Multi-material injection molding (MMM) is the process of molding two or more different materials into one plastic part at one time.[1] As is the case in traditional injection molding, multi material injection molding uses materials that are at or near their melting point so that the semi-liquidous (viscous) material can fill voids and cavities within a pre-machined mold, thus taking on the desired shape of designed tooling. In general, advantages of MMM over other production techniques include, but are not limited to, creating parts that have an elastic modulus that varies with location on the part (different regional polymer hardness), creating a single-structure part with different regional materials (similar to the previous advantage, but more focused on joining different types of polymers like rubber and plastic), and also creating a single part with multiple independent polymer colors. Applications range from simple household items like a toothbrush to more heavy duty construction of items like power tools.[2]
The three most widely used methods of MMM fabrication are:[3]
multi-component
multi-shot
over-molding
Each MMM primary subset can also be further subdivided into secondary and tertiary subsets, and even further in some cases.[4] This can be advantageous when fine tuning or other general calibration of a specific MMM process is desired. Each primary subset is outlined further in the following sections.
[4] Co- Injection Molding Process[4] Battenfield three-channel MMM technique used for MMM of three materials at one time
Also referred to as co-injection molding,[4] multi-component injection molding describes insertion of multiple viscous materials injected simultaneously, as opposed to placing one material as an additional layer relative to another. In other words, it creates a sandwich-like structure where both materials mold around each other as dissimilar liquids, and exist in such a state at the same time. Relative to the part center, materials can be injected concentrically using the same mold/gate, or regionally using gates at different locations.[2]
Multi-shot injection molding (MSM)edit
Also referred to as sequential injection molding,[4] multi-shot injection molding refers to creation of multiple layers relative to the starting axis of the initial mold. In other words, the warm, heated materials are inserted into the mold in a very specific sequence one after another. This creates a layering effect between materials while maintaining relatively high-energy interactions at material boundaries. This is important because it implies that the inter-layer bonds are stronger in many cases than when the layers are applied to a previously cooled part, as is more closely the case of over molding. While there are other applications, this operation is preferred when varying molds (different geometries) are desired between material layers.[2]
Over-moldingedit
Over molding is effectively the use of layering effects in polymer application techniques. This process is centered around the use of a liquidous resin to add additional layers of shape and structure to an existing component. An example of such a resin could be a polymer that has been heated to a temperature just above its glass transition temperature). The existing component to which the resin is being added is often injection molded as well, and may be near its own glass transition temperature. This process works well when layers with varying geometric profiles are desired around a central "core" structure.[2]
Benefitsedit
If the desired object is manufacturable using MMM, it is definitely best to use MMM over traditional injection molding. Some of the key features that makes MMM a better approach are:
^ abcdBanerjee, Ashis; Li, Xuejun; Fowler, Greg; Gupta, Satyandra K. (March 2007). "Incorporating manufacturability considerations during design of injection molded multi-material objects". Research in Engineering Design. 17 (4): 207. CiteSeerX10.1.1.114.8590. doi:10.1007/s00163-007-0027-9. S2CID 15614704.
January 01, 1970
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Multi material injection molding MMM is the process of molding two or more different materials into one plastic part at one time 1 As is the case in traditional injection molding multi material injection molding uses materials that are at or near their melting point so that the semi liquidous viscous material can fill voids and cavities within a pre machined mold thus taking on the desired shape of designed tooling In general advantages of MMM over other production techniques include but are not limited to creating parts that have an elastic modulus that varies with location on the part different regional polymer hardness creating a single structure part with different regional materials similar to the previous advantage but more focused on joining different types of polymers like rubber and plastic and also creating a single part with multiple independent polymer colors Applications range from simple household items like a toothbrush to more heavy duty construction of items like power tools 2 The three most widely used methods of MMM fabrication are 3 multi component multi shot over molding Each MMM primary subset can also be further subdivided into secondary and tertiary subsets and even further in some cases 4 This can be advantageous when fine tuning or other general calibration of a specific MMM process is desired Each primary subset is outlined further in the following sections Contents 1 Multi component injection molding 2 Multi shot injection molding MSM 3 Over molding 4 Benefits 5 ReferencesMulti component injection molding edit nbsp 4 Co Injection Molding Process nbsp 4 Battenfield three channel MMM technique used for MMM of three materials at one time Also referred to as co injection molding 4 multi component injection molding describes insertion of multiple viscous materials injected simultaneously as opposed to placing one material as an additional layer relative to another In other words it creates a sandwich like structure where both materials mold around each other as dissimilar liquids and exist in such a state at the same time Relative to the part center materials can be injected concentrically using the same mold gate or regionally using gates at different locations 2 Multi shot injection molding MSM editAlso referred to as sequential injection molding 4 multi shot injection molding refers to creation of multiple layers relative to the starting axis of the initial mold In other words the warm heated materials are inserted into the mold in a very specific sequence one after another This creates a layering effect between materials while maintaining relatively high energy interactions at material boundaries This is important because it implies that the inter layer bonds are stronger in many cases than when the layers are applied to a previously cooled part as is more closely the case of over molding While there are other applications this operation is preferred when varying molds different geometries are desired between material layers 2 Over molding editOver molding is effectively the use of layering effects in polymer application techniques This process is centered around the use of a liquidous resin to add additional layers of shape and structure to an existing component An example of such a resin could be a polymer that has been heated to a temperature just above its glass transition temperature The existing component to which the resin is being added is often injection molded as well and may be near its own glass transition temperature This process works well when layers with varying geometric profiles are desired around a central core structure 2 Benefits editIf the desired object is manufacturable using MMM it is definitely best to use MMM over traditional injection molding Some of the key features that makes MMM a better approach are lower cost 5 higher quality product 5 significant reduction in assembly operations 5 reduction in cycle times 5 References edit Multi Component Injection Molding www mhs hotrunners com Retrieved February 12 2016 a b c d Banerjee Ashis Gopal Li Xuejun Fowler Greg Gupta Satyandra K February 21 2007 Incorporating manufacturability considerations during design of injection molded multi material objects Research in Engineering Design 17 4 207 231 CiteSeerX 10 1 1 114 8590 doi 10 1007 s00163 007 0027 9 ISSN 0934 9839 S2CID 15614704 Multi Material Injection Moulding Injection molding www chemtec org Retrieved February 5 2016 a b c d e Goodship Vanessa Love J C 2002 Multi Material Injection Moulding Smithers Rapra pp 9 15 ISBN 9781859574218 a b c d Banerjee Ashis Li Xuejun Fowler Greg Gupta Satyandra K March 2007 Incorporating manufacturability considerations during design of injection molded multi material objects Research in Engineering Design 17 4 207 CiteSeerX 10 1 1 114 8590 doi 10 1007 s00163 007 0027 9 S2CID 15614704 Retrieved from https en wikipedia org w index php title Multi material injection molding amp oldid 1069119958, wikipedia, wiki, book, 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