6.7 SELECTING A CAD SYSTEM
• 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.
6.7.1 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.
6.7.2 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
Computer
Type
Personal Computer
Unix Workstation
Proprietary
Network ready
Backup capabilities
Disk space
CPU performance
Uninterruptable power supply (UPS)
Monitor
Screen resolution (768*1024 or 1024*1280 are suggested)
screen size (14” is absolute minimum)
dual monitors
I/O Devices
Drawing output
plotter
laser printer (color?)
ink jet printer
Input Devices
mouse
tablet
track ball/roller ball
• System Software
Operating System
Unix
MS-Dos/Windows 3.1,95,NT/etc.
Apple
Other ? (VMS, ???)
• CAD Software
Geometrical model
2D/3D
Exact or faceted with planar polygons
Mass properties
Editing
Parametric
Object Organization
Named Objects
Layers
Part libraries
Drawing Output
Drafting module
Analysis Module
Finite Elements
Plastic Flow
Kinematics/Collisions
Dynamics
Importing/Exporting
Surface formats: IGES, DXF, CDL
Solid Formats: PDES/STEP, SAT
Files for systems such as NASTRAN
Can be linked to a user written program
Rendering
Hidden line
Shaded Image
Ray Tracing
Real Time Rotations