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SHOPFLOOR SONA KOYO

Sona Koyo Steering Systems Ltd (SKSSL), the flagship company of the Sona Group, was established in 1985

through a technical and financial collaboration with JTEKT Corporation, Japan (formally known as Koyo Seiko Co

Ltd), the largest producer of passenger vehicles’ steering systems in the world. The company today is the largest

manufacturer of steering systems in India, catering to passenger cars, utility vehicles and light commercial vehi-

cles. Valued at $800 mn currently, the group has presence across 16 locations in India, three in Germany and

one plant in the US. We visited Sona Koyo Steering System Ltd’s mother plant in Gurgaon to understand the

manufacturing philosophy on the steering major.

SONA KOYO STEERING SYSTEMS – INDIGENISATION-LED GROWTH

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PRODUCTS & TECHNOLOGY

Sona Koyo Steering System Ltd primarily manufactures steering systems for differ-ent applications, with the Rack & Pinion Steering (RPS) and Hydraulic Power Steer-ing (HPS) accounting for the bulk of sales. A company spokesperson we spoke to informed us that the hugely popular SUV from Mahindra & Mahindra, the XUV500, is one of the company’s latest business acquisitions for the HPS.

The company presently manufactures a wide range of steering columns including tilt, tilt/ telescopic, collapsible and rigid type for major Indian custom-ers including M&M, Maruti Suzuki and Tata Motors.

In recent times, SKSSL has expanded its focus on new products, customer and product diversification as well as enhancement in engineering capabilities. On the product front, one of the most advanced new introductions is the Col-umn Electric Power Steering (CEPS), while the Electric Power Assisted Module (EPAM) is the other key technology developed recently. This is presently being supplied to a company in the USA for off-highway and recreational vehicles. The same system can also be used in tractors. The EPAM is a combination of electrical and mechanical systems gener-ally found on steering systems and the company has a patent for this product. The benefit of the system is the lower torque requirement for movement, which results in fuel-savings. In India, the com-pany is already in talks with various manufacturers such as Escorts and M&M for tractor applications.

At the production facility in Gurgaon, SKSSL operates four plants, dedicated to making specific products. The company presently accounts for 100 % supply of

rack & pinion CEPS steering systems for the Maruti Suzuki Swift. The Gurgaon plant manufactures about 600 such units per day and about 1,400 units are made at the Dharuhera plant. This sys-tem has been entirely designed and developed in-house by SKSSL engineers. Parts such as the pinion and housing too are manufactured at the facility, which are then assembled with the remaining sourced parts.

The company is also supplying manual steering systems for Mahindra Maxximo, which is manufactured at M&M’s Pune plant. Despite being rela-tively old, SKSSL’s Gurgaon facility has partly adopted modular manufacturing. Presently, two different products can be manufactured on the same product line and the company plans to continue adopting newer production techniques & technologies.

The rack & pinion manual steering assembly line at the plant is multi-modal in nature. This line is responsible for producing steering systems for seven

different models of Maruti Suzuki India (MSIL).

Operated on the principles of Poka-yoke, the present capacity of this line is 53 units per hour. This Japanese technique plays a critical role, since manufacturing of this system involves assembly of up to 27 parts and even the slightest error could result in part failure and warranty claims for the OEM. In the event of any particular step going wrong, the assembly line automatically comes to a stop and signals the problem area through a light system. The line resumes production only when the indicated problem has been resolved. Usage of the Poka-yoke technique also helps the line workers ensure that assembly parts do not get mixed up when steering systems for multiple models are being manufactured on the same time.

During assembly, special care is taken for safety parameters that can affect the human body in a direct or indirect way. For example, if an operator doesn’t torque the steering assembly appropriately, it could result in steering failure, when the vehicle is in motion. In order to ensure zero error, the line is equipped with an electronic torque zone, again based on Poka-yoke. In case of an operator missing out, the zone detects the miss and stops the conveyor belt and resumes only once the problem has been addressed.

Post the torque process, the assembly is checked for fitment parameters. These assemblies are Direct on Line (DOL) parts, meaning they are sent directly to

Grooves being cut into the steering components

Manual steering columns Column electric power steering unit

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SHOPFLOOR SONA KOYO

Maruti’s assembly line in installation-ready state. Since such assemblies do not undergo any quality check each time at the OEM’s end, it needs to be ensured at the supplier’s end that there are no defects.

Driveline products by Sona Koyo include axle assemblies and case differ-ential, which are made at plant No. 4. The rear axle assemblies manufactured by the company are supplied to Maruti’s Omni, Eeco and Gypsy models. Pres-ently, the company manufactures about 650 units of rear axles daily. This plant also manufactures Recirculating Ball Screw (RBS) assemblies. RBS steering systems are normally used in light com-mercial vehicles. These are manual units without any hydraulic or electric-assist. Presently, these assemblies are being supplied for M&M Bolero, Chevrolet Tavera, Swaraj Mazda etc. The assisted steering found on the same models is supplied by another company.

The company has a test track at the facility to check the performance of any new product during or after develop-ment. The steering system is installed in a car and then tested on the track, which includes various surfaces. This test allows the engineers to check the sound, vibration and durability on a particular system.

Sona Koyo has adopted several tech-niques to reduce its manufacturing costs. The facility has its own furnace and paint shop, thereby reducing its depend-ence on external companies. Sona Koyo is aggressively pursuing a strategy of maximum possible in-house capabilities.

Interestingly, the company has started making its own manufacturing machines too. This activity was started by the com-pany two years ago.

At the Gurgaon facility, there’s a sepa-rate machine-building area dedicated to the production of these machines. The machines manufactured here are also supplied to the company’s plants in Dharuhera and Chennai. Presently, man-ufactured units include washing machines, presses, fabrication & lathe machines and a few other machines. Such moves have brought dual-benefits for the company – reduction in its manu-facturing costs and increase of its techni-cal expertise in the process.

HYDRAULIC POWER STEERING ASSEMBLY PROCESS

The plant responsible for manufacturing the hydraulic power steering assemblies is one the newest and most mechanised plants at the Gurgaon facility. Present cus-tomers include Fiat, Maruti Suzuki, Toy-ota, M&M and Tata Motors.

Hydraulic steering primarily consists of a pump, fluid lines and a piston. The system works in a way that when the steering is operated, only about 10 % of force is required from the driver and the remaining is supplied by the hydraulic pump. The assembly process for the hydraulic steering is explained below:

The assembly process starts with a cyl-inder tube and pinion housing. The first step is to wash the components to elimi-nate any foreign particles. Post this, two rod seals are pressed into the component to prevent any fluid leakage followed by the bearing pressing for pinion support. After this the rack bar is installed, which converts the rotary motion of the pinion into linear motion, allowing sideways movement of the wheels.

The rack bar is integrated with the pinion housing and cylinder tube. The insertion of the rack bar needs to be pre-cise and even a fractional deviation can result in damage to the rod seals. If dam-aged, the hydraulic fluid can leak, lead-ing to failure of the component. The next step is to match the pinion with the greased teeth of the rack bar, after which the inlet/ outlet fluid tubes are installed in the assembly. These tubes are respon-sible for circulating the hydraulic fluid through the system. A specially formu-lated white-coloured fluid is then sprayed onto the seals of these tubes. The white layer enables the line operators to spot any leakage in the tubes.

The assembly is then placed in an air testing machine, which circulates air through the system at pressures ranging between seven to eight kg/cm2. In case of

Components ready to be shipped

Rack & pinion manual steering assembly line Furnace shop at the Gurgaon plant

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any leakage being detected, the compo-nent is taken off the assembly line and sent for further appropriate procedures. The next process of furnishing helps remove any high or low-points in the teeth of the rack and pinion. Going for-ward, a machine creates a clearance of 50 to 100 microns in the rack bar and pinion. In absence of this clearance, the steering will be uncomfortably tight to operate.

In the next step, the assembly is passed through an endurance-testing machine, which detects any leakage in the internal seals of the system. In case of any defect, the component is taken off the assembly line and sent for inspec-tion. A load & torque testing machine then applies pre-determined torque and load on the steering. This process ena-bles to check for any variation in the torque and load readings for a system.

Following the endurance test, the assembly is passed through a perfor-mance-testing machine, which checks the performance of the pinion. The machine can detect any sound anomalies in the steering, allowing operators to

spot a defect. Nearing the end of the assembly line, the hydraulic fluid is removed from the assemblies as they are delivered to the OEMs in a dry state.

The steering is then integrated with the rod gear and tie-rods and sent to the final station. At this point, line operators check the assembly for any dimensional irregularities. In case of any, the assem-

bly is sent back for appropriate correc-tive measures. In case of everything going well, the product is sent for pack-ing and logistics.

OUTLOOK

Quick adoption of new techniques and focus on development of technology haven’t been a forte of the Indian suppli-ers. Sona Koyo Steering Systems Ltd, however, has been different and has actively invested in new product devel-opment and upgrades of manufacturing techniques. Producing the manufacturing machines in-house and increasing the in-house capability of production will sig-nificantly help the company streamline its cost structure.

The strategy of expanding outside India seems on track for the company. Given the focus on new product develop-ment and engineering, we expect Sona Koyo to further diversify its product port-folio, thereby hedging its risks. Business in India too should continue to grow at a steady pace as the company has been adding new names regularly to its cus-tomer base.

TExT: Arpit Mahendra

PHOTO: Bharat Bhushan Upadhyay

Gurgaon plant has continuously adopted new manufacturing techniques over the past years

Axle assembly line for supply to Maruti Omni, Eeco and Gypsy

Test track at the facility Steering assembly in progress