Rapidly changing customer demands are prompting companies to come up with innovative car wheel designs. Set-up with an initial capacity to roll out 90,000 units per month in 2016, Minda Kosei Aluminium Wheels underwent a capacity ramp-up last year to serve the growing alloy wheel demand in India. Auto Tech Review recently visited the company’s Bawal facility to know more about its manufacturing capabilities.
A 70-30 joint venture between Uno Minda Group and Japan-based Kosei Group, Minda Kosei Aluminium Wheels Ltd (MKAWL) was inked in May 2015, and a year later – in May 2016 – the company set-up its first facility in Bawal to cater to the alloy wheel requirements for Maruti Suzuki India’s passenger car portfolio with an initial capacity of 90,000 units per month. MKAWL’s Bawal facility currently operates across three shifts and rolls out around 4,000 alloy wheels per day, with radius size in the range of 13 to 17 inches. VP Singh, VP – Operations Head, MKAWL said 15 and 16 inch radius sizes of alloy wheels contribute around 50 % of the company’s volumes.
MKAWL primarily imports alloys certified under A3562 nomenclature of American Society for Testing of Materials (ASTM) from trusted vendors of Kosei. The alloy mixture used is a blend of aluminium, magnesium, silicon, titanium, strontium and titanium in the form of bricks. MKAWL has installed eight melting furnaces that operate at a temperature of 670-680 °C to melt alloy bricks into liquid metal. Aluminium has the tendency to react with atmospheric oxygen, thus liquid nitrogen is passed through the molten material for degassing operation, Singh said.
The MKAWL top official said this passing of nitrogen is helpful towards removing unwanted gases from the alloy and make the material more robust for production. Each melting furnace is powered by CNG to reduce conventional fuel consumption and is assigned with one person, who manually pours the metal into two dies simultaneously. The casting procedure of one alloy wheel in a die is completed in five minutes, following which the wheel is transferred to heat treatment furnace on a conveyor. Singh said the facility is also equipped with an X-ray lab to maintain in-house quality and conducts random checks on the wheel casted out of a die.
After casting, the alloy wheels are transferred to the T6 treatment process that is spread across eight lines. Each process line at MKAWL is initiated by two robots sourced from Yaskawa to perform the heat treatment process, followed by shot blasting. The hardening process treatment includes heating of the alloy at up to
540 °C in order to make the solution more homogenised in the wheel and develop the micro structure of the wheel. This is followed by quenching of the alloy wheel with solutions to cool down before it goes into cutting operations. Singh said riser cutting machines are deployed to get rid of excess material in the casted alloy wheel. The ageing process is carried out and the alloy wheel is again treated at 165-170 °C heat to maintain its hardness at around 75-85 BHN. The wheel subsequently goes for shot blasting to clean up and smoothen the surface before it becomes ready for the machining process.
MKAWL has installed 48 machines for treating alloy wheels with CNC machining, with three machines for each of the 16 lines. The three machines per line conduct air leak testing (by submerging the wheel in water) and balancing operation of the wheel, followed by bolt hole drill and valve hole drill. The entire machining process is completed in less than four minutes before the wheel is transferred to the paint shop.
Following the CNC machining process, the wheels are loaded on the conveyor belts for 16-stage pre-treatment operations for surface washing and coating of up to 2-3 microns to save the wheels from corroding. This is followed by degreasing operations to make it oil and grease-free before the wheel undergoes powder coating for primer. The wheel is subsequently subjected to heat of up to 180 °C to help the paint settle down and make it ready for the two liquid paint lines set-up at the Bawal facility.
The two liquid paint lines spread out operations among the base coat and top coat of the alloy wheel as per the manufacturer’s demand. Electrostatic bell guns that sense the area that needs to be painted have been imported from Germany to reduce paint wastage. Each wheel undergoes not more than 30 s for the completion of the paint job per line. The wheel once again undergoes baking operation before it is transferred to the inspection area for final dispatch. It is at the base coat itself that the wheel gets its final colour and the top coat is only for lacquer finishing, Singh said.
MKAWL has also installed a separate line to serve the fast growing demand for diamond-cut alloy wheels in the country. Once the final paint job is completed, the wheel is put through a different machining process to give finer cuts to shape up the diamond-cut alloy wheel. After the machining process is completed, the wheel again goes thorough pre-treatment washing, followed by new paint job. Sans the base coat and primer coat, only the top coat of the wheel gets reworked for final detailing to manufacture diamond-cut alloy wheels.
Every manufacturer adopts a unique style of vehicle designing and adheres to its specifications like load, stress, tyre thickness, internal mounting, packaging of brakes, centre diameter. Singh claims MKAWL’s engineers strive to make alloy wheels that ensure a smoother drive and maintain up to 30 % extra buffer on pressure the tyre undergoes. Aluminium wheels are 7-8 % more elastic as compared to a rim wheel, and can shave off up to 15 kg from the vehicle’s kerb weight, thus rendering the vehicle lightweight and fuel-efficient, Singh stated.
MKAWL has also set-up an alloy wheel test lab inside the Bawal facility to conduct various tests before the wheel gets into manufacturing mode. Singh said the complete process may take around four to six weeks depending on the necessary tests and approvals from OEMs. Once the sample wheel is prepared based on the design inputs by the manufacturer, wheel simulation is conducted to figure out its expected performance levels under real life conditions.
MKAWL conducts radial fatigue tests to check dynamic loads that the wheel is exposed for a fixed number of cycles. As part of this process, the wheel is subsequently tested for tyre modelling, simulation methods and load applications for analysing the amount of stress the wheel can encounter during real life operations. The company also conducts cornering fatigue test to determine the alloy wheel's structural performance even under heavier loads. Under this test process, the wheel is mounted on a machine to simulate cornering both normal and heavy loads to test the wheel’s performance during daily operations. MKAWL has also equipped the lab with impact testing machines that test various impacts that a tyre can witness spanning from 13 degree, 30 degree and 90 degree. The company has also put in place a pendulum impact testing machine.
Kosei’s R&D centre in Japan is working in tandem with MKAWL to facilitate the execution of new projects at the Bawal facility. MKAWL is expanding its technical capacities to widen its horizons in terms of process knowhow and tooling knowhow.
Singh said while the large chunk of the company’s volumes is still being supplied to Maruti Suzuki, its volumes are also picking up momentum for Mahindra & Mahindra passenger vehicles, including the Marazzo and XUV500. Given the increasing demand, MKAWL has also set-up a new facility in Gujarat that rolled out 45,000 wheels in September 2018 and is expected to touch 60,000 wheels over the next few months.
TEXT & PHOTO: Anirudh Raheja