3D 3Dprinting printing

[Pages:5]3D printing

The three most common mistakes in 3D printing plastic gears and how to avoid them

polymer gears

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How 3D printed gears are revolutionising production and maintenance

Replacement gears in fire engine water cannons.

Bevel gear in a medication dispenser drive unit.

The large airport fire-fighting vehicles from Fraport AG use roof-mounted water cannon that change the spray nozzle angle via a servomotor during fire-fighting operations. The gears with which these servomotors work wore out after a little more than ten years in use. In order to prevent the complete motors from needing replacement, which would cost a great deal, only the gears were replaced with special gears made of the abrasion-resistant iglidur? I3 SLS plastic. These gears were manufactured for a fraction of the cost of a complete swivel unit within two days and promise a long service life at the enormous load of 5,300 litres per minute of water pressure during extinguishing operations.

For the linear drive of a separating unit in a dispenser, the manufacturer was looking for a bevel gear that would fit into a very small installation space and guarantee more than five years of service life. An individually designed and printed bevel gear made of iglidur? I3 not only passed the endurance test of 25,000 doses, but also moved along the dispenser's series production. The separating units have already been installed in about 400 devices that dispense medicines up to five times a day.

These and other interesting applications can be found at igus.eu/3d-printing-stories

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The manufacturing process

Gears in an e-bike planetary gearbox.

The e-bike's initial performance dropped noticeably after some time. The reason was heavily worn gears in the planetary gearbox. The manufacturer was unable to resupply original parts, so the customer turned to 3D printing at igus?. Precisely fitting gears made of iglidur? I3 were manufactured in close cooperation, enhancing e-bike performance thanks to their abrasion resistance.

How does selective laser sintering work? One laser instead of several expensive special tools

In order to make gears that have complex geometries with traditional methods, a whole arsenal of special tools is often necessary. The so-called selective laser sintering (SLS) of industrial 3D printers is much more economically advantageous. A coater spreads a 0.1mm-thick layer of powder on a construction platform. The laser melts the powder where the gear is to be created - with the precision of a fraction of a millimetre (?0.1mm). The platform is then lowered by the thickness of a layer and the process starts again. Layer by layer, up to 3,000 gears are produced every day in the 170x220x300mm installation space. They are usually ready to ship within 24 hours.

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Why 3D printed gears?

What are the advantages? Geometry freedom and lightweight construction

Your result Cost reduction

Machining has clear disadvantages for gear manufacture. Design engineers often have to make compromises in order to remain within their budget. The consequence: simplified gear geometries with somewhat less-thanperfect operating characteristics. Additive manufacturing without tools, in contrast, opens up new possibilities of design. You no longer have to design components to meet production requirements but can concentrate fully on the gear's feature. Greater complexity does not cause any additional costs. You can rest assured: the 3D printer can also handle extremely complex geometries and minimum wall thicknesses of 0.7mm. And you never have to provide space-wasting supporting structures as the powder that is not melted holds the gears being made in position.

More and more designers are taking nature as a model - for example, they are using honeycomb-like material recesses in lightweight construction. These bionic structures are difficult to produce with conventional subtractive manufacturing methods such as turning or milling and are associated with high waste during the machining process. For such methods, the amount of material removed is proportional to costs. The reverse is the case in additive manufacturing. The costs for 3D printing are proportional to the component volume - the more material recess, the lower the printing costs. An example: if a plastic gear has holes in it, the weight of the gear can be reduced by 45% and costs by 12%.

The more material recess, the more costeffective does 3D printing becomes.

Subtractive vs. additive

Subtractive manufacturing: compromise between design and cost due to simplified gear geometry

In general, the more complex the geometry and the smaller the series, the greater the price advantage of 3D printing. Why? Because the 3D printer needs only plastic powder and a CAD file with the digital blueprint of the gear to do its job. No expensive special tools, complex moulds, or long preparation phases are necessary. igus? passes these savings on to its customers.

Additive manufacturing: without compromise

Larger contact area Lower surface pressure High service life

The more complex the geometry and the smaller the series, the greater the price advantage of 3D printing - smaller gear geometries tend to be more costeffective.

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The three most common mistakes in 3D printed gears

1.

Imprecise 3D model

Use the free igus? gear configurator

A perfect 3D model of the gear is the basis for successful 3D printing. Since the printer prints the 3D model just as it is, the model should be created carefully. It is advisable to integrate an involute with tooth root radius into the model to achieve more exact results. In addition, the dimensions should be on averaged tolerance; otherwise, operating properties and durability suffer. Averaged tolerance for a square hole with a tolerance of 10 + 0.2mm would be 10.1mm. Outer toothed profiles require no further designed clearance, but can be modelled here to nominal size. For internal toothed profiles, a gap of approx. 0.1mm should be provided for. The igus? online CAD configurator for gears

enables you to design your individual gear free of charge and without registration and easily enter required data, such as tooth module (from 0.5mm), number of teeth (starting at eight), width, and inner diameter. In just a few steps, you can go from configuration to ordering your gear with the material that best fits your desires and needs. Would you like to duplicate a gear, but don't have a CAD file? No problem! Simply send an intact sample of the component to igus?. The experts will create the digital model using a 3D scanner. If no intact specimen is available, it may even be possible to design the gear based on its mating partner.

In just a few steps to the printed wearresistant parts

No

3D model available?

Yes

Gear data available?

Yes No

Straight-

No

toothed gear? Yes

Modelled gear available?*

*Presupposes tooth data

Bad quality with edges

Yes

No

Other tools, such as configurator,

available in CAD program?

Such as: Inventor

Start the igus? gear configurator:

igus.eu/gear-configurator

Good quality rounded, smooth

No

Intact gear available? Yes

No

Design the gear on the basis of a counter partner, if necessary

Yes

3D scan Yes

Yes

Yes

3D printing service igus.eu/3dprintservice

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2.

Wrong material Wear tests help with material selection

There are very large differences in 3D printed gear service life. Different materials are also required for different gear applications. Tests have shown that the iglidur? I3 SLS plastic's high strength makes it particularly suitable for spur gears and bevel gears, but that it can also be used for all other forms of gears. The optimised gliding properties of iglidur? I6 are particularly good for worm gears. iglidur? I6 is also approved for any gear applications with food contact. iglidur? I8-ESD is a third plastic that should be mentioned here; it is suitable for any applications requiring ESD properties.

Cycles until tooth breakage

45,000

42,262

40,000

35,000 30,000 25,000

23,761

20,000

15,000 10,000

5,000

8,435 5,464

1,704 1,082 716

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0

12345678

Materials under test

1) iglidur? I3 (printed) 2) iglidur? I8-ESD (printed) 3) POM (machined) 4) iglidur? I6 (printed)

5) iglidur? I190 (printed) 6) PLA (printed) 7) PETG (printed) 8) SLA

Test parameters: pivoting 1,440?: n = 64rpm M = 2.25Nm, z = 30, m = 1, b = 6.5mm

Extremely long service life of worm gears with optimised sliding properties

POM 321,000 cycles

POM 621,000 cycles

iglidur? I6 1 million cycles

Tired of plastic gears wearing out too quickly? Then try 3D-printed gears made of iglidur? I6, a high-performance plastic. Laboratory tests have proven that worm gears made of this plastic are still fully functional even after a million rotation cycles, unlike their machined counterparts made of polyoxymethylene (POM). In the test, they were worn after 321,000 cycles, and the teeth became blunt and finally broke after 621,000 cycles. In another test (shown above right), a rack was driven with a gear until breakage and the number of cycles recorded. Here, too, 3D-printed iglidur? gears lasted up to five times as long in the test as gears milled from POM.

POM

XBreaking point

Coe cient of wear

1,i8glidur ? I6 Service life [cycles]

Test parameters: M = 4.9Nm, n = 12rpm, running time: 2M

For the industrial 3D printing of gears, use high-performance plastics that ensure high resistance to wear.

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3.

Do not calculate service life yourself Use the gear service life calculator from igus?

A gear is often unsuitable for the application in question, resulting in a greatly shortened service life. Gears that are too large can drive up costs, while gears that are too small simply won't last long. The igus? online gear life calculator uses data from the test lab to determine the right size for your gear made of iglidur? I3 and iglidur? I8-ESD. The calculator determines the service life in hours for a gear pair. Additional data such as speed, torque, mode of operation, application temperature, etc., allows the service life to be determined very accurately, which is helpful in planning your application. This online tool, too, is free of charge and can be used without registration. igus.eu/gear-expert

3D printing almost always pays off

Worthwhile alternatives for series of 10,000 or more. Injection moulding and print2mold?

3D-printed gears are used where complex geometries mean increased costs for conventional processes. Gears produced with the additive process are also suitable for prototypes or small series. Depending on gear size and complexity, 3D printing is economical up to a quantity of 10,000; that is the latest point at which, injection moulding becomes more economical for customers. Injection moulding is particularly recommended for gears with standard dimensions. But 3D printing can also support the series production of special parts: The print2mold? process, in which the injection mould is additively manufactured in a very short time, works well here. The mould is good for series of up to 100,000. The print2mold? process costs as little as 2% of what laser sintering a complete series of complex components would, depending on the application.

Find out more about additively manufactured injection moulds at: igus.eu/print2mold

Learn more about igus? injection moulded gears: igus.eu/gears

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/20h

Place your orders until late. Ordering and deliveries weekdays from 7.00am to 8.00pm, Saturday from 8.00am to 12.00pm. No minimum order quantity, no surcharges. Quick delivery.

igus.eu Phone +49 2203 9649-145 Fax -334

Tom Krause Head of Business Unit Additive manufacturing igus? GmbH Phone: +49 2203 9649-975 Fax: +49 2203 9698-975 e-mail: tkrause@

/9001:2015 /16949:2016

Disclaimer Legal information: The information in this brochure, and the technical data in particular, is based on our current knowledge of the products described as of [11/2021]. The information in this brochure does not constitute a legally binding assurance of certain properties or suitability for a specific purpose. Due to constant technical refinement, we reserve the right to make technical changes to products at any time. Subject to printing errors. Our offers are directed to traders/resellers only. The delivery times indicated correspond to the time until the goods are dispatched, and transport costs are not included in the price. We recommend that you always check the suitability of the products for a particular purpose in a practical trial. Contact us for advice. Copyright The articles and illustrations published in this brochure are protected by copyright. Any use not permitted by copyright law requires prior written consent from igus? GmbH. This specifically includes copying, editing, translation, storage, processing, and reproduction of content in other (electronic) media, databases, and systems. The terms "igus", "Apiro", "CFRIP", "chainflex", "conprotect", "CTD", "drygear", "drylin", "dryspin", "dry-tech", "easy chain", "e-chain", "e-chain systems", "e-ketten", "e-kettensysteme", "e-loop", "e-spool", "e-skin", "flizz", "ibow", "igear", "iglidur", "igubal", "kineKIT", "manus", "motion plastics", "pikchain", "plastics for longer life", ,,print2mold", "readycable", "readychain", "ReBeL", "robolink", "speedigus", "tribofilament", "triflex", "xirodur" and "xiros" are protected by trademark laws in the Federal Republic of German and also internationally, where applicable.

igus? GmbH Spicher Str. 1a 51147 Cologne Phone +49 2203 9649-975 Fax +49 2203 9649-975 info@igus.deigus.eu

? 2021 igus? GmbH

Subject to technical alterations.

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