Popular manufacturing process for plastic products and here we explain how product design considerations must be made.

Advantages:

• Allows excellent surface finish, repeatability and speed.
• Mould decorations can be integrated into the actual moulding process, eliminating the need for a separate printing process
• Colouring is possible
• Inserts and snap-fits can be moulded to aid assembly

Disadvantages:

• Tooling costs are very high, depending on the number of cavities and complexity of the design
• Large parts take longer to solidify and thus can increase mould cycle times

Design Considerations:

• High volume production runs only
• Mould cycle times depend on the size of the part
• Warping and shrinkage can occur after the part is ejected from the mould cavity, ribbing can help reduce these effects
• Stress can occur at sharp corners and draft angles
• Draft angles should be at least 0.5^o
• The melted plastic must inject into the thickest section and finish at the thinnest
• Wall thickness should be uniform (ideal) or within 10%
• Uneven wall sections cause the part to warp
• Ribs should not exceed 5 times the height of the wall thickness, so use many shallow ribs instead

Injection moulding machine. Source: http://www.crabdev.co.uk/comp%20manufacturing.htm

 Source: Manufacturing processes for design professionals; Rob Thompson [2007]