Page 114 - Engineering Plastics Handbook

88 Engineering Plastics

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company’s Ertacetal colored extruded polyacetal stock shapes advance
precolored polyacetal applications. Advantages include color consistency
and accuracy, brand recognition, reduced lead time for delivery to cus-
tomers, and simplified color coding according to the company [15]. Color
coding has several benefits; it allows multiple-component assemblies to
be accurately changed out or replaced, which can avoid the possibility
of mistakes in assembly; saves time; facilitates inspection of assem-
blies; and improves safety [15]. The precolored stock shapes meet FDA
regulation 21 CFR Section 177.2470(e)(1),(2). They are supplied in the
three primary colors (red, yellow, and blue) as well as in orange, green,
brown, and gray, beyond black and white [15]. Polyacetals are supplied
in all standard colors, custom colors, and natural, which is a translu-
cent white. When processors use color concentrates from colorant sup-
pliers other than the polyacetal supplier, they should check compatibility
with their resin supplier. The stock shapes have all the attributes of
polyacetals, which include low coefficient of friction, abrasion resist-
ance, hardness, stiffness, and solvent resistance [15].

Design
Software for product and process design is available to any company,
with prices aimed at processors, independent design firms, and the
entire plastics industry; and polyacetal resin companies are contribut-
ing to this movement. Ticona’s P-GEAR (Plastic Gear Evaluation And
Research) tester software optimizes gear designs based on service tem-
peratures, moisture pickup, and other ambient environmental condi-
tions. The software is used specifically to evaluate plastics for gears in
various service environments, according to the company [10]. P-GEAR
predicts gear performance more accurately, and this results in faster
design time according to Ticona [10].
Polyacetal design can use design software referred to in Chap. 2 of this
handbook. These programs are CAD, CAE, FEA, and FEM (finite ele-
ment modeling), MES (manufacturing execution systems), “Superflow”
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CAD-like program, ABAQUS Standard , DesignXplorer VT, ANSYS
Paramesh™, I-DEAS, Unigraphic Solutions, CAPTIA, Pro/Engineer,
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and the NISA family of FEA software. Moldflow Plastics Insight MPI
5.0 software includes three-dimensional simulation for part and mold
design and analysis for thin-wall designs and warpage.
Design for polyacetal resins follows conventional methods, generally
based on short-term properties with a safety factor. There are certain
design considerations that are more important with polyacetal resins
than with some other engineering thermoplastics. These considerations
are largely due to the high degree of crystallinity of acetal polymeric
macromolecules. Polyacetals are notch-sensitive as a result of their high
degree of crystallinity (DC). Radii and fillets at wall corners, ribs, and