Executive Summary
This white paper demonstrates how early Design for Manufacturability (DFM) collaboration helps medical device manufacturers reduce risk, improve production readiness, and accelerate time-to-market. By aligning design intent, machining strategy, inspection requirements, and production scalability from the start, Velosity helps customers achieve higher quality outcomes, more predictable lead times, and a smoother path to commercialization.
Download Velosity DFM Precision Machining White PaperWhy preform Precision Machining DFM?
Precision machining programs often appear straightforward until process development reveals hidden constraints: material lead times, limited manufacturability of a feature, unclear critical dimensions, or an inspection method that cannot repeatably inspect the part to the print. DFM resolves these risks early by bringing manufacturing, quality, and design into the same conversation before raw material, tooling, process, and fixtures are committed.
DFM objectives are:
• Lower total cost by identifying true cost drivers (material, tooling, labor, secondary operations) early.
• Reduce lead time and improve predictability with fewer false starts, fewer print changes, and fewer iterations.
• Increase repeatability by selecting scalable processes and inspection methods up front.
• Protect long‑term production by widening the process window and reducing scrap risk.
• Improve OTIF (On Time In Full) delivery by avoiding late-stage rework and external bottlenecks.
When to employ Precision Machining DFM?
Successful Precision Machining DFM begins when there is still time to make meaningful design changes. This ideally occurs during early CAD and drawing development or as a transfer product scope is being determined. The next critical opportunity occurs during initial engineering sample production; when real-time feedback from Machining Technicians and Quality Engineers can be incorporated. Once this window closes, the review process and recommendations remain the same, but the ability to implement improvements becomes limited, harder to justify, and overall risk increases.
Early involvement delivers measurable benefits throughout the machined part development timeline: reduced tooling complexity, fewer sample/engineering part events, more robust inspection methodology, longer tool life, dimensional stability, and a more dependable production ramp.
How to prepare for Precision Machining DFM
Arrive to DFM with a clean CAD model, a clear drawing, and the “why” behind critical requirements. Define boundaries for change, but remain open to adjustments that improve manufacturability, inspection repeatability, and long-term capability.
• Provide CAD and drawings with fully modeled features and clear revision control.
• Identify critical‑to‑function dimensions and explain their purpose (not just “tight because”).
• Share estimated annual usage (EAU) and demand patterns affecting process choice and cost.
• Document secondary requirements (finish, coating, EP, grit blast, laser etch) and acceptance criteria.
• Align early on inspection expectations (CMM/vision/hand tools, sampling, correlation and reporting).
The five core elements of Precision Machining DFM
Precision Machining DFM is most effective when these elements are evaluated together. Each decision can ripple into tooling, cycle time, inspection approach, and scrap risk. The goal is to balance requirements with a robust, scalable production plan.
1) Assembly: How Used / Function
Velosity wants to start by understanding fit, form, and function. Knowing how the component is used clarifies what must be protected and where flexibility exists. This prevents changes that improve machining but unintentionally compromise assembly performance.
• Confirm functional intent for critical features before proposing tolerance or geometry changes.
• Identify and protect features which could create assembly risk if variation increases.
• Review specifications beyond the print (e.g., added trays, special radii, handling constraints).
• Account for downstream activities (grit blasting, coating, electropolish, laser etch) that add development time and lead time.
• Consider packaging strategy early (bulk vs. special trays/bags) and quantity per to avoid late redesigns.
2) Raw Material Selection
Material choice affects lead time, cost, machinability, dimensional stability, and regulatory pathways. DFM validates the specified grade is available, practical to machine to the part geometry, and aligned to qualification needs.
• Check availability and minimum purchase requirements; specialty grades can drive long lead times.
• Validate compliance needs (ASTM deviations, certifications, traceability requirements).
• Account for machinability challenges (e.g., “gummy” materials) and processing limitations.
• Consider thermal expansion and how it impacts tolerances and inspection conditions.
• Use Material Contact List (MCL) strategies when biocompatibility/regulatory approval is relevant.
3) Challenging Features (Manufacturing Risk)
Challenging features can limit machine options, increase tooling complexity, reduce tool life, raise scrap rates, or force secondary operations. DFM focuses on whether a feature is achievable, inspectable, and production scalable.
• Confirm the feature can be produced with available processes (Swiss, 3/4/5‑axis, mill‑turn, EDM).
• Assess whether the feature unnecessarily constrains machine choice or fixture strategy.
• Recognize tight tolerances can reduce tool life/capability and increase scrap.
• Identify secondary operations early (tumble, deburr, OSV) and their schedule/cost risk.
• Ask “What is this feature meant to accomplish?” and explore simpler alternatives.
• Evaluate inspection feasibility (repeatability, correlation, uncertainty ratio; avoid destructive checks when possible).
4) Inspection & Tolerancing
Inspection capability is often the hidden limiter in precision machining. A print can be theoretically correct but practically unverifiable at production speed. DFM aligns critical dimensions, methods, and tolerance strategy, so results are repeatable and defensible.
• Define critical dimensions and WHY they are critical—prioritize instead of measuring everything.
• Evaluate block tolerances and GD&T strategy for cost impact.
• Select inspection method early (vision, CMM, hand tools) and align correlation criteria.
• Clarify inspection evaluation methods (least squares vs. min/max inscribed) to avoid mismatched results or correlation issues.
• Detail visual inspection requirements (distance, magnification, lighting, inspection time).
• Avoid ambiguous requirements (e.g., “no burrs”) without defined acceptance criteria.
5) Estimated Annual Usage (EAU)
Volume influences process choice, automation potential, deburr strategy, qualification approach, and changeover economics. DFM uses EAU to select methods that scale without compromising quality or delivery.
• Choose deburr strategy based on volume (hand deburr vs. automated/abrasive processes).
• Determine whether outside services (OSV) are needed or can be internalized for lead-time control.
• Align qualification strategy (per serial number vs. equipment family) to minimize cost and schedule risk.
• Account for material run requirements and changeover/startup time in total cost of ownership.
Here’s What Sets Velosity Apart
Velosity applies DFM with a practical, production-first mindset—backed by deep technical expertise and vertically integrated resources reducing risk and accelerating time‑to‑market. To understand what sets Velosity apart, consider our points of difference:
• Our people and their deep experience across machining, tooling, molding, and manufacturing engineering.
• Hands-on collaboration—work directly with the teams making your parts.
• Proven technical problem solving and risk mitigation before production.
• State-of-the-art Velosity Lab facilities and metrology resources to support repeatable results.
• Vertical integration reducing supply chain bottlenecks.
Contact Us
We are ready to answer your questions, and we offer many resources to help with all stages of this process. Reach out to your Velosity Business Development Manager for an initial conversation.