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Design for Mill/Turning/Drilling
or how to save yourself or your machinist a lot of time and effort
Overview
• 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
• Axial and milled geometry
• Flat/planar geometry
• Odd (not circular) shapes
• Pockets, holes, surface geometry
Drill or MillLathe
CNC LatheWith live tooling 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
• 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
Look for departmental
resourcesTOMORROW Machine shop resources
Buy materialMake materialcorrect 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
• Machinery’s Handbook• Manufacturing textbooks (Kalpakjian)• Your local machinist• MIT shops
– MIT departmental shops– Edgerton Student Shop (on Vassar Street)– MIT Hobby Shop