20-Delcam MeasuringForManufacturePartAlignment Philip ... · Part Setting by probing • Measuring probes can be used for part setting • Set rough work offset • Measure features

Part Alignment

Using measurement and software to optimise part setup for machining

Philip Hewitt, Delcam

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Part Alignment

• Machining operations require a known datum• Work offset or Workpiece coordinate system (WCS)

• Part setting matches positions of• Input- Material or semi-finished part• Output- Finished part (through WCS)

• Difficulty is affected by many factors• Amount of stock material• Complexity of shape• Size and weight• Multi-stage manufacturing processes



Part Alignment- the problem

• Traditional solution is physical adjustment

• Labour intensive, unpredictable

• Unsuitable for very large machines & parts

• Very difficult for complex curved shapes



Part Setting by probing

• Measuring probes can be used for part setting• Set rough work offset

• Measure features on part

• ‘Canned cycles’ measure planes, edges, bores

• Compare measured and nominal positions to calculate required correction

• Adjust work offset accordingly

• Long established technique• Fast, convenient

• Limited by available measuring cycles



Extending machine tool probing

• Basic probing cycles are restrictive

• On Machine Verification- OMV- extends machine tool probing capability• Developed to allow measurements ‘in situ’

• Verification rather than final inspection

• Avoid unnecessary setups

• Gives inspection software alignment functionality



Part Alignment

• If the part is out of tolerance…

• Is it still possible to make a good part?

• Part Alignment optimises setup for machining

• Recalculates datum with measurement results



Part Alignment- the benefits

• Replace manual operation with software• Move setup to measured position

• Slash setup time• Improve setup accuracy• Improve consistency in setup time• Reduce variation in the process• Improve quality• Reduce waste• Reduce fixture requirements and costs



Part Alignment- Video



Case Study

• BAe Systems Eurofighter Typhoon foreplane

• Titanium component, 2.2m x 1.1m• Several sheets titanium, diffusion bonded

• Superplastic formed

• Machined to blend with adjoining surfaces

• Variability in forming process• Very high temperatures

• Deviations up to 4mm normal



Case Study- Original process

• Original process was complicated and most parts required rework• Four different fixtures

• Manually turned over and repositioned each time

• Time consuming: 20-30 hours

• Dependent on operator skill

• Variability in quality and time

• Not satisfactory for production



Case Study- Revised process

• Revised process- measurement• Machine tool probing and NC PartLocator software

• Simplified fixturing• Single vacuum fixture

• Overhang eliminates need to turn part over

• Part Alignment by measuring• Vacuum fixture maintains rough alignment

• Probing program measures selected points

• Software calculates optimised alignment

• Applies optimised alignment to workpiece offset

• Run machining program



Case Study- Benefits

• More than 700 production foreplanes have been produced• Improved quality- rework almost eliminated

• Manufacturing time reduced by 60%

• Dramatic reduction in setup times

• Better process planning- consistent setup

• Subcontract machining work back in-house

• Savings in fixture storage, calibration & handling



Adaptive Machining

• Modifying shape as well as position• Probe part

• Measure shape and position

• Reshape CAD model• Morph using probing results

• Regenerate toolpaths• Recalculate for new shape

• Composites, turbine blades• Finishing and blending

• Eliminate hand finishing



• Machine tool probing is the easiest way to correct work offset• Current work offset is known

• Measurements relative to current work offset

• Easy to correct work offset

• Not appropriate for all applications• May not be able to measure whole part (trimming

large structures)

• May be accuracy problems• For example robot machining

Limitations of machine tool probing



Part Alignment with Portable Measurement

• Portable measurement equipment can be used for part alignment

• Extra step- measure to determine WCS• Measure accurate datum features,

• Or mix portable measurement and OMV probing

• Calculate part alignment relative to WCS

• Provides similar setup improvements with extra versatility• Larger measurement volume

• Good results with accurate measurement



Thank You



20-Delcam MeasuringForManufacturePartAlignment Philip ... · Part Setting by probing • Measuring probes can be used for part setting • Set rough work offset • Measure features

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