Injection Mold Design Checklist 

Mold Design Drawing

An injection mold design checklist enables a mold designer to ask the right questions so that any new mold build will go according to plan and be producing parts in the shortest possible lead-time. 

Right-click here to download a checklist in PDF format

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1.        Part Information


  •          Part shape
  •          Part size
  •          Part wall thickness
  •          Part plastic material
  •          Surface finish requirement: polishing grade or texture
  •          In mold labeling or decorating requirement

A part drawing will have all of this information.

The part drawing is then used to pre-determine the following basic mold design:


2.       Basic Mold Design


  •          Gate location
  •          Ejection method
  •          Parting lines (also called split line)
  •          Venting positions
  •          Estimated cycle time
  •          Basic cooling design
  •          Interlocking method between fixed and moving sides of mould
  •          Heat treating requirements such as nitriding on moving mould components

With this information, the ratio of the maximum flow length to wall thickness is be calculated. The maximum flow length is the distance from the gate to the furthest parting line.

This ratio is used to estimate the cavity pressure inside the mould tool during first stage filling. The higher it is the more robust the mould design must be.

These can be determined by experience or by computer simulation software.

3.       Annual Production Quantity

The annual production quantity requirement will determine the type of material that the injection mould will made from and the accuracy of the mold build. It will also determine the number of cavities the mould will need.


  • Annual production quantity
  • Number of mould cavities
  •  Mould material for core and cavity inserts
  •  Heat treatment requirement for core and cavity inserts
  •  Mould material  for mould bolster
  •  Heat treatment requirement for mold bolster

4.        Molding Machine Specifications

A new injection mold is often required to fit into several different machines in any one molding company for production flexibility. The following platen layout information is required for each machine.  This information is supplied by the injection molder.


  • Location ring diameter
  • Space between tie bars (both horizontally and vertically)
  • Maximum opening stroke
  • Minimum opening stroke
  • Minimum die height
  • Maximum die height
  • Clamp hole size and position
  • Maximum machine ejector stroke
  • Machine ejector bar  positions and diameter
  • Platen length and width
  • Number of available cooling circuits on machine
  • Number of available air lines on machine
  • Robot take out or free fall requirement
  • Mould clamping technique - direct bolting or use of clamps

5.        Additional items to include in injection mold design checklist:

  • Hot runner or cold runner
  • Pitching distance between cavities
  • Pre alignment between fixed and moving halves - usually guide pins and    bushes
  • Plate thicknesses – especially back plates for mould rigidity
  • Sufficient support pillars for mould rigidity
  • Mould design for easy mould assembly
  • Mould design for easy maintenance in the moulding machine:  for example cleaning blocked gates or removing cold runners by hand
  • Mould design for easy machine installation and removal
  • Corrosion protection coatings such as electroless nickel plating on P20 bolster plates
Right-click here to download a checklist in PDF format

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