Making Injection Molding Price-Efficient: How Many Items Do You Have to Order?

Injection molding is usually described as an economical manufacturing course of… when ordering giant portions of components.

The rationale for that is easy: with injection molding, the preliminary tooling prices are very excessive, whereas the precise plastic molding prices are very low, which suggests the efficient cost-per-unit turns into decrease when extra items are required.

For instance, think about that a stainless-steel mould for a toy automobile prices $5,000, and every plastic toy automobile made with the mould prices $zero.50. On this state of affairs, ordering 1x unit of the toy automobile would price $5,000.50, ordering 2x items would price $5,001, and ordering 1,000x items would price $5,500.

In the entire situations, the mould accounts for the majority of the price, so the entire price doesn’t differ enormously.

Nevertheless, in these three situations, the efficient cost-per-unit does differ enormously:

State of affairs by which mould prices $5,000 and every molded half prices $zero.50

Whole price ($)
Price-per-unit ($)





As you may see, there’s a dramatic discount in cost-per-unit when the unit amount will increase, for the reason that additional items amortize the excessive price of the mould.

Ordering extra items of the toy automobile clearly represents higher worth for cash. (In truth, ordering a single unit would look like a colossal waste of cash.)

However simply how “giant” will we imply once we say that injection molding is suited to giant portions of components? 100? 1,000? 10,000? One million? As an organization deciding between a number of manufacturing processes for a medium-size order of prototypes or end-use components, we wish to know at what level injection molding turns into less expensive than the alternate options similar to 3D printing.

And whereas there is no such thing as a easy system for figuring out the purpose at which injection molding turns into less expensive than 3D printing, there are particular components we are able to take note of that can assist us make the appropriate choice.

3ERP, an professional in injection molding and different on-demand manufacturing companies, right here gives recommendation on selecting between injection molding 3D printing primarily based on the required order measurement.

Injection molding vs 3D printing: First issues

For firms seeking to full prototyping or manufacturing of plastic components, each injection and 3D printing could look like tempting choices, and it could appear onerous to weigh up the respective advantages of every.

Making Injection Molding Price-Efficient: How Many Items Do You Have to Order? 1

Nevertheless, earlier than stepping into any exact calculations, it’s price stating some conditions the place one manufacturing course of is clearly preferable to the opposite.

Let’s begin with a state of affairs by which an organization wants a really small variety of prototypes (maybe only one), and the fabric and aesthetic properties of the prototype(s) are of negligible significance. Maybe the in-house R&D crew merely needs to see, very loosely, how a yellow plastic casing appears on its new digital machine.

In such a state of affairs, 3D printing can be the clearly preferable selection: it will be considerably cheaper, and any technical deficiencies within the prototype wouldn’t matter.

Alternatively, think about a state of affairs by which only a handful of prototypes (maybe only one) are wanted, however the firm is seeking to pitch its product to an investor, who must be satisfied that the end-use half (to be made with injection molding throughout mass manufacturing) will operate correctly for its supposed function.

In such a state of affairs, whereas 3D printing the prototype could also be cheaper, it’d nonetheless be worthwhile for the corporate to create an injection molded prototype as a way to display the viability of its end-use product.

Key financial variations between injection molding & 3D printing

It’s tough to check the prices of injection molding and 3D printing as a result of the processes are basically completely different — not simply by way of how they work, however in how their respective prices are decided.

Basically phrases, injection molding is a course of with excessive startup prices: metallic molds are costly to make, and that preliminary step could be an insurmountable hurdle for some small companies. Nevertheless, as soon as a mould has been fabricated, the price of every injected “shot” of plastic could be very low.

Making Injection Molding Price-Efficient: How Many Items Do You Have to Order? 2

3D printing is completely different as a result of, not like injection molding, it’s a one-step course of. No tooling is required, and the completed half comes straight out of the printer. This implies there aren’t any obstructive startup prices.

That being stated, the price of a single plastic 3D printed half is mostly larger than a shot of injected plastic. It’s because 3D printing filament (for FDM printers) is dearer than plastic pellets, and since the sheer slowness of 3D printers signifies that service suppliers should cost extra for his or her operation.

With that in thoughts, essentially the most significance distinction between the 2 processes is that the cost-per-unit of injection molding is dynamic: it decreases because the variety of items will increase. With 3D printing, then again, the cost-per-unit is static: components will normally price the identical quantity whether or not you order one or 1,000 of them.

Because of this 3D printing in small portions is cheaper than injection molding, whereas injection molding in giant portions is cheaper than 3D printing. That additionally means, logically, that there’s some particular amount at which the “greatest worth” choice switches from 3D printing to injection molding.

Discovering that amount is determined by a number of components.

What number of components to be cost-effective: Elements to think about

The mould

When evaluating the potential prices of injection molding and 3D printing, it’s price beginning with probably the most costly a part of the challenge: the mould.

Molds can price hundreds of , since they’re machined from metallic and must final a very long time — probably lots of of hundreds of plastic photographs. Nevertheless, it’s potential to drastically cut back the price of molds by means of fast tooling, the creation of prototype-grade molds with CNC machines or metallic 3D printers.

The price of molds will also be decreased by utilizing aluminum as an alternative of metal. Aluminum is much less sturdy than device metal, however remains to be able to producing high-quality molded components from non-corrosive supplies.

If the price of the mould could be decreased, the variety of molded components required to be cost-effective decreases.

For example, think about that a metal mould for a toy automobile prices $5,000, that an aluminum mould prices $1,000, and that the price per plastic shot with both mould is $zero.50. Think about, additionally, that a 3D printed model of the toy automobile prices $20.

On this instance, the potential prices of the challenge can be as follows:

Metal mould IM
Aluminum mould IM
3D printing

Whole price ($)
Price-per-unit ($)
Whole price ($)
Price-per-unit ($)
Whole price ($)
Price-per-unit ($)







On this state of affairs, a 50-unit order is cheaper with 3D printing, however a 60-unit order is cheaper utilizing injection molding with an aluminum mould. (In the meantime, the dearer metal mould turns into less expensive than 3D printing simply above the 250-unit mark.)


One other consideration that can have an effect on the calculation is the plastic used to make the half, and there are a number of variables to think about right here.

One issue to think about is that not all 3D printable plastics are moldable, and vice versa. One other is that 3D printing filament is by and enormous, dearer than the plastic pellets used for injection molding, because it have to be exactly formed by the fabric producer.

Importantly, the price of plastics will not be constant between pellet and filament codecs: supplies like Nylon and Polycarbonate, for instance, stay comparatively premium merchandise within the 3D printing filament market, so a comparatively small variety of Nylon components can be required to make injection molding less expensive than 3D printing. (A standard 3D printing materials like ABS, nonetheless, would require a a lot bigger quantity.)

The kind of plastic used to make the components could subsequently decide which manufacturing course of is extra economical for a given order quantity.

Half form and measurement

The design of the half may have an effect on its potential price for injection molding and 3D printing. An element with overhangs, for instance, could also be considerably cheaper to 3D print, since injection molded components with overhangs require extra complicated tooling.

In different phrases, in case your half design is just not suited to injection molding, you’ll in all probability must order extra components to make injection molding cost-effective.

Manufacturing course of

FDM stays the commonest 3D printing course of, however various choices embody Stereolithography and Selective Laser Sintering. These different processes are dearer than FDM, which naturally impacts their affordability as compared with injection molding.

For instance, 200 FDM components could also be cheaper than 200 equal injection molded components, however 200 SLS components could also be dearer than 200 injection molded components.


Because the cost-per-unit of plastic components is dynamic for injection molding and static for 3D printing, it may be tough to evaluate which choice is the perfect worth for cash for a given order.

Quite a few components, together with mould creation, half materials and half form can have an effect on the price of the order — and to completely different levels relying on the manufacturing course of.

With that in thoughts, the perfect answer to the dilemma could also be merely requesting a quote for each processes.

3ERP has experience in each injection molding and 3D printing, and might assess tasks on a case-by-case foundation to see which represents the perfect worth for cash.

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