1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW14335 Determining the Moisture Content of Plastic Components and Molding Compounds Copyright 2011 General Motors Company All Rights Reserved September 2011 Originating Department: North American Engineering Standards Page 1 of 2 1 Scope Note: Nothin
2、g in this standard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. This standard is an alternative procedure to ISO 62 or ISO 15512 to determine the moisture (water) content
3、 of plastic components and molding compounds. In case of dispute, the responsible GM Material Engineer defines which procedure to use. 1.2 Foreword. Not applicable. 1.3 Applicability. It is particularly applicable to polyamide (except polyamide 11 and 12) components, which in order to attain their o
4、ptimum performance characteristics at +23 5 C and 50 6% relative humidity (RH) must have moisture content of 2% minimum in their finished form. The absorption of water affects the physical properties of polyamide (except polyamide 11 and 12). After manufacture, therefore, components shall be conditi
5、oned by suitable means (i.e., immersion in hot water) such that the moisture content thus attained approximates to that necessary to achieve optimum properties and dimensional stability during normal service and assembly conditions. 1.4 Definition of Moisture Content. Moisture content as determined
6、by this test procedure shall be defined as the mass loss of a test piece resulting from heating for 48 hours at +105 C. The test procedure has an accuracy of 0.2%. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications.
7、ISO 62 ISO 15512 2.2 GM Standards/Specifications. None 3 Resources 3.1 Facilities. 3.2 Equipment. 3.2.1 Drying Oven. Drying oven with natural forced air circulation capable of maintaining the required temperature to within 3 C. Alternatively any other suitable apparatus may be used, e.g., electronic
8、 balance with infrared dryer and automatic evaluation. A suitable apparatus is type LP 15/PE 360 manufactured by Mettler Toledo GmbH, Postfach 110840, D-35353 Giessen. Drying shall be carried out at | +140 C to constant mass. 3.2.2 Balance. Accurate to 0.5 mg. 3.2.3 Desiccator. 3.2.4 Shears, etc., f
9、or preparation of test pieces. 3.2.5 Crucibles, watch glasses etc., of suitable size. 3.3 Test Vehicle/Test Piece. Finished parts, suitable sections there from, or granules shall be used as test piece. 3.4 Test Time. Calendar time: 2 days Test hours: 49 hours Coordination hours: 1 hour 3.5 Test Requ
10、ired Information. Not applicable. 3.6 Personnel/Skills. Not applicable. 4 Procedure 4.1 Preparation. Finished parts, suitable sections there from, or granules shall be used as test pieces. For initial sample approval and arbitration purposes at least three test pieces, and for routine quality contro
11、l at least one test piece shall be tested. For tests on granules care shall be taken that test pieces are truly representative of the material under test. 4.2 Conditions. 4.2.1 Environmental Conditions. Tests shall be conducted on test pieces in the as received condition (i.e., no special preconditi
12、oning). Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14335 Copyright 2011 General Motors Company All Rights Reserved September 2011 Pa
13、ge 2 of 2 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. 4.3 Instructions. 4.3.1 Summary of Test Method. The test sample is weighed, dried and weighed a
14、gain. From the weight difference the moisture content is calculated. Note: For granules it is recommended that portions no smaller than 5 g in weight be tested in previously dried and weighed crucibles. 4.3.2 The test pieces shall be weighed to the nearest 0.5 mg. 4.3.3 The test pieces shall be plac
15、ed in the oven at +105 3 C for 48 2 hours. 4.3.4 After removal from the oven, the test pieces shall be allowed to cool in a desiccator for 30 5 minutes at +23 5 C, and then reweighed. 5 Data 5.1 Calculations. The moisture (water) content shall be calculated as follows: 100*1m2m1mW in % by mass Where
16、: W = moisture (water) content in % m1 = mass of test piece as received in grams m2 = mass of test piece after heating in grams 5.2 Interpretation of Results. Not applicable. 5.3 Test Documentation. 5.3.1 With reference to this test standard, the results of the measurements shall be presented in a t
17、est report. The moisture (water) content shall be expressed as the arithmetical average of multiple tests or as the individual result for single tests, in percent rounded to the nearest 0.1%. 6 Safety This standard may involve hazardous materials, operations, and equipment. This standard does not pr
18、opose to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 7 Notes 7.1 Glossary. Not applicable. 7.2 Acronyms, Abb
19、reviations, and Symbols. RH Relative Humidity 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW14335 9 Release and Revisions This standard was originated in September 2005. It was first approved by the Global Plastics Team in November 2006.
20、 It was first published in February 2007. Issue Publication Date Description (Organization) 1 FEB 2007 Initial publication. 2 Sep 2011 Five year refresh to current template, editorial changes, and updated formula. (Global Plastics Team) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
