The goal of our Digital Manufacturing workstream is always to provide the optimal solution to the end user. Whilst 3D printing is a novel and exciting technology – sometimes it isn’t the most appropriate path.
Any part that experiences significant tensile or fatigue loading conditions whilst in service must be manufactured using a material that can withstand this. This, therefore, limits material choices to Aluminium and Steel alloys that are typically manufactured using methods such as CNC machining. The anisotropic properties of 3D printed parts are sometimes unable to be used for these types of parts.
Larger rail parts must also be compliant with BS EN 45545. Whilst we do have 3D printed materials that are fire compliant, they can be expensive, dependant on the size and other properties of the part. However, using alternative manufacturing technologies with materials such as Aluminium and Steel alloys allow fire compliance to be met as well as provide a cost-effective solution for large rail parts.
For parts that require rigid connections to the rail vehicle or have connectors that are governed by standards or have a structural/pressure requirement (i.e. hydraulic/pneumatic adaptors, hinges and door locks) alternative manufacturing technologies and metal alloy materials are generally most suitable.
We always select the manufacturing method that is most suited to the specific requirements of the end user.
The Yaw Damper bracket is a great example of using 3D printing to enhance more traditional production methods. The customer required two of these parts for their 158 fleet, due to a lack of spares. The original part was produced by casting; this manufacturing method needs a sufficient minimum order quantity to justify the cost of creating the moulds, leaving the customer with a high cost per part and more parts than required which take up storage space and ultimately, increase the overall cost.
As this part would not be able to be 3D printed due to its structural integrity requirements, a more effective way of using 3D printing to enhance the traditional casting process was to 3D print the mould pattern, then cast using spheroidal graphite cast iron (BS EN 1563:2018 Grade EN-GJS-400-18-LT) originally specified for this part by the British Rail design. A pattern could be 3D printed and a mould produced quicker and cheaper than the traditional method. This therefore, Increased speed, decreased cost and allowed for no minimum order quantity requirements which solved the problem the customer had.
The initial batch was delivered with a similar lead time to the traditional method, largely down to the amount of investigatory work required. However, due to the success of this project, after the initial two parts were produced – the customer placed a further order for two more. This second batch was delivered much quicker than the original timescales and at considerably lower cost.
Angel Trains’ Class 466s were undergoing PRM refurbishment works. For the move from the depot to maintenance works, the vehicle tread plates had to be removed due to gauging issues, however a significant, but variable, number of tread plate brackets were cracking on each vehicle during removal. New tread plates were therefore required, but the quotes for these parts from the existing supply chain had a lead-time of 6 weeks and a minimum order quantity of 30.
Each Class 466 unit was in for work for only 5 days and it was impossible to predict how many tread plate brackets would crack prior to start of works. The options were therefore to significantly over-order at large expense, or a risky under-order approach, which would prevent units returning into service until new parts were available.
The Digital Manufacturing process was used to produce the tread plate brackets to mitigate the issues highlighted above.
Work Undertaken by DB ESG
DB ESG were able to reverse-engineer this part in minimal time and approve its production using CNC-machined 6082 aluminium alloy. The replacement pieces were not only of a higher grade of material, but the lead time was reduced from six weeks to just 12 business days at a considerable cost saving per unit of 81%.
A common problem that TOCs, ROSCOs and maintainers run into is a single component within a wider assembly failing. Often times, due to availability of production, this means replacing the entire assembly rather than the individual component. The CNC Door Lock was part of the wider Gangway Door Lock Assembly and we were commissioned to look at the feasibility of producing the single component.
The benefit of not having to replace the entire assembly was obvious – a quicker, lower cost and less time intensive replacement of the component.
We often utilise 3D printing & scanning within our Alternative Methods projects. 3D scanning and our design expertise can remove the necessity for 2D drawings and speed up time to production. 3D printing can speed up production itself. We have extensive knowledge of processes such as additive casting, where a mould or pattern is 3D printed from which metal parts can be cast and we are currently undertaking an R&D project into Additive GRP Moulding. The end goal is to have a quick, cost-effective solution for large panelling such as a valance.
We utilise many alternative manufacturing processes to meet the specific requirements of any given project. Whilst additive manufacturing (3D Printing) has been the focus of our initial investigations and remains one of our key manufacturing processes, our goal is always to provide the optimal solution by factoring in important non-technical variables such as cost and speed.
We have experience in casting, CNC machining, sheet metal forming, welded fabrications, extrusions and many, many more.
These alternative, often more traditional manufacturing processes complement our additive manufacturing capabilities perfectly. Whether the priorities are speed, cost or flexibility, we have the experience, flexibility and pragmatism require to solve the specific problem whilst meet the specific needs of our customers / end users and meeting all relevant railway standards.
So what materials can we work with? Well, our core strength is that first and foremost, we are a rolling-stock engineering consultancy. We have a large team of mechanical and design engineers with vast experience in metallurgy, structural analysis and bonding/ special processes. So, the simple answer is, we can investigate the feasibility of almost any material.
Alongside our knowledge of additively manufactured materials and processes, we have specific experience of manufacturing parts using various alloys of iron, steel and aluminium as well as various other materials such as, laminates and various types of polymers amongst many others.
In short, we always deliver the optimal solution for the specific requirements and we will utilise the most appropriate material to that end.
So, we have manufactured a part with the correct fit and function for its specific requirements but what about its form? Requirements like weight and size are often self-explanatory and sometimes governed by railways standards and pre-existing vehicle equipment but what about the parts visual appearance?
There are many things to consider when deciding on how a part should be finished; is it within a wider assembly? Is it customer facing? Does it fit within the specific livery or brand guidelines of the end customer?
We have extensive experience in a wide array of finishing techniques. From the more well-established processes such as machining and railway approved coatings to more complex human-factors related techniques such as knurled patterns. We also have experience in laser engraving, dyeing, chemical/vibration smoothing, electroplating and many, many more. Whatever your requirements are for part finish, we can help.
These alternative manufacturing processes allow for a greater range of materials to be used. From metal alloys and composites to various types of polymer, to meet the specific requirements of the rail application. In addition to our additive manufacturing technologies, these alternative manufacturing processes allow any part geometry and specifications to be achieved; solving obsolescence and an array of other engineering challenges you may face.