Key takeaways
- Bridge CMMs deliver the highest precision; portable arms trade accuracy for cost and flexibility.
- Match the CMM type to part size, tolerances, and inspection volume.
- Include software, maintenance, and total cost of ownership in the decision.
Understanding CMM options
The CMM market offers solutions ranging from high-end bridge CMMs to portable measurement arms, each suited for different applications and budgets.
Premium bridge CMMs from manufacturers like Zeiss, Hexagon, and Mitutoyo represent the gold standard for aerospace inspection. These machines offer:
- Measurement accuracy within microns
- Large working envelopes for big components
- Environmental compensation for temperature variations
- Advanced software packages for GD&T analysis
- Excellent repeatability for FAI and production inspection
Zeiss machines are known for exceptional accuracy and build quality but command premium pricing. Hexagon (which owns brands like Brown & Sharpe, DEA, and Leitz) offers a broad range from entry-level to ultra-precision systems. Mitutoyo provides reliable performance with strong support networks, often at a slight value advantage compared to European competitors.
Portable CMMs like FARO arms have changed the economics of measurement for many shops. These articulating arm systems cost 50-70% less than comparable bridge CMMs while offering surprising capability for many aerospace inspection tasks. They excel at measuring large parts, complex geometries, and features that are difficult to access on a fixed CMM.
Matching capability to your requirements
Start by analyzing your inspection needs. Review your typical part sizes, tolerances, and measurement features required for FAIRs and production inspection.
If you are inspecting small to medium precision parts with tolerances under 0.0005 inch, a bridge CMM from Zeiss, Hexagon, or Mitutoyo makes sense. The investment -- typically $80,000 to $300,000+ depending on size and features -- delivers the accuracy and repeatability aerospace customers expect.
For shops working with larger assemblies, castings, or parts that do not fit easily in a climate-controlled CMM room, portable solutions deserve serious consideration. FARO arms (typically $30,000 to $60,000) provide excellent value when:
- Part sizes exceed your budget for a large bridge CMM
- You need to measure parts on the shop floor or at assembly stations
- Inspection volume does not justify a dedicated CMM room
- You are measuring features with tolerances in the 0.001 inch range or larger
Consider your inspection software needs as well. Programs like PC-DMIS, Calypso (Zeiss), or PolyWorks are critical for programming, GD&T evaluation, and generating AS9102 inspection reports. Software capabilities and ease of use should factor into your CMM selection.
Making the investment decision
CMM selection involves more than upfront equipment cost. Factor in:
- Installation requirements: Bridge CMMs need climate-controlled environments with stable foundations.
- Training: Budget for operator training and programming courses.
- Maintenance: Annual service contracts typically run 10-15% of purchase price.
- Throughput: How many parts do you need to inspect per week?
Do not overlook the total cost of ownership. A premium CMM with lower maintenance costs and better uptime may deliver better ROI than a cheaper machine that sits down regularly or requires constant recalibration.
Many shops find success with a hybrid approach: a high-accuracy bridge CMM for critical features and FAIRs, supplemented by a portable arm for larger parts and shop floor verification. This strategy maximizes capability while managing capital costs.
The right tool for the job
Your CMM investment should align with your customer requirements, part mix, and quality strategy. Take time to demo equipment with your actual parts, talk to other aerospace shops about their experiences, and ensure your selection supports not just today's needs but your growth plans.
The right measurement equipment enables confident AS9102 FAIRs, reduces inspection bottlenecks, and demonstrates measurement capability to aerospace customers. Choose wisely, and your CMM becomes a competitive advantage.
See how GroundControl simplifies FAIRs for quality teams using any CMM platform -- schedule a demo today.
