Flash (manufacturing): Difference between revisions
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{{Use American English|date=January 2022}} |
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'''Molding flash''' is excess material attached to a [[molding (process)|molded]] product, which must usually be removed. This is typically caused by leakage of the material between the two surfaces of a mold. Molding flash is seen when the optimized parameter on cull height is not calibrated. |
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{{Short description|Excess material attached to a molded, forged, or cast product}} |
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[[File:Flashes di bakul.png|thumb|Flash, center, on a molded plastic laundry basket. Plastic has filled an area that should be an empty space, probably by seeping through a gap where the molds were not clamped sufficiently close together.]] |
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'''Flash''', also known as '''flashing''', is excess material attached to a [[molding (process)|molded]], [[forging|forged]], or [[casting|cast]] product, which must usually be removed. This is typically caused by leakage of the material between the two surfaces of a mold (beginning along the [[parting line]]<ref name="Kazmer2007">{{cite book|author=David Kazmer|title=Injection mold design engineering|url=https://books.google.com/books?id=fWTftzWhBp4C&pg=PA70|accessdate=15 April 2011|year=2007|publisher=Hanser Verlag|isbn=978-1-56990-417-6|page=70}}</ref>) or between the base material and the mold in the case of [[overmolding]]. |
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==Details== |
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Note: The excess material, commonly considered a quality defect in various industries, is on occasion mistakenly described as 'flashing'. |
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Molding flash is seen when the optimized parameter on cull height is not calibrated.{{citation needed|date=July 2009}} Proper design of mold parting surfaces can reduce or eliminate flash.<ref name="VGX">{{cite web|url=http://www.plm.automation.siemens.com/en_sg/Images/3014_tcm963-4308.pdf|title=NX I-deasVGX Core/Cavity|year=2007|publisher=Siemens PLM Software|accessdate=2009-07-01}}</ref> |
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{{Industry-stub}} |
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Molding flash can be caused from old or worn mold cavities that no longer fit tightly together. Other times, the complexity of the part requires so many mating pieces with such precise geometries that it is almost impossible to create a perfect fit on every impression. Most often, the type of material being molded, and its attendant viscosity in its liquid form, is the primary factor that leads to the creation of the unwanted mold flash.<ref name="bozzelli">Bozzelli, John [http://www.ptonline.com/articles/an-expert-tells-how-to-stop-flash "An Expert Tells How to Stop Flash"], ''Plastics Technology'', July 2004, accessed May 9, 2011.</ref> |
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The process of removing flash, known as '''deflashing''', is commonly performed via cutting, breaking, [[grinding (abrasive cutting)|grinding]], or [[Tumble finishing|tumbling]]. Some foundries use robot autogrinders to remove this unwanted material. It is very typical for molders to have their operators trim flash with hand tools at the molding machine between cycles. Many molders and OEMs seek out the use of batch processes including vibratory tumbling, [[cryogenic deflashing]]<ref name="Nitrofreeze">{{cite web|url=http://www.nitrofreeze.com/services/deflashing/cryogenic-deflashing-using-blast-media/|title=Cryogenic Deflashing for Molded Plastic, Rubber & Silicone|date=26 April 2012 |publisher=Nitrofreeze Cryogenic Solutions|accessdate=2014-04-03}}</ref> or media blasting to remove unwanted flash from large batches of parts. |
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== Witness mark == |
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{{redirect|Witness marks|the episode of The Haunting of Hill House TV series|Witness Marks}} |
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In plastic injection, a faint mark called a '''witness mark''' (or '''witness line''') will occur along the parting line.<ref name="Kazmer2007"/> This is unavoidable and is usually accepted despite the minor aesthetics issue. However, some part surfaces (e.g. when used for sealing<ref name="Bernard2005">{{cite patent|country=US | number = 6939500 | status = patent | title = Method and apparatus for eliminating a parting line witness mark from a molded part | gdate = 2005-09-06 | invent1 = Bernard, Edward Helmut}}</ref>) cannot tolerate witness marks, and thus either the marks must be removed post-molding or the mold redesigned. |
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== References == |
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{{reflist}} |
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{{DEFAULTSORT:Flash (Manufacturing)}} |
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[[Category:Plastics industry]] |
[[Category:Plastics industry]] |
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[[Category:Metalworking terminology]] |
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Latest revision as of 04:21, 9 August 2023
Flash, also known as flashing, is excess material attached to a molded, forged, or cast product, which must usually be removed. This is typically caused by leakage of the material between the two surfaces of a mold (beginning along the parting line[1]) or between the base material and the mold in the case of overmolding.
Details
[edit]Molding flash is seen when the optimized parameter on cull height is not calibrated.[citation needed] Proper design of mold parting surfaces can reduce or eliminate flash.[2]
Molding flash can be caused from old or worn mold cavities that no longer fit tightly together. Other times, the complexity of the part requires so many mating pieces with such precise geometries that it is almost impossible to create a perfect fit on every impression. Most often, the type of material being molded, and its attendant viscosity in its liquid form, is the primary factor that leads to the creation of the unwanted mold flash.[3]
The process of removing flash, known as deflashing, is commonly performed via cutting, breaking, grinding, or tumbling. Some foundries use robot autogrinders to remove this unwanted material. It is very typical for molders to have their operators trim flash with hand tools at the molding machine between cycles. Many molders and OEMs seek out the use of batch processes including vibratory tumbling, cryogenic deflashing[4] or media blasting to remove unwanted flash from large batches of parts.
Witness mark
[edit]In plastic injection, a faint mark called a witness mark (or witness line) will occur along the parting line.[1] This is unavoidable and is usually accepted despite the minor aesthetics issue. However, some part surfaces (e.g. when used for sealing[5]) cannot tolerate witness marks, and thus either the marks must be removed post-molding or the mold redesigned.
References
[edit]- ^ a b David Kazmer (2007). Injection mold design engineering. Hanser Verlag. p. 70. ISBN 978-1-56990-417-6. Retrieved 15 April 2011.
- ^ "NX I-deasVGX Core/Cavity" (PDF). Siemens PLM Software. 2007. Retrieved 2009-07-01.
- ^ Bozzelli, John "An Expert Tells How to Stop Flash", Plastics Technology, July 2004, accessed May 9, 2011.
- ^ "Cryogenic Deflashing for Molded Plastic, Rubber & Silicone". Nitrofreeze Cryogenic Solutions. 26 April 2012. Retrieved 2014-04-03.
- ^ US patent 6939500, Bernard, Edward Helmut, "Method and apparatus for eliminating a parting line witness mark from a molded part", issued 2005-09-06