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Properties:
Very good physical properties, however moisture has a significant effect
on properties, very good heat resistance, excellent chemical resistance,
excellent wear resistance, moderate to high price, fair to easy
processing.
Applications:
Electrical connectors, gears, slides, cams and bearings.
Descriptions:
The family of nylons consists of many different types. Nylon 6/6, nylon 6,
nylon 6/10, nylon 6/12, nylon 11, nylon 12, and nylon 6-6/6 copolymer are
the most common. Of these, nylon 6/6 and nylon 6 are the common ones
readily available as sheet or rod.
Tips for machining:
Nylon has a high coefficient of thermal expansion (about three times that
of aluminium) and low heat conductivity.
Make sure that it has been exposed to normal room temperature for several
hours before it is machined into finished parts.
Saw cutting:
Nylon can be easily sawed on standard metal working equipment. Wood
working equipment may be suitable but the high cutting speeds may cause
excessive heat build-up. A blade that has been used for cutting metal is
usually not sharp enough for nylon. Use a new coarse tooth blade with good
set. Coolant may be used to control heat build up and to prevent melting
the nylon.
Holding:
Keep in mind that nylon is not as strong as metal and can be deformed by
improper chucking methods. On small accurately sized rod, use standard
spring collets. On larger parts, use a 6-jaw universal chuck instead of a
conventional 3-jaw chuck to distribute the holding force more uniformly.
For thin walled tubular shapes, machine soft jaws so that the part is
almost entirely confined.
Turning:
Satisfactory finishes can be easily obtained on nylon over a wide range of
surface speeds. Use tools that are honed sharp and have high rake and
clearance angles, to minimise cutting force and reduce heat build-up.
Chips will be continuous and stringy. They should be directed away from
the cut and prevented from winding around the work piece. Coolants are
generally not necessary for lathe work unless there is excessive heat
build-up.
Milling:
Milling cutters should be honed sharp and should have high positive
cutting angles. Care should be used in clamping the part to prevent
distortion. Cutting speeds and speeds will be determined by the finish
required and will be limited by heat build-up.
Drilling:
Use conventional twist drill or flat type drills. Polished flutes will aid
in the removal of chips. Do not use metal cutting reamers with nylon. They
do not cut freely enough. Drill small holes to size in one operation.
Rough drill large holes and finish by single point boring.
Thread cutting:
Use only sharp taps and dies on nylon parts. Don't use tools that have
been used to cut metal. H5 or even larger oversized taps may be required
because a threaded hole in nylon closes in when the tap is removed.
Threads to close tolerances can be easily single point chased.
Grinding:
The large amounts of heat generated by grinding, together with the low
heat conductance of nylon, usually dictate that liberal amounts of coolant
he used in most grinding operations. Through-feed centre less grinding of
long, flexible parts of nylon can be easily accomplished, and tolerances
as close as .01mm are possible. Cylindrical grinding on nylon is usually
not required because it is easy to get good finishes and close tolerances
on a lathe. Surface grinding of nylon is usually not necessary. If a flat
surface with close tolerances and good finish are required, the best
approach is fly cutting in a mill.
Stamping:
Thin pieces may be stamped with standard equipment. Thick sections will
require high shear angles if good edges are required. Steel rule dies may
be used for some parts.
Measuring:
Use ordinary measuring equipment. However, use a light touch because the
material is not as hard as metal. A micrometer anvil can deform a nylon
surface as much as several thousandths. Homemade, soft plug and ring
gauges are useful on thin walled parts. If extremely close tolerances are
involved, ensure any temperature changes that the part will see are taken
into account.
Typical properties of Nylon
Property
|
A.S.T.M
|
TYPE 6
|
TYPE 66
|
| Specific Gravity |
D792 |
1.12 - 1.14 |
1.14 - 1.1 |
| Water Absorption Method A |
D570 |
2.9 |
1.24 |
| Tensile strength at yield, 1000
psi |
D638 |
9.4 |
12 |
| Elongation at yield, % |
D638 |
25 |
>150 |
| Elastic Modulus in Tension,
10~5 psi |
D638 |
_ |
4.4 |
| Flexural Strength at yield,
1000 psi |
D790 |
NO YIELD |
16 |
| Elastic modulus in flexure,
10~5 psi |
D790 |
1.5 |
4.1 |
| Rockwell Hardness (Method A) |
D785 |
R104 |
88 |
| Izod impact strength, ft-lb/in.
notch 3 mm |
D256 |
2.2 |
1.2 |
| Deform. under load(2000 psi;
122f), % |
D621 |
_ |
0.8 |
| Deflection temp, F at 66 psi
fiber stress |
D648 |
340 |
450 |
| Max recommended
service Temp., C |
continuous |
120 |
140 |
| Coeff. of Linear Thermal
Expansion, F |
D696 |
4 x 10~5 |
4.5 x 10~5 |
| Underwriters' Lab Rating (Subj.
94) |
_ |
HB |
V - 2 |
| Dielectric strength, v/mil,
short time |
D149 |
_ |
555 |
| Dielectric constant at 60 Hertz |
D150 |
7.2 |
4 |
| Dielectric constant at 1
MegaHertz |
D150 |
3.7 |
3.5 |
| Dissipation factor, at 60 Hertz |
D150 |
_ |
0.02 |
| Dissipation factor, at 1
MegaHertz |
D150 |
0.12 |
0.03 |
| Volume resistivity, ohm-cm |
D257 |
10~12 |
10~15 |
| Arc resistance (SS Electrode),
sec. |
D495 |
_ |
123 |
These values are representative of those obtained under standard ASTM
conditions and should not be used to design parts which function under
different conditions.
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