels like an exaggeration.

As this publication has documented many times over the years, Renishaw has been relentless in its pursuit of achieving process control over its own high-mix, low-volume manufacturing operations, turning to its own production facilities in the United Kingdom as proving grounds for new innovations. The company’s system for machine-level process control, called RAMTIC (Renishaw’s Automated Milling, Turning and Inspection Center), has served as the foundation of its production methodology since the 1990s.

Earlier this year, on the occasion of the company’s 50^th anniversary, I had the chance to visit those production facilities in the U.K. Besides the anniversary, the core reason for the visit was to learn about a development in Renishaw’s quest for end-to-end process control — a new manufacturing connectivity and data platform called Renishaw Central. The platform, which you can read about here, leverages data from connected shopfloor devices such as Equator gaging systems, machine tools, CMMs, tool setters and machine tool probing systems. Using its own Intelligent Process Control (IPC) software, the system can detect the presence of tool wear and send tool offsets to the machine tool CNC in real time.

During my time visiting Renishaw’s production facilities in England and Wales, the evolution of the company’s own production strategies was often referred to as a “journey.” Whether or not the touch-trigger probe can be considered a form of automation may be debatable, but from the moment of the probe’s invention to the implementation of RAMITC, to the release of Renishaw Central, identifying and controlling variation in its production processes has been a mission of Renishaw since its inception. And so you can, at least in part, thank Renishaw and other OEMs on similar missions for the 10-year/100,000-mile powertrain warranty.

As for automation? On one afternoon tour of Renishaw’s Stonehouse plant, I found myself walking side-by-side with Sir David after the two of us had broken off from the group to look at one of the automation cells on the shop floor. Passing by a row of Mazak Integrex machines running unattended, I asked McMurtry: “What is going through your mind as you walk through this plant, 50 years after starting the company?” He thought for a second then pointed up to the line of Mazaks and said, “As long as the lights are green, I’m happy.”