Rockman Industries, a part of the Hero Group, is a leading supplier of aluminium die casting components, machined & painted assemblies. With two-wheeler alloy wheel penetration reaching as high as 90 % of the market, Rockman Industries is going full throttle to make the most of this growing demand. Auto Tech Review recently visited the company’s Bawal facility to know more about its operations and manufacturing prowess.
Rockman Industries’ Bawal facility has been producing alloy wheels at a rather feverish pace. Starting from raw materials to a finished product, the batch of alloy wheels passes through the manufacturing line and follows a 12-hr cycle at Rockman Industries’ Bawal facility. Built on a land spanning across five acre, this facility rolls out a fresh batch of around 200 units in approximately 43 min, and a cumulative 3,500 sets of alloy wheels in three operational shifts a day.
Out of the cumulative annual capacity of 5.6 mn alloy wheels rolled out by the company, the Bawal facility manufactures 1.8 mn units of 12-inch and 18-inch diameter wheels, with the remaining contributed by Rockman’s Haridwar facility.
Rockman imports raw material for its alloy wheels in the form of ingots under the A356 nomenclature of the American Society for Testing and Materials (ASTM). The primary alloy ingots are checked with the spectrometer for their chemistry. Once a quality check of ingots is undertaken, they are subjected to two melting towers, which operate at 650-700 °C to convert ingots into molten metal. The liquid is then passed through degassing operation, where inert gases like nitrogen are passed through the metal. The operation gets rid of trapped gases like hydrogen in metal and avoids development of porosity during casting of wheels. Two-wheeler alloy wheels follow different nomenclatures for front and rear alloy wheel. Thus, Rockman’s engineers conduct similar wheel processing in the same line for monitoring quality levels.
The company has installed four robots sourced from ABB to manage the pouring of metal into casting dyes. Pouring of metal by robots leads to high consistency and quality maintenance, which is impossible during manual pouring of metal, stated the company. The Bawal facility currently has four cells for dye casting of wheels. Each cell has six dyes managed by one robot for wheel casting and is inclusive of one dye for backup during contingencies. Once the robot pours the metal, it takes around five minutes for wheel casting, which is also introduced with cast iron rings for brake lining. It is followed by a controlled induction heating process for increasing the overall casting quality.
The casted wheels are subsequently transferred to riser cutting area, which is managed both manually as well as by robots to cut down the excess metal from the wheels. Subsequently, the wheel is passed through robo-deburring to give a touch up on the parting lines, which tend to show up during the paint job, said Sanjeev Prabhakar, Head Engineering, Rockman Industries. The robots for both operations have been sourced from Kuka Robotics to make the wheel ready for the heat treatment process.
The wheel is subjected to a temperature of 530 °C to improve the tensile strength of the structure and refining of grains. The idea is to avoid any breakage when the wheel passes through the rough patches or a sudden jerk. The casted wheel tends to gain elongation properties during the heat treatment process, which is eight per cent as a specification. If you only cast – without putting it through the heating process – the wheel does not get more than two percent elongation. If heated, it can elongate by up to 10 %, Prabhakar said.
The company also conducts time temperature recording (TTR) to check the process consistency and validation. The shift supervisors and quality inspectors keep a bird eye view of the actual process being undertaken against the specification standards set by Rockman Industries. The wheels are then passed through the shot blasting procedure in which steel shots of 0.8 mm dia are hurled at the wheels at a high speed for less than a minute. The process tends to remove small undulations and increases the fatigue life of the wheel. Shot blasting is followed by machining of the wheels to make them ready for assembly.
MACHINING & PAINT JOB
Rockman Industries has installed 19 sets of lines that undertake two operations for each line for CNC machining. Here, all the wheels are checked for critical dimensions, also for run-offs to avoid wobbling during on-road operations and air leakage. The two-wheelers generally ply two types of tyres – tube type and tubeless tyres. Subsequently, for tube type tyre, air leakage is largely from the tyre and not from the rim; thus run-off test is conducted first. However, in tubeless tyres, the run-off and air leakage are checked after performing all the processes, as air leak can happen from the rim as well. The wobbling test is repeated after the tyre is mounted. After the air leak testing, the wheels are transferred for the paint job process located on the first floor of the facility. Here, the wheels are treated with 15 stage automatic treatment process that includes pre-degreasing at up to 60 °C, hot water rinse, followed by water drying oven along with other critical operations to make them ready for the paint job.
The paint job room is completely air controlled to avoid dust playing its part during the painting of wheels. On the same conveyor belt, the wheels are put on hangers to first undergo a primer paint process and then lined up for two coats – base and top coat. Both paint coats are undertaken by electrostatic bellguns for better paint spread-out and to save paint wastage. At each operation, the hanger is stationed for 15-21 s. The colour change for alloy wheels is ensured by keeping a certain gap in the same conveyor belt; the new colour scheme kickstarts in less than 10 min. The company’s engineers have also designed a water curtain at the back of the paint job room to capture the excess paint spray from going into the atmosphere. The water is subsequently treated in the Effluent Treatment Plant setup inside the facility. The freshly painted wheels are subjected to the baking process operating at 120 °C for polymerisation, so that the paint remains stuck to the metal.
It is the R&D set-up at Rockman Industries’ Haridwar facility that helps the Bawal facility during the new product development process. The Bawal facility houses radial fatigue tests, cornering fatigue tests, torsion fatigue test, bending, impact, X-ray and drop test, from where data is also shared back to the Haridwar facility for new product development. The company also obtains support from ICAT, Manesar for new design checks due to its proximity. Once the wheel is assembly-ready, two different lines, one each for front and rear tyre, undertake tyre mounting. After the whole assembly is ready, it is then subjected to vacuum decay testing to check any leakage from the entire system before delivery.
We are looking at material composition, new designs, different heat treatments and different processes that deliver the same results with lesser weight in alloy wheels, said Ujjwal Kant Munjal, Managing Director, Rockman Industries. The Haridwar facility houses a performance test lab for alloy wheels, while the Bawal facility has a design centre for two-wheeler alloy wheel optimisation for various operations, including weight reduction and cost optimisation.
The company is currently looking at scaling-up its capacity at Bawal by 600,000 units and has lined up plans to set up two more cells (12 dye casting machines, two robots and another furnace). The company is also gearing up to set-up two new facilities for two-wheeler alloy wheels in India by Q2 2019. The upcoming facility in Gujarat will have the capacity to manufacture up to two million units, whereas the facility in Andhra Pradesh is expected to see up to four million alloy wheel manufacturing capacity, taking Rockman’s overall volumes to over 11 mn units in the future. The company has earmarked investments of Rs 650 cr for the two new projects.
FOUR-WHEELER ALLOY WHEELS
Given the increased duty on imported auto components and dollar price, the market has turned into a level playing field for domestic manufacturers competing against the market-dominating Chinese products, states Munjal. Interestingly, on one hand, penetration of alloy wheels has been high at 90 % in the two-wheeler segment, while penetration in the Indian passenger car segment has also grown from just four percent a few years back to over 30 %.
Having established a base in the two-wheeler alloy wheel market, Rockman Industries also has a sharp eye on the fast-growing alloy wheel demand in the passenger car segment. The company has tied up with Korean-based Hands Corporation to build technical know-how in four-wheeler alloy wheels. Munjal plans to start manufacturing four-wheeler alloy wheels at its Andhra Pradesh facility along with two-wheelers to set-up a base in the passenger car segment.
As of date, around half of Rockman Industries’ revenues are sourced from alloy wheel manufacturing and it expects it to further increase to 60 % in coming times along with expectations of revenues doubling over the next three years. As part of its technology absorption, the company has also chalked up plans to focus on in-house designing of wheels in India rather than depending on its overseas partners.
TEXT: Anirudh Raheja
PHOTO: Bharat Bhushan Upadhyay