INSERT MOLDING vs OVERMOLDING | Two-Shot Injection Molding EXPLAINED - Serious Engineering - Ep16

[@starrapid]

Have you ever created a plastic part using two-shot injection molding method? How was your experience? Leave your thoughts in the comments below and don't forget to follow Gordon on LinkedIn for great engineering and manufacturing tech updates and explainers - www.linkedin.com/in/gordon-styles-091b552/

[@dddl4582]

this is the best explaination of 2K, by the way, the Zwei Komponenten in German are perfectly pronunced.

[@EzatezGreen]

This video helps me to better understand 2k PIM in a short period compared to google-read. Thanks Gordon Styles and TEAM who crafted the video, by far the best 2k PIM video for learners like me

[@starrapid]

This is exactly why we created this series. We are very glad. Thank you.

[@Hsilvag4]

The quality and amount of content on this channel are amazing. As a plastic injection mould designer, its a pleasure to watch this.

[@starrapid]

Glad you enjoy it!

[@cptpowerpuff]

This is amazing, thank you ! How is this channel not more known?

[@marknaglreiter9330]

Excellent job of explaining the processes.

[@slipperyslope3912]

Incredibly informative and to the point.

[@johnnycastro9796]

When i seen that mold turn on the moveable platten i was amazed lol ive only been in plastics for about 5 yrs and that shit was pretty damn cool lol

[@pawetrznadel7770]

How are the surfaces to be covered during insert molding / overmodling isolated from those that cannot be contaminated by the injected material, e.g. a thread of motal threaded insert has to be clean after insert modling, so how it is made?

[@starrapid]

Hi Pawel. Thanks for your question. The threaded insert would be loaded over the top of a closely fitting pin. The pin internal diameter would be shielded from the plastic.

[@Waku117]

Amazing and informative video. Thanks for taking your time of your day to produce these.

[@starrapid]

Thank you Jared :)

[@AShiftySpock]

About to embark on trying to insert mould toothbrush bristles onto a toothbrush handle for a client, both parts are to be injection moulded... We're using a bolster plate die set from Meusburger for use with insert plates, do you think it is possible to make the handle in on set of insert plates then the overmoulded bristle part in another, IM a load of the handles then place these into the second insert plate set that will IM the bristles on?

[@chrisdaniel1339]

I need to fully encapsulate a steel bar in UHMW polyethylene, what is the best processes for that type of application? Thank you

[@starrapid]

"When insert molding a bar like this, you have to support the bar in the mold so that it can be surrounded evenly by the resin and not able to move under injection pressures. This would lead to the bar being exposed in certain areas. You would then have to overmold the whole thing again to fill those 1st support areas. That would be the simplest solution without seeing drawings and specifications." - Dave, Injection Molding Expert - Star Rapid

[@chrisdaniel1339]

@@starrapid I had read that because of the ultra high molecular weight of this type of polyethylene injection molding is not possible, that compression molding must be used. I would use 4 retractable pins in the mold cavity that retract using internal mold pressure as the initiator.

[@LYPeng-h4j]

Thanks for amazing sharing，it's useful！

[@starrapid]

Thank you. We produce weekly videos on engineering and manufacturing topics. Make sure to subscribe to our channel and stay tuned :)

[@noahhastings6145]

3:49 Hey, that's a thermopen! Love those things.

[@starrapid]

Same!

[@mmorena2787]

What are the best practices for design-for-insert molding for say a power supply that has the electric contacts molded into the plastic (i.e. A Wall Wart)? I struggle to find information on how to design for this to accommodate 'holding' the metal insert so it properly creates the shuts offs and parting surfaces as expected, while not crushing/deforming the insert during mold close. Would be great for a video topic!

[@starrapid]

Hi Michael. Great question. We will get back to you shortly. And we've noted the suggestion for an upcoming video. Thank you.

[@starrapid]

Hi, response from our Injection Molding expert: We really need to know the geometry of what you are looking for. In many cases the contacts are loaded onto a sliding core which needs to be pushed into the moulding position before the mould closes. This requires a special open slot to allow the angle pin to enter as the mould closes and pull open the sliding core when the mould opens. Usually simple ball catches can achieve this. Hope this helps.

[@mmorena2787]

@@starrapid Thank you for the helpful reply - I believe I follow what you are saying. This is why a video would be excellent on this topic - a picture/video/illustration would go a far ways. The specific geometry I'm referring to is a two metal prongs (such as NEMA 1-15P style for USA) for a wall wart being insert-molded into a clamshell enclosure. Generally these are some style of plated steel or brass stamped metal components oriented along the pull-direction axis. The funny thing is there are probably 10's of the thousands of molds generating 10's of millions of parts like this each year given the size of the power supply market - but not a ton of information on how to design plastic components accommodating this style of manufacturing method. The main reason I ask this is because there a certainly several ways to marry a stamped metal component to a plastic component - one of these ways being insert-molding. Given that insert molding feels a bit more complex I wonder how to make the engineering tradeoff between insert-molding and say a secondary operating such as heat-staking or simple mechanical assembly with a fastener.

[@PrintThatThing]

Very helpful. Thanks!

[@starrapid]

We are glad! Thanks.

[@glenmcneill1675]

In my experience the term insert molding is more of a catch all phrase for the process of overmolding.

[@starrapid]

Yes, both insert molding and overmolding are techniques used to combine different materials in a single plastic part, but they are different. Insert molding involves placing a pre-made insert (often metal) into a mold cavity before injecting plastic. Overmolding is a two-shot process where one plastic material is molded onto another.

[@glenmcneill1675]

@@starrapid sorry I still object to your interpretation. We’ve done up to 7 stages of overmolding an insert. We also have 3 shot machines. The terms are interchangeable. It does not mater if

[@marquisdaily7715]

Thank you very much, great content. I am wondering what the tooling and process would like in case of plastic overmolding on a steel part. For instance, on the Tesla Model 3 front suspension wishbone

[@starrapid]

Thanks Marquis. The key to overmolding steel is to ensure that the overmolding material can stretch as the plastic/rubber cools down around the non-shrinking steel substrate. (Obviously the steel will shrink a tiny amount if it has warmed up in process, but the difference in shrinkage rates will be huge.) Two extreme examples might be PC, which is fairly brittle, and a rubber, which is extremely elastic. The PC will want to shrink, but the metal won't, so the PC will shatter. We often see this when we are overmolding brass Nutserts. The shattering effect may not show itself for hours, days, weeks, or even months, but you can guarantee that the plastic is under enormous stress. Therefore we always recommend Heat-Staking the inserts into PC after molding. If you are overmolding with a rubber, then clearly the rubber can stretch as it shrinks. So, in summary, you need to choose a material that can shrink and not shatter or snap due to the differential shrinkage. Hope that helps.

[@pdub2762]

TY SIR

[@khj5582]

This video treats overmolding and two-shot as the same process, but I've found that tooling companies make a clear distinction between the two. However, for the life of me I cannot figure out the exact difference between these two processes and what shapes can be made with one process, but not the other.

[@starrapid]

No wonder you are confused. It is not that clear. Over-molding and Two-shot (2K) Molding achieve the same end goal of two materials being fused together to form a hybrid part. Typically, that is a rigid substrate and a softer over-molding, maybe a rubber. This is done for visual effect, or maybe to add an area of the part that has greater grip. Over-molding typically means that a part has been over-molded at some point in time, not necessarily in the same mold or during the same cycle or even on the same day; whereas, two-shot (2K) typically refers to the over-molding being done on the same machine, in the same mold, and maybe only seconds or minutes apart. These kinds of 2K machines usually have two barrels on the same machine, one as usually the main barrel, and one is an auxiliary. These machines can be horizontal, and that process uses what is called a rotating mold; or it can be vertical, and that is often called a shuttle mold, but can also use a rotating mold, or even a carousel mold. There are so many variations on this theme. Over-molding is really a generic description, and 2K is more specific about the type of machine or process used. Hope this helps. - Gordon

[@khj5582]

​@@starrapid Thank you, Gordon. However, I would like to know more about the different capabilities of these two molding techniques. For example, I assume that for 2K, since the second shot happens immediately after the first shot, and before the first shot has been completely cured, the second material will stick better to the first material as opposed to overmolding, where the first material has been cooled down for a day, before commencing the second shot? Does that mean that 2K allows for a greater range of second shot materials like silicon, nylon, ABS and maybe even PC? Someone told me that the second material can only be TPE/R/U, but I assume that applies only to the overmolding technique? As a designer, if I want the soft feel of silicon rather than TPR, and the factory tells me it can't be done, I can reply back that "this can be done with the 2K method, so I suggest 2K, not overmolding"? Also, I would like to know, since 2K seems more versatile than overmolding, but more suitable for high volume production, if the same parts can be achieved with overmolding. For example, I've seen pictures of 2K parts of plastic buttons, like a numpad, with an additional plastic mechanical part on the inside of each key which was done as the second shot. Can this type of part be done with the overmolding technique?

[@lisasnow3346]

has anybody ever used insert molding multiple parts? and how do you hold the insert into the mold

[@philadams493]

there is no reason for the insert to fall out, the processes is smoother than most realize, the treads on an insert are not all over the place either usually within + .001 to .003 lastly is the if the insert is metal, it can rest on a post that has been magnetized

[@harendratharu1936]

I have for 3 years experience injection moulding

[@starrapid]

Great :)

[@kamgangmei4075]

Fascinating. Wanna work in star Rapid.

[@starrapid]

Please go through our career page for openings :)

[@stozov2]

Let's say you overmolded on metal parts with wrong plastic...Anyway to remove coating that surrounds part

[@Cattabitcat]

Please make a Quality thumbnail than the current one. Becuase video is really good but the thumbnail looks quite cheap which made me click other videos other than this.

[@starrapid]

Thanks for the suggestion, we will take it into consideration :)

[@bikepacker9850]

What do i just watch?

[@willemverheyen2345]

Overmolding or (co-extrusion) is mostly used to combine hard plastics with a rubber. Its a big shame, because these products cant be recycled properly.

[@makerstem]

They also tend to react chemically over time and degrade. That's my experience at least.

[@tankc4103]

👍