Historically, the choice of part production method has been grounded in requirements. Mating geometries, strength and chemical resistance needs, and expected number of “cycles” have dictated choices in both material and manufacturing method.
There are now multiple processes that can produce parts that meet the same engineering requirements. Additive processes are often massively more cost-efficient than traditional manufacturing at small (and many times moderate) volumes. This opens up options for engineering and supply chain to collaborate on production efficiency.
At first, “Dual Manufacturing” may sound like a familiar supply chain term, “Dual Sourcing,” but there are important distinctions:
Dual Sourcing is the process of using two or more suppliers for a given component, raw material, or service. Often dual sourcing is used to reduce risk, lower cost, diversify geographically, or for other strategic reasons.
Dual Manufacturing is the process of using two production processes in parallel to produce equivalent parts. The production processes will complement each other to give some advantage (e.g. efficient production over a wide range of volumes, geographic diversity, or shortened lead times). Often, one process will be a traditional manufacturing process (injection molding, pressing, casting, etc.) which is efficient at volume, at the expense of flexibility and fixed startup cost. The second process usually makes use of digital production, like additive manufacturing or CNC machining.
Design for dual manufacturing
The flexibility of having two processes has a tradeoff. You gain increased production flexibility, but often incur some cost of engineering work to design for two manufacturing methods. Odds are low that a design will be optimal for two different manufacturing methods (i.e. injection molding and additive), so two part designs (equivalent parts) will typically be necessary.
As an example, a nylon gear (pictured) may be designed with an interior cutout to allow for part cooling when injection-molded. That same gear might be designed as a solid gear using additive to optimize for speed of printing and post-processing.
When dual manufacturing makes sense
Dual manufacturing can make sense when some aspect of production changes to make one type of manufacturing advantageous than another. Some examples:
- Lead times become critical (e.g. for a production launch)
- Volumes of production runs vary widely (because of seasonality, unexpected demand, or aftermarket needs)
- Economics of production (labor costs, import duties, etc.) vary across different markets.
In the case of additive, dual manufacturing may make sense when you require production at an acceptable total cost per part at both high volumes (for production runs) and low volumes (for aftermarket needs).
Understanding the economics of dual manufacturing
Gleaning the economic advantages of dual manufacturing may sound daunting, but it comes down to understanding the cost drivers of your processes; something engineers and supply chain professionals will find familiar. As an example, let’s look at injection molding and fixed deposition modeling (FDM) 3D printing.
In injection molding, fixed costs of production include tooling, line setup, and producing/verifying first articles. Those costs must be amortized across all the parts in your production run. In contrast, production using FDM 3D printing incurs none of these fixed costs and produces parts with very little lead time, but generally comes with higher material costs. In the case of long, predictable production runs, injection molding will be the right production method. However, if a short run is needed, additional production capacity is needed temporarialy, or a part stocks out unexpectedly in high demand, 3D printing sometimes will be the right way to go. Only by having both processes validated can your manufacturing operation achieve the advantages of both processes.
Additive manufacturing isn’t always the solution to every problem, but where the economics and engineering work, we’ve been able to help companies achieve impressive results:
- 50% reductions in part cost for production line spare parts
- Reduction of lead times from 6 months to 2 days for key repair parts
- Low volume manufacturing enablement that makes entire product lines feasable
It is clear to me that additive has massive untapped potential as a manufacturing tool. On a personal level, that’s what’s exciting to me about working with Stratasys Consulting, where we’re clarifying these issues and partnering with clients to help them make informed decisions in their supply chains.