Will 3D Printing Eliminate Injection Molding? · tools suitable for injection molding up to 1,000 parts. We also elicited injection molding piece-part prices based on the production

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Will 3D Printing Eliminate Injection Molding? I S 3 D P R I N T I N G PA RT S A V I A B L E A LT E R N AT I V E T O I N J E C T I O N M O L D I N G

This white paper considers the potential for using the Stratasys Continuous Build™ 3D Demonstrator (SCBD), a novel configuration

of scalable hardware and cloud-based software, as an alternative to injection molding. Centered on a detailed review of four

functional component parts manufactured in ABS plastic, the economic implications of using the Demonstrator will be compared

to the more traditional injection molding process, using hard tooling. The paper considers the economic and lead time breakeven

points below which 3D printing may now be more favorable. Also, the longer term implications of using 3D printing for ongoing batch

production and spare parts manufacture will be explored, as compared to the more traditional approaches of either warehousing or

injection molding tool storage, refurbishment and reuse.

Will 3D Printing Eliminate Injection Molding? I S 3 D P R I N T I N G PA RT S A V I A B L E A LT E R N AT I V E

T O I N J E C T I O N M O L D I N G

EXECUTIVE SUMMARY

This paper shows that for volumes below 2,000

units, fused deposition modeling (FDM), is now a

more cost-effective production process and has

a shorter lead time than injection molding (IM), for

certain small parts. The paper shows that in some

cases for small parts, the economic breakeven

can now exceed 8,000 units, making FDM a

viable alternative for a large number of plastic part

use cases. Moreover, for some small parts, the

SCBD process may now be quicker than injection

molding, irrespective of the volume of parts

needed. For the parts reviewed in this paper, a

74% cost saving was demonstrated by using FDM

along with an 86% reduction in supply time.

INTRODUCTION

3D printing was a technology originally

conceived to support and accelerate the product

development process, and as a way of making

realistic and rapid prototypes directly from 3D

CAD data. As the technology has matured over the

last 25 years, the number of applications for the

technology has grown. Today, 3D printing is used

to make jigs and fixtures, casting patterns, tooling

and an ever-increasing array of low volume, high

value component parts.

Whenever discussion turns to 3D printing plastic

component parts, one of the most common topics

always centers around when 3D printing will

compete with injection molding. Of course this

is a challenging question, and one that has

been mostly bypassed by the 3D printing

community in the past. The question has largely

been one of value, and at what build numbers

3D printing overtakes injection molding from a

cost standpoint.

Injection molding gives you very low cost parts at

high productivity rates but with significant up-front

capital investment in tooling with the associated

tool-making lead times. 3D printing, on the other

hand, gives you quick production turnaround with

no tooling investment, but with higher part cost.

Unfortunately, a process which fuses the

advantages of both IM and 3D printing, delivering

high productivity, quick turnaround with attractive

part costs has been elusive.

CNC machining and tooling have made some

progress in part manufacturing, but this approach

is still constrained by needing both tool making

and injection molding capabilities in close

proximity. It also requires commitment, as once

a tool is cut, design iterations can be both costly

WILL 3D PRINTING ELIMINATE INJECTION MOLDING? / 2



and time consuming. In short, a manufacturing

gap has existed for companies needing high

volume, low-cost parts with rapid turnaround time.

Also, the problems of injection molding are not

only constrained to initial part manufacture,

but can continue through the supply chain.

Warehousing, or the storing of parts ties up

working capital and results in end-of-life write-

downs. Also, parts needing to be molded just-in-

time, with the resulting disruption of production

runs, pushes up the cost of production. These

limitations provide a strong reason to look to other

manufacturing technologies for part production.

3D printing is capable of producing high-quality,

repeatable parts from a range of thermoplastics,

including ABS, PC and Nylon, and high-value

engineering polymers such as PEI, PPSF

and PEKK.

3D printing has the additional advantage of part

cost not being tied to part complexity. Complex

injection molded parts require expensive mold

tools, driving up costs. Conversely, in additive

manufacturing, complex geometries can actually

be cost-saving. In short, both 3D printing and

injection molding have their advantages. Figure 1

details these benefits and disadvantages to date.

This paper will now look to quantify which

approach is best for a series of example

component parts.

BENEFITS (PROS) DRAWBACKS (CONS)

Injection Molding • Faster time-to-part • Accurate and repeatable• Low raw material cost• Wide variety of materials• Uninterrupted production process• Readily available, low-cost hardware

• Time-consuming tooling build process• Up-front tooling costs• Production limited to tooling location• Requires warehousing and capital outlay• Tooling requires storage• Costly design iteration• Part complexity directly linked to tool cost

3D Printing • Nearly unlimited geometric freedom• Part cost not dictated by complexity• Access to CAD design files• Zero tooling investment• Zero iteration cost • Downtime in production cycle

• Slower process for each part made• Capital expenditure for 3D printer• Limited accuracy and surface finish• Limited pallet of available material• Higher cost materials

Figure 1: Benefits and drawbacks of FDM compared to injection molding.




SO WHY MAKE THIS

COMPARATIVE ANALYSIS NOW?

Occasionally, there is a leap in technology that

causes us to re-evaluate the status quo. For many

years we have been dismissing 3D printing as

a viable alternative to injection molding, largely

based on the three core elements of quality, cost

and delivery (QCD), which are detailed in Figure 2.

However, with the new Stratasys Continuous Build

3D Demonstrator, many of these constraints have

now been challenged or removed, as detailed

below in Figure 3.

WHAT IS THE STRATASYS

CONTINUOUS BUILD

3D DEMONSTRATOR?

The Stratasys Continuous Build 3D Demonstrator

is a smart, cloud-based system that allows

users to print multiple, simultaneous print jobs,

without downtime. Scalable, high quality parts are

produced with no operator intervention.

The Hardware

The SCBD solution is configured by banking one

or more multi-platform FDM production units, as

shown in Figure 4. Each production unit has three

integral FDM platforms. Each platform has a 5” x

5” x 5” working envelope onto which ABS plastic

parts can be printed. Rather than the typical rigid

and manually removable build platform seen on

typical FDM printers, the SCBD deposits material

onto a flexible sheet fed into the machine from

a roll. Once the build is complete, the flexible

sheet and part are ejected automatically from

the machine. The sheet is then cut, allowing the

part to fall into a collection bin. The machine then

automatically resets the extrusion nozzle, chamber

temperature and build sheet before starting the

next print job. The final step involves manually

placing the parts in a water wash station where the

support structure material is dissolved, leaving the

finished part.

Quality Using comparable hardware architecture and control systems found on the Stratasys Fortus® technology, highly accurate, repeatable, end-use 3D printed parts can now be manufactured.

Cost Zero tooling and a zero inventory supply chain delivers just-in-time parts in a cost-controlled environment.

Delivery The Demonstrator, with its multiple 3D print cells is driven by a centralized cloud-based architecture, and works simultaneously in a continuous stream, automatically ejecting parts for a continuous build.

Figure 3: The impact on QCD of the new SCBD process.

Quality Many 3D printed parts lack the mechanical integrity, accuracy and aesthetic of injection molded parts.

Cost 3D printed parts are expensive compared to moldings, as they are made on low productivity, high cost machines, using high-cost material.

Delivery the low build speeds of 3D printing compared to injection molding make it unattractive for all but small-volume production runs.

Figure 2: The impact of 3D printing on quality, cost and delivery.




The Software

To ensure maximum productivity and

interconnectivity, the Demonstrator utilizes

a sophisticated cloud-based print queue

management software tool. This software sends

3D data files to the print system and automatically

brokers these print jobs to the next available

production cell.

The cloud-based management system sorts

incoming data (such as STL files), and loads them

into a data stack. Printability is analyzed before

the job is positioned for the most appropriate

build orientation. Support structure is added

on a ‘virtual’ build platform. Finally, a digital

representation of the part is sliced into horizontal

layers before being added to another virtual queue

where it awaits the next available production cell.

Should a production cell fail for any reason, the

system automatically alerts the cloud management

solution, which reassigns the job to the next

available cell at that location, providing resilience

within the production process.

This cloud-based approach allows the

Demonstrator to be located within distributed

networks allowing new configurations of supply

chains and new value stream.

SO HOW DOES THE

DEMONSTRATOR COMPARE

TO INJECTION MOLDING?

To make a realistic comparison between 3D

printing and injection molding we have selected

four geometries of varying levels of complexity

that fit within the build chamber of the SCBD.

The parts in question, shown in Figure 5, are all

ABS plastic components used as production parts

Figure 4: Two different configurations of the SCBD. (1 x 3 cell unit and a 5x3 cell unit)




on the Stratasys Fortus 900mc™. For the sake of

argument, let us assume for this study that 1,000

parts are required across the product life-cycle of

the 900mc.

ARE THESE PARTS A FAIR

COMPARISON FOR INJECTION

MOLDING?

One of the larger 4” long parts can be made using

a simple injection mold tool with no sliding cores.

Inversely, the larger 5” long part requires at least

three sliding core mechanisms within the tool. One

of the small parts requires a single simple core,

while the other has a more complicated internal

socket geometry, requiring more complex ejection

from the IM tool. These parts are typical of the

many billions of small plastic component parts

molded every year.

SO WHAT WOULD THESE PARTS

COST TO MOLD AND HOW LONG

WOULD IT TAKE?

To ensure a realistic comparison, quotations from

tool makers were elicited for the production of soft

tools suitable for injection molding up to 1,000

parts. We also elicited injection molding piece-

part prices based on the production of 1,000 units.

In all cases, we asked for single impression tools

with simple heating and cooling channels enabling

an injection mold cycle time of one minute.

We received prices for tooling and part production

ranging from $8,763 for the simplest and smallest

geometry part, to $23,122 for the most complex

and largest part. In all cases, the tool-making lead

time was quoted as eight weeks from order to the

first part.

UNDERSTANDING THE

ECONOMICS OF FDM

In order to calculate the part cost of using

the Stratasys Demonstrator, we first need to

establish the cost of the machine and the

resulting depreciation of the asset per hour of use,

along with a cost for the raw material consumed

per part.




MACHINE PRICE

It is difficult to put a cost on the SCBD, as it is

currently a technology Demonstrator, rather than

a commercially available machine. However,

by looking at other similar size build platform

Stratasys technologies, we can make some broad

assumptions on possible machine cost.

Figure 6 below shows the relative cost of the

Stratasys Mojo™ and uPrint™ 3D Printers, both of

which have similar build envelopes to the SCBD.

For this analysis, we are using a 9-unit SCBD,

for which we will use a projected hardware cost

of $87,745.

MATERIAL PRICE

Given that the SCBD is intended to support

high volume, mass production, it is important

that the material price allows for this, as it will

be competing with thermoplastic injection

molded polymers.

For this analysis we have used a material price

of $167 per Kg based on the mean of the current

uPrint ABS material price and the price of ABS

used on the entry level desktop MakerBot

Replicator II, as shown in Figure 7.

BUILD TIME

Given the configuration of the SCBD process,

there is little to no productivity gain achieved by

filling the machine bed with parts. As such, we

have based our analysis on the SCBD, producing

one part at a time, within each production cell

(based on a 9-cell configuration), and allowing an

additional 2 minutes between builds for the parts

to be ejected and the machine to restart.

For the parts within this study, build times

ranging from 23 minutes to just over 4 hours

were recorded.

HARDWAREMOJO (LIST)

MEAN COST

UPRINT (LIST)

single unit $5,599 $9,749 $13,900

9 units $50,391 $87,745 $125,100

Figure 6: Calculating a hypothetical machine cost for SCBD.

MATERIAL (ABS)

MAKERBOT (LIST)

MEAN COST

UPRINT (LIST)

Per Kg $42 $167 $292

Figure 7: Calculating a hypothetical material price.




ESTABLISHING THE PART COST

Having established the machine and material cost and the build-time per part, we can now calculate the

piece-part cost using the SCBD. Part cost is a function of the material used (part and support), the machine

purchase price, (depreciated over a known period), pre- and post-process labor, machine utilization, service

costs, the time taken to print each part and associated operational overheads, such as power.

The figures used in our analysis are shown below in Figure 8.

DESCRIPTION VALUE

Machine cost (9 cell configuration) $87,745

Build materials (per Kg) $167

Support material (per Kg) $167

Capital depreciation period (years) 7 years

Utilization 85% uptime

Power consumption per cell 1.2Kw max

Power charge per Kwh $0.12

Clean-up time per part (water wash) 1 minute per part

STL file preparation Automatic

Operational period 24/7

Labor availability 1 x 8 hour shift

Excluded overheads Land cost or facility rental, indirect labor, QA, dispatch, maintenance

Figure 8: Costs and assumptions used in this comparison.




COMPARING THE DEMONSTRATOR WITH INJECTION MOLDING

Now that we have the price-per-part and productivity data for both the SCBD and injection molding

production, we can consider both the economic and volume breakeven point for each example part.

Figure 9 shows the total cost of production against the unit volume production for both injection molding and

SCBD for the largest of the parts considered.

Figure 10 shows the lead time of production against the total number of parts produced using IM and the

Demonstrator for the largest part considered.

SCBD IM

Tota

l Co

st o

f P

rod

ucti

on

Unit Produced

$14,000

Cost Breakeven

$12,000

$10,000

$8,000

$6,000

$4,000

$2,000

1,000 2,000 3,000 4,000

$-

-

Figure 9: Unit volume against total part cost.

SCBD IM

Lead

Tim

e In

Wee

ks

Unit Produced

12

Time Breakeven

10

8

6

4

2

4,000

$-

- 3,5003,0002,5002,0001,5001,000500

Figure 10: Lead time breakeven for SCBD and IM.




Figure 9 shows that for this part example, FDM

is more cost effective up to approximately 2,100

units of production. Also, a savings of $5,969 is

observed with the Demonstrator in a 1,000 unit

production run over injection molding. Moreover,

as shown in Figure 10, in the production of 1,000

units, FDM is 5 weeks faster than using the more

traditional injection molding process.

As can be seen in Figure 11, all four of the parts

selected for this study can be printed more cost-

effectively using the Stratasys Continuous Build

3D Demonstrator, over injection molding, based on

the unit volume required.

For the largest part, the economic breakeven is

2,112 units, over twice the volume required. For

the smallest part, the economic breakeven is

over 8,700 units. The Demonstrator supply chain

provides a cost saving of $42K across these four

parts. This is equal to a 74% total cost savings.

Finally, the lead time for 1,000 unit production has

been cut from over eight weeks to as little as two

days using the Demonstrator. This is an overall

lead time reduction of 86% across the four parts.

For two of the parts detailed in Figure 11, FDM

may be a more productive solution than injection

molding, irrespective of the volumes required. It

may in fact be faster, given that our comparison

is based on single shift IM with a one-impression

tool, compared to 27/7 FDM (@ 85% utilization)

using a 9-cell SCBD.

1,000 OFF SCBD IM

Time 3-weeks 8-weeks

Cost $6,024 $11,993

Saving $5,969

Breakeven (t) 3,452 units

Breakeven ($) 2,112 units

1,000 OFF SCBD IM

Time 2-days 8-weeks

Cost $1,627 $8,763

Saving $7,136

Breakeven (t) Never


1,000 OFF SCBD IM

Time 2-days 8-weeks

Cost $1,781 $12,122

Saving $10,341

Breakeven (t) Never


1,000 OFF SCBD IM

Time 6-days 8-weeks

Cost $4,495 $23,122

Saving $18,627

Breakeven (t) 20,618


Figure 11: comparison of SCBD and IM for all four parts selected




WHERE ELSE COULD FDM

PROVIDE A QUANTIFIABLE

BUSINESS BENEFIT OVER IM?

It is apparent that for the production of small

parts between 1,000 and 8,000 units, FDM can be

both faster and lower cost than injection molding.

FDM also has one other advantage over injection

molding that should not be overlooked, as this

could push the economic breakeven out even

further in favor of FDM.

FDM is digital, and as such, it can be turned on

and off at will, with zero cost penalty. But why

should this matter?

The example parts in this white paper are very

typical of plastic molded parts the world over

and can be manufactured more quickly than

demand necessitates, once tooled. In this case,

1,000 parts are molded in a matter of days,

which will suffice for both the life time production

of the Fortus 900mc model and the long tail

spares requirement.

So let’s assume that the current model of the

Fortus 900mc using these parts is marketed,

assembled and sold for 5 years, and is then

maintained by Stratasys for an additional 10 years.

Many of the 1,000 parts will then sit in storage for

up to 15 years. Therefore, warehousing costs need

to be factored into the price per part life-cycle.

Many companies choose to warehouse their own

parts on site, but this is not always the leanest

way to operate as a business. Moreover, within the

spare parts supply chain, centralized warehousing

may not be the most customer-centric model.

For these reasons, some companies choose to

outsource warehousing and logistics to a third

party supplier.

SO WHAT DO OUTSOURCED

WAREHOUSING AND

LOGISTICS COST?

If we look at the parts in this study, all 4,000

components could be stored in small bins or

boxes and placed together on a single pallet.

Many companies offer a long-term part storage

and distribution solution where goods are received

in bins on pallets, catalogued and stored for a pre-

agreed period of time. Scheduled ‘picks’ can then

be arranged to remove a pre-determined number

of parts from the pallet at given intervals. To ‘pick’

less than 50 parts from a four-bin pallet, including

1 Please note: The 1,000-unit volume of Fortus 900mc machines referenced in this case study is for representation purposes only.




storage and dispatch, would cost some $25

per month. Over the 15 year life cycle, this could

add as much as $4,500 to the cost of the IM

supply chain. Moreover, there may also be a

disposal fee for any parts left in stock at the end of

the contract period.

The Stratasys Continuous Build 3D Demonstrator

enables a zero inventory supply chain. Products

can be sold, then produced. The continuous

stream of parts, with nearly no operator

intervention, enables just-in-time parts.

WHERE ELSE COULD

INJECTION MOLDING TRIP US

UP AGAINST FDM?

If it costs money to store mass-produced parts,

why not just mold them in smaller batches?

Not only would this mitigate storage, it would also

help address some of the problems associated

with the supply chain. For example:

• If demand for a product is greater than

expected, will there be enough parts in stock?

• If forecast spare part demand exceeds the plan,

will we be able to support product?

• If forecast spare part demand does not manifest,

will there be unused parts to write off?

These questions can be mitigated by utilizing

existing tooling for short run production. However,

this may also have some hidden cost penalties.

Firstly, although many injection molders will gladly

store tools, they cannot simply put these back

onto a machine and start making parts.

To protect the tool surface, tools are often

treated with an oil or wax coating prior to storage.

These coatings must be removed and the tool

polished. Sliding cores and ejector pins must have

their articulation checked and any sieved parts

must be lubricated. This all takes time and will

typically cost $500 to $1,000 to go from stored

tool to working tool and be bolster-aligned on an

IM machine.

Once in production, it is also worth noting that

injection molders will charge a significant premium

for very low (sub 1,000 unit) runs. In the case of

the parts in this study, IM piece-part prices were

seen to increase by over 60% in this scenario.




CONCLUSION

Injection molding has long been the industry leader for small part production, despite its significant up-

front tooling costs and long production cycle. Additive manufacturing on the other hand, has brought rapid

prototyping and design complexity-without-penalty to the table, but has lagged in repeatability, cost and

speed. These factors have placed additive manufacturing squarely behind IM, for all but the smallest volume

production runs.

The introduction of the Stratasys Continuous Build 3D Demonstrator, with its cloud-based management

system, scalable output and ability to meet just-in-time production demands, has repositioned additive

manufacturing as the industry leader for the purposes of the four ABS plastic components used for

comparison in this paper. In comparisons of four small parts, the Demonstrator surpassed IM in the categories

of quality, speed and cost. Specifically, for volumes below 2,000 units, AM is now shown to be a more

cost-effective production process. In some parts, the breakeven point can now exceed 8,000 units. The

Demonstrator supply chain provides a 74% cost savings over injection molding and 1,000 unit production had

been cut from over eight weeks to roughly two days, resulting in an 86% reduction over the four parts.



About the authors

Dr. Phil Reeves is Vice President of Consulting

at Stratasys, and has worked in the field of

additive manufacturing for over 20 years. He was

the founder, managing director and principle

at Econolyst Ltd. until Stratasys acquired the

company in 2015.

From health care to warfare, gaming to consumer

goods, and recreation to education, Reeves has

worked with organizations worldwide, to integrate

3D printing for maximum impact.

Loic Le Merlus is a senior consultant with

Stratasys Expert Services and has worked in the

field of AM consulting for over 7 years. He holds

a Master’s Degree from Lancaster University with

a focus on the selective laser sintering process.

Merlus specializes in big data analytics, data

manipulation and cost modeling.

Acknowledgements

The authors would like to express their sincere

thanks to Roger Neilson, Jr., from In’Tech

Industries Inc., for his invaluable insight into the

lead times and cost of injection mold tooling and

molded parts.

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Documents

Will 3D Printing Eliminate Injection Molding? · tools suitable for injection molding up to 1,000 parts. We also elicited injection molding piece-part prices based on the production