Menu CMM Methodology

CMM MEASUREMENT FUNDAMENTALS TRAINING

Course content

Listed below is a breakdown of the curriculum of CMM Methodology - A Prerequisite to Coordinate Measuring Machine Training. Each video / chapter is listed with an overview of each lesson. The training is split into 4 different sections, with end of section tests at the end of the first 3 sections.

Introduction

An overview of the training objectives (3:38)

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This introduction video discusses the learning objectives of the CMM Methodology training course. It also discusses what you can expect to learn from the videos, in addition to what they will not teach you.



Section 1 - The tools you’ll need

1) What is a CMM (16:49)

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Video 1 describes exactly what a CMM is, the different types of CMM and PCMMs and the basic principles of how they work. It discusses the advantages and disadvantages of the different types of machines and asks the question “is a CMM the correct piece of equipment to use?” Finally, it discusses a few essential safety points.



2) Probes and calibration (24:01)

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Video 2 discusses probe calibration, including what it is, how it is completed and what it defines. It looks at probe compensation and how this issue can cause vector errors. It discusses the different styles of probes and naming conventions for multi-position probes. Finally, it discusses when and how often probe calibration should be completed.



3) Feature measurement (23:42)

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Video 3 looks at the different types of features such as Points, Circles, Planes etc. and describes how they are measured. It also discusses the difference between 2D and 3D features.



4) Work planes (4:33)

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Video 4 defines what work planes are and why they are important when measuring features. It also discusses two different naming conventions of work planes.



5) Moving off the top face (8:59)

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Video 5 looks at the steps you need to take when measuring features off the top face, the XY work plane, and what happens when you don’t follow these steps. It also describes four different methods of measuring features off the XY work plane and examines probe selection for these types of feature.



End of section 1 test

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A multiple-choice quiz designed to test your knowledge of the information covered in section 1.



Section 2 - Understanding Alignment

6) Alignment (11:27)

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Video 6 discusses the first principles of alignment including how to level, rotate and set the component’s datum locations in all three axes.



7) Geometric alignment (9:49)

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Video 7 delves deeper into the issue of alignment examined in Video 6, with a focus on how a feature's direction affects alignment. It also shows what can happen when the incorrect work plane is selected when setting the alignment. Finally, it reiterates how each feature is used to create the alignment and how to check an alignment is correct once complete.



8) Alternative geometric alignment (10:41)

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Video 8 applies the principles learnt in video 7 to another geometric alignment, this being a Cylinder / Circle / Circle alignment. It then examines six other common alignment methods, describing how each of the axes is set. Finally, it explains how a Plane / Line / Point is completed when the plane isn’t measured on the top face.



9) Datum shift and rotation (20:23)

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Video 9 explains how an alignment is modified by a datum shift or rotation. It takes a look at the different methods of applying those modifications, including the use of theoretical and measured data, and why they may be required. It also discusses two different examples of applying alignment modifications and then summarises the lesson. Finally, it takes a look at the angular directions for each work plane.



10) RPS alignment (11:51)

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Video 10 discusses the fundamentals of RPS alignment, what it is and how the CMM software calculates an alignment by setting features to their theoretical values. It also discusses techniques you can use to help you visualise the alignment and how to create a robust alignment. Finally, it summarises RPS alignments and discusses different methods of using them in practice.



11) Car-line alignments (6:45)

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Video 11 describes what a car alignment is before explaining where and why it may be used. It discusses how a local alignment is created on the component and how the alignment is modified to create a car-line alignment. Finally, it explains why working with a car-line alignment can complicate inspection and programming and why additional care is required.



12) Best-fit alignments (18:28)

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Video 12 firstly describes what a best-fit alignment is. It then examines why and when you would select to use one and the effects using one may have on the alignment’s datum position and results of any measured features. It takes a look at a six-point best-fit alignment, describing the principles using a simple prismatic component, and then takes another look using a more complex component. It discusses a multi-point best-fit alignment and how the deviations are spread among the datum features and how it differs to a six-point best-fit alignment. It also looks at some of the practicalities of working with a best-fit alignment and a few methods of simplifying their use.



13) Alignment bad practices (13:04)

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Video 13 discusses some common alignment errors and bad practices that may not be apparent but will cause problems once you start measuring. These include: the effect none-square faces and form error has on a Plane / Line / Point alignment, why selecting concentric circles doesn’t work when setting rotation, and setting the rotation to the same axis as the first axis and when the alignment is rotated about the incorrect axis. It also looks at the effects of using a short length to set the rotation and the measurement errors caused when an alignment hasn’t been created and work planes haven’t been set.



End of section 2 test

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A multiple-choice quiz designed to test your knowledge of the information covered in section 2.



Section 3 - After the basics

14) Component set-up (10:01)

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Video 14 discusses different methods of the positioning, holding or clamping of a component when completing an inspection. It looks at practical methods of positioning components ready for inspection and then the importance of documenting any setup completed.



15) Datum selection (4:46)

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Video 15 focuses on datum selection. It defines what a datum is and shows how they are defined on a drawing. It looks at the techniques you can use to help you decide what features to use for alignment when no datum is defined on the drawing. Then, it applies those techniques to an example component.



16) Reporting (21:45)

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Video 16 discusses some of the basic principles of reporting and also looks at some of the potential errors and pitfalls. The areas covered include: why being in the correct work plane is important when reporting locations, the differences between Polar and Cartesian measurement systems, and angular measurement of features, such as cones and angular positional measurement, including the reporting of 2D and 3D angles. It also shows why CMM reports can cause confusion when reporting features with a negative position relative to the datum position. And finally, it discusses the effect of form error and what can happen when features are not parallel to the datum.



17 - part 1) Programs (23:01)

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The first part of Video 17 discusses both CNC and manual CMM programs. It examines the advantages and drawbacks of each before discussing different programming methods, including the learned and predefined routine methods and common CNC commands and parameters. It looks at the different ways of moving around the component, including the use of safety planes, and explains Vectors, their use and potential errors.



17 part 2) Programs (22:44)

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The second part of Video 17 discusses automation and simplified alignments. It demonstrates how CNC CMM programs reduce the necessary skill set for production inspection. Two examples of creating a single or zero-point start program are given, along with general programming tips, including the importance of operator comments and the naming conventions for features.



18) Working with CAD (13:48)

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Video 18 defines what CAD is and lists some of the many advantages of using CAD. It discusses the importance of validation CAD files following conversion of file formats and asks the question of which is the Master, the CAD or the drawing? Offline programming is discussed, including how to position the CAD model correctly relative to the CMM machine axes. It also looks at a different reporting technique, called surface condition, which is useful for contoured surfaces when CAD files are available.



End of section 3 test

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A multiple-choice quiz designed to test your knowledge of the information covered in section 3.



Section 4 - Putting it all together

19) Putting it all together, example 1 (20:28)

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Video 19 creates an inspection plan for the door handle example from Video 15. It details the initial setup and programming steps to measure the component and report the drawing dimensions. Once the example is created, the effects of different alignment methods are discussed.



20) Putting it all together, example 2 (12:11)

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Video 20 gives an example of an inspection plan for a cylindrical component using a different alignment method to that used in Video 19. Once the inspection plan is completed, it takes another look at the alignment in terms of adding a 2D best fit to the alignment.



21) Putting it all together, example 3 (15:43)

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Video 21 shows how an RPS alignment can be used with a dedicated fixture. It also shows how a Car-line alignment is created. After the initial RPS manual alignment example, an alternative method utilising a single point start is demonstrated. Both examples use the component from Video 11, the door panel fitted to a dedicated fixture.



22) Questions (10:08)

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Video 22 discusses some of the questions that new programmers frequently ask.





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