ASTM D1896 D1896M-2010(2017) Standard Practice for Transfer Molding Test Specimens of Thermosetting Compounds《热固性混合料传递成型试样的标准实施规程》.pdf
《ASTM D1896 D1896M-2010(2017) Standard Practice for Transfer Molding Test Specimens of Thermosetting Compounds《热固性混合料传递成型试样的标准实施规程》.pdf》由会员分享,可在线阅读,更多相关《ASTM D1896 D1896M-2010(2017) Standard Practice for Transfer Molding Test Specimens of Thermosetting Compounds《热固性混合料传递成型试样的标准实施规程》.pdf(4页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D1896/D1896M 10 (Reapproved 2017)Standard Practice forTransfer Molding Test Specimens of ThermosettingCompounds1This standard is issued under the fixed designation D1896/D1896M; the number immediately following the designation indicates theyear of original adoption or, in the case of re
2、vision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a general procedure for the transfermolding of mechanical and electrical test
3、 specimens of ther-mosetting molding materials.NOTE 1The utility of this practice has been demonstrated for themolding of thermosetting molding compounds exhibiting intermediateviscosity non-Newtonian flow.1.2 The values stated in either SI or inch-pound units are tobe regarded separately as standar
4、d. The values stated in eachsystem are not always exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems can result in nonconformancewith this practice.1.3 This standard does not purport to address all of thesafety concerns, if any, as
5、sociated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 2There is no known ISO equivalent to this standard.1.4 This international standard was develo
6、ped in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Docum
7、ents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD957 Practice for Determining Surface Temperature ofMolds for PlasticsD3123 Test Method for Spiral Flow of Low-Pressure Ther-mosetting Molding CompoundsD3795 Test Method for Thermal Flow, Cure, and BehaviorProperties of Pourable Thermosett
8、ing Materials by TorqueRheometer3. Terminology3.1 Definitions:3.1.1 GeneralDefinitions of terms applying to this prac-tice appear in Terminology D883.3.1.2 transfer molding, na method of forming articles byfusing a plastic material in a chamber and then forcingessentially the whole mass into a hot m
9、old where it solidifies.3.2 Definitions of Terms Specific to This Standard:3.2.1 breathing, vthe operation of opening a mold or pressfor a very short period of time at an early stage in the processof cure.3.2.1.1 DiscussionBreathing allows the escape of gas orvapor from the molding material and redu
10、ces the tendency ofthick moldings to blister.3.2.2 cavity (of a mold), nthe space within a mold to befilled to form the molded product.3.2.3 clamp pressure, nthe pressure applied to the mold tokeep it closed, in opposition to the fluid pressure of thecompressed molding material.3.2.4 fill time, nthe
11、 time required to fill each cavity used inthe mold. Fill times can be critical to well molded parts (seeNote 3 under 4.4).3.2.5 minimum plunger pressure, nthe minimum pressure,on the ram, required to just fill each cavity used in the mold ata specified temperature and reasonable fill time.3.2.6 vent
12、, na hole, slot, or groove provided in a mold ormachine to allow air and gas to escape during molding,extrusion, or forming.4. Significance and Use4.1 Transfer molding is particularly suited to thermosettingmaterials of intermediate plasticity. Fixed molding parameterscannot be specified for each ty
13、pe of material. Molding com-pounds of the same type come in many different plasticitiesmeasured in accordance with Test Methods D3123 and D3795.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.09 on Specimen Preparation.Cur
14、rent edition approved May 1, 2017. Published July 2017. Originally approvedin 1961. Last previous edition approved in 2010 as D1896 - 10. DOI: 10.1520/D1896_D1896M-10R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu
15、al Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis internat
16、ional standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Commit
17、tee.1Consequently, for a given material type, the molding param-eters required to produce satisfactory test specimens will oftenvary dependent on the plasticity of the specific material grade.4.2 The mold shown in this practice provides for a set offive specimens. However, if only certain specimens
18、are desired,the other cavities can be blocked by inserting gate blanks.4.3 Typically, breathing of the mold is not required torelease trapped volatile matter as the gas is free to flow fromthe vent end of the mold. This is a particular advantage forheat-resistant compounds and reduces the tendency f
19、or moldedspecimens to blister at high exposure temperatures.4.4 Flow and knit lines in a molded piece are often sites ofmechanical or electrical weakness and can be found in somedegree of severity throughout the molded piece. The semisolidmolding compound passing through the gate is subject tonon-Ne
20、wtonian flow and, consequently, wrinkles and folds asit travels down the mold cavity. Fibers and other reinforce-ments in the molding compound align with the flow patternand, consequently, can orient perpendicular to the axis of thebar at the center and parallel at the surface of the bar. Moldtemper
21、ature, thermal conductivity and plasticity of the moldingcompound, degree of preheat, and plunger pressure are param-eters that influence the time to fill the mold cavities and theformation of knit lines.NOTE 3If the temperature of the mold is held constant and the plungerpressure varied for a desig
22、nated thermosetting molding compound, twoextreme characteristic conditions can be obtained. If the pressure is low,then the vent end of the cavity will not fully fill, and weld lines will formby incomplete knitting of the material. If the pressure is too high, the moldcavity will fill fast, the outs
23、ide of the specimen will case harden while thepressure is still forcing material out the vent, and a ball-and-socket grainstructure will be obtained. A ball-and-socket structure is an indication ofthe molding condition, and lower test data will result.4.5 Thermosetting compounds containing long-fibe
24、r fillerssuch as glass roving, chopped cloth, or shavings can be usedbut are not recommended for transfer molding. These fillermaterials tend to break, tear, or ball in passing through thegates of the mold, thereby not optimizing their potentialstrength.4.6 The Izod impact strength of transfer molde
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
下载文档到电脑,查找使用更方便
10000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- ASTMD1896D1896M20102017STANDARDPRACTICEFORTRANSFERMOLDINGTESTSPECIMENSOFTHERMOSETTINGCOMPOUNDS 热固性 混合
链接地址:http://www.mydoc123.com/p-510651.html