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DuPont Engineering Polymers
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Checklist
General
?Performance Requirements (Structural, Aesthetic,etc.)
?Combining Multiple Parts or Functions ?Structural Load (Static, Dynamic, Cycling, Impact,etc.)
?Environment (Temperature, Time, Chemical,etc.)?Tolerance Requirements
?Life of Product
?Quantity of Product vs. Fabrication Process ?Secondary Operation
?Packaging and Shipping
Environment
?Temperature
?Time
?Load
?Other Environments (Chemical, Water,
Humidity,etc.)
Engineering Design Facts
?Type of Load
?Frequency of Load
?Stress Rate (Compression, Tensile, Flexural)?Strain Amplitude
?Load Deformation (Tensile, Compression, Shear,etc.)
?Apparent Modulus (Includes Strain Due to Creep)?Direction of Load
?Correlating Test Data With End Use
?Safety Factor
Tests (ATIM, SAE, UL, Etc.)
?Tension
?Compression
?Creep
?Dynamic/Fatigue/Torsion
?Impact
?Poisson’s Ratio
?Electrical
?Continuous Service Temp./U.L. Temp. Index Material and Process
?Directional Flow
?Directional Layout of Reinforcements ?Regrinding
?Pre-drying
?Prototyping (Machining, Molding) Appearance
?Style
?Shape
?Color
?Surface Finish/Weld Lines/Flow Lines/ Parting Line/Gate Location
?Decoration
Economic Factors
?Cost of Present Part
?Cost Estimate of Part in DuPont Engineering Plastics
?Faster Assembly and Elimination of Finishing Operation
?Redesign Part to Simplify Product
Designing for Uniform Walls
WRONG RIGHT WRONG RIGHT
WRONG
RIGHT
WRONG
RIGHT
Designing for Ribbed Walls
Ribs
Adequate ribbing can counteract bending.However, ribs should not be used unless necessary (e.g., not for small modulus high precision gears.)
Stressed parts in a transparent material show,under polarized light, the stress concentration effect of sharp corners.
Here are two
alternative solutions;their choice will depend on the torque to be transmitted.
Redesign has reduced high stress concentration in snap-fit area.
Circular inserts with fine rounded knurling are preferred. They should not have sharp edges.Installing inserts after molding may also be a solution.
WRONG
RIGHT WRONG RIGHT
Designing without Stress Concentration
Metal insert
5N
Wall
Gate Location
WRONG
RIGHT
WRONG
RIGHT
Designing for Assembly
WRONG
RIGHT
WRONG
RIGHT
Designing with Clearance on Threads
B)Core out the part.
“L” should be kept larger (at
least – D), and a flat head screw would eliminate tan-gential stresses.A change in gate location could also help.
~Redesigned exterior snap-fit cap and addition of “O” ring
eliminate leakage.
No undercut in the mold. If the ratio L:L 1 increases,some ribs can be added.
Engineering plastics usually resist compression stresses better than tensile stresses.Threads should be provided around the exterior
diameter of the plastic part. An “O” ring ensures tightness.
The “O” ring is compressed
radially. Additional ways to control creep could be:
1)Flanges may be stiffened by ribs, or 2)Metal rings all around,placed under the bolts.
Self-tapping screw
Relief allows snap-fit without breaking
1
?32″
1
?32″
L 1
L
PRESSURE
Printed in U.S.A.
[Replaces: H-30618-1]
Reorder No.: H-81079(99.3)
DuPont Engineering Polymers
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For more information on Engineering Polymers:For Automotive Inquiries:
(800) 533-1313
(800) 441-0575Start with DuPont
U.S.A.
East
DuPont Engineering Polymers Chestnut Run Plaza 713P.O. Box 80713
Wilmington, DE 19880-0713(302) 999-4592
Automotive
DuPont Engineering Polymers Automotive Products 950 Stephenson Highway Troy, MI 48007-7013(313) 583-8000
Asia Pacific
DuPont Asia Pacific Ltd.P.O. Box TST 98851Tsim Sha Tsui
Kowloon, Hong Kong 852-3-734-5345
Canada
DuPont Canada, Inc.
DuPont Engineering Polymers P.O. Box 2200
Streetsville, Mississauga Ontario, Canada L5M 2H3(905) 821-5953
Europe
DuPont de Nemours Int’l S.A.2, chemin du Pavillon P.O. Box 50
CH-1218 Le Grand-Saconnex Geneva, Switzerland Tel.: ##41 22 7175111Telefax: ##41 22 7175200
Japan
DuPont Kabushiki Kaisha Arco Tower
8-1, Shimomeguro 1-chome Meguro-ku, Tokyo 153Japan
(011) 81-3-5434-6100
Mexico
DuPont S.A. de C.V.Homero 206
Col. Chapultepec Morales 11570 Mexico D.F.011-525-722-1456
South America
DuPont America do Sul Al. Itapecuru, 506
Alphaville—CEP: 06454-080Barueri—S?o Paulo, Brasil Tel.: (055-11) 7266.8531/8647Fax: (055-11) 7266.8513
Telex: (055-11) 71414 PONT BR DuPont Argentina S.A.Avda.Mitre y Calle 5
(1884) Berazategui-Bs.As.Tel.: (541) 319-4484/85/86Fax: (541) 319-4417
The data listed here fall within the normal range of properties, but they should not be used to establish specification limits nor used alone as the basis of design. The DuPont Company assumes no obligations or liability for any advice furnished or for any results obtained with respect to this information.All such advice is given and accepted at the buyer’s risk. The disclosure of information herein is not a license to operate under, or a recommendation to infringe, any patent of DuPont or others.DuPont warrants that the use or sale of any material that is described herein and is offered for sale by DuPont does not infringe any patent covering the material itself, but does not warrant against infringement by reason of the use thereof in combination with other materials or in the operation of any process.
CAUTION: Do not use in medical applications involving permanent implantation in the human body. For other medical applications, see “DuPont Medical Caution Statement,” H-50102.
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