Design for Mill/Turning/Drilling
or how to save yourself or your
machinist a lot of time and effort
Overview
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Drill
Mill
Lathe
Surface Finish
Tips & Tricks
Process Planning
Drill
• Make a hold in something
• Drillpress OR hand-held drill
• Usually need clamps to hold part in place
• Not highly accurate but often good enough
A BIG distinction
• MANUAL machines vs. CNC machines
A BIG distinction
• MANUAL machines vs. CNC machines
Lathes
• Manual
• CNC
How do choose the correct
machine?
• Round geometry
• Axial alignment
• Flat/planar geometry
Drill or Mill
Lathe
• Axial and milled
geometry
CNC Lathe
With live tooling
• Odd (not circular)
shapes
• Pockets, holes,
surface geometry
CNC Mill
Surface Finish
Surface Finish
From 2.008 class notes, SP03
Surface Finish
From 2.008 class notes, SP03
Tips & Tricks
For high precision, watch out for
• Overhanging geometry (deflection)
• Thin sections & tubes (vibration)
• Drilling incline planes
For ease of manufacturing
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Standard shape & size holes
Proper tolerances (discussed tomorrow)
Reference everything off one point
Avoid deep pockets & holes
NO inside right edges!
WATCH OUT for tool access!
– a short endmill used inside a deep narrow pocket might
CRASH!)
– Don’t cut into the vise or clamps!
Mill: Part in Vise
To make it faster (& less annoying)
• Minimize number of fixtures
– Every time you take the part out of the vise
you have to re-reference it – wastes time!
• Include features for easy fixturing &
referencing
Image from: http://www.wmccm.co.uk/WMCCM/DesktopDefault.aspx?tabindex=0&tabid=2049
Process Planning
Process Planning
From 2.008 Process Planning lecture, SP03
Process Planning
TOMORROW
Look for
departmental
resources
Machine shop resources
Buy material
Make material
correct size
From 2.008 Process Planning lecture, SP03
Detailed Process Planning for
Manufacturing
• Choose material and order it
• Make material correct starting size/shape
– Watch for tolerances when ordering – parts
aren’t always exact size or perfectly square
• Plan what cuts/features to make first,
second, third based on complexity, yield of
process, etc. - SKETCH
– If something is likely to not work, don’t do that
step last!
Detailed Process Planning for
Manufacturing, Continued…
• Determine when to check for
quality/accuracy in the process
– Easier to measure twice and cut once than
the other way around!
• For any hand-machining operations, mark
the parts in an OBVIOUS way!
– ei, an X on the part that you don’t want,
scribble where you want material removed
Optimizing your Process Plan
• Fewer steps = better
• Make a flowchart
How Its Made Examples
Resources
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Machinery’s Handbook
Manufacturing textbooks (Kalpakjian)
Your local machinist
MIT shops
– MIT departmental shops
– Edgerton Student Shop (on Vassar Street)
– MIT Hobby Shop