Designing plastic parts is a complex process, however, a few general guidelines can be given. By following a structured approach when designing plastic parts, problem areas can be identified at an early stage. We generally recommend spending the necessary time to define requirements, before any design be made.
 
We recommend that you run through the following checklist before you start designing the part:
 

Based on the property profile and the functional analysis, it is usually possible to asses the commercial and technical feasibility of making a component in thermoplastic. At this point, a material selection is made, and you can start making the final component design.
 
After the part design has been finalized, usually a prototype is made via a stereo lithography or machining. Such prototypes can be used to check the looks of the part, to see whether or not it physically fits in place or to see if the motion transfer is carried out correctly. They should never be used to check mechanical performance.


1. Property Profile
.    1.1 Target costs
          1.1.1 How many parts need to be made
          1.1.2 Estimated part volume
          1.1.3 Target cost for component
    1.2 Environment
          1.2.1 Operating temperature range
          1.2.2 Expected service life @ operating temperature
          1.2.3 Peak temperatures
          1.2.4 Are parts loaded when peak temperatures occur
          1.2.5 List of chemicals in contact with part
          1.2.6 Is UV or weathering an issue
          1.2.7 Gamma, beta or other radiation
          1.2.8 Are there any abrasive media
    1.3 Mechanical loads
          1.3.1 What are the abuse loads
          1.3.2´What are the continuous loads
          1.3.3 How high is the cyclic load, and how many cycles
          1.3.4 What maximum deformation is allowed
          1.3.5 What are the limits on the natural frequency of the part
          1.3.6 Any shock loads at minus temperatures
    1.4 Wear and Friction
          1.4.1 In case of wear and friction, what is sliding velocity and the surface pressure
          1.4.2 How much wear is allowed
          1.4.3 Is wear debris a problem
          1.4.4 What is the external lubricating medium
          1.4.5 What is the maximum friction that is allowed
    1.5 Electrical Properties
          1.5.1 Volume resistivity
          1.5.2 Di electric strength
          1.5.3 Di electric loss factor
          1.5.4 CTI value
          1.5.5 Arc resistance
          1.5.6 Ignition behaviour or flammability
          1.5.7 Smoke density in case of fire
          1.5.8 Smoke toxicity in case of fire
          1.5.9 Is build up of static electricity an issue
          1.5.10 Is EMI shielding an issue
    1.6 Pollution Control & waste disposal
          1.6.1 Is recycling an issue
          1.6.2 Are there unwanted chemicals (lead, PBB, PDBE, Chrom VI etc.)
    1.7 Aesthetics
          1.7.1 Is the part visible
          1.7.2´What colours are needed
          1.7.3 Is the part matched with other coloured parts
          1.7.4 Surface requirements (glossy, dull etc.)
          1.7.5 Scratch resistance
    1.8 Safety and standards
          1.8.1 Is this a safety critical part
          1.8.2 Are there any food standards involved (KTW, FDA, WRc, NSF etc.)
          1.8.3 Are there any electrical standards involved (UL, EDF, Kema, TÃœV etc.)
          1.8.4 Any other standards

2. Functional analysis
    2.1 Design space
          2.1.1 Is there room to add ribs
          2.1.2 Are there any surfaces where ribs can not be added for f.i. for aesthetic reasons
    2.2 Kinematics
          2.2.1 What motion needs to be transferred
          2.2.2 What forced need to be transferred
    2.3 Ergonomics
          2.3.1 Is a 'soft touch' needed
          2.3.2 Does the motion transfer need a certain 'feel'
          2.3.3 Is noise generation a problem
          2.3.4 Are sharp edges an issue
    2.4 Environmental issues
          2.4.1 Are gaskets needed to keep out the environment (dust, oil etc.)
          2.4.2 Does the part need to keep out electro magnetic radiation
    2.5 Tolerances
          2.5.1 Is thermal expansion an issue
          2.5.2 Is expansion due to moisture uptake an issue
          2.5.3 Are there any areas with specific tolerances (f.i. positioning pins, edges etc.)
          2.5.4 Flatness required
     2.6 Heat conduction
          2.6.1 Does the part act as a heat insulator
          2.6.2 Does the part need to act as a heat sink

3. Conclusion
Based on the property profile and the functional analysis, it is usually possible to asses the commercial and technical feasibility of making a component in thermoplastic. At this point, a material selection is made, and you can start making the final component design.
 
After the part design has been finalized, usually a prototype is made via a stereo lithography or machining. Such prototypes can be used to check the looks of the part, to see whether or not it physically fits in place or to see if the motion transfer is carried out correctly. They should never be used to check mechanical performance.