Point Cloud Operations

No output is always perfect no matter how much the technology has evolved. Even though point cloud generation has eased up manufacturing process, it comes with its own anomaly. Generally, a point cloud data is accompanied by Noises and Outliers.

Noises or Noisy data means the data information is contaminated by unwanted information; such unwanted information contributes to the impurity of the data while the underlying information still dominates. A noisy point cloud data can be filtered and the noise can be absolutely discarded to produce a much refined result.

If we carefully examine the image below, it illustrates a point cloud data with noises. The surface area is usually filled with extra features which can be eliminated.

 

Point Cloud Before noise redeuction

 

After carrying out Noise Reduction process, the image below illustrates the outcome, which a lot smoother data without any unwanted elements. There are many algorithms and processes for noise reduction.

 

Point Cloud After noise reduction

 

Outlier, on the contrary, is a type of data which is not totally meaningless, but might turn out to be of interest. Outlier is a data value that differs considerably from the main set of data. It is mostly different from the existing group. Unlike noises, outliers are not removed outright but rather, it is put under analysis sometimes.

The images below clearly portray what outliers are and how the point cloud data looks like once the outliers are removed.

 

Point Cloud With outliers

 

Point Cloud Without outliers

 

Point Cloud Decimation

We have learned how a point cloud data obtained comes with noise and outliers and the methods to reduce them to make the data more executable for meshing. Point cloud data undergoes several operations to treat the anomalies existing within. Two of the commonly used operations are Point Cloud Decimation and Point Cloud Registration.

A point cloud data consists of millions of small points, sometimes even more than what is necessary. Decimation is the process of discarding points from the data to improve performance and reduce usage of disk. Decimate point cloud command reduces the size of point clouds.

The following example shows how a point cloud underwent decimation to reduce the excess points.

Point Cloud Before decimation

 

Point Cloud After decimation

 

Point Cloud Registration

Scanning a commodity is not a one step process. A lot of time, scanning needs to be done separately from different angles to get views. Each of the acquired data view is called a dataset. Every dataset obtained from different views needs to be aligned together into a single point cloud data model, so that subsequent processing steps can be applied. The process of aligning various 3D point cloud data views into a complete point cloud model is known as registration. The purpose is to find the relative positions and orientations of the separately acquired views, such that the intersecting regions between them overlap perfectly.

Take a look at the example given below. The car door data sets have been merged to get a complete model.

 

Point Cloud before registration

 

Point Cloud After registration

 

 

 

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Point Clouds | Point cloud formats and issues

Whether working on a renovation project or making an information data about an as-built situation, it is understandable that the amount of time and energy spent on analysis of the object/project in hand can be quite debilitating. Technical literatures over the years, has come up with several methods to make a precise approach. But inarguably, the most prominent method is the application of Point Clouds.

3D scanners gather point measurements from real-world objects or photos for a point cloud that can be translated to a 3D mesh or CAD model.

But what is a Point Cloud?

A common definition of point clouds would be — A point cloud is a collection of data points defined by a given coordinates system. In a 3D coordinates system, for example, a point cloud may define the shape of some real or created physical system.

Point clouds are used to create 3D meshes and other models used in 3D modeling for various fields including medical imaging, architecture, 3D printing, manufacturing, 3D gaming and various virtual reality (VR) applications. A point is identified by three coordinates that, correlate to a precise point in space relative to a point of origin, when taken together.
Point CloudThere are numerous ways of scanning an object or an area, with the help of laser scanners which vary based on project requirement. However, to give a generic overview of point cloud generation process, let us go through the following steps:

  1. The generation of a point cloud, and thus the visualization of the data points, is an essential step in the creation of a 3D scan. Hence, 3D laser scanners are the tools for the task. While taking a scan, the laser scanner records a huge number of data points returned from the surfaces in the area being scanned.
  1. Import the point cloud that the scanner creates into the point cloud modeling software. The software enables visualizing and modeling point cloud, which transforms it into a pixelated, digital version of the project. 
  1. Export the point cloud from the software and import it into the CAD/BIM system, where the data points can converted to 3D objects.
Different 3D point cloud file formats

Scanning a space or an object and bringing it into designated software lets us to further manipulate the scans, stitch them together which can be exported to be converted into a 3D model. Now there are numerous file formats for 3D modeling. Different scanners yield raw data in different formats. One needs different processing software for such files and each & every software has its own exporting capabilities. Most software systems are designed to receive large number of file formats and have flexible export options. This section will walk you through some known and commonly used file formats. Securing the data in these common formats enables the usage of different software for processing without having to approach a third party converter.

Common point cloud file formats

OBJ: It is a simple data format that only represents 3D geometry, color and texture. And this format has been adopted by a wide range of 3D graphics applications. It is commonly ASCII (American Standard Code for Information Interchange).

PLY: The full form of PLY is the polygon file format. PLY was built to store 3D data. It uses lists of nominally flat polygons to represent objects. The aim is to store a greater number of physical elements. This makes the file format capable of representing transparency, color, texture, coordinates and data confidence values. It is found in ASCII and binary versions.

PTS, PTX & XYZ: These three formats are quite common and are compatible with most BIM software. It conveys data in lines of text. They can be easily converted and manipulated.

PCG, RCS & RCP: These three formats were developed by Autodesk to specifically meet the demands of their software suite. RCS and RCP are relatively newer.

E57: E57 is a compact and widely used vendor-neutral file format and it can also be used to store images and data produced by laser scanners and other 3D imaging systems.

Challenges with point cloud data

The laser scanning procedure has catapulted the technology of product design to new heights. 3D data capturing system has come a long way and we can see where it’s headed. As more and more professionals and end users are using new devices, the scanner market is rising in a quick pace. But along with a positive market change, handling and controlling the data available becomes a key issue.

Five key challenges professionals working with point cloud face are:

  • Data Format: New devices out there in the market yields back data in a new form. Often, one needs to bring together data in different formats from different devices against a compatible software tool. This presents a not-so-easy situation
  • Data Size: With the advent of new devices, scanning has become cheaper with greater outputs. It is possible to scan huge assets from a single scan. This has resulted in the creation of tens of thousands of data points. A huge data of points can be challenging to handle and share between project partners.
  • Inter-operability: Integration between new technologies with the existing software can be quite arduous. Although, with careful investment of time and money, the goal can be achieved nonetheless.
  • Access: All the professionals involved in the entire lifecycle of a product can benefit from having access to point cloud data. But multiple datasets in multiple formats usually makes it more of a hassle.
  • Ownership: Who owns point cloud data? In the past, EPCs and the contractors who capture the data become custodians of the information.
  • Rendering: Different formats can result in rendering problems for point clouds.
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Product Tear Down Analysis

How do you determine procurement costs for product design, materials, and specifications? A superb way to get valuable insights and pinpoint design improvement and cost reduction opportunities is through a product teardown study. What is a product teardown?

In simple words, the process of disassembling a part to understand how it has been made and its functionalities are known as product teardown.

A product teardown process is an orderly way to know about a particular product and identify its parts, system functionality to recognize modeling improvement and identify cost reduction opportunities. Unlike the traditional costing method, tear down analysis collects information to determine product quality and price desired by the consumers. Companies can understand their competitor’s product, on what ground it differs from their own and manufacturing cost associated.

The three primary reasons for a product teardown study are:

  • Breakdown and Analysis:

It involves understanding the current technology, functionalities, and components of a product as well as identifying its strengths, weaknesses, and establishing areas for improvement.

  • Benchmarking:

Benchmarking is establishing a baseline in terms of understanding and representation of the product. It provides a comparison of new conceptual designs.

  • Knowledge and product improvement:

It involves gaining engineering knowledge to enact new room for concept development.

The entire product teardown process can be summed up in five steps:

  • Identifying the purpose of the teardown. This is to determine the models to be enacted as a result of the process
  • Creating data sheet where all insights will be listed
  • Gathering tools and documentation of the process
  • Analyzing the distribution of product
  • Disassembling of product, component measurement, and functionality assessment
  • Creating a bill of materials (BOM), models, and function flow diagram

The product tear down study technique has proven to be suitable to obtain crucial data about the manufacturing method, components, build-up model, functionality and strategies of competitors to find for improvement and coming up with a more refined version of a product.

Material Selection

Material selection stands out to be one of the most crucial aspects of engineering design as it determines the design reliability in terms of industrial and economic viewpoints. A great design needs appropriate material combinations, or else it will fail to be a profitable product. Engineers need to choose the best materials for the same, and there are several criteria they rely upon, such as property and its reaction to given conditions.  

Some important points to be included are:

  • Mechanical properties: A design needs to go through various manufacturing practices depending on the material. The primary goal is to prevent the failure of the product from a material viewpoint and ensure service fit. The materials are subject to stress, load, strength, and temperature variations.
  • Wear of materials: Most of the time, chances are that materials are contacting each other in a product. It can be seen in the case of gears. The selected materials should be able to withstand wear and tear.
  • Corrosion: This is a condition where the importance of material selection can be witnessed the most. It is evident in products open to the environment for an extended period. Materials like iron are highly prone to corrosion. So it is essential to make that the material is corrosion resistant and capable of being used for the product.
  • Manufacturing: Although the material is fit to be used for a product, it has to be appropriate for the manufacturing process. Improper machining can lead to a faulty product, and incorrect machining stems from an inability to put manufacturing functions of materials.
  • Cost: Cost is a crucial fact to consider while selecting materials. Certain metals are rare to obtain, considering their availability and lengthy refining process. Although the cost factor can be neglected when performance is given priority, overall associated costs should be considered nonetheless. There is a reason why plastics have massively replaced metals in the manufacturing process.  

 

 

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Reverse Engineering Inspection and its use

The quality control and inspection process in reverse engineering usually take three steps to determine if the 3D CAD model of the part is available or not. Those three steps are as follows:

  • The first step involves scanning the part and generating a computer model's point cloud format.
  • The second step involves merging and aligning the two computer models (CAD and Scanned one) to validate the part's specifications.
  • The final step, i.e., step three, includes visual computer model inspections and alignment of the merged models for any deviations in the geometry and dimensions.

The quality control outcome would be some recommendations for corrections, so the part meets perfectly with the blueprint specifications before the part's mass production.

Following are some uses of Reverse engineering inspection: 

  • Reverse engineering inspection comes in handy while carrying out Zero Article Inspection or ZAI. Zero article inspection is a type of workflow where the upcoming physical part doesn't follow the master design model but rather a derivative of the master model due to fluctuations in dimensions and tolerances. The review of the last digital representation before downstream purposes is known as zero article inspection. In this case, reverse engineering inspection provides sufficient information, allowing the inspector to check tolerances, dimensions, and any other information relevant to such projects. It gives assurance and confidence to produce quality components.
  • Reverse engineering inspection is an essential inspection of stylized parts/surfaces - where just dimensional inspection is not enough.
  • Reverse engineering inspection is an essential player during First Article Inspection (FAI). During the part manufacturing process, when an issue is detected with the manufactured part, the notification of the same has to go back to its design. The purpose is to keep the 3D CAD model in sync with the actual piece as manufactured. The hybridization of reverse engineering and inspection makes such updates easy to convey and apply, plus keeps the feedback circle opens across departments.
  • Reverse engineering inspection has found significant use in the additive manufacturing industry. Such a process helps bring down process-generated errors while calibrating & modifying building criteria to cut down the process itself's influence.
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Reverse Engineering vocabulary

3D Scanning – The process of collecting 3-Dimensional data from physical object through a variety of data acquisitions devices.

3D to CAD: The process of converting 3-Dimensional point to a dimensionally defined graphic model.

Accuracy: The extent of how close a measurement is to the recognized true value.

Annotation Models: A digital model containing specific coordinate locations verifying deviations from nominal data.

AS IS CAD: A CAD model that represents actual manufactured parts rather than a designed CAD model.

CAD (Computer-aided design): The use of computer technology to assist in the creation, analysis, or modification of a design.

CAM (Computer Aided Manufacturing): The use software that can support both machine tools and 3D CAD modeling capabilities.

Cone beam: A conical-shaped x-ray beam that produces two dimensional images of an object.

Design intent: The process of taking a manufactured part into account with inherent errors and modifying the same till it is true.

GD&T (Geometric Dimensioning and Tolerancing): System of languages and symbols used for defining and communicating engineering tolerances.

Hand held scanner: Portable camera that is used for capturing 3D imagery of objects with a laser or structured light based.

Hybrid Model: Combining two different modeling processes to accurately define 3D geometry.

Laser Scanner: A device used to capture 3D surface geometry, consisting of a laser output and a sensor to interpret the data.

LIDAR: A combination of the words: “Light” and “RADAR.” A LIDAR scanner employs RADAR’s technique of emitting a signal and measuring distances to objects based off of the signals reflection.

Long Range Scanning: Acquiring data at expansive distances from hundreds of feet away to miles away. Data can be captured through a variety of devices including LIDAR, Time of Flight and phase shift scanners.

Modeling: Digitally creating 2D or 3D object using CAD or data manipulation software, such as Polyworks, Geomagic or Solidworks.

NanoCT: Capturing images using CT (Computed Tomography), with a resolution of the images defined in nanometers.

Parametric Model: A sketch driven model that builds a design tree that can be opened in a CAD environment and allows the operator to manipulate the model.

Parametric Modeling: This process is taking 3d scan data and through the use of design tools, creating a sketch driven model with consistent relationships between features in the feature tree.

Phase Based Scanners: LIDAR Scanners that take measurements by sending laser pulses towards an object and measuring the phase shift of the pulses’ reflection off of the object.

Point Cloud: A set of points defined by X, Y, and Z coordinates that represent the external surfaces of an object.

Prismatic Modeling: Creating CAD geometry using basic geometry shapes, i.e. planes, cylinders, cones etc, to define correct shapes of the 3D geometry.

Re-Engineering: The process of modifying an existing part or assembly of parts digitally to improve its performance or use.

Repeatability: The variation in measurements taken with the same piece of equipment, under the same conditions, across multiple tests.

Reverse Engineering: The process by which a man-made object is dismantled to reveal its architecture, designs, or to extract knowledge from the object in order to know about its functioning and structural integrity.

SCAN to CAD: The process of collecting 3D data using 3D scanning hardware and converting the dimensional data to CAD format using a variety of software packages.

2D Drawings / Schematics: A 2D print that describes the physical characteristics of an object, how it should be made, assembled, handled, etc. These can be used to provide basic dimensional values to define its function.

Sectioning: The process of creating 2D profiles through sections of an object.

Short range scanning: A process used to collect dimensional data in 3D space from short ranges.

Solid Modeling: Defining an object with CAD tools such as extrudes, revolves, sweeps, etc. A solid model is enclosed and is said to have mass and volumetric values can be calculated.

Surface Model: An objects exterior skin defined by CAD features or NURBS surfaces.

Triangulation Scanner: Projecting a known pattern of light grids or fringe onto an object in order to calculate surface geometry by analyzing the distortions of the pattern.

White Light Scanner: A 3D camera projecting a known pattern of light grids or fringe onto an object in order to calculate surface geometry by analyzing the distortions of the pattern.

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The New Product Development Process

You might be a seasoned design professional thinking “What do my bosses sit around and do all day while I do the real design work".

This section outlines and explores the various early stages of the industrial design process that a product goes through. It does serve as a reasonable account of the overall and general product design process.

  • Ideating or initial ideas

Before any design work can begin on a product, there must first be a definition of what the product or product line might be. The idea’s genesis can be many factors such as:

Consumer demand – Reviews & feedbacks from the customers or even their ideas can help companies generate new product ideas.

Internal sources – Companies provide incentives and perks to employees who come up with new product ideas

Market research – Companies constantly review the changing needs, requirements and trends of the market by conducting plethora of market research analysis.

Competition – Competitors SWOT analysis helps companies to generate ideas.

  • Idea screening

An idea can be excellent, good, moderate or very bad. Once a suitable product opportunity has been identified, a specification document or design brief is created to define the product. It is usually created by the higher management of a company who’ll have access to information, such as budgeting and buyer/seller feedback. This step involves filtering out the good and feasible ideas which maintains the technical integrity while staying within realistic cost expectations.

Features such as a mechanical specification or a reference to an existing invention the product might be based upon, are outlined. Expectations, uses, and underlying intelligence associated to the product are included as well. Electronics, including sounds, lights, sensors, and any other specific inputs, such as colors and new materials may also be mentioned. Finally, a few reference sketches or photo images can be added to convey a possible direction.

  • Concept design & development

All ideas that pass through the screening stage are turned into concepts for testing purpose. A concept is a detailed strategy or blueprint version of the idea. In most companies, designers work up a design brief or product specification that guides their designs. It’s the designer’s role to make these ideas a reality. A professional designer has the ability to provide a large variety of designs in a quick and efficient manner. Many people can draw one or two ideas, but when asked to elaborate they often fall short. What separates the true design professional is depth and breadth of their presented ideas and vision in a clear and concise manner. Concept design generally means the use of hand-drawn or digital sketches to convey what’s in a designer’s mind onto paper or a screen.

  • Business analysis

A detailed business analysis is required to determine the feasibility of the product. This stage determines whether the product is commercially profitable or not, whether it will have a regular or seasonal demand and the possibilities of it being in the market for the long run.

  • Modeling

With the help of 3D modeling software (CAD – Computer Aided Design), the ideas/concept is rendered a shape, thereby creating a 3D model. The technical and engineering team has the biggest workload during this phase. These 3D models will often show up problematic areas where the theoretical stresses and strains on the product to be developed will be exposed. If any problem persists, it is a best phase of product development to handle the design errors and come up with modifications to address the same.

  • Prototyping & pilot runs (preliminary design stage)

In this stage, prototypes are built and tested after several iterations and pilot run of the manufacturing process is conducted. This stage involves creating rapid prototypes for a concept that has been deemed to have business relevance and value. Prototype means a ‘quick and dirty’ model rather than a refined one that will be tested and marketed later on. Adjustments are carried out as required before finalizing the design.

  • Test marketing

Apart from continuously testing the product for performance, market testing is also carried out to check the acceptability of the product in the defined market and customer group. It is usually performed by introducing the new product on a very small scale, to check if there are any shortcomings. This helps to know in advance, whether customer will accept and buy this product on launching in the market. Test marketing is a powerful tool indeed.

  • New product launch

This is the final stage in which the product is introduced to the target market. Production starts at a relatively low level of volume as the company develops confidence in its abilities to execute production consistently and marketing abilities to sell the product. Product manufacturing expenses depend on the density of the product, if there are numerous parts, material selection etc. The organization must equip its sales and customer service entities to address and handle queries. Product advertisements, website pages, press releases, and e-mail communications are kept on standby on the launching day.

Product development is an ever evolving fluid process and cannot be summed up in a few steps. The entire procedure sees insertion of additional stages or even eviction of a crucial part, depending on the nature of the project. Each group of professionals, whether designers, engineers or marketing, sales; has their role to play in this methodology. It is the company’s responsibility to continuously monitor the performance of the new product.

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The Reverse Engineering process

Sometimes, situations arise where you don’t have access to a part’s original design documentation from its original production. This might be due to the absence of the original manufacturer altogether or stoppage on the production itself.

Reverse engineering empowers us to analyze a physical part and explore how it was originally built to replicate, create variations, or improve on the design. The goal is to ultimately create a new CAD model for use in manufacturing.

Let us take a look at the steps involved in reverse engineering. Commonly, it involves careful executions of the following steps:

  • Scanning

The first step involves using a 3D scanner for collecting the geometric measurements and dimensions of the existing part quickly and accurately using projected light patterns and camera system. Generally, the types of scanners used for such execution are blue light scanner, white light scanner, CT scanner and /or laser scanner. The former two captures the outward dimension and measurements while the latter two is capable of scanning the entire inside out.

  • Point Cloud

Once a certain part is scanned, the data gets transformed in the form of point clouds. Point cloud is a 3D visualization consisting of thousands or even millions of points. Point clouds define the shape of a physical system.

  • Meshing/Triangulation

This stage serves involves conversion of point clouds to mesh (STL or Stereolithographic format). Mesh generation is the practice of converting the given set of points into a consistent polygonal model that generates vertices, edges and faces that only meet at shared edges. Common software tools used to merge point clouds are Polyworks, Geomagic, ImageWare, MeshLab. The meshed part is then run for alignment in the mentioned software tools.

  • Parametric/Non-parametric Modeling

After the meshed part is aligned, it goes through either of two stages. The first option involves applying surface modeling on meshed part in tools such as Polyworks. It results in the generation of non-parametric model (IGES or STEP format). An alternate option is creating a sketch of the meshed part instead of putting it through surfacing. This work-process is known as parametric modeling (.PRT format). For a non parametric model, predicting future data is based on not just the parameters but also in the current state of data that has been observed. For a parametric model to predict new data, knowing just the parameters is enough.

  • CAD Modeling

The next stage consists of transferring the data through CAD software tools such as NX, Catia, Solidworks, Creo etc, for applying functions such as ‘stitch’, ‘sew’, ‘knit’, ‘trim’, ‘extrude’, ‘revolve’ etc for creation of 3D CAD model.

  • Inspection

This stage includes visual computer model inspections and alignment of the merged models against actual scanned parts (STL) for any discrepancies in the geometry as well as dimensions. Generally, inspection is carried out by using tools such as Polyworks or Geomagic. Reverse engineering inspection provides sufficient information to check tolerances, dimensions and other information relevant to the project.

  • Documentation

Documentation of 3D stage model depends solely on one’s technical/business requirements. This step is about converting 3D model to 2D sketch, usually with the help of tools such as inventor or Isodraw/Coraldraw, citing measurements which can be used for reference in the future.

 

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Types of Jigs and Fixtures

Till now, we know that jigs and fixtures are the devices which help in the machining of jobs and reducing the human efforts required for producing these parts. It has been explained before why a centre lathe is an ideal machine tool for creating individual pieces of different shapes and sizes, but for manufacturing similar objects in high number, its use is not that economical.

Different types of objects may require the use of drilling,milling, planning, and grinding machines, etc. Specific tools are necessary for producing these objects in identical shapes and sizes on a mass scale, by holding and locating tasks to minimize the repetition work. That is when various types jigs and fixtures come into play.

Considering the variety in the nature of jobs to be machined, the quality, and the associated functions, the type of jig and fixture varies as well. Following are the various kinds of jigs and fixtures.

Types of Jigs

Template Jig: The template jig is the simplest of all the models. The plate, having two holes, acts as a template which is fixed on the component to be machined.The drill is guided through these holes of the template and the required holes are drilled on the work-piece at the same relative positions with each other as on the template.

 

 

Plate Jig: A plate jig is an improvement of the template jig by incorporating drill bushes on the template.The plate jig is employed to drill holes on large parts maintaining accurate spacing with each other.

 

 

Channel Jig: Channel jig is a simple type of jig having a channel-like cross section. The component is fitted within the channel and is located and clamped by rotating the knurled knob. The tool is guided through the drill bush.

 

 

Diameter Jig: Diameter jig is used to drill radial holes on a cylindrical or spherical workpiece.

 

 

Leaf Jig: Leaf jig has a leaf which may be swung open or closed on the work for loading or loading purposes.

 

 

Ring Jig: Ring jig is employed to drill holes on circular flanged parts. The work is securely clamped on the drill body, and the holes are drilled by guiding the tool through drill bushes.

 

 

Box Jig: Box jig is of box-like construction within which the work is rigidly held so that it can be drilled or machined from different angles at a single setting depending on which face of the jig is turned toward the tool.

 

 

 

Types of Fixtures

Turning Fixtures: These fixtures are generally mounted on the nose of the machine spindle or a faceplate, and the workpieces held them. Whenever necessary, the fixture may have to be provided with a counterweight or balance the unbalance fixture.

 

 

Milling Fixtures: Milling fixtures are typically mounted on the nose of the machine spindle or a faceplate, and the work-pieces held them.The table is shifted and set in proper position, in relation to the cutter. The work-pieces are located in the base of the fixture and clamped before starting the operation.

 

 

Broaching Fixtures: Broaching fixtures are used on different types of broaching machines to locate, hold and support the workpieces during the operations, such as keyway broaching operations, such as keyway broaching, hole broaching, etc.

 

 

Indexing Fixtures: Several components need machining on the different surface such that their machined surface surfaces or forms are evenly spaced. Such elements are required to be indexed equally as many as the number of surfaces to be machined. The holding devices (jigs or fixtures) used are made to carry a suitable indexing mechanism. A fixture carrying such a device is known as an indexing fixture.

 

Grinding Fixtures: These fixtures may be the standard work-holding devices, such as chucks, mandrels, chuck with shaped jaws, magnetic chucks, etc.

Boring Fixtures: This fixture incorporates almost all the prevailing principles of jig and fixture design, their construction need not be as sturdy as that of the milling fixtures, because they never have to bear as heavy cutting loads as involved in milling fixtures, because they never have to endure as heavy cutting loads as involved in milling operations.

Tapping Fixtures: Tapping fixture is specially designed to position and firmly secure identical work-pieces for cutting internal threads in drilled holes in them. Odd shaped and unbalanced components will always need the use of such fixtures, especially when the tapping operation is to be carried out repeatedly on a mass scale on such parts.

Duplex Fixtures: It is the name given to the fixture which holds two similar components simultaneously and facilitates simultaneously machining of these components at two separate stations.

 

Welding Fixtures: Welding fixtures are carefully designed to hold and support the various components to be welded in proper locations and prevent distortions in welded structures. For this, the locating element need to be carefully; clamping has to be light but firm, placement of clamping elements has to be clear of the welding area. The fixture has to be quite stable and rigid to withstand the welding stresses.

Assembly Fixtures: The function of these fixtures is to hold different components together in their proper relative position at the time of assembling them. 

 

Source

The Engineers post, https://www.theengineerspost.com/jigs-and-fixtures

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Value Engineering

During the lifecycle of a particular product, companies tend to review the existing design to look out for ways to reduce production cost. Even when coming up with a new product, so many manufacturers go for analyzing the same during its design phase so that it requires an optimum level of cost to produce. This is where Value Engineering comes in.

Value engineering is an organized method to improve the “value” of a product or service in the lowest of cost.

VE is a systematic approach aimed at obtaining the necessary functions in a product, process, or system at the minimum overall cost, thereby maintaining the quality, reliability, performance, and safety. It provides the substitution of materials and methods with less expensive alternatives, without jeopardizing the functionality. It is emphasized totally on the functions of various components and materials, rather than their physical characteristics. Value engineering is also called value analysis.

It was Lawrence Miles who came up with the concept of finding substitute materials for parts unavailable.  It was found that substitutions not only reduced cost but aided in a better-finished product. It was this new technique that evolved into value engineering today.

The value in VE means two components:

  • Function: The measure of performance abilities
  • Cost: The resources needed to achieve the function

The function of a product is the specific task it was designed to perform, and the cost refers to the cost of the item during its life cycle. The ratio of function to cost denotes that the value of a product can be increased by either improving its function or decreasing its cost. In value engineering, the cost related to production, design, maintenance, and replacement are included in the analysis.

If we take an example of a new tech product which is being designed and is slated to have a life cycle of only two years; the product will be designed with the least expensive materials and resources that will live up to the end of the product’s lifecycle, saving the manufacturer and the end-user money. This is how product value is improved by reducing costs. It is evident that with the increase in function value and decrease in price, the overall product value increases. 

Stages of Value Engineering

There are three main stages to value engineering, which are:

  • Planning: Gathering product information, and understanding its primary goals, identifying the functionality of the product.
  • Design: Designing alternative ways to incorporate in the product which enhances the value rather than affecting its function and quality
  • Methodology: Reduce the action list as much as possible. Developing alternatives to feasible plans. Allocation of costs.
Benefits of Value Engineering

Value engineering helps an organization in numerous ways:

  • Lowering O&M costs
  • Improving quality management
  • Improving resource efficiency
  • Simplifying procedures
  • Minimizing paperwork
  • Reducing staff costs
  • Increasing procedural efficiency
  • Optimizing construction expenditures
  • Developing value attitudes in staff
  • Competing more successfully in the marketplace 

Value engineering concepts apply to business as well as technical situations and consequently lead management to informed, result-oriented decisions. Value engineering has to be treated as a future investment for gaining technology leadership in the industry.

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What are BREP and CSG | Difference between BREP and CSG

The geometric modelling technique has revolutionized the design and manufacture of products to a great extent. Although there have been various ways of representing an object, the most commonly used modelling technique is Solid Modelling. The two main ways to express solid models are Boundary Representation modelling and Constructive Solid Geometry modelling.

CONSTRUCTIVE SOLID GEOMETRY

Constructive solid geometry or C-REP/CREP, previously known as computational binary solid geometry, is a reliable modelling technique that allows creating of a complex object from simple primitives using Boolean operations. It is based on the fundamental that a physical object can be divided into a set of primitives or basic elements combined in a particular order by following a set of rules (Boolean operations) to create an object. Typically, they are objects of simple shapes such as cuboids, cylinders, prisms, pyramids, spheres, and cones. CSG cannot represent fillets, chamfers, and other context-based features.

The primitives themselves are regarded as valid CSG models, where each primitive is bounded by orientable surfaces (Half-spaces).

These simple primitives are in generic form and must be confirmed by the user to be used in the design. The primitive may require transformations like scaling, translation, and rotation to be assigned a coveted position.

There are two kinds of CSG schemes:

Primitive based CSG: It is a popular CSG scheme based on bounded solid primitives, R-sets.

Half-space based CSG: This CSG scheme uses unbounded Half-spaces. Bounded solid primitives and their boundaries are considered composite half-spaces and the surfaces of the component half-spaces, respectively.

Some attributes of CSG are as follows:

  • CSG is fundamentally different from the BREP model, where it does not store faces, edges and vertices. Instead, it evaluates them as needed by algorithms.
  • CSG database stores topology and geometry.
  • The validity checking in the CSG scheme occurs indirectly. Each primitive combined using a Boolean operation (r-sets) to build the CSG model fits its validity.
  • The standard data structures used in CSG are graphs and trees.
  • CSG representation is of considerable importance to manufacturing.
BOUNDARY REPRESENTATION

In solid modelling and computer-aided design, boundary representation or B-rep / BREP—is the process of representing shapes using the limits. Here a solid is described as a collection of connected surface elements. BREP was one of the first computer-generated representations to represent three-dimensional objects.

BREP defines an object by their spatial boundaries. It details the points, edges, surfaces of a volume.

BREP can also be explained in terms of cell domain combination.

A cell is a connected limitation of the underlying geometry. There are four kinds of cells as per the spatial dimension they inhabit:

  • Vertex
  • Edge
  • Face
  • Volume

A domain is a set of connected cells grouped to define boundaries. Fields define various components inside a non-manifold object.

Boundary representation of models consists of two kinds of information:

Topology: The main topological entities are faces, edges, and vertices.

Geometry: The main geometrical entities are surfaces, curves, and points.

The topological and geometrical entities are intertwined in a way where:

  • the face is a bounded portion of a character.
  • An edge is an enclosed piece of a curve.
  • A vertex lies at a point. Topological items allow making links between geometrical entities.

BREP comes with its share of advantages and disadvantages, which are:

  • It is appropriate for constructing solid models of unusual shapes.
  • A BREP model is relatively simple to convert to the wireframe model.
  • BREP uses only primitive objects and Boolean operations to combine them, unlike CSG (Constructive Solid Geometry).
  • In addition to the Boolean operations, B-rep has extrusion (or sweeping), chamfer, blending, drafting, shelling, tweaking and other actions that use these.
  • BREP is not suitable for applications like tool path generation.
DIFFERENCE BETWEEN BREP AND CSG

 

Boundary Representation (BREP) Constructive Solid Geometry (CSG)
BREP describes only the oriented surface of a solid as a data structure composed of vertices, edges, and faces. A solid is represented as a Boolean expression of primitive solid objects of a simpler structure.
A BREP object is easily rendered on a graphic display system. A CSG object is always valid because its surface is closed and orientable and encloses a volume, provided the primitives are authentic in this
We review the possible surface types, the winged-edge representation schema, and the Euler operators for B-rep. For CSG, the basic operations include classifying points, curves, surfaces concerning a solid, detecting redundancies in the representation, and approximating CSG objects systematically.

 

Reference: https://catiatutor.com/reading-a-part-body-through/

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