© Boardworks Ltd 2005 1 of 29 © Boardworks Ltd 2005 1 of 29 Product Design CAD/CAM These icons...

© Boardworks Ltd 20051 of 29 © Boardworks Ltd 20051 of 29

Product Design CAD/CAM

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© Boardworks Ltd 20052 of 29

Learning objectives


Lea

rnin

g o

bje

ctiv

es To understand that computers now play a major role in developing and testing new products within product design.

To be able to use CAD software to create 2D and 3D designs.

To recognize the advantages and disadvantages of CAD and CAM.

To know how CNC machines are programmed and to be familiar with a range of CNC machines including milling machines, routers and cutters.


When computers were first used by product designers, software was developed that enabled them to draw products.These products ranged from architectural models to car components. The main purpose of these drawings was for engineers and manufacturers to have the necessary information to make the product.Drawing packages enabled designers to quickly convert hand drawings of products into an electronic format for safer storage and easier communication. This is called computer aided draughting (drawing).

Computer aided draughting


Computer aided draughting led software engineers to create computer packages for product designers which would enable them to create designs, rather than just draw diagrams.Special tools and functions were developed so that designers could quickly create and change the features of a design.Various types of CAD software emerged, enabling designers to create and develop designs in 2D and 3D forms within an electronic environment.

Computer aided designing


Once product designers were able to create and develop products in an electronic format, they realized the great benefits this brought.Software engineers began to further develop the product information to give it mass and volume, enabling product designers to imitate various materials and conditions under which the product would function.This led to product testing. Product designers can now conceive, develop and test a product with a very short lead time. We can see products actually working before they are even made. This has reduced the cost of developing new products.

Computer aided testing


Conventional CAD packages


3D modellingCreates shapes in three dimensions (x, y and z).Uses intuitive tools such as dimensioning, extruding and rounding edges to create wireframe and solid models.Wireframe models show the product as a coat hanger model with no solid surfaces, so the features behind and on the rear of the product are visible.Solid modelling shows the product with a skin over the top of the wireframe. Solid models are easier to visualize because they look like the real product.

Two-dimensional (2D) Create simple shapes in the X and Y directions.Does not show the Z direction (depth).Can be used for drawing, pattern draughting and for drawing images that appear to have three dimensions but are still in a 2D format.

Types of CAD


Photo realistic rendering


Advantages and disadvantages of CAD


Computer aided manufacturing (CAM) uses a computer to control manufacturing machinery. When combined with CAD, computer aided manufacturing is a very useful production process.

CAD/CAM is the process of linking computers used to aid design with computers used to aid manufacture.

A CAD drawing is essentially visual information. When this information is changed into numerical data to control the operation of a machine, it is called computer numerical control – C.N.C.

Computer aided manufacturing


Computer aided manufacturing


Advantages & disadvantages of CAM


CNC CAM machines interpret the information provided by CAD software. Many CNC machines use a special software language called FANUC.

FANUC software reads the CAD file and then produces machine code for the CNC machine to use.

Much of this special language is made up from information called G code and M code.

G codes provide the CNC machine with information about the direction of movement of the cutting tool.

M codes refer to miscellaneous functions such as starting the cutting tool and turning on the coolant.

Programming a CNC machine


Below is a list of selected G and M codes which are used in milling operations. If you have access to a CNC milling machine, see if you can spot some being used.

G00 – rapid movement G01 – straight line cutting moveG02 – clockwise cutting move G03 – anticlockwise cutting move G71 – metric unitsG81 – drilling cycleG90 – absolute programmingG91 – incremental programming

M03 – start spindle forwardsM04 – start spindle reverseM05 – stop spindleM06 – tool changeM08 – coolant onM09 – coolant offM39 – close automatic chuck

When a CNC machine moves, it must have a datum so that it knows how far to move. Incremental and absolute are two types of programming which use the datum in a different way.

Programming and coordinates


Incremental programming determines each move in relation to the position of the last one. In other words, every move starts where the last one finishes.

X Y

0 -1

+2 0

0 -2

+3 0

+2 +2Datum (start)

-y

+y

+x-xcutter

Incremental programming


Incremental programming task


Absolute programming determines each move in relation to a single datum point (usually in the bottom left corner).In other words, every move starts from the same start point.

Datum (start)

-y

+y

+x-x

X Y0 -1

2 -2

2 -3

5 -3

7 -1

cutter

Absolute programming


Absolute programming task


The work is clamped to a bed which moves in the X and Y directions.The cutting tool is placed in a chuck connected to a rotating spindle.The spindle moves in the Z direction.

Types of CNC machinery – milling machine

A milling machine uses a rotating cutting tool to shape a range of metals and plastics.


The work is clamped to a bed.The cutting tool is placed in the router chuck connected to a high-speed rotating spindle.The router moves in three axes on a complex arrangement of mechanisms.

Types of CNC machinery – router

A router uses a rotating cutting tool to shape a range of timbers.


A lathe is used to produce cylindrical objects.Materials are held in a chuck and rotated at different speeds.The cutting tool is held in the tool post and is inserted into the material as it rotates. It moves in the X and Y axes.The final shape of the material depends on the path taken by the cutting tool.

Types of CNC machinery – lathe


Laser cutters can cut several materials including wood, plastic, fabric, leather, paper and rubber. They will also mark glass, ceramic and stone.

Lasers can perform the following functions: cutting, deep engraving, precision scribing and decorative etching.

They are extremely fast and efficient to use.

Types of CNC machinery – laser cutter

A laser cutter uses a concentrated laser to cut or mark materials.


Images can be created using CAD software, taken from clipart or hand drawn and then scanned in.

Machines can be driven directly from the PC.

Types of CNC machinery – embroidery machine

Computerized embroidery machines are capable of embroidering onto fabrics, paper, card and board.


Types of CNC machinery – vinyl cutter

Vinyl cutters, like the one shown here, can cut and score paper, card and vinyl. They are available in various sizes from A5 to A0 and beyond. The video clip below shows how labels for sandwich packaging are designed on computer, and then cut out using a computer controlled vinyl cutter.


Resin based systems use a resin which sets hard when hit by a laser.Laminate systems build up a solid model from layers of material positioned on top of each other.Wax based systems are similar to an inkjet printer and squirt wax onto a moving platform.

Types of CNC machinery – rapid prototyping

These models have been produced using a rapid prototyping 3D printer, like the one pictured.

There are three main types of rapid prototyping.


CAD CAM working together

When CAD and CAM are used together, it is often referred to as CIM (Computer Integrated Manufacturing).CIM incorporates all aspects of the design and make process.Product designers from different countries can work on all stages of the design and manufacture of a product.

Computer integrated manufacturing


All aspects of the design and manufacture process are involved in CIM.

CIM

Design

Marketing

Research &development

Productionplanning

Quality control& assurance

Manufacturing& productionLogistics

Computer integrated manufacturing (CIM)


CAD/CAM game


Key points


Key

po

ints

Computer aided designing allows product designers to create 2D and 3D designs, and view and test products before they are manufactured.

Computer aided manufacturing uses a computer to control manufacturing machines.

CAD drawings can be output as numerical data which CNC machines can read.

When CAD and CAM are used together it is known as computer integrated manufacturing (CIM).

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