|Site Audit & Gear Inspection
|The condition of girth gears is evaluated at site keeping in mind the remaining working life of the gear. Recommendations on existing gear life and requirement of new gear are made according to audit findings.
|Complete dimensional inspections are done on the existing girth gears at site so as to develop detailed manufacturing drawings for production. Inspections also include drilled chips collection (if required and possible) for chemical analysis and hardness tests.
|An appropriate grade of material in steels (alloy steels and carbon steels), irons (including graded irons, SG iron etc.) or bronze (generally phosphorus bronze) is selected based on the required mechanical properties in case the same is not specified by the client. We provide gears and pinions in cast and forged forms. Various international material standards are used including ASTM (USA), AISI (USA), BS (British), JIS (Japanese), GS (German), IS (Indian) standards.
|Castings & Fabrication
|Casting or forging under Gears Pinion Shafts Manufacturers, is produced keeping minimum necessary machining allowances on all relevant and required faces and surfaces. The casting/forging is volume heat treated in special enclosed furnaces with proper temperature controls for attaining the desired mechanical properties. Chemical testing is done using latest spectrometers, mechanical properties derived from test pieces using universal testing machines and hardness obtained using equotip type hardness testers. Non destructive testing to detect internal and surface flaws including Magnetic Particle Inspection (MPI) is carried out once after the casting is heat treated and ready for machining, where as, Ultrasonic Testing (UST) is carried out after proof machining of the job for accurate results.
|Joint facing is carried out on all girth / split gears on each side of joints on the two halves on special horizontal floor borers (UNION, SKODA). Appropriate machining allowance is kept for finish machining in case further heat treatment is to be carried out that may create distortion on the job and hence variation in the sizes. In all such cases finish machining is done after the preliminary turning and heat treatment and in some cases even after one round of teeth cutting.
|After the joint facing the job is turned on special vertical turret lathes (FRORIEP, BERTHIEZ, DORRIES). Similar to the joint facing operation appropriate machining allowance is kept for finish machining in case further heat treatment is to be carried out that may create distortion on the job and hence variation in the sizes. In all such cases finish machining is done after heat treatment and finish joint facing.
|On finish turning of the gear it is teeth cut using special hobbing machines (WMW, MAAG). In most cases teeth cutting is carried out in more than two cuts- one for roughing during which major chunk of the metal is cut and the other for finishing during which finished size is maintained. Generally, stresses are developed during teeth cutting due to the large volume of metal that is cut and hence the job is stress relieved after the first (rough) cut. The job is also opened for a calculated period of time for it to expand or contract to the maximum prior to the finish cut.
|Various forms of heat treatments are performed on gears/pinions are covered under Gears Pinion Shafts Manufacturers, . All jobs are volume hardened at the casting or forging stage. As required on a case to case basis the gears are heat treated again to relieve stresses generated during machining. In some case if hardness required is more (in the range of 400-550 BHN) the jobs may be induction hardened on the surface portions where high hardness is required. Other forms of hardening include case carborizing and nitirding which are also surface hardening techniques similar to induction hardening. Jobs are also oil/polymer quenched as tempering so as to control and maintain the required range of hardness.
|The following various types of heat treatments offered:
|Gear inspections are carried out using special hand, mechanical and automatic instruments and testers manufactured by renowned companies such as MITOTOYO etc. Various checks including dimensional measurements, material tests such as chemical testing, mechanical testing and hardness testing. Non destructive testing for internal flaws includes ultrasonic testing (UST) and magnetic particle inspections (MPI). Surface crack detection includes developer penetrant testing (DP). Gear tooth profiles are checked using special instruments such as vernier calibres and profiles testers. Proper contact on the tooth flanks of both the girth gear and pinion is checked to ensure optimal meshing between the teeth. At ASHOKA stagewise inspections are carried out at various stages of production for which a complete check log in maintained for reference. Third party inspections agencies such as LLOYDS, SGS, DNV, TPL, MOODY etc. have often visited our factory for witnessing of above tests and subsequent qualitative clearance of the respective jobs. We welcome any third party inspection agency in all cases.
|On Site Installation
|ASHOKA offers supervision of on-site installation of the gears and pinions manufactured only by the company. A supervision expert is deputed to the site, however, local manpower, installation tools/tackles and lifting equipment such as movable cranes etc. are to be provided by the client. In special cases ASHOKA may also take up the entire job of installation and commissioning including all of the above but that depends upon the geographical location of the site.
|After Sales Support
|ASHOKA as one of leading Gears Pinion Shafts Manufacturers offers lifetime after sales technical support to its customers for all girth gears and pinions supplied by the company. The support includes services irrespective of guarantee period of the supplied item. On-site support is provided on chargeable basis.