Legacy Part Refresh: When tool life end, market demand, and technical debt mean you need to relook old parts in a new light

Legacy Part Refresh: When tool life end, market demand, and technical debt mean you need to relook old parts in a new light

It’s still not unusual for a mature industry (such as aerospace) to have parts that look like they were designed on a drafting table. Some of those parts likely were. If you have legacy parts with designs so “vintage” they have to be referenced by pulling an actual paper blueprint or if, in the course of mergers, all design documentation has been lost in the shuffle and all that remains is a worn tool or a “golden part”, well, it is time for a part refresh. Knowing when and how to refresh your legacy parts can save you countless hours and increasingly compounding financial costs. If you think you might be ready for a part refresh but don’t know when you should start, keep reading. 

When to refresh? 

I won’t pretend to know your particular circumstances better than you do, but here are some of the common drivers to consider.  Think of this as a checklist.  

  • Legacy Production Factors 
  • Declining product yields are a good indicator that the part needs a refresh. This is common for formed (cast or molded) parts, and is the most likely scenario for why you are interested in this topic. [For machined parts, any yield problems are typically one-off operator errors, more frequent and costly on complex parts. Sometimes this can be addressed by adding clarity to drawings but rarely by itself drives a legacy redesign.] 
  • Tool life for formed parts certainly plays into yields. So far, you’ve been able to throw enough machining labor at the parts post-casting to bring them into tolerance, but how many more shots can that tool or blank take before your part production is completely dead in the water?  
  • The retooling cost is likely why you are considering new alternatives.  It’s more than just the cost of the tools (engineering + machining); there are requalification costs, even if there is no redesign at all. 
  • Lead time and minimum order quantity (MOQ) are typically higher for forming technologies. This impacts your inventory levels, and ties up capital. 
  • Sales / Demand Factors 
  • When your sales volume is steady or even increasing. This is rare but can happen due to end of field life (the foot of the Weibull bathtub), or perhaps replacement demand due to a bulletin or recall. If this is the case, there is likely aftermarket competition coming and you’re really more in a new product scenario <insert link to article on Lean Development and Additive Manufacturing> where getting those parts to market is critical. How can you leverage the legacy to get there first and best?  
  • Design Factors 
  • Technical debt refers to the development shortcuts that have a nasty habit of catching up in manufacturing or in the field or in the competition.  Technical debt is frequently incurred when, a) features were left out of the original design to make up lost schedule, b) insufficient qualification was done in vetting reliability or manufacturability. Is this refresh an opportunity to fix technical debt? 
  • An alternate product pipeline may already be in process to replace those legacy parts with something completely different.  Will it be backward compatible and in time?  
  • Redesign, however, offers opportunities in addressing technical debt. Considering new technologies such as AM can leverage part consolidation. Why not take care of multiple legacy parts with one replacement? Always consider the next higher assembly and mating parts. AM excels in knocking down buy-to-fly ratios (i.e., material wasted). 

The truth is that the number of legacy parts in your organization will steadily increase, and the cost of not undertaking periodic part refreshes can take their toll. By being cognizant of key production factors, market demand factors, and design factors, you will know when a part refresh is in order and can use the opportunity to explore emerging technologies, such as AM. 

If you need help refreshing your product line…

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