Digital Manufacturing

Protolabs Insight: Creating Greener Parts

Monday 23 August 2021, 2:08 PM

7 Minute Read

The Protolabs Insight video series will help you master digital manufacturing.

Every Friday we’ll post a new video – each one giving you a deeper Insight into how to design better parts. We’ll cover specific topics such as choosing the right 3D printing material, optimising your design for CNC machining, surface finishes for moulded parts, and much more besides.

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Insight: Creating Greener Parts

Transcript

Hi and welcome to this week’s Insight video.  Today I’m tackling a topic that is becoming more important with every year that passes – how can we create greener products and parts?

I really wish at this point that I could give you a definitive answer to this one, but the truth is creating greener parts depends on a number of different factors.  And some of these factors may contradict each other, so there are times when you’ll need to make a judgement call.

So, the easiest way to look at this is to work my way through a list of different factors that could make that part greener, more sustainable and save carbon. To do this I think we need to trace a product from raw material right through to end of life and consider how much energy it consumes along the way.

I’ll begin right at the beginning, selecting the right amount of the right material.

I’m going to focus on two of the most common types of materials used – plastics and metals. Of course, there are hundreds of each so let’s try and get some metrics that will fit our green agenda.

One important concept that you won’t generally find quoted on a material’s datasheet is embedded energy. The embedded energy of a material is all of the energy taken to produce a certain quantity of it.

A quick search on google reveals that a kilogram of aluminium extracted from bauxite will take between 227 to 342 mega joules of energy to produce.  A typical plastic from crude oil would be 82 to 108 mega joules.  As always there is a but, a kilogram of recycled aluminium will take just 11 to 17 mega joules.  So even here you need to delve a bit deeper for answers.

This leads me rather neatly onto how much material you use.  If you use less, then you are using less embedded energy, but when you begin manufacturing you also need to factor in manufacturing and delivery into the final parts’ embedded energy calculation.

Sadly, it’s not simply a question of looking at embedded energy though. Increased manufacturing can make massive in-service savings.  For example, in the aerospace industry grams of weight saving can save kilos of fuel over an aircrafts’ life.  Light weighting, as we know it, is also important in the automotive industry for the same reasons.  Making parts more effective, in terms of fuel efficiency and serviceability further contributes to reduced lifecycle cost.

Also let’s not forget that a product that lasts longer and does not need replacing has less environmental impact than a shorter-lived version. As an aside this can throw up some surprising results.  One organic farming group actually found that it is more environmentally friendly to use plastic crates on their farms instead of wood when they factored in the number of times they used them.

This begs the question how can you make your products and its parts more durable and/or lighter?  The answer of course is to prototype, test and reiterate your design.  When you get it right you will give your customers a better performing product that will save them costly replacement, repair and servicing costs – which in turn cuts down the lifetime energy and monetary costs for them.

Manufacturing technology really helps here.  Rapid digital manufacturing technology makes rapid prototyping, well … even more rapid.  You can upload a CAD and have a prototype delivered in as little as a day using 3D printing and CNC machining and, believe it or not, even for injection moulding.

This means you can design, test and reiterate your design for a lightweight durable product in next to no time.  It’s never been easier or faster to get it right.

Also, recent technology allows you to design components in a way that was previously not possible.  Additive manufacturing means you can produce virtually any shape or geometry that you want – perhaps a honeycomb structure to use less material and save weight.

But back to our lifetime costing analysis for a product.  We all talk about designing for manufacturability and assembly, but it’s time to also consider design for serviceability.

When you design your product think through how easy it will be to service, maintain and repair it through its life.  Think about access for spanners and other tools.  Is a part easy to replace?  Do you use helicoil for higher strength threads so that replacement does not damage the product?

Which brings me to designing for end of life.  Think about how you can make your product simple to disassemble and recycle – do you know what your WEE obligations are?

Rather neatly we have come full circle at this point.  Virtually all metals can and should be recycled.  With plastics some can and some can’t.  Also, while you could use a 100% recycled metal product, a plastic’s quality decreases each time it is reused because its polymer chain grows shorter.

The answer is not necessarily to turn to metal however, because the right plastic in the right application can last a long time and also when plastic does replace metal it often provides a lighter alternative – something that is key to saving “in use” carbon in some industries.

There is an answer on the horizon for plastics with the development of ecoplastics – but that is another subject for another video in the future.

For now, I’ll say goodbye and see you next week.


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