Catch Errors Before They Fly: Your Design Review Checklist Takeoff!

Kevin Jogin -

Ever spend hours crafting a design, only to find a tiny detail missing later? We've all been there. That's why a pre-flight check, or design review checklist, is your best friend. Think of it as a mission control for your drawings, ensuring a smooth launch into manufacturing.

This checklist is your co-pilot, guiding you through key areas to ensure your design meets all specifications. Let's take a flight through the essential checks for both parts and assemblies:

Drawing Checklist

Part Drawing

  • Specify cavity no. location (if applicable)
  • Specify date stamp location (if applicable)
  • Check draft angles for moulding and casting components
  • Complete Drawing Template
  • Correct Material
  • Correct Title [include product descriptions, etc…]
  • Date drawn
  • Correct Sheet Scale displayed
  • Latest updated details as “drawn by” and “designed by”
  • Make sure all drawings are in 3rd angle projection
  • Check Revision Block
  • Tapped holes shown including tapping detail and tapping depth
  • Critical dimensions shown as specified by designer/engineer
  • Company logo on at least one visible part in the assembly
  • Cavity Numbers and Logo needs to state if detail is to be raised or sunken.
  • Correct Material to state its "grade" or "alloy”.
  • Revision Block to state past and present info (e.g. what dimension was and what is now).

Assembly Drawing

  • Check BOM and ensure numbers matches with BALLON Annotations
  • Specify Grease grade, quantity of grease and surface required
  • Specify Loctite grade, quantity and location
  • Title includes product no. and applicable project numbers
  • In BOM include kitting information if it is supplied in pack.
  • Packaging details specified
  • If a "Newton Metre" or "Torque" requirement is needed, this should be shown on the assembly drawing.

Drafting Checklist

Things to Consider

  • All units are assumed to be mm.
  • Dimension lines should never cross other dimension lines.
  • Dimension lines should avoid crossing extension lines.
    • Extension lines may cross each other.
    • Longer dimensions should be placed further to the outside. (to avoid crossing).
  • Try to avoid long extension lines.
  • Dimensions should not be duplicated, or the same information given in two different ways, and no dimensions should be given except those needed to produce or inspect the part.
  • Dimensions should be placed in the views where the features dimensioned are shown in true shape. This may require auxiliary views. (i.e. Dimension only to true lengths).
  • Notes should always be lettered horizontally on the drawing.
  • Make sure drawings are checked.

Tips

  • Create dimensions from datum point, like bearing, dowel holes or center line instead of curved surfaces.
  • Spreading out views on sheet is cleaner than squeezing in.o Specify Geometric Tolerances on sheet metal and machined parts as required.
  • A dimension should be attached to only one view: extension lines should not connect two views.
  • Notes should always be lettered horizontally on the drawing.o Avoid dimensioning to hidden lines.
  • Avoid a complete chain of detail dimensions; better to omit one. 
    • Otherwise, add REF (reference) of brackets to one detail dimension, or to the overall dimension. This allows tolerances to determine the omitted dimension.
  • Dimension lines should be spaced uniformly throughout the drawing. Approx. 10mm from the object, and 6mm apart.
  • Dimension figures should be approximately centred between the arrowheads if possible.o No dimensions unless absolutely necessary.
  • No hidden detail unless absolutely necessary.
  • Keep number of views (projections) to a minimum. 
    • Three views are normal, the maximum (6 views) are extremely rare.
  • Add centre lines and cross-hairs to holes.

By following this checklist and these pro tips, your designs will be ready to soar! Remember, a little pre-flight prep can save you a lot of time and frustration down the runway. So, fire up your design software and prepare for a successful launch!