Computer Aided Design (CAD)

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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Design principles of Jigs and Fixtures

The art of metalworking has a primary concern, which is locating the part to be machined relative to the platform. A CNC machine starts machining at a specific point corresponding to the fixture and proceeds from there. Therefore, the preciseness with which a job is machined is very dependent on the accuracy with which it is held in the fixture.Accurate locating of every part loaded into the fixture is essential. Any deviation in part location adds to the dimensional tolerance that must be assigned to the finished pieces. Furthermore, improper supporting and securing of the part in the fixture affects surface finishes as well, by temporarily or permanently deforming it. Hence, techniques for supporting, clamping, and locating must be considered together to assure repeatability from part-to-part.

The 3-2-1 principle

Locating a part to be machined involves mainly three steps: Supporting, Positioning, and Clamping.

Two main intentions of when placing a job on a jig/fixture are:

  • Precisely positioning the part at the desired coordinates.
  • Curbing all six degrees of movement so that the part cannot budge.

An extensively used method for obtaining these objectives is known as the 3-2-1 principle or six degrees of freedom for part location.

The 3-2-1 method is a work holding principle where three pins are located on the 1st principle plane, i.e. either XY, YZ, ZX. And two pins are located on the 2nd plane which is perpendicular to the 1st plane, and at last one pin on the plane which is mutually perpendicular to the 1st and 2nd planes. The ultimate goal is to constrain the movement of the workpiece along all the three axes.

 

 

Design objectives of Jigs and Fixtures

Before sitting down to design jigs/fixtures, the designer must consider the following points:

  • The tool must be fool proof to prevent any mishandling or accidental usage by the operator
  • Easy to operate for increasing efficiency
  • Easy to manufacture using the lowest costs
  • Can weather the tool life instead of appropriate materials
  • Must be consistent at producing high-quality parts
  • Must be safe and secure to use

The designer must know the basic of the process and tools associated in it for which the jig/fixture is to be designed. Overall objectives to look out for a while designing such tools are:

  • Cycle time
  • Type of Jig/Fixture 
  • Part Assembly sequence or Machining locations
  • Number of parts to be  
  • Type of joining or machining process
  • Clamping method and clamping sequence 
  • Required output accuracy
  • Type of equipment to be used with the jig
  • Method of ejecting finished output and transferring it to the next platform, whether the manual or automatic mode
  • The type of material, recommended weight, number of spots involving welding
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Designing Jigs and Fixtures

The design of jigs and fixtures is dependent on numerous factors which are analysed to achieve optimum output. Jigs should be made of rigid light materials to facilitate secure handling, as it has to be rotated severally to enable holes to be drilled from different angles. It is recommended that four feet should be provided for jigs that are not bolted on the machine tool, to enable the jig to wobble if not well positioned on the table and thereby alert the operator. Drill jigs provide procedures for proper location of the work-piece concerning the cutting tool, tightly clamp and rigidly support the work-piece during machining, and also guide the tool position and fasten the jig on the machine tool.

To achieve their expected objectives, jigs and fixtures consist of many elements:

  • Frame or body and base which has features for clamping
  • The accuracy and availability of indexing systems or plates
  • The extent of automation, capacity, and type of machine tool where jigs and fixtures will be employed
  • Bushes and tool guiding frames for jigs
  • The availability of locating devices in the machine for blank orientation and suitable positioning
  • Auxiliary elements
  • The strength of the machine tool under consideration
  • The precision level of the expected product
  • Fastening parts
  • The available safety mechanisms in the machine tool
  • The study of the fluctuation level of the machine tool

 

 

The factors below are to be reflected upon during design, production, and assembly of jigs and fixtures due to the targeted increase in throughput, quality of products, interchangeability, and more accuracy.

  • Guiding of tools for slim cutting tools like drills
  • Type of operations
  • Inspection requirements
  • Provision of reliable, rigid, and robust reinforcement to the blank
  • Production of jigs and fixtures with a minimum number of parts
  • Fast and accurate location of the jig or fixture blank
  • Rapid mounting and un-mounting of the work-piece from the jig or fixture
  • Set up time reduction
  • Standard and quality parts must be used
  • Reduction of lead time
  • Easy disposal of chips
  • Enhanced flexibility
Elements of Jigs and Fixtures

The significant features of Jigs and Fixtures are:

The body: The body is the most outstanding element of jigs and fixtures. It is constructed by welding of different slabs and metals. After the fabrication, it is often heat-treated for stress reduction as its main objective is to accommodate and support the job.

Clamping devices: The clamping devices must be straightforward and easy to operate, without sacrificing efficiency and effectiveness. Apart from holding the work-piece firmly in place, the clamping devices are capable of withholding the strain of the cutting tool during operations. The need for clamping the work-piece on the jig or fixture is to apply pressure and press it against the locating components, thereby fastening it in the right position for the cutting tools.

Locating devices: Thepin is the most popular device applied for the location of work-piece in jigs and fixtures.The pin’s shank is press-fitted or driven into a jig or fixture. The locating width of the pin is made bigger than the shank to stop it from being pressed into the jig or fixture body because of the weight of the cutting tools or work-piece. It is made with hardened steel.

Jig bushing or tool guide:Guiding parts like jig bushings and templates are used to locate the cutting tool relative to the component being machined. Jig bushes are applied in drilling and boring, which must be wear resistant, interchangeable, and precise. Bushes are mainly made of a reliable grade of tool steel to ensure hardening at a low temperature and also reduce the risk of fire crackling.

 

 

Selection of Materials

There is a wide range of materials from where jigs and fixtures could be made, to resist tear and wear, the materials are often tempered and hardened. Also, phosphor bronze and other non-ferrous metals, as well as composites, and nylons for wear reduction of the mating parts, and damage prevention to the manufacturing part is used. Some of the materials are discussed below:

  • Phosphor Bronze: phosphor bronze is used in the production of jigs and fixtures for processes that involve making of interchangeable nuts in clamping systems like vices, and also incorporated feedings that require screws. As the manufacturing of screws is costly and also wastes a lot of time, the reduction of their tear and wear is often achieved by using replaceable bronze mating nuts made with phosphor bronze.
  • Die Steels: the three variants of die steel - high chromium (12 %), high carbon (1.5 to 2.3%), and cold working steels are applied in the production of jigs and fixtures for the making of thread forming rolls, as well as cutting of press tools. When alloyed with vanadium and molybdenum for it to retain toughness at very high temperature, die steels are applied in the fabrication of jigs and fixtures that are used in high-temperature work processes which include extrusion, forging, and casting processes.
  • High-Speed Steels: High-speed steels which contain more quantity of tungsten and less quantity of chromium and vanadium have high toughness, hardness retention at high temperature, and excellent wear, tear and impact resistance. When tempered, they are applied in the production of jigs and fixtures for reaming, drilling, boring, and cutting operations.
  • Carbon Steels: when tempered with oil, carbon steels are applied in the making of some jig and fixture parts which are exposed to tear and wear like the locators and jig bushes.
  • Mild steels: Mild steel, which contains about 0.29% of Carbon, is very cheap and because of their easy availability is often the choicest material for the making of jigs of fixtures.

Other materials for the making of jigs and fixtures include Nylon and Fibre, steel castings, stainless steel, cast iron, high tensile steels, case hardening steels, and spring steels.

Reference

Charles ChikwenduOkpala, EzeanyimOkechukwu C “The Design and Need for Jigs and Fixtures in Manufacturing” Science Research.Vol. 3, No. 4, 2015, pp. 213-219. DOI: 10.11648/j.sr.20150304.19

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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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Difference between New Product Development (NPD) & Industrial Design (ID)

Let us take a step back and walkthrough the definitions as presented earlier in this article.

New Product Development: The process which involves forming strategy, organizing requirements, generating concepts, creating product & marketing plan, evaluating and subsequent commercialization, thereby bringing a new product to the marketplace.

Product development is a complete cycle which starts from market analysis, product specifications to concept/industrial design, costing, scheduling, testing, manufacturing and ends at logistics, customer feedback, improvements and the final act of getting a product into the market.

Industrial Design:The practice of forming concepts and designing products, which are to be manufactured through techniques of mass production.

Product Design is complete process that includes product industrial design, user experience, 3D Cad modeling, design calculations, simulation. Responsibility of a good product design is to make product working as per design specifications. It is safe to say that product industrial design is one of the many stages of NPD. It is a crucial subset of NPD which is necessary for the successful completion of entire development cycle.

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FEA, CFD and Mold Flow Analysis

Over the years, the term “Design Analysis” has found a significant place for itself in the manufacturing sector. Instead of making a prototype and creating elaborate testing regimens to analyze the physical behavior of a product, engineers can evoke this information quickly and accurately on the computer.

Design analysis is a specialized computer software technology designed to simulate the physical behavior of an object.

If an object will break or deform or how it may react to heat are the sort of queries design analysis can answer. Design analysis helps in minimizing or even eliminate the need to build a physical prototype for testing. As a result, the technology has gone mainstream as a prized product development tool and found its presence in almost all sectors of engineering.

This article discusses three major design analysis software, namely:

  • Finite Element Analysis (FEA)
  • Computational Fluid Dynamics (CFD)
  • Mold Flow Analysis
Finite Element Analysis (FEA)

The Finite Element Analysis (FEA) is a specialized simulation of a physical entity using the numerical algorithm known as Finite Element Method (FEM). It is used to reduce the number of physical prototypes and experiments and analyze objects in their design stage to develop better products faster. The term ‘finite’ is used to denote the limited, or finite, number of degrees of freedom used to model the behavior of each element.

FEA will analyze an object in question by breaking down its entire geometry into small ‘elements,’ which are put under simulated conditions see how the elements react. It displays the results as color-coded 3D images where red denotes an area of failure, and blue indicates fields that maintain their integrity under the load applied. However, note it down that FEA gives an approximate solution to the problem.

Mathematics is used to understand and quantify a physical phenomena such as structural or fluid behavior, wave propagation, thermal transport, the growth of biological cells, etc. Most of these processes are described using Partial Differential Equations. Finite Element Analysis has proven to be on of the most prominent numerical technique for a computer to solve these PEDs.

FEA is used in:

Problems where analytical solution is not easily obtained,

And mathematical expressions required because of complex geometries, loadings and material properties.

Computational Fluid Dynamics (CFD)

Computational Fluid Dynamics (CFD) is a specilaized simulation used for the analysis of fluid flows through an object using numerical solution methods. CFD incorporates applied mathematics, physics and computing software to evaluate how a gas or liquid flows and how it affects an object as it flows past. CFD is based on Navier-Stokes equations which describe the way velocity, temperature, pressure, and density of a moving fluid are related.

Aerodynamics and hydrodynamics are two engineering streams where CFD analyses are often used. Physical quantities such as lift and drag or field properties as pressures and velocities are computed using CFD. Fluid dynamics is connected with physical laws in the form of partial differential equations. Engineers transform these laws into algebraical equations and can efficiently solve these equations numerically.The CFD analysis reliability depends on the whole structure of the process. The determination of proper numerical methods to develop a pathway through the solution is highly important. The software, which conducts the analysis is one of the key elements in generating a sustainable product development process, as the amount of physical prototypes can be reduced drastically.

CFD is used in almost all industrial domains, such as:

  • Food processing
  • Water treatment
  • Marine engineering
  • Automotive
  • Aerodynamics
  • Aerospace

With the help of CFD, fluid flow can be analyzed faster in more detail at an earlier stage, than by tesing, at a lower cost and lower risk. CFD solves the fundamental equations governing fluid flow processes, and provides information on important flow characteristics such as pressure loss, flow distribution, and mixing rates.

CFD has become an integral part of engineering and design domains of prominent companies due to its ability to predict performance of new designs and it intends to remain so.

Mold Flow Analysis

Moldflow, formerly known as C-mould, is one of the leading software used in processwide plastics solutions. Mold flow computes the injection molding process where plastic flows into a mold and analyzes the given mold design to check how the parts react to injection and ensure that the mold will be able to produce the strongest and uniform pieces. Two of the most popular mold flow analysis software are Moldflow and Moldex3D used exclusively by many mold makers.

There are three types of Mold flow analysis which are as follows:

  • Moldflow Filling Analysis (MFA): It facilitates visualization of shear rate and shear stress plus determination of fiber orientation and venting. MFA can predict fill pattern and injection pressure while optimizing gating and runner system.
  • Moldflow Cooling Analysis (MCA): MCA specializes in finding hot spots and calculating time to freeze. It helps in determining uneven cooling between core and cavity while specifying required cooling flow rates.
  • Moldflow Warpage Analysis (MWA): Moldflow warpage is all about predicting, finding and determining warpage due to orientation.

We can see benefits of using different analysis procedures that correctly understand the power of the different simulation tools. During the product design, many these methods affect the cost and quality of the product, thereby ensuring the optimum productivity as aimed by the manufacturer.

 

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Future of Reverse Engineering

Reverse engineering found its use in various industries gradually, as more and more industry leaders adopted this approach and implemented the same, thereby easing out their own work-process. Here is a list of industries that use reverse engineering as a part of their methods:

  • Manufacturing/Heavy machine
  • Automotive
  • Software development
  • Military projects
  • Space expeditions
  • Aerospace
  • Architecture
  • Oil & gas
The future

It is the 21st century. These are great times for design engineers. Over the past two decades, their job has been dramatically changed, with the transformation of finite element analysis (FEA) software from mainframe to desktop computer. With the easy availability of computer-aided design software packages, reverse engineering technology has become a practical means to create a 3D virtual model of an existing physical part. That, in turn, has made the use of 3D CAD, CAM, or other CAE applications easier.

The convenience in the usage, affordability and the ability of its software to tightly integrate with a CAD program has made this process a much favored among engineers. At the same time, the costs of scanners and other hardware used to input measurements have been dropping, and the hardware is becoming smaller and easier to use, according to the hardware makers.

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Geometric Dimensioning and Tolerancing (GD&T)

The design model is a depiction of a part design. However, the design model can never be an accurate representation of the product itself. Due to shortcomings in manufacturing and inspection processes, physical parts never match the design model exactly. An essential aspect of a design is to specify the lengths the part features may deviate from their theoretically accurate geometry. It is vital that the design intent and functionality of the part be communicated between the design engineers and the manufacturing unit. It is where the approach of GD&T comes into play.

Geometric dimensioning and tolerancing or GD&T is a language of symbols and standards used on engineering drawings and models to determine the allowable deviation of feature geometry. 

GD&T consists of dimensions, tolerances, definitions, symbols, and rules that enable the design engineers to convey the design models appropriately. The manufacturing unit uses the language to understand the design intent.

To master GD&T, one needs to understand the crucial concepts, which includes:

  • Machining tolerances: Tolerances mean the allowable amount of deviation from the proposed drawing. Machined parts look flat and straight through the naked eye, but if viewed with calipers, one can find imperfections all over. These imperfections or variations are allowed within the tolerance constraints placed on the parts. Tolerances should be kept as large while preserving the functions of the part.
  • The Datum Reference Frame: DRF is the most important aspect of GD&T. It is a three-dimensional cartesian coordinate system. It’s a skeletal reference to which all referenced geometric specifications are related.
  • GD&T Symbols: It is essential to be familiar with numerous symbols and types of applied tolerance in GD&T. The language of symbols makes it easier to interpret designs and improve communications from the designer to the shop. By using GD&T standard, the design intent is fully understood by suppliers all over the world.

  • Feature Control Frame: The feature control frame describes the requirements or instructions for the feature to which it is attached. A feature control frame contains only one message. If a feature needs two messages, the feature would need the corresponding amount of feature control frames for every message required.
  • Basic Dimensions: Basic dimensions are exact numerical values in theory, which defines the size, orientation, form, or location of a part or feature. 
  • Material Condition Modifiers: It is often necessary to state that a tolerance applies to a feature at a particular feature size. The Maximum Material Condition (MMC) allows an engineer to communicate that intent.

GD&T is an efficient way to describe the dimensions and tolerances compared to traditional approximation tolerancing. The engineer might design a part with perfect geometry in CAD, but the produced part, more often than not, turns out to be not accurate. Proper use of GD&T improves quality and reduce time and cost of delivery by providing a common language for expressing design intent.

 

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Importance of Product Development(NPD) & Industrial Design(ID) for a business

Over the first fiscal quarter of 2018, Apple accelerated investments in research and development operations spending more than $3.4 billion on new hires and initiatives which will keep the company competitive in a fast-paced tech market.

Product development is like the gasoline that keeps the wheels rolling. But what drives companies to spend valuable resources such as time, money, human capital, etc. on new product development? And why is it so important?

 Here are five reasons:

  • Value for customers

The primary reason for any new product development is to provide value to its customers. The increasing demands of customers for innovation & new technology calls for the need to develop new or existing products. Otherwise, there is no reason to pour in huge amounts of money in the first place.

  • Keeping up with the competition

Staying ahead of the competition should always be the primary goal for any business. And increased competition is one of the major reasons leading to go for new products development. New products give us a competitive advantage over our rivals. Every firm struggles to fulfill and retain consumers by offering exceptional products. To offer more competitive advantage over the other and to satisfy consumer needs more effectively and efficiently, the product innovation seems to be needed.

  • Changing markets

Today’s market is more dynamic as compared to the past; it keeps on changing due to the wide variety of customer needs, all thanks to increased literacy rate, globalized market, heavy competition, and availability of a number of substitute. Consumers are constantly evolving which means their tastes and preferences change with them. It is the changing consumer behavior that drives the innovation and development of products. Plus, it also counters seasonal fluctuations.

  • Explore technology

Just as consumer trends drive new products, advances in technology drives companies to invest in new products. If your company has not upgraded its technology arsenal for ten years, count yourself to be at the last one in the queue within a few years.

  • Reputation and goodwill

Building image and reputation as a dynamic innovation and creative firm boosts a company’s legacy. The new product development is approached. Company desires to convince the market that it works hard to meet customer’s expectations. In fact, company developing new products frequently has more reputation and can easily attract customers.

Industrial design is a very crucial part of the entire new product development process. We are aware of the fact that industrial design develops aspects of a product that create emotional connections with the user. It integrates all aspects of form, fit, and function, hence optimizing them to create the best possible user experience. Industrial design’s role in product development process is to establish the design language of a product, as well as the corporate branding and identity.

How successfully a company is able to carry out development or modification, incorporating the ergonomics aspect, can often determine the success of a product in the market. Firms that leave industrial design to the end of the engineering lifecycle, or out completely will struggle to find success in consumer-driven markets.

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Jigs and Fixtures

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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