Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 5 : Detail design - Coggle Diagram
Chapter 5 : Detail design
Definition and Concept of Mechanical
In engineering, information needs to be passed on through drawings.
analysis, manufacturing and assembly of the product is based on drawings
objectives of the drawings
Drawings are preferred form of data communications in engineering
Used to communicate the ideas between the designers and between the designers and manufacturing personnel.
Simulate the operation of the product.
Used to check for the completeness of the product.
3 types of drawings
sketches (layout drawing)
Generated during conceptualization stage.
They are working documents that support the development of the major components and their relations.
They are made to scale but only the important dimensions are shown.
Tolerance are usually not shown
Detail drawing
The important characteristic of a detail drawings:
All dimensions must be tolerance.
Materials and manufacturing detail must be clear and presented in specific language.
These drawings are made by CAD system such as solidwork, AutoCAD, ProEngineer
Assembly drawing
goal of assembly drawing is to show how components fit together.
The characteristics of assembly drawing
Each component is identified with a number referenced to a list of all components
Necessary, detailed views are included to explain information that is not clear in other view
Bill of Material
BOM is an index of the parts that were used in the product
1.item number
This is a key to the components on the assembly drawings.
The part number
This is a number used throughout the purchasing, manufacturing and assembly system to identify the component
quantity needed in the assembly
name and description of the component
material from which the component is made
source of the component (which company)
cost of the individual component
Four construction techniques
Mock-up
constructed to scale from plastics, woods, cardboard to give the designer the feel for the design.
Used to check the clearance, assembly techniques, manufacturing considerations and appearance.
Least expensive
A solid model in the CAD system can replace the mock-up
Mock-ups are referred to as a proof of concept prototype
Modelling
relates the physical behavior of the system through mathematical similitude
Referred to as a proof of product prototype.
3 different types of models used to predict the behavior of a real system:
True
exact geometric reproduction of a real system, built to scale and satisfying all the constraints imposed by design parameter
Adequate
Constructed to test specific characteristics of the design and is not intended to yield information of total design
Distorted
Purposely violates one or more design conditions
Required when it is difficult or impossible to satisfy the specific conditions
Prototype
most expensive construction technique
Produces the greatest amount of useful information
prototype is constructed, full-scale working physical system
can be comprehensive or focused
Comprehensive corresponds to a full-scale, fully operational version of a whole product
Focused corresponds to one or a few of the product elements
Virtual prototyping
CAD and CAE
Solid modelling has enabled the use of geometry to visualize product models quickly and to detect gross interference problems
Able to automate design changes
Parametric modelling allows the presentation of dimensions of the parts in term of parameters
Visual prototyping can have its biggest payoff in manufacturing and analysis
Analysis
Once the product is well defined, a complete analysis is conducted
need to evaluate the integrity of the design in terms of its safety concerns, material selection that fits the requirement and compute the cost involved
proceeds as follows
1.Check for the design safety in terms of computing the forces that act on each component. Evaluate the stresses associated with these components. Then list the materials that would satisfy the stress requirements. CAE software can be used to perform the stress analysis
2.Manufacturability of the components needs to be checked. Having a sketch of a component does not mean that the machinist able to produce the component. Need to provide the drawing to machinist
3.Cost analysis of the components . be able to vary among components listed in morphological chart if certain components are cost effective or fit the product better
4.The aesthetics or the look of the product needs to be maintained
Design for manufacturing (DFM)
based on minimizing the cost of production including minimizing the time to market while maintaining a high standard of quality for the product
provides guidance in the selection of materials and processes and generates piece part and tooling cost estimates at any stage of product design
several methods that have been used in DFM to assess in analysis such as
process-driven design
failure mode and effect analysis (FMEA)
Taguchi method
design of experiment (DOE)
Design for Assembly (DFA)
Design for assembly is the study of the ease of assembling various parts and components into a final product
lower number of parts and an ease of assembly contribute to reducing the overall cost of the product
every part has to be checked. It must be determined if it is a necessary part or would it be better integrated into other parts or be replaced by a similar function part that is simpler and costs less
Integrating both DFM and DFA helps contribute to the competitive success of any given product by matching that product’s demands to its manufacturability and assembly capabilities
Design for Environment
often called green design, environmentally conscious design, life-cycle design or design for recyclability
a product’s useful life is over, one of three things happens to its components
Disposed
reused
recycled
3 factors contributed to design for environmen
Economics
less expensive to recycle some material than it is to pay the expense of processing new raw materials
Especially for the product that it is easily disassembled into components made of single material
Customer expectation
Consumers are increasingly more environmentally conscious and aware of the value of recycling
company that produce the product that affect the environment, are looked down by the public
Government regulation
Government regulation is forcing attention on the environment