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Machining Materials Guide

Raw Metal MaterialsYou are invited to share our handy reference documents on metal and plastic materials for CNC turning, CNC machining and automatic screw machine manufacturing. For general machining questions, consult our companion Knowledge Base.

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Type General Characteristics Alloy Common Applications Tolerances for a 1/2" Dia. Bar Material Cost Factor Machining Cost Factor
Brass
Low cost, low strength, heavy, free machining
CDA 360
Electronic hardware and contacts, fittings, numerous commercial products
+/-.0015 2.5
(High scrap return provides cost savings )
.6
Copper Alloys
Excellent electrical conductivity
TeCu, CA 145
Electrical contacts
+/-.0015 5.4 .7
Higher strength and excellent electrical conductivity
BeCu alloy 25
Electrical contacts
+/-.002 (Can be ordered to +/-.0002 ) 30.0 .75
Aluminum
Designed for machining
2011
Electronic hardware, endless commercial products
Cold finish
+/-.0015
1.6 .6
Improved strength
2024
Electronic hardware, aircraft components
+/-.0015 2.2 .7
Good formability, weldability, and corrosion resistance
6061
Electronic hardware
Cold finish
+/-.0015

Extruded
+/-.009
0.8 .75
Higher strength
7075
Aircraft components
+/-.0015 2.3  
Steel
Plain low carbon steel, poor machinability but good formability and weldability. Case harden only
1018
Rivets and parts requiring strong welds
Cold drawn
+.000/.002
0.75 3.0
Designed for good machinability
Case harden only
1215
Parts needing better formability or weldability than 12L14
Cold drawn
+.000/.002
0.95 1.5
Designed for excellent machinability
Case hardening only
12L14
Endless commercial products; probably more pounds used in turned products than any other bar stock
Cold drawn
+.000/.002
1 1
Excellent machinability w/o lead (Biadded)
Case hardening only
1215 Bi
Same as 12L14, non-leaded replacement for 12L14
Cold drawn
+.000/.002
1.1 1
Higher carbon, higher strength, direct hardening
1137
Higher stress applications, gears, shafts, studs, etc.
Cold drawn
+.000/-.003
1.25 2.5
Alloy Steel
Direct hardening
4140 or 4142
Higher stress applications needing the strength of an alloy
Cold drawn
+.000/-.003
1.25 3.0
Designed for better machining w/lead additive; direct hardening
41L40
Higher stress applications needing the strength of an alloy
Cold drawn
+.000/-.003
1.4 2.7
.55% Ni, .50% Cr, .20% Mo, heat treatable and case hardening
8620
High stress applications needing the strength of an alloy.
Cold drawn
+.000/.002
1.8 2.7
Very high 1% carbon, .25% Ni,1.4% Cr, .08% Mo
52100
Bearing applications
Cold finished

Spheroidize annealed
+/- .006
2.0 5.1
Stainless Steel
Designed for machining, non-magnetic
303
Electronic hardware, automotive, aerospace, medical instruments, and many applications requiring corrosion resistance
Cold finished
+/- .002
4.5 2.7
Better weldability and formability, slightly more corrosion resistant
304
Applications needing formability or weldability
Cold finished
+/-.002
3.7 5.0
Better corrosion resistance
316
Medical implants and surgical instruments, aerospace
Cold finished
+/-.002
4.3 5.6
Free machining; less corosion resistant than 300 series; can be heat treated
416
Applications that need less corrosion resistance, more hardness, or lower cost
Cold finished- annealed
+/-.002
3.8 2.6
High carbon, can harden to RC 60
440°C
Applications requiring stainless steel with highest hardness
  5.9 5.0
Excellent corrosion resistance and heat treatable
17-4 PH
Medical, aerospace, applications needing corrosion resistance and hardness
+/-.002 4.4 5.0
Titanium
High strength, light weight, good bio-compatibility
Ti-6Al-4V
Ti-6Al-4VEli
Aircraft
Medical implants
Ground & polished
+/-.002
21.3 6
Plastics
Low cost plastic
PVC
Gray color
Insulators
Ground
+/-.003
0.9 .8
Good machining
Nylon, extruded
"Natural" or "black" color
Insulator, bearing, short runs of products that will be converted to injection molding
Ground
+.002/-.000
1.2 .75
Similar to nylon, better machinability
Delrin (acetal)
"Natural" or "black" color
Insulator, bearing
Ground
+.002/-.000
1.5 .7
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