2. HEXAGON METROLOGY AT HxGN LIVE
Strategies for Efficient Offline Programming - 8000
Grant Sewell
Version Date: 03 06 2013
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The PC-DMIS offline choice
⢠Contract Inspection services were facing more
and more remote programming requestsBusiness Problem
⢠PC-DMIS offline allows remote programs to be
built quickly and efficientlySolution
⢠Programs can be created and debugged for
customers off site, saving time and travel to the
customer facility
Benefits
⢠Using PC-DMIS offline will allow us to provide
programming services to customers in any part of
Canada without regard to expansive travel costs.
Anticipated Long-Term
Benefits
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It All Starts with the model
⢠Not all Cad formats are created equal
⢠PC-DMIS can use GD&T, CSYâs, Layers/Levels, Saved Views, Groups and
Assemblies imbedded into the CAD model
⢠In General, the Native format (Catia, Pro-Engineer, Solidworks) is a better
choice
⢠IGES, STEP, JTL require manual creation of the above attributes
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Fixture Modelling
⢠Model from the fixture designer is best
⢠PC-DMIS allows âQuick Fixturingâ models
⢠Create only clamps and other obstructions
⢠Save models for future use
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Using Machine Models
⢠Allows visualization of machine volume
⢠Part placement
⢠Probe length
⢠Animation
⢠Easier to use than the Part/Setup dialog
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Probe Considerations
⢠Use existing probe builds
⢠Ensure the stylus diameter and length are appropriate for the part
⢠Use Analog for more accuracy
⢠Let PC-DMIS calculate the wrist angles (Auto Wrist, Edit Optimize)
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Alignment Considerations
⢠Always use a minimum of two alignments
⢠The first alignment should be manual and easily executed
⢠Iterative is better than best fit if the alignment is constrained to datum targets
⢠Use the âDatum Definitionâ dialog for all GD&T callouts to define additional
alignments
⢠Use the âConstructed Featuresâ dialog for any missing datum's after
performing an Iterative alignment
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Making the Most of the PC-DMIS interface
⢠Custom Toolbars
⢠Optimize existing toolbars
⢠Window Layouts for different tasks
⢠Hit Targets Toggle
⢠Void Detection magic
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Making the Most of the PC-DMIS interface Continued
⢠Understand Program mode mouse behaviour
⢠Using Box selections for groups of features
⢠Measure now toggle
⢠Status Window
⢠Make use of âDocument Commentsâ
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Reporting the results
⢠Choose the report format before creating any dimensions
⢠Feature Control Frame Dimensioning is easier and Quicker
⢠Auto Dimensioning
⢠Save and recall views for graphic reports
⢠Use the Dimension dialog for inputting tolerance
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Offline testing
⢠View Path Lines
⢠Animation speed
⢠Collision detection
⢠Adding moves based on path lines
⢠Adding moves based on existing features or CAD entities
⢠Changing âClearance Cubeâ properties
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CMMI would like to start with a bit of background on our company. Canadian Measurement Metrology or C.M.M. has been in the metrology industry since 1986. We are the Canadian distributor for Hexagon metrology products including coordinate measuring machines, Romer arms and Leica laser trackers. We service, calibrate and provide the applications training at our office in Mississauga Ontario. We also provide contract inspect services to customers across Canada. This brings me to our choice to use PC-DMIS as an offline programming package. As a company, most of our employees were already intimately familiar with PC-DMIS, having used the product since the DOS days. Most of our customer base are long term PC-DMIS users as well. So for us, using PC-DMIS in Contract Inspect services was a âNo Brainerâ decision.
It All Starts With The ModelAny offline program will require a good CAD model as a basis for programming. If I have my choice with the customer, I ask for both an STEP or IGES file plus a Catia 5 file or the âNative CAD formatâ. I also ask for a PDF or Tiff file of the drawing. What the customer is able to provide me ,determines the work flow that I use. If Iâm provided with a Catia 5 file that contains embedded GD&T data than I can program almost entirely without the use of the drawing. If Iâm provided with STEP or IGES data then I have to use the PDF or Tiff drawing to program both the datum structure and the features of interest. Show Movie â 1_Hidden CAD InfoShow Movie â 2_ProgramWithNOImbeddedGDTShow Movie â 3_ProgramWithImbeddedGDT
Visualizing the holding fixture.PC-Dmis allows the programmer to simulate or load actual fixtures models. I donât do this for every part but it is an advantage when you have a complex holding fixture with multiple clamps that you need to program around. Show Movie â 4_FixtureModelling
Simulating the Measuring MachinePC-DMIS also allows you too simulate different models of CMM . This gives the programmer the advantage of visualizing machine volume, part placement, probe length and animation. This allows simplification of the part setup process.Show Movie â 5_MachineModels
Interacting with the part through the probe buildThe next thing we should consider is the probe build. Chances are that your customer will have a âStandardâ length and build that they use. Use this if you can, as it will save time in tearing down and rebuilding a probe just for a single program. If you are making offline programs for internal use then it pays in âtime savedâ to define your own âstandardâ probe build that you can use over and over again. ANALOGUE If you need more accuracy in probing, then you may wish to consider using an analogue probe such as the Leitz LSP or the Renishaw SP25. These probes actually take multiple points for every one point measured.ANGLES If you have taken the time to use the Part/CMM dialog then PC-DMIS can automatically calculate the wrist angles to use for any given feature. There are two methods that will do this for you. One is the âAuto Wristâ function built into all the âAuto Featuresâ the other is in the âOptimizeâ dialogue.Show Movie â 6_AutoWristAngles
Building the AlignmentIf you are using a CAD model that contains imbedded coordinate systems then you will want to activate one of them. I normally employ at least two alignments, one simple manual alignment and then a DCC measurement and alignment of the actual datum features. If you have the benefit of imbedded GD&T data then you can simply use the model datum definitions to define any additional alignments. If you are aligning to datum targets then keep in mind that an iterative alignment will respect the datum priority and a best fit alignment will not. If you are using an iterative alignment and need to define datums afterward, then simply use the construction dialog.Show Movie â 7_Alignment Tricks
Controlling MotionYou have many choices for programming move points. You can create individual moves on a âOne by Oneâ basis. You can insert moves offset from CAD or measured features. You can enable âAuto Move Pointsâ by using the Auto Features dialog. You can also use auto clearance planes, clearance cubes and finally you can have PC-DMIS create the moves for you using the âAuto Insert Movesâ command. My personal preference is to use either clearance planes or the newer clearance cube for planer parts and âAuto Insert Movesâ for more complex parts.Show Movie â 8_CMM Motion
Interacting with the PC-DMIS softwareIf you are going to work efficiently in the PC-DMIS software you will want to take advantage of the tools that allow the user to customize the interface. I build custom tool bars for myself and even modify the icons displayed on the existing tool bars to optimize the graphic âreal estateâ. Don't forget about saving your different layouts using the âWindows Layoutâ toolbar. In the âAuto Featuresâ dialog in regularly display and manipulate the hits using the âHit Targetsâ button. I also like using the âVoid Detectionâ button to place hits on Auto Plane features.Show Movie â 9_PCDMIS_Interface1
More Interface informationAs a matter of course, to be successful with PC-DMIS offline you will want to ensure that you have a full understanding of how the mouse behaves in both âProgram Modeâ and âTranslate Modeâ. I find myself constantly switching back and forth between both of these modes. I also make use of âBox Selectionsâ for groups of holes or points when I can. You will find that this speeds up program creation considerably! I also use the âStatusâ window to get quick feedback from the dimension items that I create. âAuto Dimensionâ is also a tool that I employ when I have a large number of points or diameters that I need to program. If I am doing anything unusual in the program, like a mathematical construction, then I use the âDocumentâ comment to make note of it. Show Movie â 10_BoxSelection
ReportingYou will want to decide on the report format, that is appropriate to your part before creating your program. The reason for this is tied to the behaviour of the CAD only style of report. This report style makes use of saved views in your program to display the CAD model in your report. My workflow, when using the CAD report templates, is to Save and then recall an appropriate view for each area on my part that I dimension. I do this before creating the dimension and then PC-DMIS will use that saved view for that area of the report. Show PC-DMIS Program - Reporting
Testing the Finished ProgramA critical step in the programming workflow is to test out your program. PC-DMIS has a very nice set of collision detection tools that will allow you to simulate the inspection and machine motion offline. You can also use this tool to âFixâ any moves that look suspect. Show Movie â 11_CollisionDetection