After losing its three-axis co-ordinate measuring machine (CMM) in a devastating flood, Precision Machine & Auto Components (PMAC) had to act fast to find an alternative solution. Renishaw’s REVO five-axis measurement system not only helped return a water-damaged CMM to operation but also reduced cycle times by up to 55%.

Founded in 1974, PMAC is one of India’s most respected manufacturers of large high-quality mechanical components. The company, which operates 35 CNC machines at two sites in Chennai, and employs more than 350 people, serves seven major industrial sectors and works with market-leading OEMs in the USA, Europe, the Middle East and throughout India.

Its diverse output includes transmission cases, gearboxes, cylinder blocks, knuckle joints, valves and compressors. Quality has always been a cornerstone of all PMAC operations, with the company’s precision manufacturing processes and procedures complying with recognised national and international standards.

Moreover, its quality inspection facilities are all in-house and feature ‘state of the art’ equipment, operated by an expert team. Chennai, the capital of India’s southern Tamil Nadu state, is no stranger to heavy rains and cyclonic storms. The north-east monsoon brings intense rain to the region in October and November, and last year’s relentless rainfall caused widespread flooding.

Rivers burst their banks, and PMAC — like many other businesses in the area — was unable to escape the devastating effects. One of the company’s two factories was severely flooded, and the CMM was rendered inoperable due to water damage, but it still had an operational frame and was considered salvageable.

Many of the components produced by PMAC — such as locomotive parts — require 100% CMM inspection, so a solution was needed fast. The executive director, Mr Karthik, requested the immediate replacement of the damaged CMM with a brand-new upgraded version of the existing three-axis machine. However, he also saw an opportunity to double the company’s CMM capacity by repairing the damaged CMM. However, at almost 70% of the cost of a new machine, a system retrofit by the original supplier for the salvaged CMM frame was considered too costly.

‘Sparking an idea’
At a meeting with Renishaw during the IMTEX exhibition, Mr Karthik was introduced to the REVO five-axis measurement system, and this sparked the idea of using it to retrofit the water-damaged CMM. He decided to purchase a REVO system from Renishaw, and the retrofit was completed within six weeks of order placement. The five-axis measurement technology embedded in Renishaw’s UCC S5 CMM controller is at the heart of the retrofit for PMAC, synchronising the three axes of the CMM with the two additional rotary axes of the REVO-2 probe head.

By programming this head to perform the fastest acceleration and deceleration motions during the inspection process, while leaving the CMM to move in a slower linear fashion, the REVO five-axis system minimises dynamic deflections and inertia loads on the CMM’s machine frame; and unlike alternative systems based on indexing heads or fixed probes, the five-axis motion enables the stylus to follow a continuous path around even the largest and most complex features without having to leave the surface to change a stylus or re-index the head.

Using the RSP2 probe for scanning and touch-trigger measurement, together with RSH350 and RSH500 extended-reach stylus holders, the refurbished CMM system was able to meet all PMAC’s inspection requirements; and by comparing the performance of the five-axis Renishaw CMM retrofit with that of the brand new three-axis CMM on a range of PMAC parts, it was determined that the cycle time saving of the five-axis system was 46% on average — and sometimes as much as 55%.

Furthermore, the ability of the five-axis CMM system to access and inspect all critical features on very complex parts has also helped PMAC alleviate some significant manual-handling and health-and-safety issues. With a large number of finished parts weighing hundreds of kilograms each, the previous three-axis CMM required frequent manual intervention plus the use of a large gantry crane to move the parts in order to complete inspection processes.

With the five-axis solution, this is no longer the case; and the REVO system can handle a complete part inspection using just one or two styli, which has greatly simplified operations (only one calibration is needed). Furthermore, the REVO five-axis system with its Modus metrology software allows programming to be done offline, eliminating down-time.

Further details of this application and Renishaw products can be found at the Web site (www.renishaw.com/pmac).