Start With the Functional Requirement
Titanium is selected for different reasons across aerospace accessories, robotics, medical equipment, industrial assemblies, and high-performance products. Before optimizing the geometry, define the load path, temperature, corrosion exposure, wear condition, weight target, mating parts, and required service life. The material grade and heat treatment should follow the function rather than the material name alone.
A clear design brief also separates critical interfaces from non-functional surfaces. Bearing seats, locating faces, threaded joints, sealing areas, and hole patterns may need controlled geometry. Cosmetic pockets or clearance features may not need the same tolerance. This distinction helps reduce machining time, inspection effort, and unnecessary tool engagement.
Choose the Grade and Stock Condition Early
Ti-6Al-4V is a common starting point for strength-to-weight applications, while commercially pure titanium and other alloy families may suit different corrosion, strength, temperature, or forming requirements. The selected grade affects cutting behavior, tool wear, material availability, finishing, and cost.
State the exact grade, condition, stock form, and certificate requirement on the drawing or RFQ. If an alternative grade is acceptable, identify the performance limits and approval process. A material substitution should not be made solely because the nominal composition appears similar.
Design Walls, Ribs, and Pockets for Stability
Thin titanium walls can deflect under cutting forces and may be difficult to support without distorting the part. Use ribs, flanges, gradual transitions, and a sensible material distribution along the load path. If a very thin section is required for clearance or mass, identify the functional reason so the fixture and toolpath can be evaluated around it.
Deep narrow pockets increase tool reach, heat, chip evacuation, and vibration risk. Use pocket dimensions that allow practical tool access and avoid unnecessarily deep corners. Weight reduction is often more reliable when it leaves a stable clamping area and protects the datums used for later operations.
Use Machinable Internal Corners
A rotating cutter naturally produces a radius in an internal corner. Sharp internal corners require smaller tools, additional passes, or a different process and may increase cycle time and tool wear. Specify the largest practical radius that does not interfere with assembly.
When a mating component needs clearance at a corner, consider a localized relief, dog-bone feature, or designed radius instead of forcing every internal corner to be sharp. This keeps the geometry aligned with the cutting tool and makes the requirement easier to inspect.
Plan Holes, Threads, and Intersections
Holes in titanium should be considered together with depth, diameter, tolerance, location, edge distance, intersecting pockets, and chip evacuation. Identify which holes are locating, which are clearance holes, and which are threaded. The same general tolerance should not be applied to every hole if only a few control assembly.
Thread requirements should state the standard, size, class or fit, depth, entry condition, and whether a coating or insert is permitted. Consider tool access and inspection access before placing a deep thread near a thin wall. If a purchased fastener or insert controls the interface, include its supplier specification with the design input.
Build Tolerances Around Assembly Datums
Start the datum reference frame from how the part locates in the assembly. A primary face, pilot, hole pattern, bearing seat, or shaft axis may be more meaningful than an exterior edge. Dimension critical features directly from those references so the machining and inspection plan can prioritize the relationships that affect function.
For a suitable process and verified inspection method, a project may define a tight target such as +/-0.005 mm on a critical feature. That target is not automatically achievable on every geometry. Feasibility depends on part size, material condition, toolpath, workholding, temperature, surface treatment, and measurement uncertainty. Discuss critical tolerances before finalizing the design.
Leave a Practical Workholding Strategy
An optimized exterior can become difficult to machine if no surface remains for stable clamping or relocation. Reserve clamping areas, fixture holes, sacrificial stock, or temporary support where the process needs them. Identify which surfaces may carry marks and which must remain cosmetic or functional.
For multiple setups, include repeatable locating features and a datum scheme that survives reorientation. A five-axis process can reduce setup exposure on suitable multi-face geometries, but it still needs a stable workholding plan and verified tool access. See the five-axis structural-part guide for related process considerations.
Define Finish and Post-Machining Dimensions
Surface treatment can alter dimensions, appearance, friction, corrosion behavior, and electrical contact. Specify whether critical dimensions apply before or after treatment, and identify masking for threads, bearing seats, sealing areas, and grounding surfaces. State the required roughness for functional surfaces instead of using one roughness value for the whole part.
Deburring and edge treatment should be defined as part of the final condition. If a titanium part needs coating, passivation, blasting, or another treatment, include the required appearance, thickness, color, and acceptance standard in the RFQ. Post-processing coordination should be reviewed before the part is quoted.
Move From Prototype to Repeat Production
Prototype machining is useful for checking fit, assembly, stiffness, and weight before releasing a repeat order. Keep the CAD model, drawing, material certificate, finish requirement, and inspection record synchronized through each design revision. A physical sample should not be the only definition of the next batch.
For low quantities, a flexible fixture and a focused inspection plan may be more appropriate than a highly specialized production setup. As volume grows, review tool life, fixture repeatability, first-piece approval, packaging, traceability, and the cost of any additional finishing or testing. Our low-volume CNC machining service covers prototype and small-batch planning.
Titanium Part DFM and RFQ Checklist
- Exact alloy grade, material condition, stock form, and certificate needs
- 3D model, dimensioned drawing, assembly context, and current revision
- Functional datums, critical fits, hole positions, and geometric tolerances
- Minimum wall thickness, pocket depth, internal radii, and tool access constraints
- Thread standard, depth, inserts, fastener interfaces, and inspection method
- Surface roughness, deburring, masking, coating, and post-finish dimensions
- Prototype quantity, expected repeat volume, packaging, and traceability
- Required inspection records, delivery date, and destination