Motorsport

3D printing has developed significantly and now performs a crucial role in many applications. 3D printed products vary from fully functional to purely aesthetic applications; with the most common application being for manufacturing. Here we discuss how our engineers use 3D printing to demonstrate a seal concept.

What is 3D printing?

3D printing is typically the more common name used for additive manufacturing. This process involves the construction of a three dimensional shape that is designed and generated from a computer aided design program (or CAD). The most typical process used for 3D printing is FFF (Fused Filament Fabrication) or FDM (Fused Deposition Modelling).

The FDM process uses a continuous filament of a thermoplastic material that is then deposited onto the 3D print bed, creating layer by layer and gradually building up the structure of the 3D model.

This is the process we commonly use to create our design and development range of 3D printed models and seal prototypes.

What material is suitable for 3D printing?

The materials used for 3D printing must of course be compatible with the process – these include a range of thermoplastic grades. Typical suitable material grades include; Polylactic acid (PLA), Acrylonitrile Butadiene Styrene (ABS), Thermoplastic Polyurethane (TPU), Nylon and Polypropylene (PP).

The most common grade we use for 3D printing is PLA – for its great strength and stability. We’ve also adapted our design process to use more TPU based material grades, as it loosely demonstrates the same properties as elastomer grades and is better for using in prototype programmes where mechanical fit in groove is tested.

Why use 3D printing for seals?

3D printing can be used for a variety of designs and seal types; from O-rings, gaskets and lip seals – to grommets, multi shot mouldings and large seal assemblies.

There are many benefits of using 3D printing during the initial design stages of a project. The rapid turnaround means that a simple seal design can be produced in around 15 minutes, and even more complicated parts can be manufactured in the same day. We can even print the application housings and it’s the perfect way to demonstrate to an engineer what they can expect from a seal part in terms of shape and fit for hardware without the lead time and cost of cutting a prototype tool for moulded parts.

One example of this is by quick turnaround of gasket designs typically to suit automotive applications or similar critical markets. Our engineers can design the concept and then 3D print a rapid prototype of a gasket to suit a 3D printed gauge groove.

This further demonstrates to the customer that the seal has been fit checked for installation and builds further confidence in the design recommendation. Our engineers combine the 3D print with FEA simulation reports to offer a fully engineered sealing solution.

Learn more about our design and simulation service HERE

The electric vehicle industry is growing; global manufacturing and registrations of electric vehicles is increasing exponentially each year. Our engineers have extensive experience in designing seals for automotive applications, but we still find new challenges involved in sealing components within hybrid, hydrogen fuel and full battery powered electric vehicles.

The Application

Our customer has 30 years’ experience of providing pioneering technologies globally to the mobility industry. This established organisation is a supplier of powertrain solutions for electric and hybrid vehicles and traditional internal combustion power engines. The team of powertrain development experts approached our engineers for a high speed rotary seal. This is for the gearbox within an electric vehicle. The position of the rotary seal is needed between the wet transmission and dry e-motor, and pressed into a bulkhead housing.

The sealing lip runs on the surface of the transmission rotor shaft. It is pressed radially by a tension spring onto the shaft, and requires a dust lip to provide protection against dirt and debris from the environment on the dry motor side.

The shaft and housing dimensions, are all fixed and provided by the customer. These include full dimensional, surface finish, pressure, temperature and media specification for our engineers to review and propose a bespoke seal design.

Our sealing solution

The application media was a synthetic oil. This is relatively standard for an automotive application. However, because of the maximum working temperature, FKM (Viton) was the elastomer material to meet the required range.

As with many applications within electric vehicle gearboxes, the shaft speed is particularly high at 8500 RPM. Typically with these high speeds, seal design needs to ensure minimal friction to ensure the service life required.

Our application engineers designed a bespoke, double lipped spring energised seal.

On the dry e-motor side, the rubber lip has been designed to act as a dirt and dust excluder. There is a slight clearance from the shaft to avoid friction which prevents damage to the seal, additionally any unnecessary wear to the rotary system as a whole.

In the wet transmission side it is imperative that the oil is kept away from the e-motor with the same minimal friction requirements. Consequently, our engineers designed the seal with an inlaid PTFE lip with 15% graphite fill. It is energised with spring to ensure force to achieve ultimate shaft sealing performance.

Read more about our rotary seals HERE

An existing customer (an automotive manufacturer) approached our engineers with an application where they were experiencing failures of a seal designed and manufactured by another rubber seal provider.

The application

This moulded gasket is used within a valve housing in an automotive application. The competitor gasket experienced failure at the “T-junction” areas of the seal. Our customer had experienced chronic failures of their existing moulded gasket design at high temperatures and high pressures.

The seal is required to perform under pulsating pressure of up to 50 Bar and temperatures of up to 150°C. Our engineers reviewed the existing gasket design and application conditions and recommended an increase in height of 0.40 mm. This was to increase the compression and improve the sealing function. Additional beads were also added to further stabilise the gasket in the groove.

The challenges

Prototype parts were manufactured from a single cavity soft tool and sent to the customer for in-house testing and validation. The prototype gaskets very nearly passed testing but did not quite reach the 50 Bar pressure requirement at 150° C (42 Bar reached). This was still a great improvement on the performance of the customer’s original gasket.

Analysis of the customers test data and images of the tested parts, determined there were areas where the gasket was sliding in the groove and then shearing as the pressure pulsed.  We resolved this issue by our engineers adding beads to the rear of the T-intersections of the gasket. This provided additional support and further stabilised the gasket at the high-pressure stress points in the groove, and reduced movement within the housing.

The number of additional beads added needed to be balanced carefully with calculations on groove fill. Further development captured the cleanliness requirements and altered radii on the beads.

Customer satisfaction

The new design was approved, and the customer moved to production tooling stage and sample parts were produced to PPAP Level 3 for production.

More information about our mouldings & gaskets on the link HERE

Our customer manufactures high performance oil and vacuum pump solutions, and approached our engineers with a new O-ring application for review.

The application

Our customer required an FKM (Viton™) 60 shore special O-ring. This is to meet Porsche material specification PN707 Class 2 (Oil), Class 5 (Fuel/FAME mix) and Class 12 (Blowby gas).

This proved to be a very cost sensitive project with a short lead time. Additionally, we did not have an existing grade in our materials portfolio to meet this specialised O-ring specification.

The challenges

Our engineers reviewed the application and we provided two material options. The first is a lower cost grade of FKM (Viton™) A grade, and would possibly meet the Porsche specification required. The second material, a medium to higher cost FKM (Viton™) B grade that will definitely meet the specification.

We supplied a quotation for the two material types. Additionally, the quotation included production tooling, PPAP Level 3 submission, testing for both materials and a pre-production batch of O-rings. The project was urgent and we were able to accommodate PPAP Level 3 grade O-rings for both materials to be manufactured from the same tool. Also, to save time we conducted material testing in tandem with the manufacture and preparation of the the production tool. The choice of compound to be used in the tool would be made on review of the results of material testing.

On completion of the material testing, the customer reviewed the results with Porsche. The decision to produce O-rings from the FKM B grade was made.

Customer satisfaction

By this stage of testing, production tooling was complete, allowing manufacture of PPAP 3 samples and the pre-production batch to commence. Pre-production O-rings were supplied to the customer in the promised 12-week lead time together with PPAP Level 3 and PPAP 3 samples.

See this link for more on our O-ring range and expertise: HERE