Overmolding alternatives, especially for tools

Every time I see a hand or power tool, it’s almost always overmolded in a few places, especially the grip. The problem is, overmolding prevents recycling at the end of the product’s life cycle. Are there any good alternatives to this process? If I were designing for DeWalt/Bosch/Makita/etc., what’s the most environmentally-friendly way to accomplish the same thing?

Going to be extremely difficult to reproduce the same qualities. Overmolds are often chemically interlocked and mechanically interlocked. Essentially making the two inseparable. Its also the most economical way to get soft gripability and the strength of the main plastic body in large volumes. Trying to recreate that while also maintaining the design is pretty damn hard short of having a bunch of tight fitting orings wrapped around the grip. Might work but doubt would fit your design vision. Instead of trying to duplicate the process try exploring the materials. Maybe there are some bio friendly soft and hard compatible materials.

ditto studiomkllc, looking into alternative materials for something less obnoxious is a good baby step.

I’ve struggled with this in my industry as well, and we’ve made some headway in replacing overmolded self-skinning urethane foam parts with injection molded parts that performed better. But that’s not what you are talking about.

The shock absorption, tight fit, color matching, and low cost for volume manufacturing are the attractive parts of the Santoprene elastomer overmolding. Even if you broke out the grip parts into a smaller assembly (thus being able to recycle the larger components) you’d still be wrestling with more screws/bosses/cost… and does the customer really care anyway?

Maybe there’s some paint or spray deposition type process that would be ok.

Yeah lets be honest this is the dirty secret about ID. A lot of the materials we use have such varied an amazing qualities: grip, texture, detail, color, economics, but atleast from my experience they are all toxic and less than ideal for the environment. I actually did work in school on injection molding bio resins. Given that was 7 years ago things may have changed. What i found was some good resins but most were either too expensive, couldnt retain pigment, had major mold flow issues or just ended up looking terrible.

Sorry less than helpful!

You have polyurethane plastics that can span from the elastomer area to the plastic area of shore hardness.
So a core of hard polyurethane overmolded with soft polyurethane would make it recycled as one piece of polyurethane.

The short answer is no, and most of these tools don’t end up in a recycling-friendly supply chain at the end of their life anyways. Even if you designed something that could be disassembled, end users won’t disassemble it, most areas don’t have e-waste recycling programs, and the manufacturers (at least to my knowledge) don’t offer any type of take back or recycling incentives. The price of shipping a drill back to a manufacturer would likely be higher than the material gained back in recycling.

But that’s just our planet and the moral conundrum of being a person who makes things.

No, the customer doesn’t care–I do! (And so does Mother Nature.) I see what you’re saying, though. Ultimately those workarounds add complexity and reduce overall product performance.

Very interesting, I never thought about that. This could be a good option if it’s feasible. I’m going to dive deeper into this.

New material technologies are always going to be more expensive at first, though… I’m willing to at least investigate the cost for the sake of comparison. As for the other issues, those are certainly a deterrent. Biotech has made huge strides in the last 7 years though, so let’s hope things have changed!

None of those problems are insurmountable, though, are they? And the solutions need to start somewhere. Lawmakers need to do their part to improve recycling programs, and designers need to do their part to design for recycling and educate users. It feels like sort of a cop-out to blame the existing systems and users; we’re all guilty of doing it.

No one is forcing you to use overmolded parts. If this design for disassembly & recycling is a priority, you could make housings from metal, or from rigid plastics that are only assembled. You can also petition your company to start an internal recycling/refurbishing process.

The reality though is in most cases, sustainability falls too little too late. The government can’t even agree on global warming, you can petition your local municipality for an e-Waste recycling program, but even with that the reality is we ship 90% of that waste to China, where they just tear it apart with zero regard for the earth.

As long as some country is willing to take our garbage, we will never have incentives that make this viable from a business perspective. It will most likely take the dystopian future where the sun gets blocked out from the smoke clouds and we’re all regretting our decisions to fuel consumerism.

No one is forcing me personally to use them–but I’m sure designers at major tool brands are being told they need to overmold because their competitors are doing it. And there is a quality increase. Shock absorption, for example.

All good points. If/when we get to that dystopian future, I just want to be able to say I did the best I could, you know what I mean? E-waste is a whole other can of worms. I don’t even know where to start with that. Frankly, it’s probably a much bigger issue than overmolding, given the types of chemicals you find in e-waste.

Yes…you have to keep trying, we all have to keep trying. It might not be this go-around, or the next, or the tenth. I don’t know the magic bullet, or I would tell you. When I ask “does the customer care” its because those intentional design choices have a way of finding themselves on the bottom line of profitability, and many times its a matter of cents that make these projects actually go to market or not. But when you feel strongly about something, you have to keep pushing and trying to find a way to make it happen.

In 1995 I did a school project on a completely modular music system, where individual components (CD transport, tray, PCB, power supply) were individual parts. It made the most sense to me at the time. Fast forward 20 years and CE companies are still investigating projects like this (Google Aura).

One day we will figure it out.

Thermoset polyurethane is not recyclable.

Thermoplastic polyurethane is a class 7 recyclable. Meaning no one recycles it. I would say, while expensive, it is most definitely less toxic and “better” for the environment than PVC.

Also, my experience with TPUs is mostly breathable films.

Is there a TPU that would be rigid enough for a drill housing?

Good point. But to be honest I don’t believe in recycling plastics, the properties degrade too much after recycling and there are almost no pure plastics today. Most of the plastics used in the industry and consumer products are a mix of many different plastics. But there are exceptions, PET bottles are quite successful and have a high yield of recycling.

Even we swedes who recycle everything, end up using plastic for fuel in our combined heat-power biomass plants. It is more economical and more environmentally effective then to refine and ship the plastic back to china for new products.

And I don’t see the problem to take it one step further, why bother separating the parts of a cordless drill when you can grind everything down to dust, separate the metal, burn the rest and continue to separate the untouched materials in the ash. Products made entirely from one type of material especially glass, wood/paper, plastics such as PET or metal should still be recycled separate because of the high yield.

Designers should focus on design - recycling plants on recycling.

Although this sounds like “throw it over the wall, its not the designer’s problem”, I think its a valuable perspective. Designers can reasonably hope to control only their front-end activities and some of production. Of course being able to spec materials that could be ground into dust or combusted more readily would be the responsible angle for a designer. But your statement reminds me of one of our VP’s constantly saying that product development cannot and should not be perceived as the Heroes coming to save the damsels in distress (operations, marketing, etc.) and instead doing our job as best as possible.

I had a marketing person tell me to make the plastic product bigger and “greener” in the same sentence.

Boggles the mind.

This crosses into the “ethics of being a designer” but I suppose there’s a certain extent at which you have to decide which battles you pick.

For example - you are fighting for a greener strategy on the overmold, but what about the lithium ion batteries which are also going to most likely end up getting thrown in the trash to eventually leach heavy metals into the earth? Overmold won’t break down, but it also is going to do a far less impact to the environment and can at least be burned.

We see Tesla’s as the green car, transportation of the future. But we blindside ourselves to the amount of energy needed to produce a new car in general, and the massive amount of batteries we’ll be dumping into the ground 5 or 10 years from now when your car won’t hold a charge. The environmental impact of issues like that suddenly makes you think “is this overmold the battle we need to win? or is it just the battle I feel like I can pick and feel good about”.

I would argue if that is your passion, there are plenty of areas where you can focus that energy. My sister in law is a green-architect who left her job entirely to focus on pushing for recycled and green materials in building construction. But I can tell you as a jaded designer that spending a decade making widgets means most people are going to sound like Slippy’s VP who realize that most of these are goose chases that won’t change the way consumers buy product, or the reality is the best product should be one that is designed and built to last forever - there’s a reason so many people say “they don’t make them like they used to”. My 4 year old, $600 Dyson just broke because it was made of plastic, but my mothers 1970’s electrolux still works like a tank. If Dyson cared about sustainability they’d build things that are tanks and that can be easily repaired, but unfortunately that’s not as profitable or sustainable business model.

I like the term “hand-picked hypocrisy” (apologies to G -Love).

Its a noble cause, which ever of the battles you might pick, whether ridding the world of toxic non-recyclable overmolds, or discarded Tesla batteries.

And on a more meta-jaded level, whatever you can sell as being an environmentally better or energy-efficient solution will net you personally the most benefit (see Fuseproject Juno C1 for one example).

To the original poster,

As a long time power and hand tool designer (I’ve designed tools for B&D, DeWALT, Craftsman, Ryobi, AEG and many others), I can tell you we’ve tried everything under the sun to provide enhanced grip and tactile feel outside of overmolding - often for various reasons aside from recycling. I tried to be a driving force for recycling / reuse/ end-of-life disassembly during my 12 years at B&D but my efforts were never embraced.

Many of the comments above (ie, users won’t disassemble it anyway) are sadly true but don’t let that stop you from trying, as we will only change the perceptions and actions of users with constant reinforcement of a more responsible way to do things - and it’ll take generations to do so.

We need first of all a good idea of how to prioritize global sustainability programs.
And we need more and more innovation and education geared towards the reprocessing phase.

Overmolding is a superior technique, although for many applications you can find ways to join the flexible and rigid part separately for disassembly, like stretching it over a flange or over the entire product. Also flexible bioplastics are already available and further in development. Then again it will be more long-term thinking if there can be a process to melt and regrind the plastic so the elastomer/silicone is left from the overmolded product. We can always process rest material into materials such as bricks and leave them in static structures until we can reprocess them in the future in a more advanced way.

Petro Chemicals aren’t recyclable, they are only downcycled and destined either for burning or dumped. One alternative is PLA, it works fine as long as it is kept away from long exposure in the elements, like iron. I’m 3d printing working parts with it and they work perfectly well, if not better than ABS.