מבוא
ISO (הארגון הבינלאומי לתקינה) היא ברית גלובלית של גופי תקינה לאומיים (גופים חברי ISO). פיתוח תקנים בינלאומיים מתבצע בדרך כלל באמצעות ועדות טכניות של ISO. כל מוסד חבר המעוניין בנושא שעליו הוקמה ועדה טכנית זכאי להיות מיוצג באותה ועדה. ארגונים ממשלתיים ולא-ממשלתיים בינלאומיים המקיימים קשר עם ISO מעורבים גם הם בעבודה זו. ISO עובדת בשיתוף פעולה הדוק עם הנציבות האלקטרוטכנית הבינלאומית (חברת החשמל) בכל הקשור לתקינה חשמלית.
The draft international standard adopted by the Technical Committee will be circulated to the member bodies for voting. פרסום כתקן בינלאומי דורש אישור של לפחות 75% of member institutions.
The international standard ISO 8295 was developed by the Technical Committee ISO/TC 61, Plastics, ועדת המשנה SC 11, מוצרים.
המהדורה השנייה מבטלת ומחליפה את המהדורה הראשונה (ISO 8295:1986), אשר עבר תיקון טכני.
Annex A to this standard is for reference only.
ISO 8295-1995 “Determination of friction coefficient of plastic film and sheet”
1 טווח
1.1 This standard specifies methods for determining the starting and sliding friction coefficients of plastic films and sheets when sliding on themselves or other substances. The method is intended for use with non-adhesive plastic films and sheets up to a thickness of approximately 0.5 מ"מ (hereinafter referred to as “סרטים”).
1.2 This test method is mainly used for quality control. It does not provide a comprehensive assessment of the machinability of packaging or processing machines, as other effects are often involved, such as electrostatic charges, air cushions, local temperature increases and wear.
1.3 Static friction forces usually increase with the time of surface contact. לָכֵן, this time span is specified in order to obtain comparable results.
1.4 Slippery properties are sometimes produced by additives in plastic materials. The additive has different degree of compatibility with the film matrix. They may bloom or seep to the surface and change slip characteristics. Since these effects are time-dependent, the measurement of such films needs to be related to the age of the film.
ISO 8295-1995 “Determination of friction coefficient of plastic film and sheet”
2 Normative Reference
The following standards contain provisions that, by reference herein, constitute the provisions of this International Standard. At the time of publication, the version shown is valid. All standards are subject to revision and parties to an agreement based on this international Standard are encouraged to investigate the possibility of applying the following new versions of the standard. IEC and ISO members maintain a register of currently valid international standards.
ISO 291:1977, Plastics – Standard atmospheres for regulation and testing.
3 Definition
For the purposes of this standard, the following definitions apply.
3.1 Friction
Two surfaces in contact with each other will accumulate resistance to sliding. There is a difference between static friction and dynamic friction.
ISO 8295-1995 “Determination of friction coefficient of plastic film and sheet”
3.1.1 Static friction
Friction that needs to be overcome as a “threshold” at the beginning of sliding motion.
3.1.2 Dynamic friction
Friction that persists during sliding motion at a given speed.
3.2 Friction Force
The force needed to overcome friction. There is a difference between static friction force F S and dynamic friction force FD.
3.3 Normal force Fp
Force perpendicular to the contact surface.
ISO 8295-1995 “Determination of friction coefficient of plastic film and sheet”
3.4 Friction coefficient
The ratio of the friction force to the normal force perpendicular to the two surfaces in contact.
3.4.1 Static friction coefficient mml_m1
3.4.2 Dynamic friction coefficient mml_m2
הערה 1: The friction coefficient of the film is usually between 0,2 השלבים השונים של ייבוש ואשפרה המתרחשים בסרטים קלים לזיהוי אך קשים להגדרה במונחים של עקרונות כימיים ופיזיקליים 1.
הערה 2: * In this case, the coefficient of friction is a property independent of the test equipment and test conditions. Since thin films generally perform poorly, all test parameters are specified in this international standard.
רק מדור המידע הסטנדרטי הוא ציבורי. לצפייה בתוכן המלא, אתה צריך לרכוש את התקן דרך הערוצים הרשמיים.