What are DFMA and DFMEA

During the last few decades, with the developments in technology, manufacturers have been enabled to source parts globally. More and more manufacturers have entered the competition as it grows fierce. Companies in developing nation market offer products at lower prices. To sustain business and achieve growth, many manufacturers are coming up with new products to cater to the consumers and widen it as well. They must be very marketable and of high quality. The Design for Manufacturing and Assembly (DFMA) method enables firms to develop quality products in lesser time and at lower production costs.

Design for Manufacturing and Assembly (DFMA)

Design for Manufacturing and Assembly or DFMA is a design process that targets on ease of manufacturing and efficiency of assembly.

Simplifying the design of a product makes it possible to manufacture and assemble it in the minimum time and lower cost. DFMA approach has been used in the automotive and industrial sectors mostly. However, the process has been adopted in the construction domain as well.

DFMA is a combination of two methodologies which are:

  • Design for Manufacturing (DFM): DFM focuses on the design of constituent parts to ease up their manufacturing process. The primary goal is to select the most cost-efficient materials and procedures to be used in production and minimize the complexity of the manufacturing operations.
  • Design for Assembly (DFA): DFA focuses on design for the ease of assembly in the product. The aim is to reduce product assembly cost and minimize the number of assembly operations.

Both DFM and DFA seek to reduce material, labour costs associated with designing and manufacture of a product. For a successful application of DFMA, the two activities should operate in unison to earn the most significant benefit. Through the DFMA approach, a company can prevent, detect, quantify, and eliminate waste and manufacturing inefficiency within a product design.

Design Failure Mode and Effect Analysis (DFMEA)

Design Failure Mode and Effect Analysis (DFMEA) is a methodical string of activities to identify and analyze potential systems, products, or process failures.

Design Failure Mode and Effects Analysis or DFMEA focuses on finding potential design flaws and failures of components before they can make a significant impact on the end users of a product and the business distributing the product.

DFMEA identifies –

The potential risks introduced in a  new or modified design,

 The effects and outcomes of failures,

The actions that could eliminate the failures, and

provides a historical written record of the work performed. 

DFMEA is an ideal process for any sector where risk reduction and failure prevention are crucial, which includes:

  • Manufacturing
  • Industrial
  • Aerospace
  • Software
  • Service industries

 

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What are Jigs and Fixtures, their Advantages, and Differences

With the rapid advancement in manufacturing technology, consumerism has increased over the years. Therefore, to meet the higher demands, manufacturers have come up with innovative methods of producing high-quality products at a much faster rate.

The production process has observed the introduction of inventive manufacturing concepts such as Lean Production System, Cellular Manufacturing, Single Minute Exchange of Dies, and Tact Time Analysis. These creative approaches require the need for a horde of efficient, cheaper tools, and work-holding devices.

The manufacturing company requires a simple work positioning strategy and devices for correct operations. This is to ensure:

  • Non-complexities in assembly and unit cost reduction,
  • Reduction in the massive manufacturing cost, and
  • Increase their profitability.

The industry has resorted to easing upthe supply chain in a bid to maintaining a low amount of inventory. This resulted in the emergence of better and cost-effective work-holding devices which ensure better quality products, increase throughput, and reduce lead time. The requirement for production standard work-holding devices has paved the way for two specific terms named: Jigs and Fixtures.

The jig is the device which guides the tool, while the fixture is a tool that securely and firmly holds the job in position during machining operations.

Jigs

In simple terms, a jig is a tool that guides the machining tool.

A common type of jig is the drill jig, which guides the drill for making holes at desired locations. Using drill jigs increases production rate drastically.

 

Fixtures

A fixture is a tool which firmly grips a workpiece on the machine bed accurately at the desired location. The fixture also reduces the loading, unloading, and fixing the time of the workpiece, which significantly reduces the non-productive hours.

 

 

Difference between Jig and Fixture

“Jig” and “Fixture” are many times referred to as the synonyms of each other while sometimes both of them are used together as jig fixture. Although both jig and fixture are used in the mass production process, functionally the two are quite different tools.

Let us go through the main points which differs a Jig from a fixture

 

Jig
Fixture

A jig controls and guides the machining tool

A fixture holds and supports the component precisely for machining operations

Jig ensures accuracy, repeatability, and interchangeability

The fixture provides a reduction in error by holding a component firmly on a table

Jigs are usually on the lighter side

The fixture is bulky, rigid and heavy

Jigs can be put in place and held by hand pressure

Fixtures are always placed firmly on a machine table

Drilling, reaming, tapping, boring are some of the standard jig functions

Fixtures are used explicitly in milling machine, slotting machine and shapers

Jigs cost more

Fixtures are not that cost-savvy compared to Jigs

Jigs require intricate design operations

Fixture design operations are relatively less complicated

 

Advantages of Jigs and Fixtures

Jigs and Fixtures have made manufacturing processes less time consuming, more precise, and hassle-free from a human factor perspective. The benefits of jigs and fixtures including but not limited to, the following:

  • Increase in production
  • The consistent quality of manufactured products due to low variability in dimension
  • Cost reduction
  • Inter-changeability and high accuracy of parts
  • Inspection and quality control expenses are significantly reduced
  • The decrease in an accident with improved safety standards
  • Due to relatively simple manoeuvrability, semi-skilled workers can operate these tools which reduce the cost of the workforce.
  • The machine tool can be automated to a reasonable extent
  • Complex, rigid and, heavy components can be easily machined
  • Simple assembly operations reduce non-productive hours
  • Eliminates the need for measuring, punching, positioning, alignments, and setting up for each work-piece thereby reducing the cycle and set up a time
  • Increases technological capacities of machine tools
  • More than one device can be used simultaneously on a work-piece
  • Setting of higher values of some operating conditions like depth of cut, speed, and rate of feed can be attained because of the increased clamping capability of jigs and fixtures.

Both jigs and the fixtures are used to ease up machining operations and reduce the non-productive time of any mass production process. The principle of location or the 3-2-1 principle, CAD tools, and FEA tools are used for the design of both jigs and fixtures. In the next article, we will go through more detailed information about 3-2-1 principle and design standards of jigs and fixtures. 

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What are Parametric and Non-parametric Modeling

Up until now, we believe our readers got a clear explanation of reverse engineering. Let us give walkthrough — Reverse engineering is the process of extracting design information after studying a physical product, with the intent to reproduce the product, or to create another object that can interact with it.

In the past, designers resorted to physical measurement of the product to redraw its geometry. Today, designers use 3D scanners to capture measurements. The scanned data is then imported to CAD where the design can be analyzed, processed, manipulated and refined. Two key aspects that fall in place when focusing on reverse engineering process are:

Parametric Model/Modeling

A parametric model captures all its information about the data within its parameters. All you need to know for predicting a future data value from the current state of the model is just its parameters.
The parameters are usually finite in dimensions. For a parametric model to predict new data, knowing just the parameters is enough. A parametric model is one where we assume the ‘shape’ of the data, and therefore only have to estimate the coefficients of the model.

Non-parametric Model/Modeling

A non parametric model can capture more subtle aspects of the data. It allows more information to pass from the current set of data that is attached to the model at the current state, to be able to predict any future data.
The parameters are usually said to be infinite in dimensions. Hence, it can express the characteristics in the data much better than parametric models. 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. A non-parametric model is one where we do not assume the ‘shape’ of the data, and we have to estimate the most suitable form of the model, along with the coefficients.

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What is CAD | Types of CAD Models and CAD Formats

The previous sections dealt with the initial and middle stages of reverse engineering. This section highlights a stage which is undoubtedly crucial for product development. After a meshed part is aligned, it goes through either—surface modeling in tools such as Polyworks, which generates a non-parametric model (IGES or STEP format) or parametric modeling where a sketch of the meshed part is created instead of putting it through surfacing (.PRT format). The resultant is generally called, 3D computer aided model or CAD model.

But, what is CAD?  

CAD is the acronym for Computer Aided Design. It covers different variety of design tools used by various professionals like artists, game designers, manufacturers and design engineers.

The technology of CAD systems has tremendously helped users by performing thousands of complex geometrical calculations in the background without anyone having to drop a sweat for it. CAD has its origin in early 2D drawings where one could draw objects using basic views: top, bottom, left, right, front, back, and the angled isometric view.  3D CAD programs allow users to take 2D views and convert them into a 3D object on the screen.  In simple definition, CAD design is converting basic design data into a more perceptible and more understandable design.

Each CAD system has its own algorithm for describing geometry, both mathematically and structurally.  

Different CAD models

Everything comes with its own varieties and CAD modeling is no stranger to it. As the technology evolved, CAD modeling came up in different styles. There are many methods of classifying them, but a broad general classification can be as follows:

  • 2 dimensional or 2D CAD: The early version of CAD that most of us are aware of. These are 2-dimensional drawings on flat sheet with dimensions, layouts and other information needed to manufacture the object.
  • 3 dimensional or 3D CAD: The purpose of both 2D and 3D models is the same. But what sets 3D models apart is its ability to present greater details about the individual component and/or assembly by projecting it as a full-scale 3-dimensional object. 3D models can be viewed and rotated in X, Y, or Z axes. It also shows how two objects can fit and operate which is not possible with 2D CAD.

3D models can be further classified into three categories:

  • 3D Wire-frame Models: These models resemble an entire object made of just wires, with the background visible through the skeletal structure.
  • Surface Models: Surface models are created by joining the 3D surfaces together and look like real-life objects.
  • Solid Models: They are the best representation of real physical objects in a virtual environment. Unlike other models, solid models have properties like weight, volume and density. They are the most commonly used models and serve as prototypes for engineering projects.

CAD model

Types of CAD formats

Different professionals use different software, owing to different reasons like cost, project requirements, features etc. Although, software comes with their own file formats, there are instances where one needs to share their project with someone else, either partners or clients, who are using different software. In such cases, it is necessary that both party software understand each other’s file formats. As a result of this situation, it is necessary to have file formats which can be accommodated in variety of software.

 CAD file formats can be broadly classified into two types:

  • Native File Formats: Such CAD file formats are intended to be used only with the software it comes with. They cannot be shared with any other software which comes with their own CAD formats.
  • Neutral File Formats: These file formats are created to be shared among different software. Thereby it increases interoperability, which is necessary.

 Although there are almost hundreds of file formats out there, the more popular CAD formats are as follows:

STEP: This is the most popular CAD file format of all. It is widely used and highly recommended as most software support STEP files. STEP is the acronym for Standard for the Exchange of Product Data.

IGES: IGES is the acronym for Initial Graphics Exchange Specification. It is an old CAD file format which is vendor-neutral. IGES has fallen out lately since it lacks many features which newer file formats have.

Parasolid: Parasolid was originally developed by ShapeData and is currently owned by Siemens PLM Software.

STL: STL stands for Stereolithography which is the format for 3D information created by 3D systems. STL finds its usage mostly in 3D printers. STL describes only the outer structure or surface geometry of a physical object but doesn’t give out color, texture and other attributes of an object.

VRML: VRML stands for Virtual Reality Modeling Language. Although it gives back more attributes than STL but it can be read by a handful of software.

X3D: X3D is an XML based file format for representing 3D computer graphics.

COLLADA: COLLADA stands for Collaborative Design Activity and is mostly used in gaming and 3D modeling.

DXF: DXF stands for Drawing Exchange Format which is a pure 2D file format native to Autocad.

Use of CAD

Computer-aided design or CAD has pushed the entire engineering process to the next level. One can actually mould or fold, modify or make a new part from scratch, all with the help of CAD modeling software. The many uses of CAD are as follows:

  • CAD is used to generate design and layouts, design details and calculations, 3-D models.
  • CAD transfers details of information about a product in a format that can be easily interpreted by a skilled professional, which therefore facilitates manufacturing process.
  • The editing process in CAD is very fast as compared to manual process.
  • CAD helps in speeding up manufacturing process by facilitating accurate simulation, hence reducing time taken to design.
  • CAD can be assimilated with CAM (Computer Aided Manufacturing), which eases up product development.
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What is Geometric Modeling

The culture of design & manufacturing incorporates various crucial aspects for the production of a market efficient product. Computer-aided Engineering or CAE comes up as a central part of the entire manufacturing process. Over the years, the function of CAE has evolved so much that it has developed its applications depending upon the type of usage and execution.  Geometric Modeling happens to be one of the most popular CAE applications.  

The computer/software generated mathematical representation of an object’s geometry is called Geometric Modeling. As curves are easy to manipulate and bend as per application, geometric modeling uses curves extensively to construct surfaces. The formation of curves can be achieved by,

A set of points,

Analytic functions, or

Other curves/functions

The mathematical representation of an object can be displayed on a computer and used for generation of drawings; which go on for analysis and eventual manufacturing of the object. In general, there are three conventional steps to create a geometric model:

  • Creating key geometric elements by using commands like points, lines, and circles.
  • Applying Transformations on the geometric elements using commands like rotation, achieve scaling, and other related transformations functions.
  • Constructing the geometric model using various commands that integrates the elements of the geometric model to form the desired shape.
 REPRESENTAION OF GEOMETRIC MODELS
  • Two Dimensional or 2D: It projects a two-dimensional view and is used for flat objects.
  • 1 2D: It projects the views beyond the 2D and enables viewing of 3D objects that have no sidewall details.
  • Three Dimensional or 3D: This representation permits complete three-dimensional viewing of the model with intricate geometry. The most leading process of geometric modeling in 3D is Solid modeling.
TYPES OF GEOMETRIC MODELINGS

Depending upon the representations of objects, geometric modeling system can be classified into three categories, which are:

  • Solid modeling

Also known as volume modeling, this is the most widely used method as it provides a complete description of solid modeling.

  • Wireframe modeling

It is a simple modeling system, which is used to represent the object by the help of lines only. Hence, it is also known as Line model representation. However, wireframe modeling is not enough to express complex solids; therefore, it is used to describe only wiring systems.  

  • Surface modeling

This type of modeling represents the object by its surface, and it is used to describe the object with a clear view of manufacturing. By this clear point of view, surface modeling cannot be used to develop an internal surface of any model. Surface modeling uses Bezier and B-spines.

Requirements of Geometric Modeling

The various requirements of geometric modeling are as follows:

  • The cross-section, hidden lines, dimensions are needed for Graphical Visualization.
  • Interchangeable manufacturing tolerance analysis is required while inspection of parts.
  • There should also be properties evaluation and geometrical evaluations in Area, Volume, and property evaluation in Weight, Density, etc..
  • Need for Finite element analysis and Kinematic analysis.
  • Parts classification, planning, etc. in manufacturing.

Geometric modeling is a vast and elaborate field of CAE and requires in-depth study. The next articles dive deep into the various types and facets of geometric modeling.

 

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What is Industrial Product Design?

Every product you have in your home and interact with is the outcome of a design procedure. All those products have come into being after long hours of planning, sketching, rendering, 3D modeling. Not to mention the numerous prototypes and testing it has gone through to finally hit the shelves. The ideation and the procedure to develop a certain product is collectively called Industrial Design process or simply ‘Industrial Design’ (ID).

Industrial Design is the professional practice of conceptualizing and designing products, which are to be manufactured through techniques of mass production, eventually to be used by millions of people around the world every day.

An industrial product design process incorporates inputs from diverse domains such as ergonomics, form studies, studio skills, advanced cad, research methods, design management, materials & manufacturing processes and social sciences.

An industrial designer’s purpose is to emphasize on — appearance of a product, the functioning, how the product is manufactured and the value & experience it provides for users. Their sole intent is aimed at improving your life through design.

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What is Mesh and what are the types of Meshing

For those acquainted with mechanical design and reverse engineering, they can testify to the fact that the road to a new product design involves several steps. In reverse engineering, the summary of the entire process involves scanning, point cloud generation, meshing, computer-aided designing, prototyping and final production. This section covers a very crucial part of the process — Meshing or simply put, Mesh.

To put a simple definition, a mesh is a network that constitutes of cells and points.

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. It can have almost any shape in any size. Each cell of the mesh represents an individual solution, which when combined, results in a solution for the entire mesh.

 

mesh

Mesh is formed of facets which are connected to each other topologically. The topology is created using following entities:

  • Facet - A triangle connecting three data points
  • Edge - A line connecting two data points
  • Vertex - A data point
Mesh Property

Before we proceed to know the types of meshes, it is necessary to understand the various aspects that constitute a mesh. It is important to know the concept of a polygonal mesh.

A polygon mesh is a collection of vertices, edges and faces that defines the shape of a polyhedral object in 3D graphics and solid modeling. The faces usually consist of triangles, quadrilaterals or other simple polygons as that simplifies rendering. It may also be composed of more general concave polygons or polygons with holes.

Objects created with polygon meshes must store different types of elements. These include:

  • Vertex: A position (usually in 3D space) along with other information such as color, normal vector and texture coordinates
  • Edge: A connection between two vertices
  • Face: A closed set of edges, in which a triangle face has three edges, and a quad face has four edges
  • Surfaces: They are often called smoothing groups. Generally, surfaces are not required to group smooth regions

A polygon mesh may be represented in a variety of ways, using different methods to store the vertex, edge and face data. These include:

  • Face-vertex meshes
  • Winged edge meshes
  • Corner tables
  • Vertex-vertex meshes
Types of meshes

Meshes are commonly classified into two divisions, Surface mesh and Solid mesh. Let us go through each section one by one.

Surface Mesh: A surface mesh is a representation of each individual surface constituting a volume mesh. It consists of faces (triangles) and vertices. Depending on the pre-processing software package, feature curves may be included as well.

Generally, a surface mesh should not have free edges and the edges should not be shared by two triangles.

The surface should ideally contain the following qualities of triangle faces:

  • Equilateral sized triangles
  • No sharp angles/surface folds etc. within the triangle proximity sphere
  • Gradual variation in triangle size from one to the next

The surface mesh generation process should be considered carefully. It has a direct influence on the quality of the resulting volume mesh and the effort it takes to get to this step.

surface mesh

Solid Mesh: Solid mesh, also known as volume mesh, is a polygonal representation of the interior volume of an object. There are three different types of meshing models that can be used to generate a volume mesh from a well prepared surface mesh.

The three types of meshing models are as follows:

  • Tetrahedral - tetrahedral cell shape based core mesh
  • Polyhedral - polyhedral cell shape based core mesh
  • Trimmed - trimmed hexahedral cell shape based core mesh

Once the volume mesh has been built, it can be checked for errors and exported to other packages if desired.

solid mesh

Mesh type as per Grid structure

A grid is a cuboid that covers entire mesh under consideration. Grid mainly helps in fast neighbor manipulation for a seed point.

mesh grid

Meshes can be classified into two divisions from the grid perspective, namely Structured and Unstructured mesh. Let us have a look at each of these types.

Structured Mesh: Structured meshes are meshes which exhibits a well-known pattern in which the cells are arranged. As the cells are in a particular order, the topology of such mesh is regular. Such meshes enable easy identification of neighboring cells and points, because of their formation and structure. Structured meshes are applied over rectangular, elliptical, spherical coordinate systems, thus forming a regular grid. Structured meshes are often used in CFD.

structured mesh

Unstructured Mesh: Unstructured meshes, as the name suggests, are more general and can randomly form any geometry shape. Unlike structured meshes, the connectivity pattern is not fixed hence unstructured meshes do not follow a uniform pattern. However, unstructured meshes are more flexible. Unstructured meshes are generally used in complex mechanical engineering projects.

Unstructured Mesh

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What is Reverse Engineering ?

Let us start with an example. One day you get into your garage and find on the workbench a 'black box'. Stricken by curiosity, you build up an urge to discover what it 'is' and what it 'does'. You start with an inspection of the box's dimensions, color. Then you try to find its purpose and then how it operates. Not satisfied, you try to open it, break it apart, piece by piece in an attempt to understand what each component does and build up a pattern of how they would all interact together as one system. Finally you reach the end of your inquisition. You now fully (or partially) understand the box. This very approach is termed as Reverse Engineering.
Reverse engineering, also known as back engineering, is the process where a man-made object is dismantled completely to reveal its architecture, design or to extract knowledge from the object about its functioning and structural integrity.

Why do you need Reverse Engineering?

There might be innumerable reasons to adopt reverse engineering process. Some of the common cases are as follows:

  • The original manufacturer of a particular product no longer produces it. In some cases, situations arise where original manufacturer ceased to exist, but a customer needs the product. Then there are cases where an original supplier is unable or unwilling to provide additional parts
  • There is inadequate documentation or no documentation at all of the original design
  • To enhance and strengthen the good features of a product based on its long-term usage
  • To analyze the shortcomings of the product, thereby exploring new possibilities to improve product performance and features
  • To update obsolete materials or replace outdated manufacturing processes with more current, less-expensive technologies
  • The CAD model is not sufficient to support current manufacturing process; hence creating 3D models
 
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