Rheinmetall UK Additive Manufacturing Case Study MiniFactory Ignite for production of Challenger 3 Ducting

About Rheinmetall UK

Rheinmetall UK serves as a primary defence contractor in the UK, delivering advanced land, electronics, and weapon systems to the British Army, with a strong focus on sovereign capability and local manufacturing. Key programs include the Boxer Mechanised Infantry Vehicle (MIV), the Challenger 3 Main Battle Tank, and the new "UK Gun Hall" for barrel manufacturing

What was the challenge to overcome?

In previous vehicle development programmes, ducting for systems like the Crew Temperature Control System were designed using flexible tubing connecting junction boxes fabricated from sheet metal. This approach has worked well for many years and offers a simple and affordable solution to vehicle ducting. In vehicle upgrade programmes like Rheinmetall UK’s Challenger 3 programme, this approach is no longer viable due to the significant space constraints and adaptation of the existing vehicle architecture.

Why Choose Additive Manufacturing for the production of vehicle air ducting?

A variety of production methods for complex ducting components could be used such as injection moulding or rotational moulding. These however require costly tooling and for low volume production, this tooling cost is significant. Furthermore, in vehicle development programmes, air ducting tends to go through many iterations and often requires late changes due to other subsystems competing for space. There is therefore a risk that tooling may need to be re-manufactured, and parts originally produced in time for trials have to be remade for the vehicle production run.

With these pressures in mind, additive manufacturing offers a solution. There are no tooling costs for parts, the designs can be changed rapidly to accommodate other system changes and part complexity doesn’t add cost.

What type of Additive Manufacturing should be used? FFF, SLS or SLA?

SLS and SLA were both investigated in detail for this application with the decision to select FFF being multifaceted.

1. Materials properties, strength,flame retardance, low smoke and toxicity, upper and lower operating temperatures
• The first consideration is the functionality required of the parts being produced. Within this application, there are strict requirements for flame retardance, low smoke generation and low toxicity. Upper and lower operating temperatures further eliminated material options leaving candidates like PA2241FR (SLS) and ULTEM 9805 (FFF). At the time, no suitable SLA materials were identified that met all the requirements.
2. Product functionality – key considerations being, surface finish and air tightness
• Surface finish is important, not only for part aesthetics but also for good air flow within ducting. SLS and SLA parts have extremely good, out of the machine, surface finish. Surface finish on FFF parts can be coarser, requiring post processing to improve.
• The ducting needs to hold air well to ensure no unnecessary drop in pressure. SLA and SLS produce solid part walls whereas FFF can leave air gaps which require sealing or painting to mitigate.
3. Product size
• Large ducting sections were required e.g. 400mm+, meaning some of the more affordable SLA machines were not suitable.
• Larger build volumes with SLS machines drives significant cost whereas larger build volume FFF machines are available a lower costs.
4. Productivity vs. cost
• For this low volume production application we need a suitable balance of cost and productivity.
• SLS can be highly productive but comes at a high capital cost for equipment and infrastructure.
• Large format SLA machines can also be highly productive, producing batches of parts quickly but also comes at a high price point.
• High temperature, large format FFF machines can be more affordable than SLS or SLA but don’t have the level of productivity the other two processes offer.
5. Make vs. Buy
• Finally, the question of whether we manufacture these parts in house or contract them out to supply for manufacture. This is another key decision and requires consideration of the overall cost to the programme, supply chain readiness, the production agility required and control of the production process.

To reach a decision, we had to consider the pros and cons of each technology and whether we would bring it in-house or contract to supply.

The advantages of contracting production, such as no capital expenditure and accessing supplier knowhow, were outmatched by the lack of qualifying suppliers available e.g. holding Cyber Essentials + accreditation, the lower level of production control, the lower pace of learning and slower iterations by not having access to the machinery.

Both SLA and SLS demand higher capital expenditure and more challenging integration onto the shop floor.

SLS couldn’t offer a suitable material choice that met all of the requirements and with enough confidence to outweigh the greater production process complexity.

The UK supply chain for SLS parts in PA2241FR at the time was not competitive. For in-house adoption, the process was too expensive and we wouldn’t use the machine to capacity on these parts alone. If we had much higher volume requirements then SLS production in-house may have been more cost competitive.

The capital cost for FFF was substantially lower than the other options, with installation into the factory floor being far easier, fewer safety hazards and lower training requirements to be met. Rheinmetall UK had lots of experience of using FFF for producing prototypes as a design aid. This knowhow meant that adopting FFF for end use part production also presented less of a cultural and training challenge.

FFF's productivity matched the required production capacity that Rheinmetall UK needed within the Challenger 3 programme and demanded minimal shop floor space.

The weaknesses of FFF within this application can be affordably mitigated. By using vibratory tumbling and painting of the FFF ULTEM 9085 parts, a good quality of product can be made without adding significant capital and piece part cost.

Considering all these trades together. It was decided that for the production of ducting, Rheinmetall UK should pursue a strategy of manufacturing the parts in house using FFF with ULTEM 9085 since this offered the most affordable, most flexible and lowest risk solution vs. the other solutions explored.

Why did we choose the miniFactory Ignite?

There are a good selection of manufacturers around the globe offering high temperature FFF printers able to produce parts in ULTEM 9085. During our down selection process, we considered several manufacturers offerings.

In the end, the decision to purchase a miniFactory Ignite boiled down to:

1. Machine Cost vs. productivity – The miniFactory Ignite was one of the lowest cost machines but still provided a large build volume and competitive level of productivity.
2. Build Area – for the price of machine, miniFactory offered a large build volume enabling batch production. This means that we can reduce labour costs on managing builds and use more lights out hours for printing during the week and weekend.

3. Security – miniFactory machines are manufactured in Finland and therefore were considered to be lower cyber risk than some of the other manufacturers.
4. Operating costs – the miniFactory Ignite is an open system meaning that Rheinmetall UK could bulk purchase feedstock direct from the manufacturer at highly competitive prices. This has a significant impact of the piece part cost. Furthermore, the cost of ownership was lower. Fewer consumables were required e.g. reusable build plates, long lasting nozzles and affordable support package. All of these facets contribute to lower production costs.
5. UK Support – not all of the printer manufacturers could offer a UK based support solution. This is important as machine downtime can not only impact productivity but can lead to programme delays. 3DGBIRE deliver the support for miniFactory in the UK and are only a few hours down the road from Rheinmetall UK facility in Telford.

What did we need to do once we had bought and installed the miniFactory Ignite?

Purchasing and installing the machine was only the first step to developing and optimising the production capability.

By having a machine on the factory floor, our designers were able to learn about the impacts of their design decisions and could quickly make changes to enhancing functionality as well as cost efficiency. We were also able to optimise the printing profiles to get the best results.

The convention for AM optimisation is normally to consolidate parts. We discovered that for this application, the opposite was true. By splitting parts and creating joints, we could reduce the amount of support material needed or even eliminate it all together. This meant that we could print parts faster with less material and less post processing labour hours. It also enabled us to reach our productivity requirements on the one machine providing significant savings.

We were able to optimise our batch layouts and establish the most cost-effective post processing approach for the given application.

Having access to the machinery also made it far easier to experiment with solutions e.g. the optimum jointing method, compatible adhesives, part numbering approaches, surface finishing methods and paint finishes. Developing this bespoke solution in the supply chain would have been time consuming and expensive.

What was the outcome for the business?

Following the acquisition of the miniFactory Ignite machine and the work undertaken to develop the production processes, Additive Manufacturing is now the baseline solution for ducting manufacture in the Challenger 3 programme.

The adoption of additive manufacturing has enabled rapid design iteration previously unimagined. We have been able to demonstrate making design changes and producing a replacement part in day.

The change to additive manufacturing has provided large overall cost savings but the biggest benefit is in cash flow savings. By manufacturing on demand, the cost of procuring parts and placing them in stores has been mitigated. There are no tooling cost and no risk of significant increase in costs due to design changes.

With production on demand, there’s no risk of parts being lost or broken in storage and if parts to get damaged during fitting, then replacements can be quickly made.

Having the machinery on site has greatly accelerated learning. Our ‘Design for Additive Manufacturing’ skills have been improved giving better quality products, enhanced productivity and lower costs.

The adoption of additive manufacturing has also lowered programme risk overall despite being a new manufacturing process. The ability to respond rapidly to change minimises the potential for programme delays and lengthy procurement cycles.

Finally adopting Additive Manufacturing for end use parts has emphasised thinking about design optimisation and cost efficiency in manufacturing. Having the manufacturing equipment accessible to the designers has helped greatly.

This project has further accelerated Rheinmetall UK’s adoption of Additive Manufacturing for end use parts. For example, since adopting the miniFactory for manufacture of polymer ducting, the company have since invested in Rapidia’s Metal Paste Deposition technology to produce steel vehicle components. It’s likely that in the future, even more components will become cost competitive to produce with Additive Manufacturing.