The automotive industry is fiercely competitive. Tier One car manufacturers are constantly looking for breakthroughs in performance, safety and innovative design, all of which places ever stricter requirements on the processing of metal components.

SuperAlloy Industrial Co Ltd (SAI) is a supplier of high-quality lightweight forged metal products. The forged wheel and car chassis components the company produces are used by the world’s top car manufacturers; and to ensure that these parts meet customers’ quality expectations, SAI uses machine tool probe systems from Renishaw (www.renishaw.com). These include the OLP40, RMP60, OMP60 and NC4 units.

SAI’s relationship with Renishaw began with CMM measurement, as CEO Henry Shih explains: “When we entered the European market in 2008, we realised that our customers’ quality, dimensional stability and precision requirements for metal products were extremely high. While our equipment at the time was able to meet their volume requirements, we needed to enhance product quality and reduce the amount of re-work we were undertaking.

“Through Renishaw, we discovered machine tool probe measurement solutions that could deliver in-process measurement control and real-time feedback on our existing CNC machines, thereby providing effective control of precision manufacturing. This was a massive help in terms of increasing production efficiency and precision.”

High-profile customers

SAI is currently focused on supplying high-quality forged metal products to high-end automotive manufacturers, including BMW, Mercedes-Benz, VW, Porsche, Ferrari, Bentley, Audi, Rolls-Royce, Jaguar Land Rover, Ford, Chrysler, Toyota, GM and Honda — plus Ducati.

The forged-wheel production process is complex, particularly for low-volume high-diversity production. SAI produces more than 200 types of wheel, which requires the utmost production flexibility. Strict standards are applied to workpiece setting and assessing key dimensions during the machining process, as the precision requirements for wheel-mounting surfaces exceed those of even the aerospace industry.

SAI currently has 600 CNC machine tools working on wheel rim production, including 150 Victor Taichung lathes and 450 YCM milling machines. All these are engaged in production on a three-shift basis five days a week. To ensure the stability and precision of the machining process — and reduce scrap — SAI equipped the relevant lathes with Renishaw OLP40 touch probes; these use optical signal transmission and are adapted for turning processes. The CNC milling machines are equipped with RMP60 machine tool probes; these use wireless radio transmission to measure workpiece position and reference height, as well as provide data on key dimensions.

Mr YC Kao, senior manager of SAI’s wheel production department, says: “The automated workpiece set-up provided by Renishaw machine tool probes allows us to ensure that the cutting dimensions remain stable and consistent when we are producing wheel rims; probing also reduces human error. For example, the process capability index (CPK) for the air valve hole-cutting thickness rose from 0.71-1.13 to 1.35-1.43 when using Renishaw machine tool probes.”

3-D forged features

Wheel design has moved on in recent years, away from flatter surfaces towards the use of 3-D effects; this has resulted in wheel rims becoming ever larger, placing increasingly stringent demands on processing precision.

Until 2011, SAI’s acceptable tolerances for wheel rim production with the flatter designs used at the time were 0.05-0.10mm. However, the tighter tolerance requirements — plus the complexity of the current 3-D designs — has gradually increased cutting times, with ‘wheel rim appearance’ processing taking up to 240min per wheel. As a consequence, any rework imposes considerable pressures in terms of both production time and cost.

OLP40 probes allow SAI to carry out in-process measurement control to achieve tolerances of less than 0.02mm; moreover, these probes can replace manual measurement and update workpiece co-ordinates, greatly improving ‘surface precision processing’ after coating.

More important is the fact that in-process probing has reduced re-work by 80% and reduced scrap to zero. Before the introduction of in-process measurement, wheels generally had to be processed twice to achieve the required level of precision; now, probing provides in-process control and real-time feedback, immediately updating and correcting data during metal cutting and efficiently monitoring and controlling dimensions.

Chassis components

With the automotive industry evolving from an emphasis on basic safety requirements and performance to focus on enhanced driving comfort, improved fuel efficiency and reduced emissions, there has been increasing emphasis on the use aluminium chassis components to achieve these objectives.

“The higher the precision of chassis parts produced with aluminium alloys, the safer and more stable the car is when travelling at speed — and the more comfortable the driving experience,” says Mr Shih. “The lighter the chassis, the lower the fuel consumption, and thus the easier it is for the vehicle to meet environmental requirements.”

SAI has continually improved its forging and mechanical processing technology, and it now has 38 Tongtai five-axis CNC machine tools — all equipped with Renishaw OMP60 optical machine tool probes and NC4 non-contact laser tool setters.

Unlike wheel rim production, chassis production tends to involve higher volumes and lower diversity; nevertheless, it still requires high-precision metal-cutting and processing. Here, Renishaw’s OMP60 touch probes are used; these feature advanced modulated optical transmission to provide 360deg signal transmission. The probes simplify measurement and calibration processes and achieve high-precision measurement for workpieces with complex profiles. Meanwhile, Renishaw’s NC4 uses laser technology for the high-speed high-precision measurement of cutting tools with diameters down to 0.2mm — and tool-breakage detection on tools as small as 0.1mm.

In conclusion, Mr Shih says: “When we choose suppliers, we don’t just look at the price of the product; we also attach a great deal of value to their R&D capabilities and service. For us, Renishaw hasn’t just offered a product or a solution; it shares with us its experience, expertise and industry best practice. Furthermore, we use Renishaw QC20-W telescopic ballbar measuring instruments for the diagnostic testing and verification of our machining centres.”