Meeting Air Compressor Needs For The Automotive Sector

Meeting Air Compressor Needs For The Automotive Sector

ELGi Shopfloor Air Compressor Automotive Sector

The manufacturing sector, including the automotive industry, requires air compressors for various operations. In fact, the automotive sector has been a key procurer of air compressors and ELGi Equipments Limited has been a preferred choice for OEMs and component makers for their requirements in this context. We had the opportunity to visit the Coimbatore facility of ELGi in Tamil Nadu to understand the production process of air compressors and the advantages offered by the company’s products.

ELGi’s foundry produces high-precision grey and SG iron castings, using advanced and environmentally friendly processes. The company has manufacturing facilities in three locations globally and has direct presence in 18 countries. The total business outreach spreads to 70 countries and the company is gearing up for expansion in other markets. Auto Tech Review met Dr Jay Varadraj, Managing Director, ELGi Equipments Limited, to get a detailed overview of the air compressor production process and the manufacturing prowess of the company.


The company has an expanding product line comprising of reciprocating compressors and rotary screw compressors, together with air auditing systems, control systems and lubricants. The main plant in Coimbatore is spread across 37,000 sq m of foundry land area, of which one-fourth is dedicated to the factory space. It also has its manufacturing locations in the US and in Italy, while subsidiaries and offices are located in Australia, Bangladesh, Brazil, China, Indonesia, Italy, Sri Lanka, Thailand and UAE. In India, ELGi has 13 branch offices and a global support centre to study customer requirements and rectify issues, if any.

ELGi uses high precision instruments for on-line quality assurance and calibration

ELGi currently offers a wide range of compressors, including solutions ranging from oil-lubricated and oil-free rotary screw compressors, oil-lubricated and oil-free reciprocating compressors and centrifugal compressors, to dryers, filters and downstream accessories. Its product portfolio comprises 400 products and has multiple applications across industries. ELGi operates three factories in the world using its own ‘airends’ (a piece of equipment that channelises air pressure) for uniform quality. The current production capacity at ELGi’s Coimbatore plant is 9,000 metric tons a year. The foundry division produces stator bodies, centrifugal control units, crankcases and cast rotors from SG iron.


The compressor production division follows an integrated operational approach and all castings are produced in-house, using globally accepted machine tools. This unit can manufacture castings of 3-25 kg, depending upon customer requirements. ELGi produces 38,000 such parts every year, having an accuracy of within two microns.

ELGi custom designs and builds its own rotor milling machines to produce high quality rotors at an affordable price point. These machines boast low vibration characteristics, resulting in tighter milled rotors. A high rigidity quotient in these rotor milling machines enables faster production, and they also have a self-monitoring mechanism to prevent or minimise defects and errors.

Further in the grinding process in rotor production, ELGi has employed high-grade machine tools for profile grinding and rotor finishing. The grinding machines have a compact setup to ensure high quality of 15 microns for lead tolerance. The airend assembly line conveyor is manned by skilled and trained personnel, to avoid quality niggles. Up to 15,000 airend units are produced each year and are offered with a lifetime warranty in the North American market.

The integrated process ends with the final compressor assembly line, which is equipped with automated monitoring and testing stations. 40,000 air compressors are manufactured at this plant every year, of which 15,000 units are screw air compressors and 25,000 units are piston compressors.


ELGi manufactures pressure vessels that meet international standards. Around 5,500 sq m of space within the factory is dedicated to pressure vessel manufacturing, and it produces 29,000 receivers per year. This product adheres to multiple global certifications.

In terms of the machines installed, this section has laser cutting machines and automatic welding machines, coupled with powder coating and hydrostatic testing equipment. This unit involves 100 % hydrostatic test with pressure sensor detection and boasts of 100 % automatic welding duty cycle power source. The receivers range from 117 to 750 mm in diameter, 300 to 2500 mm in length and three to 14 mm in thickness. These are industrially accepted dimensions and diversions are rare.


In order to conform to stringent quality norms, ELGi uses high precision instruments for on-line quality assurance and calibration. The profile measurement accuracy is less than two microns, while the housing measurement accuracy is less than three microns. In order to provide on-time service to its customers, ELGi maintains high levels of response and resolution records in the industry.

The company has set for itself, a 48-hour restoration time for all its domestic customers, and over the years, has a 96 % score on reducing complaints between scheduled services. This is part of the company’s first time right (FTR) policy, to resolve customer complaints at the first instance. ELGi has also received a score of 90 % in the customer satisfaction index (CSI) across its business centres.

ELGi products have made a mark for themselves in terms of quality and reliability. The company ensures that every manufactured component and product passes through stringent quality audits and is tested to ensure performance and reliability in the long run. The manufacturing test rooms are atmospheric controlled and all products are built to comply with international standards.

In order to manufacture compact and reliable compressors, the company has its own industrial design centre, named Ergo Design, which focuses on form, fit and finish of products, documentation and collaterals. The studio is spread across 600 sq m of space and has a team strength of 10 experts.

The software used by the team includes Solidworks and AutoCAD Inventor for CAD modelling and engineering. For concept design, the centre uses Alias Design Studio, while Adobe’s Illustrator suite and CorelDraw are employed for graphics and graphic designing.


ELGi’s technology centre designs subsystems for compressor packages and supports product design teams to reduce the number of physical prototypes. It uses computational fluid dynamics (CFD) simulation methodologies for turbo machinery and heat exchangers. It also features nonlinear finite element analysis (FEA), fatigue testing, steady state dynamics and roto-dynamics. Structural analysis involves static and transient dynamic analysis of base frame for design optimisation. CFD analysis track the air-oil separator for better separation properties.

The NVH team at ELGi designs and develops engineering solutions for noise reduction, torsional stability and low vibration. This team is involved in NVH analysis, data acquisition and processing, analytical designing, finite element designing and drivetrain lateral and torsional analysis.


A MATLAB-based tool for torsional vibration analysis was developed in-house by the company, and is used in drivetrain optimisation. In order to ensure refinement of prototypes, compressor packages are constantly upgraded on noise and vibration through sound intensity mapping, aided by an indigenously designed traversing robot.

Indigenous acoustic impedance design and development was undertaken, for absorption optimisation of noise reduction foams, validation and tuning of resonators for transmission loss of ducted noise control in intake of compressors. An in-house development of 1D noise prediction model was also put in place to evaluate product concept designs at the conceptual phase of new product development.

Over the years, ELGi has designed compressor controllers for oil-flooded, oil free and centrifugal compressors. These feature high performance hardware and software systems, coupled with user-friendly multi-language interfaces and in-built wireless networking remote monitoring and failure prediction. Also, these units feature in-built compressor energy management systems and motor protection mechanisms. ELGi has various functional and reliability tests for design verification of electronic products, in line with global standards.

ELGi has its own industrial design house which focuses on form, fit and finish of industrial products


Elgi’s focus on quality has seen the company depend heavily on its manufacturing expertise and sourcing of best quality material from global suppliers. It has also achieved a high level of automation in manufacturing compressors, which is on a par with that of international players. Earlier, the company used to buy a majority of its expensive machines from abroad capacity expansion, but now ELGi builds these machines in-house at a fraction of the cost.

TEXT: Anwesh Koley

PHOTO: ELGi Equipments Ltd