CHALLENGES IN REENGINEERING 2 DAY WORKSHOP – PRE COURSE INTRO GUIDE

15 Dec 2013

PREAMBLE

In reengineering, it is not that much difficult to get an identical sample ready. But the common challenge is to get consistent product performance in batch manufacturing.

Meeting these challenges during initial design stage will avoid frequent redesigning necessity between sample and pilot production stages to get consistent product performance. CHALLENGES

Product performances will vary from the original, generally due to the following challenges:

… Poor strength of the parts – heat treated or natural material (deformation, wear) … Poor geometry of the parts (concentricity, straightness, cylindricity, squareness …) … Poor surface finish (coarse Ra) … Poor electromagnetic properties (weaker properties and varying hysteresis) … Poor sub assembly performance (varying responsiveness and hysteresis) … Lower life (premature wear/failure) … Weaker corrosion resistance … Wide variations in aesthetics (metal finish colour shades) CONTRIBUTORS

General contributing factors leading to the above challenges are: Material – Chemistry with wider tolerances, strength Part design – Configuration – higher l/d ratio, thinner sections, corners, fillets Parts – Strength, tribological properties, heat treated properties, corrosion resistance, surface finish MATERIAL

Global leaders have the power to purchase raw materials to customized chemistry (composition) due to large volume procurement. This customized chemistry cannot be found from material analysis of a few samples. Concluding the material spec to IS or EN spec, based on this sample result will many a times lead to wrong results, especially when heat treated or electromagnetic properties are required for the parts. If chromium is reported in the original as 12.0 %, then we tend to choose SS 410 in which, the chromium will vary from 11.5 to 13.5%. In original, chromium might have been customized between 11.5 to 12.5%. This difference will have significant impact if the material is used in electromagnetic properties.

Such differences in the elements of the material can significantly impact on,

… Heat treatment (hardness/case depth, affecting wear resistance) … Corrosion resistance … Metal finishing - electroplating, anodizing … Strength (buckling/bending effect under load in assembly, welding/soldering strength)

… Finish in machining/grinding These impacts can be managed by suitable changes from the original including part configuration, dimensions, assembly fits –clearances/interferences, section thickness, part configuration.

consulting | manufacturing | trading

1 Raam Nagar North Extension Vaigai Street Madipaakkam Chennai 600 091 India jpj.co.in

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CHALLENGES IN REENGINEERING 2 DAY WORKSHOP – PRE COURSE INTRO GUIDE

15 Dec 2013

SPRINGS

Springs pose a major challenge especially in small products and electromagnetic products.

The property of the material of the wire will be varying over the length (coil) affecting the spring rating. Hence the springs made from this wire will have wide variation in their spring rating from spring to spring. Hence the hysteresis of the spring will be larger than any original springs.

In helical compressed springs, the quality of the end face grinding, square to the axis, will be much superior in originals. Hence the cp/cpk of the spring load produced at specified compression/elongation is closer than the springs manufactured from Indian material. The tolerance required by Indian manufacturers will be much wider and have serious impact on the product performances.

This challenge can be met by one of the following or combinations thereof, ... Indian manufacturers will require wider tolerances for spring tension (at specified compression/elongation). Feasible solution will be selecting through 100 % inspection, rejecting the balance and amortizing the cost of the rejection among the accepted quantity. … Importing the springs – though the MOQ would be huge … Redesign the associated parts – in terms of configuration, dimensions … Conical springs will be a reliable replacement of any precision helical springs

SUMMARY

We will be studying more such challenges in depth wrt a few case studies during the workshop. Your questions to j.jconsultants@yahoo.com will help in improving the delivery

consulting | manufacturing | trading

1 Raam Nagar North Extension Vaigai Street Madipaakkam Chennai 600 091 India jpj.co.in

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