Unit 6

CAD customization and Automation

Q1) Give the limitations of 2D drawing

A1)

2D drawings aren’t able to capture the complexities of product design. They don’t consider assembly and fit. Products that are created from a 2D sketch require a lot of work, as there are bound to be more errors. If products are created by numerous people, the checking process gets even more colluded. The drawings are forced to go back and forth over and over until finally, after laborious hours, the process is done.

3D models communicate a lot of information regarding fit and potential issues. Because 2D drawings can’t adequately display that information, they are forced into physical prototyping. In the case of a 2D drawing, the only way you can spot problems is to create the prototype, tear it down, and rebuild. This prolongs the product development cycle dramatically as you’re forced to include reworks and re-engineering of prototypes.

Making changes in designs is a time-consuming process, and it’s even more tedious for 2D designs. Designs may need to be recreated numerous times in different views to capture all the details of a single part. When changes do happen, they need to be reflected in all of the drawing views, requiring the designer to recreate numerous drawings. As you can tell, this is entirely unnecessary when, for example, 3D CAD models are quick to make an easy to edit, all in one file.

Q2) What are the benefits of PMI?

A2) Benefits of PMI

Product Manufacturing Information, or PMI, consists of dimensions and annotations that are added to the 3D model and can be used in the review, manufacturing, and inspection processes.

In synchronous and ordered modeling, PMI dimensions also provide an important design modification tool. By editing dimension values, you can make changes to the model. You can lock and unlock dimensions to control how connected model faces respond to dimension value edits. And you can control the direction in which dimension edits are applied. This greatly simplifies the process of design, testing, and update.

The Solid Edge PMI application combines the functionality of adding dimensions and annotations, generating fully rendered 3D model views with 3D section views, drawing formatting, and publishing the information.

Q3) What is MBD? Give its advantages.

A3) Model Based Definition (MBD) is the practice of using 3D digital data (models) combined with other data, such as 3D dimensions and tolerances, within 3D CAD software to provide a technical definition for individual components and product assemblies. The goal of MBD is to create 3D technical data packages (TDPs) to be used for manufacture, logistics, and acquisition.

MBD is the practice of placing either traditional or GD&T dimensions on the 3D model itself during the design process. The engineer or designer can place these dimensions on the model for a variety of uses.

The most important takeaway about MBD is that the 3D CAD model with PMI should be both human and machine readable (interpretable by humans with data leveraged for downstream use) with full traceability to the authority model. 

Advantages

Q4) What are the applications of PMI?

A4) PMI in 3D viewing

The most important application of PMI is 3D viewing. With the use of PMI, the CAD model can be viewed in 3D with the dimensions and tolerances. One can edit the dimensions and change the 3D model according to the requirement.

PMIs in 3D viewing will be a tool that helps the user of this analysis to have directly the PMIs information in 3D models in early phases. In future, it is possible to imagine a tool that allows to perform the tolerance analysis directly from a 3D model in DMU with PMIs.

PMI in NC-Simulation

During the use of NC-Simulation, one critical point is programming. The software of NC has to detect all the PMIs and Features in order to create the sequences of manufacturing. The main method concerning the transfer of information for the programming in NC is divided in 3 phases: the first phase is the implementation in the model CAD of the information important for the finish (Features). Then an interface insures their transmission to a programming NC tool. In this last one, the sequences of manufacturing necessary, the tools and other technological parameters for manufacturing are chosen according to the transferred data. 3D viewing with PMIs is a possible solution for the interface between CAD systems and NC programming. PMI in 3D model can be used efficiently during the creation of NC programs, which are used in NC simulation.

PMI in Finite element analysis

For finite element analysis, the user has to access several information concerning the product to be simulated. Generally, all the information necessary for the model creation are given in 2D drawings. PMIs as information describing the geometry and some properties of the product to be simulated have an important role. The main PMIs used for the simulation are functional dimensions with minimum and maximum tolerances: simulations can be made for each limit. Moreover, for sensitivity studies during the simulation (critical parameter, etc.), the user varies the value of a dimension between the upper and the lower value of its tolerance. The other PMIs as roughness are used for particular cases. PMIs will be a tool that helps the user to take the information he needs for the modelization of the product used for the simulation. PMI in 3D model can be used directly by the user for creating the simulation model and for leading sensitive studies.

PMI in Tolerance analysis

The tolerance analysis is a fundamental point for design engineers in performing tolerance studies and optimizing tolerance budgets. Some tools already exist and use generally 5 steps:

• Creation of the design

• Definition of functional features for each component

• Verification of the functional features for each element

• Creation of the functional assembly model

• Performance of the functional features analysis of the assembly

Functional features are defined and related to one another according to the Geometric Dimensioning and Tolerancing (GD&T) Datum references and feature control constraints (i.e. form, orientation, location...). PMIs are also fundamental because they are the basis of all this study.

Q5) Give the applications of MBD?

A5) MBD in Process and Automation

Traditionally, designers used to develop in 3D CAD using tools like NX, CATIA, Creo, Solidworks, and others, however, their product and process information is then projected down into 2D drawings--some on literal paper--which is not machine readable.

Thus. it takes the manufacturing or quality control engineer to MANUALLY enter the GD&T and other vital details

Using MBD, there is no need to project the information into 2D drawings. Due to MBD, the CAD file can be directly translated to systems for manufacturing, inspection, etc.

MBD ensures for less errors, more time saved, and most importantly, company-encoded knowledge to be performed faster with quality repeatability. 

MBD in Data and Analytics

Industry 4.0, digital twin, digital thread, advanced manufacturing, and model-based enterprise.

Essentially, these terms and MBD are about using good quality data to solve business problems or improve business products.

Unfortunately for most manufacturers, that data is being unused. 

Quality and inspection departments carry out the validation of products coming out the shop floor, measuring parts and coming with pass or fail decisions. However, that data is rarely reintroduced back to ecosystem and often discarded despite being highly valuable. 

MBD ensures having data tied to the model for improved designs, improved parts, improved operations, and most importantly, improved business decisions.

MBD in Inspection

NOW-a-days, MBD plays an important role in the inspection of the product.

After the identification of measurement tasks aka Bill of Characteristics, information is stored in MBD model to generate FAI (first article inspection) or PPAP (production part approval process) documents. Using PMI, the model is given 3D dimensioning. Measurement plan is assigned to generate inspection program for CMM. After gathering results, statistical analysis is carried out. Final step is to tie back to MBD model for single source of truth.

MBD in Additive manufacturing

AM offers the ability to create complex designs never before imagined. Many of these designs are too complex to document in a conventional 2D drawing File. Only through MBD, can these new designs be properly documented.

Q6) What is CAD customization used for?

A6) CAD customization can be used for the following:

Q7) Give advantages and disadvantages of CAD customization.

A7) Advantages of CAD customization

Customization of CAD software has indeed introduced us to many benefits which are as follows:

Disadvantages of CAD customization

Q8) Explain part modeling customization approach for product customization.

A8) In part modeling customization, the commands or features or tools used for the mort model construction can be customized in the CAD software according to the user satisfaction.

User can add the commands he wants to design a product model and can hide other commands he don’t want for the design of the product. Or he can hide those commands he rarely use.

For example, to construct the product part model, user don’t require Data migration tool or MBD tool, he can hide that tool. And user will require the sketch tool and feature tool to model the part. He will place those commands in the way he want, such that he can have easy access to it.

Generally, many CAD software provide tool for customization. It can be accessed by right click on the command manager or header bar of the software’s UI. Access to customization may vary from UI to UI for different CAD softwares.

If the customer requires only some specific commands for the part modeling, he can contact vendor and customize the CAD system in the way he wants.

For example, If the customer only needs to design the parts of uniform cross-section. He may ask the vendor to hide commands like Loft, Sweep, etc. and place the commands like extrude, revolve such that he may have easy access to it.

If the customer needs to check the mass properties of the part models, he may customize the CAD system such that, Evaluate command tool will be placed on first screen where, generally sketch command is present in most of the CAD systems.

Suppose user have to create the part model require for sheet metal working, he may customize the CAD systems UI such that he can access the commands require for sheet metal working easily.

Along with commands user can change the icon size or color of the part modeling environment.

User have the option, in many CAD systems, to add the shortcut tool. In part modeling customization approach, user can customize the shortcut tool by adding or removing the commands like extrude, revolve, sweep, fillet, chamfer, mirror, circular pattern, linear pattern, measure, etc. in the shortcut menu.

Along with shortcut bar, one can add commands in the mouse gesture menu. The commonly used part modeling commands can be added to this feature of customization. One can add 4, 6, 8 or 12 commands or buttons in mouse gesture for part modeling customization.

Q9) What is CAD automation?

A9) The entire history of CAD is based on automation; computers made creating and editing 2D drawings faster, ultimately leading to intuitive 3D modeling and automatic drawing view creation. But, no matter how fast and intuitive our CAD systems get, users still get tied up doing tedious CAD translation and repair work.

CAD automation enables users to automate translation and repair processes without having to open or view the files graphically. Literally thousands of files can be processed automatically at one time, breaking through CAD data bottlenecks in engineering and design departments.

CAD design automation automates the process of creating a technical drawing or model efficiently. Design automation should be viewed as a new way of working, not as a single project with a beginning and an end. Design automation enables designers and engineers to speed the development of design variants and automate repetitive design tasks, which accelerates the design process, saves time and development costs, and increases productivity. In a nutshell, design automation enables engineer-to-order manufacturers to complete days of custom engineering in just minutes.

Q10) Explain different types of APIs.

A10)

Web APIs are APIs that can be accessed using the HTTP protocol. The API defines endpoints, and valid request and response formats. Web APIs include the APIs used to communicate with the browse

Open APIs, also known as external or public APIs, are available to developers and other users with minimal restrictions. They may require registration, and use of an API key, or may be completely open. They are intended for external users (developers at other companies, for example) to access data or services

In contrast to open APIs, internal APIs are designed to be hidden from external users. They are used within a company to share resources. They allow different teams or sections of a business to consume each other’s tools, data and programs.

Partner APIs are technically similar to open APIs, but they feature restricted access, often controlled through a third-party API gateway. They are usually intended for a specific purpose, such as providing access to a paid-for service. This is a very common pattern in software as a service ecosystem.

Composite APIs allow developers to access several endpoints in one call. These could be different endpoints of a single API, or they could be multiple services or data sources. Composite APIs are especially useful in microservice architectures, where a user may need information from several services to perform a single task. Using composite APIs can reduce server load and improve application performance, as one call can return all the data a user needs.