• While this apparently seems easy, it is a very complex decision


• There are a number of factors which affect how the system is received,

- Current computer use by employees

- Perceived role of computer by employees

- Cost of computer system and software

- Available training for staff

- Maintenance requirements for computer

- Required number of users

- Design complexity

- Availability of CAM Facilities

- Successful implementation in similar facilities

- Management philosophy

- Redundancy of design


• Major mistakes are,

- Assuming more expensive is better

- Assuming it will be well received because it will make work easier

- Assuming that high tech means easier to use

- Failing to get the potential users interested and involved in the decision to buy/selection/implementation

- Neglecting the break in period

- Not thoroughly examining the existing manual/computerized system which ALREADY WORKS

- Forgetting that accountants want numbers plus a rate of return.



1.7.1 An Example Plan for Selecting a CAD system

1. Examine the existing situation. Involve staff to find out what they perceive as problems, and possible solutions. This establishes allies required for whatever decision you choose. (Expect some who will resist, but they can become allies if handled properly).

2. Identify key people with an interest in the system, and get them involved with selection.

3. Devise a definite list of requirements, to support existing functions, and problems which exist, and possible solutions.

4. Get the accountant on your side by consulting them about costs, budgets, etc.

5. Gather information about existing systems by visiting trade shows, reading magazines, talking to others using systems.

6. Talk to Salesmen and companies of interest.

7. Get the salesmen to present to the CAD selection group

8. Narrow the possible vendors to about three.

9. Talk to their other customers about their system problems, and advantages, support, etc.

10. Pick a package using the CAD selection group and management.

11. Prepare budget, using help from accounting, and include a large portion of the budget for training, and maintenance.

12. Schedule training and implementation dates. Ensure that implementation is gradual, and does not overlap with the busiest times

13. Propose the budget and schedule to management, and request approval.

14. Give a general announcement to all concerned, and those partially concerned. A General meeting will help. The more information the better.

15. Follow schedule, and evaluate after each stage of implementation.


1.7.2 A Checklist of CAD/CAM System Features


• A list below is suggested for hardware, but in light of recent advances in consumer computing, most of the previous concerns, such as special plotter papers, are no longer problems.


• Hardware



Personal Computer

Unix Workstation


Network ready

Backup capabilities

Disk space

CPU performance

Uninterruptable power supply (UPS)


Screen resolution (768*1024 or 1024*1280 are suggested)

screen size (14” is absolute minimum)

dual monitors

I/O Devices

Drawing output


laser printer (color?)

ink jet printer

Input Devices



track ball/roller ball


• System Software

Operating System


MS-Dos/Windows 3.1,95,NT/etc.


Other ? (VMS, ???)


• CAD Software

Geometrical model


Exact or faceted with planar polygons

Mass properties



Object Organization

Named Objects


Part libraries

Drawing Output

Drafting module

Analysis Module

Finite Elements

Plastic Flow




Surface formats: IGES, DXF, CDL

Solid Formats: PDES/STEP, SAT

Files for systems such as NASTRAN

Can be linked to a user written program


Hidden line

Shaded Image

Ray Tracing

Real Time Rotations