CAD/CAM CONSIDERATIONS ABOUT FMS

SUDHIR REDDY S.V.R

(09311D0412)

Topics to be Covered:

CAD Considerations About FMS

CAM Considerations About FMS

CAD Considerations About FMS:

CAD is the point where design intent takes on electronic form, can facilities the manufacturing operation

In operation for many years are forced to rethink their approach to design and drafting to enable the company to enjoy the advantages of flexible Manufacturing.

The following tools which can help with the implementation of this direction.

(a). Library of Parts.

(b). Group Technology.

(c). Special CAD requirements for FMS data preparation.

(a). Library of Parts:

A library of parts is a database which aids the product designer who is faced with a very large selection of potential components when creating a design.

Its major application is a catalog of parts to be included in an assembly .

In many cases , it is necessary to custom –develop a library of parts system optimized to the product, business and company to be using it.

The library of parts requires the following capabilities are shown in below figure,

Attributes are related to geometry logically

(i).It must be searchable so that designers can let the computer do the work of selecting the right component for a specific application from a large catalog( perhaps tens of thousands).

(ii).It must provide ancillary information on parts that meet search criteria so that the designers can decide if parts suggested by the computer will meet the need.

When a fully Functional library of parts is available , it is found that more efficient use of available parts can be made.

Ancillary information about each component is generally stored in the library of parts along with the design so that it can be included in an assembly.

When component attributes are stored in the assembly ,they may be extracted by software to produce files required for assembly , machining operations , bills of material and other uses.

Designing , populating and maintaining a library of parts data base can be very labor intensive and time consuming.

(b). Group Technology:

GT deals with the identification of similar parts and group them for the purpose of manufacturing and design generally.

It is possible only if it is convenient to retrieve the needed information and therefore , duplication would invariably takes place.

So, an efficient design retrieval system is essential which would require some form of part identification and coding.

For part identification and coding , the attributes of the component should be used namely of design and manufacturing , i.e., geometric shape , size and the process of manufacture.

GT approach is different from the existing one and the working of the entire organization will be effected due to this approach .

This technology streamlines procedure and is amenable to computerization and in the longer process.

It forms the basis of integrated manufacture and thus would prove an important step in inducting automation in small and medium batch manufacture.

(c). Special CAD requirements for FMS data preparation:

When product and process are designed together , a product model can be developed which contains all the information necessary for effective interfacing to the FMS.

The usefulness of a model created in CAD is directly proportional to its intelligence content .

They are three major facts of intelligence are

(i) Geometry.

(ii) Attributes.

(iii) Design Cycle Data Preparation.

(i) Geometry:

•The geometry of a part is the computer’s model of its physical shape.

•The minimum requirement in a CAD model destined to be used for FMS is a 3D wire frame.

•When part designs may contain ambiguities in a wire frame model , it is necessary to add surface representation to the part.

•Solid modeling offers the ultimate in part intelligence content , but adds little that is of use to the CAM engineer.

(ii) Attributes:• Attributes are information items about a part which are stored along with the CAD design , they contain data that may or may not be displayed when the part is viewed or plotted.

•These attributes can be created manually when the CAD designer draws the part or created by engineering-assistance software which queries the designer for information,

- Once a design has been created, software can be created which extracts attribute information as required for use in various FMS subsystems.

•Design of the attribute database for a product is based on the product’s characteristics and the needs of downstream applications.

•For an assembly , a database often will have a hierarchical structure.

Steps in going from CAD to CAM to FMS-ready system

CAM Considerations About FMS:

A new part to the FMS is a multistep procedure which includes considerations of requirements for machining, raw material, material handling and inspection.

Each additional item then becomes part that can be produced in the FMS.

Manufacturing data therefore require the same level of control as is provided to tracking engineering changes and design levels in the CAD arena.

A typical FMS cell will have a fairly limited range of products.

It can build, so it is possible for NC programmers to develop a high skill level within this narrow range.

Robot Programming can be improved by using a simulator package for off-line programming.

A number of systems are available which provide the ability to develop robot programs off-line and visualize the robot moving through steps.

A difficulty often encountered is that there are few standards in robot languages.