| Step One | Step Two | Step Three | Step Four | Step Five | Step Six & Seven |Step Four:
 Before proceeding to steps 5-7 it may be appropriate to consider additional material characteristics including:
 |
Relative Impact Resistance/Toughness |
|
Dimensional Stability |
|
Regulatory/Agency Compliance |
Materials with higher tensile elongation, Izod impact and tensile impact strengths are generally tougher and less notch sensitive for shock loading applications (See Table 1).
| Mechanical Property Comparisons |
| |
Tensile
Strength
psi |
Compressive
Strength
psi |
Flexural
Modulus
psi |
Elongation
% |
Izod
Impact
(73°F) |
Water
Absorp.
(24hr.) |
| Nylatron® NSM Nylon |
11,000 |
14,000 |
475,000 |
20 |
0.5 |
0.25 |
| Acetron® GP Acetal |
9,500 |
15,000 |
400,000 |
30 |
1.0 |
0.2 |
| Ertalyte® PET-P |
12,400 |
15,000 |
490,000 |
20 |
0.5 |
0.07 |
| Radel® R PPSU |
11,000 |
13,400 |
345,000 |
30 |
2.5 |
0.37 |
| Ultem®1000 |
16,500 |
22,000 |
500,000 |
80 |
0.5 |
0.25 |
| Ultem® 2300 |
17,000 |
32,000 |
900,000 |
3 |
1.0 |
0.18 |
| Fluorosint®500 |
1,100 |
4,000 |
500,000 |
10 |
0.9 |
0.10 |
| Techtron® PPS |
13,500 |
21,500 |
575,000 |
15 |
0.6 |
0.01 |
| 40% GF Ryton* PPS |
13,000 |
24,000 |
1,000,000 |
2 |
1.0 |
0.02 |
| Ketron®(Extd) PEEK |
16,000 |
20,000 |
600,000 |
20 |
1.0 |
0.10 |
| 30% GF Ketron (Extd) |
18,000 |
26,000 |
1,000,000 |
3 |
1.4 |
0.10 |
| Torlon* 4203 PAI |
18,000 |
30,000 |
600,000 |
5 |
2.0 |
0.33 |
| Torlon* 4301 PAI |
12,000 |
24,000 |
1,000,000 |
3 |
0.8 |
0.28 |
| Torlon* 5530 PAI |
14,000 |
27,000 |
900,000 |
3 |
0.7 |
0.30 |
| Duratron® XP |
13,500 |
19,000 |
530,000 |
3 |
0.6 |
0.62 |
| Duratron® 150 XP |
9,600 |
17,000 |
610,000 |
1.5 |
0.5 |
0.65 |
| Celazole* PBI |
23,000 |
50,000 |
950,000 |
3 |
0.5 |
0.40 |
TABLE 1
Engineering plastics can expand and contract with temperature changes 10 to 15 times more than many metals including steel. The coefficient of linear thermal expansion (CLTE) is used to estimate the expansion rate for engineering plastic materials. CLTE is reported both as a function of temperature and as an average value. Figure 6 shows how many different engineering plastics react to increased temperature.
Modulus of elasticity and water absorption also contribute to the dimensional stability of a material. Be sure to consider the effects of humidity and steam.
Agencies such as the Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA), Underwriters Laboratory (UL), 3A-Diary Association and American Bureau of Shipping (ABS) commonly approve or set specific guidelines for material usage within their industrial segments. |
