How machine builders can benefit from 3D printing

How can machine builders benefit from 3D printing?

Machine builders in the UK are under pressure to reduce lead times, deliver machines with higher throughput and, of course, reduce costs. For those building assembly systems, their customers also want the flexibility to produce multiple variants or different products with little or no changeover time.

Fortunately, there is a technology that can help achieve all of these goals. 3D printing is already being used to some extent by many machine builders but few are making full use of its potential. In this article we will explore the many ways in which machine builders can benefit from 3D printing. No single 3D printing technology is perfect for every application so, here at Prototype Projects, we support our clients with five different 3D printing technologies and are happy to advise on which to use for a given project. In addition, we have in-house CNC machining for those parts that benefit from being produced this way instead.

Typical machine parts made with 3D printing

If a machine is handling injection moulded plastic components, then 3D printing is excellent for producing ‘contact’ machine parts such as gripper fingers, nests, fixtures and clamp pads. These parts provide near-perfect support for the moulded component because the surface geometry is so well matched. Furthermore, the contact is non-marking and wear-resistant – provided the optimum 3D printing technology and material are used.

When a machine is required to handle multiple variants or products, 3D printed change parts can incorporate snap fits or other features so they can be exchanged automatically. Or, if tool changes are performed manually, change parts can be designed to make this task as quick and easy as possible. Depending on the 3D printing technology used, these changeable tooling elements can be colour coded or, alternatively, identification can be printed indelibly on the surface as human-readable alphanumeric text and/or machine-readable bar codes or 2D Data Matrix codes.

Cobot tooling

Cobots (collaborative robots) have taken off in the last few years and are boosting productivity across a wide range of manufacturing sectors. Operating alongside human operatives without the need for physical guards, cobots cost less to buy, instal and programme than conventional industrial robots. Ease of programming means they can quickly be deployed from one task to the next, and this redeployment is where 3D printing can be invaluable. Custom gripper fingers or end of arm tooling (EOAT) can be quickly designed and manufactured so the advantages of low cost and quick redeployment are not lost due to expensive tooling with a long lead time.

To minimise machine cycle times, movements must be fast, with high rates of acceleration/deceleration. Lightweighting has an important role to play here because lighter machine elements require less energy to accelerate. If parts are CNC machined from solid, much of the unnecessary material can be removed but 3D printing takes lightweighting to a higher level. Parts can be designed to have the minimum material necessary to function and, while the mass saved might be small for one part, the overall savings quickly add up if a highly dynamic machine utilises multiple optimised 3D printed parts.

Simple components

A number of our machine builder customers have discovered that 3D printing is a very cost-effective way of producing relatively simple components. For example, sensor brackets can be quicker and cheaper to 3D print than purchasing standard off-the-shelf parts. Furthermore, a standard sensor bracket might be adjustable in order that the sensor can be set correctly, whereas a 3D printed bracket can be made to set the sensor at the desired orientation from the outset. This helps to save time and prevent errors during the machine build and commissioning. It also ensures the sensor cannot go out of alignment due to vibration or incorrect adjustment by a maintenance technician.

3D printing is also very convenient for producing bespoke channels, clips, brackets and attachment points for cabling and pneumatic lines. Without suitable support, cabling and pneumatic lines can work loose during transportation to the customer’s site, as well as due to vibration during normal operation. By ensuring cabling and pneumatic lines are secure, machine builders can avoid problems when commissioning the machine, and prevent unnecessary call-outs relating to in-service failures.

Fine-tuning the design

During commissioning, if it is found that a 3D printed part is not quite right, it is simple and quick to amend the 3D CAD model and 3D print a replacement part. 3D printing technology can therefore play an important part in overcoming teething problems and reducing commissioning time.

Similarly, 3D printing can be used iteratively to fine-tune a part’s geometry. Once the design has been finalised, the part can be produced by CNC machining from metal if there is a need for greater strength or longevity than could be provided by a 3D printed plastic part.

Another good use for 3D printing is the production of ergonomic grips and handles. This can improve usability and customer satisfaction with semi-automated machinery where operatives have frequent contact with certain machine elements.

3D printed elastomers

Remember that 3D printing is not just about producing rigid components, as elastomeric materials can also be processed. This provides a simple and low-cost way to manufacture custom seals and gaskets, particularly if the surfaces to seal are not planar. Alternatively, we have a laser cutting machine that we use to cut flat gaskets.

3D printed elastomeric parts can also be ideal as buffers, vibration dampening elements and as a way of incorporating compliance within mechanisms.

Complex and combined parts

3D printing is an incredibly versatile manufacturing process, to the extent that designing parts for 3D printing requires a different mindset from designing for CNC machining. When 3D printing parts, it is easy to combine parts – such as a gear, cam and sensor trigger feature. Doing so reduces mass, simplifies the design, reduces the parts count, and cuts the costs of both manufacture and assembly.

Other possibilities include the incorporation of air passages into robotic end-of-arm-tooling for pneumatic actuators or vacuum grippers, or using the PolyJet 3D printing technology to create rigid parts with integral elastomeric seals. PolyJet can also produce custom single-component vacuum grippers with integral rigid mountings and elastomeric bellows of the desired profile.

Another niche application for 3D printing is the incorporation of living hinges in parts. This could be to provide for small amounts of movement or compliance without the need for separate mechanical components. Another example is snap fits to retain tooling or a component within a nest. Care is required in the design of living hinges and the selection of the optimum 3D printing technology and material, but this approach offers substantial benefits in certain applications.

Concept development and early testing

As we have seen above, 3D printing presents machine builders with many opportunities in the design of machines. However, there is another important area where 3D printed parts can help in the design of assembly systems. At the early stages of a project, before production has commenced, the machine builder may want to experiment with different handling concepts. Without having mass-produced parts available, this can be difficult. But small volumes of representative parts can quickly be 3D printed to enable handling concepts to be tested and developed.

Depending on the quantities required, an alternative is to use 3D printing to manufacture a master pattern from which multiple polyurethane parts are vacuum cast.

When the machine has been built, 3D printed or vacuum cast parts can be very helpful during the assembly and initial testing of the machine. Once production parts are ready, the commissioning time will be shorter because many of the teething problems have been solved already thanks to the work done with the interim parts.

Spares and stockholding

If you are a special-purpose machine builder producing a unique design, the end user might have certain requirements relating to spares availability. Manufacturing parts by 3D printing may avoid the need for spares to be stocked, as replacement parts can be produced very quickly. For example, with our Express 3D printing service we ship parts the next working day, or we ship in three working days with our Standard service.

On the other hand, if you build, say, ten machines per year to the same design, 3D printed parts can be manufactured and supplied as required. This means you do not need to order ten parts, pay for them all at once, then keep most of them in stock until required. 3D printing therefore offers machine builders the opportunity to improve cashflow and reduce the space required for storage.

Hints and tips

Engineers who are unfamiliar with 3D printing need to understand not only the potential offered by additive manufacturing but also the limitations and pitfalls – and how these can be overcome.

For instance, some 3D printing technologies build parts in which the material properties are not isotropic. Because 3D printing builds parts later by layer, the strength in the X and Y axes can be greater than that in the Z axis. However, by taking this into account during the design process and by specifying the build orientation, problems can be avoided.

Furthermore, due to a combination of the 3D printing technology and the material used, in some cases the part’s fatigue performance is relatively low. If fatigue strength is important, care needs to be taken when designing the part and specifying the 3D printing technology and material.
Often 3D printing will be used to manufacture plastic parts that might otherwise have been machined from, say, aluminium alloy. If so, Helicoils or other threaded inserts can be installed in the 3D printed part to improve the performance of threaded joints.

If a 3D printed part is to be used in an area on the machine that gets warm, due consideration should be given to the material choice. For instance, HI TEMP 300-AMB resin for the Figure 4 3D printer can withstand temperatures of up to 300°C, whereas other materials are less tolerant of heat.

Finally, note that vacuum casting can be used for insert moulding. For example, a stainless steel CNC machined part can be incorporated within a lightweight casting with complex geometry, with the stainless steel providing critical strength and/or precision.

Talk to us

If you are a machine builder and want to find out more about how 3D printed parts could benefit your projects, contact us on 01763 249760.