The Hidden Costs of Designing Around Manufacturing Constraints
- Kirk Abolafia
- 3 hours ago
- 4 min read
Pulsed electrochemical machining (PECM) is changing how complex components can be manufactured, yet most engineered parts are still designed around the limitations of conventional machining methods such as CNC. Constraints like tool access, line-of-sight machining, and material-dependent cutting behavior often force engineers to simplify internal features, reduce feature density, or compromise critical geometries. In practice, this means many parts are designed for manufacturability first, rather than for optimal performance.
Key Takeaways
Designing for manufacturability introduces hidden costs: Engineering decisions made around CNC constraints often reduce performance and create long-term inefficiencies that compound at production scale.
“Safe” design choices can create downstream risk: What appears practical during prototyping can lock in higher cycle times, variability, and cost structures that are difficult to remove once production is established.
PECM enables performance-driven design at scale: By removing tool access and mechanical constraints, PECM allows complex, high-density, and internal geometries to be manufactured consistently without proportional increases in time or cost.
Why Engineers Still Design Around CNC
Despite many advancements in design iteration and prototyping, the fact remains that most engineered parts today are still designed with conventional machining methods in mind. Designing for CNC means both predictability and familiarity: unless the alternative can introduce significant, provable cost reductions and/or help manufacturers penetrate new markets, most companies don't put much thought into alternative machining methods.
This implicit agreement inherently holds back design engineers by building around tool access, workholding and more: often forcing internal features to be redesigned as external ones, or split into multiple components...just to make them machinable.
As an illustrative example of how small design changes can create disproportionately large manufacturing penalties: consider reducing a wall thickness on a component. This is not simply asking the cutting process to "cut more carefully", rather, can mean lower feed rates, or greater risks of scrap/rework, or add unnecessary inspection time-- and is that always worth the slight improvement in lightweighting or thermal efficiency of the component? How about if the flow efficiency of a microhole array can increase proportional to the number of microholes-- would drilling 36 instead of 24 holes be necessarily worth the ~50% added drilling time, alongside the deburring or tool change costs? When parts are designed around specific constraints, a variety of examples of performance tradeoffs may occur, including but not limited to:
Thermal performance: heat exchanger channels being simplified or spaced further apart, reducing heat transfer efficiency
Surface quality: internal surfaces especially may retain a degree of roughness or recast layers, which can ultimately affect fatigue life and introduce other structural issues
Feature density: High-density arrays of microchannels or microholes may be reduced in count or uniformity, limiting flow performance (particularly in applications such as semiconductor gas delivery systems or drug delivery devices where uniform distribution is critical)
Design Requirement | Conventional Machining (CNC) | PECM |
Internal Features | Limited by tool access and line-of-sight | Non-line-of-sight features achievable |
Feature Density (Microholes) | Each additional feature increases machining time | Multiple features processed simultaneously |
Thin Walls | Slower feeds, higher scrap risk due to cutting forces | No mechanical forces; reduced risk of distortion |
Surface Finish (Internal) | Often requires secondary operations (deburring, polishing) | Achieved directly during machining process |
Material Constraints | Performance affected by hardness, tool wear, and machinability | Largely material-agnostic for conductive materials |
Process Consistency | Variability increases with setups, tools, and complexity | High feature-to-feature and part-to-part repeatability |
Scaling to Production | Complexity increases cycle time, cost, and variability | Complexity scales through tooling, not proportional cycle times |
Compounding Costs in Scalable Production
While these design compromises may feel like the "financially safe" option, in many cases they can introduce a considerable amount of financial risk and lost opportunity costs down the road.
A geometry that is easier to machine may at first appear "safe" in early production, but may carry a number of hidden "cost multipliers". Cycle time, inspection, or other variables often increase much faster than part volumes, not scaling linearly as tolerances tighten or feature densities increase.
Consider how these components may have increased reliance on postprocessing operations, which can multiply at-scale. "Safe" design decisions may also become baked-in to the production model, as the inherent flaws can become embedded into the entire operation: removing it would mean completely redesigning the part, machining process, production operation and inspection framework. Requalifying a part, changing tools, and restructuring an entire production lifecycle to fix a seemingly small design flaw can be unrealistic for most manufacturing scenarios.
Consider the lost market opportunities surrounding an inferior design going to production, as the impact of poor design choices can extend into broader business performance for many companies. If a heat exchanger has suboptimal thermal performance, or is limited from achieving higher performance thresholds, the "safe" route can hold an entire organization back from new customers.
Furthermore, the "baked-in" structural issues with these safe designs (additional processing steps, complex assemblies) can reduce margins, making the prospect of exploring new design ideas even less attainable for a business to explore new markets.
Reframing Design with PECM
Pulsed electrochemical machining (PECM) offers a unique alternative for these manufacturers: inherently changing the relationship between design and manufacturing by removing some of the limitations imposed by conventional machining.
Essentially, because material is being removed electrochemically rather than through mechanical or thermal forces, PECM is simply not constrained by tool access in the same way as traditional processes. This enables:
Internal, non-line-of-sight feature machining and finishing
High-density feature arrays with consistent, uniform geometries without requiring individual drilling/machining times to increase
New material machining such as refractory metals or superalloys, as the process is largely material-agnostic so long as it is conductive
PECM may allow engineers to revisit their original design intents, enabling geometries previously dismissed as un-manufacturable. Notably, PECM can maintain these capabilities at production scale.
For instance, PECM is capable of parallel-processing with a single multi-featured cathode, allowing feature-to-feature and part-to-part repeatability and scalability, thereby making high-density geometries viable for volume production. PECM also allows automated and repeatable workflows into lights-out production environments with minimal manual intervention. Finally, PECM supports longer production runs by significantly minimizing the average rates of tool wear.