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