--- title: Common Molding Defects & Easy Solutions description: Asaclean Purging Expert Jerry Weddell discusses common molding defects and easy ways you can solve them. image: https://www.asaclean.com/hubfs/Blog%20Header%20Purge%20Defects.jpg --- [ Order Online ](https://asaclean.my.site.com/b2bstore) [ Free Sample ](https://offers.asaclean.com/free-sample) ## [ Asaclean Blog ](https://www.asaclean.com/blog) Browse by Topic " aerospace asaclean asaclean news Asaclean® benefits asahi kasei automotive Best Practices black specks blisters blow molding blown-film extrusion buyers caps and closures carbon contamination cast-film extrusion Chemical Purging Compounds clear applications Color Changeovers Company News compounding consumer products contamination Cost savings custom molders Customer Success Story decreasing scrap defects electronics Energy Efficiency EX Grade extruder cleaning Extrusion fillament glass filled Glitter Grade Selection HDPE High and Low Temp Changeovers hold a bubble Hot Runners Injection Molding Injection Molding Tips LDPE Lightweight automotive components LLDPE low residue maintenance Material Changeovers Mechanical Purging Compounds medical Melt Flow Index NPE 24 nylons on the fly packaging PCR PEEK Polypropylene Post Consumer Resins preventative preventative purging processing tips profile extrusion Purge Program purge programs Purge Training Purge Trial purging purging compounds purging concentrates purging procedures Purging Tips quality recycled resins residue issues scrap reduction Screw Pulls sheet extrusion shutdown and sealing start-up super engineering resins Sustainability Tech Day technical support training trials Troubleshooting Twin Screw twin screw extrusion two step purging U Grade ULTEM venting Viscosity webinars wire extrusion - 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[Twin Screw](https://www.asaclean.com/blog/topic/twin-screw) - [twin screw extrusion](https://www.asaclean.com/blog/topic/twin-screw-extrusion) - [two step purging](https://www.asaclean.com/blog/topic/two-step-purging) - [U Grade](https://www.asaclean.com/blog/topic/u-grade) - [ULTEM](https://www.asaclean.com/blog/topic/ultem) - [venting](https://www.asaclean.com/blog/topic/venting) - [Viscosity](https://www.asaclean.com/blog/topic/viscosity) - [webinars](https://www.asaclean.com/blog/topic/webinars) - [wire extrusion](https://www.asaclean.com/blog/topic/wire-extrusion) [ Subscribe ](https://www.asaclean.com/blog/common-molding-defects-easy-solutions#subscribe-modal) ### Suscribirse Troubleshooting / 3 min read / April 13, 2022 # Common Molding Defects & Easy Solutions - [Facebook Share ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fcommon-molding-defects-easy-solutions) - [Twitter Tweet ](https://twitter.com/intent/tweet?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fcommon-molding-defects-easy-solutions&text=Common+Molding+Defects+%26amp%3B+Easy+Solutions) - [LinkedIn Share ](https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fcommon-molding-defects-easy-solutions&title=Common%20Molding%20Defects%20%26amp%3B%20Easy%20Solutions&summary=Asaclean+Purging+Expert+Jerry+Weddell+discusses+common+molding+defects+and+easy+ways+you+can+solve+them.&source=) - [Pinterest Pin ](https://pinterest.com/pin/create/button/?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fcommon-molding-defects-easy-solutions) - [Email Email ](mailto:?subject=Common%20Molding%20Defects%20%26amp%3B%20Easy%20Solutions&body=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fcommon-molding-defects-easy-solutions) ![Common Molding Defects & Easy Solutions](https://www.asaclean.com/hs-fs/hubfs/Blog%20Header%20Purge%20Defects.jpg?width=640&height=500&name=Blog%20Header%20Purge%20Defects.jpg)   ![Blog Header Purge Defects](https://www.asaclean.com/hs-fs/hubfs/Blog%20Header%20Purge%20Defects.jpg?width=362&name=Blog%20Header%20Purge%20Defects.jpg) There are many factors and conditions that affect the processing of quality plastic parts. What resin, colorant, temperature, additives, gate size/location, mold design, etc.? This article will discuss symptoms, possible causes, and possible solutions. Defects In injection molding occur during fill time or pack/hold time. Examples of defects caused in the filling process can be flow lines, jetting, gas burn, weld line, etc. Examples of defects during the pack/hold pressure time can be a sink, voids, flash, wrappage, etc. **Flow lines** – a ripple-looking pattern on the front of melt flow caused from filling too slowly. Possible molding process issues - low temperature, too low injection speed, insufficient hold pressure, insufficient cushion. Solutions – increase temperature, increase velocity, increase pack pressure and time. Mold could have cooling issues or be too cold. **Sink/Voids**- Area(s) of a plastic part not filled out or sunk in on the surface. Many molding processes to check - too short cure time, too slow velocity, too small shot size, pressure loss, insufficient hold time. Possible mold problems – too hot mold temperature, Gates, runner too small, part dimension too thick. Solutions – Increase pack pressure and time, increase injection speed, allow proper cooling time, more up transfer position. **Black specs / Burn – **dark spots, streaks, chunks appearing in and on the surface of the parts. Common molding issues are degraded material, excessive injection speed, and pressure, clogged or not enough vents/ gas burn, and residence time of the material. Mold issues could be inadequate vents or plugged/damaged vents causing trapped gas. Solutions – Purge for carbon build-up, inspect vents for damage or blocked, add more venting if needed (common practice is at least 30% of parting line to be vented), decrease the temperature, decrease velocity, back pressure, make sure material is not residing in the barrel too long (residence time). **Warp / Bend – **Parts that twist, bend, warp out of shape and dimension after being ejected from the Mold. Pressure and over-packing are very common causes. Mold problems could be unbalanced or not enough cooling/water, mold temperature too high, gate size, part sticking during ejection. Molding issues include too much pack and hold pressure, too low melt temperature, and Injection speed too slow. Solutions- increase velocity, move transfer up, increase mold and melt temp, decrease hold pressure With so many different variables, conditions, settings, etc. causing problems within your plastic processing equipment it’s vital to control what we can. One major component and many times overlooked is a quality purge compound. Keeping your equipment purged and cleaned on a regular basis will eliminate time troubleshooting later. Purging your equipment is absolutely one variable you have complete control over. Stop wasting money and start using Asaclean! **Want to save *a little more money?  *Try purging with Asaclean today by requesting your free sample below.** ![Jerry Weddell](https://www.asaclean.com/hs-fs/hubfs/1713568728231.jpg?width=150&name=1713568728231.jpg) #### [ Jerry Weddell ](https://www.asaclean.com/blog/author/jerry-weddell) With over 30 years in the field, Jerry Weddell is a Technical Sales Representative with a wealth of knowledge in mold-making and purging compounds. While his expertise spans injection molding, extrusion, and blow molding, he is particularly distinguished in injection molding. Jerry's profound understanding of these processes enables him to offer targeted, practical solutions, especially in the nuanced aspects of injection molding. His commitment to providing exceptional guidance and support to clients has made him a respected and trusted figure in the industry. - [Share On LinkedIn ](https://www.linkedin.com/in/jerry-weddell-b0747538) ## Related Posts [![Value-Add: More Than a Buzzword](https://www.asaclean.com/hs-fs/hubfs/AI-Generated%20Media/Images/This%20image%20shows%20the%20word%20Value%20with%20arrows%20increasingly%20pointing%20up-3.jpeg?width=450&height=250&name=This%20image%20shows%20the%20word%20Value%20with%20arrows%20increasingly%20pointing%20up-3.jpeg) Value-Add: More Than a Buzzword Troubleshooting / 2 min read / March 21, 2019 ](https://www.asaclean.com/blog/value-added-more-than-a-buzzword) [![](https://www.asaclean.com/hs-fs/hubfs/Process%20%26%20Industry%20Header%20Photo.jpg?width=450&height=250&name=Process%20%26%20Industry%20Header%20Photo.jpg) Faster Profile Extrusion Color Changes with Chemical Purging Troubleshooting / 2 min read / October 21, 2021 ](https://www.asaclean.com/blog/easier-profile-extrusion-color-changes-with-chemical-purges-concentrates) ## Comments Get Started ## Ready to start improving your efficiency and increasing your profitability? - [Request a Consultation](https://www.asaclean.com/blog/common-molding-defects-easy-solutions#) - [Contact Sales](https://www.asaclean.com/blog/common-molding-defects-easy-solutions#) ![](https://www.asaclean.com/hubfs/assets/images/icons/icon-layers.svg) #### Free Sample Request a free sample of Asaclean® Purging Compounds for your plant and start saving today. 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[See your savings](https://www.asaclean.com/cost-savings-calculator) [ Back to Top ](https://www.asaclean.com/blog/common-molding-defects-easy-solutions#top) ```json { "@context" : "https://schema.org", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "Jerry Weddell", "url" : "https://www.asaclean.com/blog/author/jerry-weddell" }, "dateModified" : "2022-04-13T21:59:09.644Z", "datePublished" : "2022-04-13T21:59:09.000Z", "headline" : "Common Molding Defects & Easy Solutions", "image" : [ "https://www.asaclean.com/hubfs/Blog%20Header%20Purge%20Defects.jpg" ], "mainEntityOfPage" : { "@id" : "https://www.asaclean.com/blog/common-molding-defects-easy-solutions", "@type" : "WebPage" }, "publisher" : { "@type" : "Organization", "logo" : { "@type" : "ImageObject", "url" : "https://www.asaclean.com/hubfs/Asaclean%20Logo%20TM.jpg" }, "name" : "Asahi Kasei Plastics North America" } } ``` ```json { "@context" : "http://schema.org", "@type" : "Article", "articleBody" : "There are many factors and conditions that affect the processing of quality plastic parts. What resin, colorant, temperature, additives, gate size/location, mold design, etc.? This article will discuss symptoms, possible causes, and possible solutions. Defects In injection molding occur during fill time or pack/hold time. Examples of defects caused in the filling process can be flow lines, jetting, gas burn, weld line, etc. Examples of defects during the pack/hold pressure time can be a sink, voids, flash, wrappage, etc. Flow lines – a ripple-looking pattern on the front of melt flow caused from filling too slowly. Possible molding process issues - low temperature, too low injection speed, insufficient hold pressure, insufficient cushion. Solutions – increase temperature, increase velocity, increase pack pressure and time. Mold could have cooling issues or be too cold.", "author" : { "@type" : "Person", "name" : "Jerry Weddell" }, "datePublished" : "April 13, 2022", "headline" : "Common Molding Defects & Easy Solutions", "image" : "https://468726.fs1.hubspotusercontent-na1.net/hubfs/468726/Blog%20Header%20Purge%20Defects.jpg", "name" : "Common Molding Defects & Easy Solutions", "url" : "https://www.asaclean.com/blog/common-molding-defects-easy-solutions" } ```