OVERHAUL OF EQUIPMENT – INSIGHT

By J Narasimhan

INTRODUCTION.

1.         Overhauling of equipment is a unique rebuild process after a designated period based on exploitation. Overhaul is applied mostly on equipment for affordability as replacement involves high costs every other decade. The aim is to restore equipment capability to that of a new current generation or new equipment. By overhauling, the equipment is planned to be retained for four to six decades, and rebuilding offers a cost-effective option to the state.

2.         The Overhaul process is different from regular maintenance and repair processes. In the Overhaul process, the equipment is completely stripped to its last component. Then a deliberate inspection is carried out on each component to assess its suitability for reuse. During the overhaul of the equipment, first the assemblies are rebuilt by replacing the outlived components by either newly manufactured or reclaimed components. Then these assemblies are integrated as equipment.

3.         During this process, It can be planned for the unification of various variants received during induction and effect the latest upgradation. This will make further equipment management as simple with less inventory.

4.         The cost of overhaul is aimed at 30-50% of the original equipment to rebuild the equipment to perform the same intended purpose.

5.         The Overhaul of any equipment is carried out after a specific period of exploitation in years or kilometres. Whereas Condition-based Overhaul is now recommended to be more cost-effective. In this, the condition of the major assembly is assessed by various monitoring tools before stripping. The assembly can be stripped and overhauled only when it does not meet the specified limits in that assessment. Otherwise, the same assembly can be reused with superficial maintenance.

TECHNOLOGY

6.         The overhaul technology is different from the manufacturing technology. Normally the designer will develop two technologies. One, for manufacturing technology for new equipment and another for overhaul with the regeneration process. The transfer of technology (ToT) needs to be different according to purpose.

• One specified value with tolerance for any parameter is applicable in manufacturing of that component. Whereas in overhauling the same parameter will have different values viz permissible value and reclaimable or discord value. 
• Means the manufacturing of the component is adhering to a specific value with plus or minus tolerance. The component is rejected if it is not within that limit.

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• Whereas in the overhaul process, the same component is assessed after stripping to segregate as reusable if it is within the permissible limit and reclaimed (by rebuild or regeneration) if it is within the reclaimable limit (above discard limit and below permissible limit) and discarded beyond this limit. These limits will be specified by the OEM when he transfers technology for overhaul purposes. Factor of safety is kept in mind by the designer while deciding on these limits.

7.         The ToT has to be appropriate for the purpose. Following manufacturing technology is not advisable in the overhaul process for mainly the absence of a regeneration process in manufacturing technology. This makes the overhaul process difficult and not cost-effective. The most important part of ToT is training on the REGENERATION process by OEM/Designer. This includes handling of special machinery/test equipment supplied by them for the recommended Overhaul process.

8.         The overhaul technology documentation shall include

a)         Detailed Project Report (DPR) having building layout, special machinery requirement for reclamation and testing with their installation layout, Electrical points etc) for each dept,

b)         Manufacturer recommended spares list (MRLS) for overhaul with source marking for each item (as Import, local manufacturing, and trade items).

c)         Manufacturing process documents/drawings (in case items can be manufactured locally),

d)         Regeneration process (if the component can be reclaimed) and

e)         Testing procedures with Specifications for overhauled equipment. 

Functions (PROCESSES)

9.         Planning: Planning and control (monitoring) are required in case of overhauling in place of marketing of OE Manufacturing. This function will monitor the target of equipment required to be overhauled in a particular year by calling in equipment for overhaul through all processes till the rebuilt equipment is dispatched with user interactions.

10.       Procurement: Initially the spares will be procured as per MRLS. Later the same can be derived as the Overhaul scale (OHS) after the Pilot Overhaul. The same can be reviewed at regular intervals and amended accordingly. Then spares required will be procured/purchased from authorised sources as per the laid down requirement as in the overhaul scale (OHS).

11.       Methods: This function is to estimate the manufacturing process of spares in case of local manufacturing/indigenisation. The indigenisation process is carried out for the parts which were originally marked for import by OEM. 

12.       Production : This function will perform two process

a)         Manufacturing the required spares and regenerate/reclaim the components and bring to their original intended dimensions for reuse.

b)         Strip the equipment/assembly to the last component, clean the stripped parts, and assess the reusability of parts with the help of inspectors. Then rebuild the assembly with serviceable parts (either new or regenerated) and integrate the assembly to as equipment.

13.       Quality: To carry out a quality audit in receipt ( new spares), in the process ( rebuilt assembly), and final trials of the integrated equipment. Ensuring the quality of the overhaul process is a responsibility of both function viz production and quality as a cross-functional team concept in modern times. This will save time and cost involved in rework. Final quality of overhauled equipment is ensured by a designated third party agency before handing over. Further joint quality audit is carried by the user and overhauling organisation at the time of handing over thus ensuring the USER SATISFACTION. Also to ensure the accuracy of measuring equipment (periodic calibration) to ensure correct observed values.

14.       Stores: This function will carry the preservation process of parts procured from authorised sources and reclaimed parts at receipt and marshaling.

15.       Maintenance: This function is to upkeep the serviceability and accuracy of machinery and testing equipment used in the overhauling process.

POST OVERHAUL ACTION

16.       The user feedback is obtained after a specific period of exploitation of overhauled equipment to analyse and make improvements in the form of correction and corrective action.

Note: This paper is written with the intention to give brief generic information on OVERHAUL PROCESS for its uniqueness to beginners.  This concept can be applied to any equipment.

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