A.J. Rose Installs World-Class Equipment in Response to Industry Trends

Electric vehicles are revolutionizing the automotive industry in a way that has not been seen since the seatbelt became mandatory in 1967. Competition among OEMs is increasing and the modern day ‘race to the moon’ is underway, lead by manufacturers such as Volkswagen, Ford, GM and Volvo as they roll-out EV & hyrbid models off the assembly line. Not to be forgotten are more than 100 ambitious startups looking to make a name in the automotive world. Take a couple steps back in the supply chain and there are countless automotive suppliers watching the competition unfold, excited for the new market opportunities this will bring.

Metal stamping companies make up a large part of the automotive suppliers wondering where they will fit into the electric vehicle landscape. Many likely wondering what their new identity will be 10 years from now. It is certain that metal stampings will remain a major part of the automotive supply chain as we transition to EV, but the type of components that will be stamped is the question mark. A reputable stamping supplier that once specialized in powertrain components may soon find their stamping presses being used for battery trays and EV motor laminations. In order to stay agile and be prepared for any type of stamping coming through the pipeline, a supplier needs two things: First, the the willingness and unity to change even if it’s outside their niche, and second, the necessary equipment and processes to support the evolution.

In the case of A.J. Rose Manufacturing Co., they recently invested in new equipment intended to support the markets of the future. That equipment is a newly-built servo press from Aida. This will be the 58th press at A.J. Rose and also the largest press at 1375 tons. At this tonnage, it opens doors to new markets and product lines with the ability to to produce larger parts and run thicker material. They are adapting to the market, not expecting the market to adapt to them. At a bed size of 191” x 70” and a 20 inch stroke, A.J. Rose will offer more capability to their customers looking for large stampings. A purchase of this magnitude was a decision based partly on current necessity and partly on strategic forecasting of future demand. A.J. Rose is positioning themselves to support the increased sourcings in battery plates, battery boxes, battery trays, large brackets and similar housing components that are becoming popular in the EV space. In order to be nimble in these new markets, the press will be capable of running transfer tools or progressive tools, and the servo motor allows for variable speeds and advanced forming capabilites, such as dwelling at the bottom of the stroke. These features make this a Swiss-Army knife of stamping presses, capable of forming metal into unique geometries in a wide range of size and thickness. This is what puts a supplier in a position for growth, making them attractive with an exisiting customer or one brand new.

A wide range of OEM customers turn to A.J. Rose for high-precision, high-quality metal stampings, therefore it is crucial to maintain their reputation as an innovator in the industry. Having such a reputation associated with their brand helps to establish credibility and lends to partnerships with up-and-coming EV startups. Out of many startups gaining momentum in the EV space, it will certainly narrow down to a short list of companies that rise to the top and begin serious competition in the pure EV markets.

A large pit is dug roughly 20 feet into the ground to prepare for the press. Supporting walls are poured from cement within the hole and a connection is made to the existing underground scrap-removal conveyer (right side).

A gantry system is used to support the weight of the press as it is assembled and secured to the foundation.

The press is assembled and secured in the pit. Capacitors are installed in the back.

High-Strength Sinter Parts for Decoupling units in e-Axles

Powder metal technology is well known for products used in the automotive industry. With the shift to electric powertrains, key requirements such as component strength had to be adapted. This has been successfully achieved by developing and implementing new innovative processes to withstand the loads required in electric axles. Powder metal parts such as planetary gears or disconnect systems can even combine these properties with a significantly lower product carbon footprint compared to conventional steel.

The disconnect system

The primary function of an e-axle disconnecting system is to improve the efficiency and performance of battery electric vehicles by automatically decoupling the transmission shaft from the wheels when no power is required from the electric motor. As soon as power is required, the connection is closed again. Various concepts for disconnect units are available on the market, utilizing shifting components such as dog clutches or sliding sleeves to achieve the mechanical disconnecting function.

Figure 4: Examples of Shifting elements for Disconnecting systems in BEVs

The key functions of a disconnecting system are:

• Energy Efficiency: By disconnecting the e-axle when it is not needed (e.g., during highway cruising when only one axle is sufficient), the system reduces power consumption, which in turn can extend the vehicle’s range.
• Performance Optimisation: It allows the vehicle to perform optimally by engaging or disengaging the e-axle according to driving conditions, ensuring that the required power available when needed.
• Component Wear Reduction: Disconnecting the e-axle when not in use can reduce wear and tear on the drivetrain components, resulting in longer component life and lower maintenance costs.
• Driving Dynamics: Improves driving dynamics by providing better traction and stability control. For example, it can disconnect at high speeds to improve fuel efficiency and re-engage at low speeds or off-road conditions to improve traction.
• Temperature Management: Helps manage the thermal load on the powertrain by disconnecting during periods when high performance is not required, preventing overheating and improving component life.

The Powder Metal Process Route – High strength and Energy efficient

The powder metallurgy process is known for its ability to efficiently produce high volume parts with comparatively low energy consumption. The following chart (Fig.2) gives an overview of all possible process steps. Low loaded parts can have a process route that ends directly after sintering, whereas highly loaded parts such as disconnect sleeves require additional operations like sizing or heat treatment.

Figure 5: The Powder Metal Process Overview

High Strength Process Innovation

Powder metal products such as mass balancer or crankshaft gears are known for their high strength, low weight and additional benefit in NVH performance [1,2]. This is achieved by combining a standard part density in the core area (~7,0g/cm³), with a near full density area where the gears are loaded (left, Fig.3). The high-density area can be achieved by rolling or sizing the sintered part. For even higher loaded components such as disconnect systems, the density in the core area of the part needs to be further increased (right, Fig. 6).

This requires two sizing operations: one to achieve a homogeneous core density of >7,4g/cm³ for the core area and a subsequent one for the highly loaded areas with almost full density. To avoid an additional sizing operation and thus save energy (and also cost), a new compacting technology was developed in a research project – “Die-Wall-Lubrication” (DWL).

In general, organic lubricants (e.g. amide waxes, ~0,8 w%) must be added to powder mixes to ensure lubrication between the compacted part, the die-wall and the core rod during ejection of the part. The disadvantage of adding any organic compound is that it also acquires “space” during compaction and thus works against achieving the highest densities – this makes press densities of >7,3g/cm³ infeasible for series production. With the new DWL-concept, the organic content in the mix can be reduced to levels >0,2 w%. Instead of adding to the powder mix, an oil film is applied directly to the pressing tool (see Fig. 7) and densities of ~7,4 g/cm³ can be reached directly after compacting.

The increase in strength as a function of the core density of a sintered part is shown in the graph below. The tooth root strength of sintered gears has been tested for different core densities. It can be seen, that the achievable tooth root strength is strongly influenced by the core density and can reach values of >900MPa (see Fig.8). An optimised heat treatment (dark blue line in Fig.) can further increase the achievable tooth root strength of the sintered gears compared to a standard heat treatment (light blue line in Fig.) by ~200MPa (+30%).

Rolling of Inner Splines

A special feature added for highly loaded disconnect components is to generate the geometric design of the coupling teeth without mechanical processing. Therefor a customised and cost-effective cold rolling process was developed. Through this rolling process, the back taper in the internal toothing of sliding sleeves, that cannot be produced by an axial compacting process and ensures the retention of the form-lock in the closed state of the disconnect system for force transmission, is formed. In

Fig. 9, a cross-sectional view of the back taper area produced by the rolling process after sintering of the components is shown.

The areas of material densification generated by rolling and the resulting reduction in porosity are clearly visible. The density in the densified area is close to 7,8 g/cm³, which allows mechanical properties similar to steel after heat treatment of the component. Another advantage of this process compared to mechanical processing is the associated strength-increasing transition radii that are inherent to this process. This enables the reduction of stress peaks in the application and providing robust solutions in PM.

Energy efficient PM Route

The PM manufacturing process developed for disconnect systems is very short compared to the conventional steel route. This is underlined by the results of a joint project with iron and steel powder supplier Höganas AB. Using the LCA software SPHERA, the PCF (Product Carbon Footprint) of a powder metal disconnect sleeve was compared with the same part produced using a conventional steel process route (Fig. 10).

The results of the PCF calculations given in Fig.11 were obtained by using the following assumptions:

• Steel powder mix PCF of 0,48 kg CO2e per kg material was calculated according to ISO 14067:2018
• Conventional steel (base scenario) for European primary steel of about 1,9 kg CO2e per kg material
• Conventional steel (scenario 3 and 4): 0,3 kgCO2/kg to represent green steel and 0,55 kgCO2/kg represent steel made of recycled material
• Simplifications for PCF on part level: consider are electricity and scrap for the processing steps of both powder metallurgy and conventional routes
• Electricity mix: For the 5 scenarios, different grid mixes were considered to cover the effect of renewable energy impact

It can be seen, that for all scenarios – even using green steel or steel made only from recycled material for the conventional route – the PM route has a significantly lower product carbon footprint. For both manufacturing routes around a third of the contribution is due to the raw material impact, giving PM a big advantage for base scenario as well as scenario 1+2. But even if only recycled steel or green steel is considered as a raw material source for the conventional route, PM still has an advantage due to the comparatively short process route.

Figure 11: PCF of PM route compared to conventional steel incl. different used energy mixes

Summary

Powder metal components can make a significant contribution to the transition to electric powertrains. The PM process has developed new process routes such as Die-Wall-Lubrication and Rolling of Inner splines to meet the higher demands of e-Axles. The strength levels of conventional steel can be matched and combined with the added benefit of a low carbon manufacturing route. This further supports end customers in their efforts to meet their sustainability goals.

Miba Sinter

Miba Sinter is the largest division within the Miba Group and specialises in the development and production of high-precision sintered components. These components are critical to improving the performance and efficiency of applications in the automotive and industrial sectors. Miba Sinter combines extensive knowledge and innovation with advanced powder metal technology to deliver top-quality products to customers worldwide.

Miba Sinter’s product portfolio includes reliable engine components, transmission parts and other sintered products that help reduce emissions and improve fuel efficiency. Thanks to advanced sintering processes, Miba Sinter can produce parts with complex geometries that offer excellent performance and cost efficiency. Sintered products are characterised by economic manufacturability, high material utilisation, low weight and precise production, making them particularly attractive for the requirements of electromobility.

A New Material Solution for Low Wear, Low Friction, and Electrical Insulation in Automotive Transmissions

Geoff Lewis, Technical Director, Duvelco

What is a New Material?

Being ‘new’ is claimed with some regularity in the world of polymers; however, step changes in performance are less frequent. Here, I am going to look at an innovation that may pass the test and rightfully be called a new material. The polymer in question has the trade name Ducoya.

In terms of chemical type, it is a semicrystalline thermoplastic block copolymer bearing the unfamiliar name PMDA-ODA or, in long form, PyroMellitic DiAnhydride – 4,4‘-OxyDiAniline. The repeat unit is shown below:

This is a polyimide with an ‘I’; not a polyamide. Polyimides are a vast and rapidly growing class of polymers. The number of polyimide papers written annually has exploded in recent years. Polyimides include thermosets, thermoplastics, amorphous, semicrystalline, and photo-imageable materials.

The above graph shows the number of papers regarding polyimide. Source: Researchgate – Number of citations per year from 1975 to 2019, Web of Science.

Some may recognise this molecule as being from the 1960s; however, that is not the new part. This molecule, initially developed for NASA’s space programme, has long seemed too difficult to source and too expensive for many automotive applications.

This is especially the case as the industry moves into an era of cost-competitive BEVs, and, from a European and North American perspective, an era of low-cost, possibly subsidised Chinese BEV imports to compete with.

So, if it isn’t the molecule, what is new?

The innovation here is a new, patented manufacturing process that also covers the resulting material. Many high-performance plastics, including those produced by the traditional PMDA-ODA Manufacturing method, utilise monomers dissolved in harmful, high-VOC solvents. The environmental and high-cost considerations of these solvents mean they must be separated, distilled, and reused, consuming a large amount of energy in the process.

Ducoya avoids most volatile solvents used in the process and instead employs supercritical carbon dioxide and a catalyst.

Therefore, it is straightforward to separate the polymer from supercritical carbon dioxide by lowering the pressure. The carbon dioxide is repressurised and stored for reuse. This single step greatly streamlines manufacturing at scale, making the polymer considerably more accessible for automotive applications. However, this is not the end of the story. While the original aim of the invention was to simplify manufacturing at scale, when the properties of the resulting polymer were compared with those of its traditional predecessors, something remarkable emerged – dramatically improved mechanical and tribological properties.

The above graph consists of Ducoya preliminary data – arithmetic mean of five specimens, and best traditional values taken from published datasheets, none of which reported data over 260 °C.

The above graph consists of Ducoya preliminary data – arithmetic mean of thirty specimens, and best traditional values taken from published datasheets, none of which reported data over 260 °C.

Datasheet1

Ducoya G021 ISO is a filled version of Ducoya, containing 15 % wear- and friction-optimised graphite. Initial investigations of tribological properties in dry conditions indicate a significant improvement in wear factor compared to the best traditionally produced polyimides of this type. While much work remains to be done with this
specific molecule, this result seems to confirm earlier work by Irisawa et al. on several polymers, showing that the wear rate is inversely proportional to the product of tensile strength and elongation.

Of particular importance is the continued performance of this molecule at significantly elevated temperatures. This is because, when dry friction occurs – whether by design or due to off-design operation under adverse conditions – temperatures on the wear surface can rise substantially compared to the bulk material. For instance, regular operation at 120 °C can quickly lead to temperatures exceeding 240 °C on the wear surface under harsh sliding conditions (High PV value).

It should be noted that this general hypothesis applies only to materials of the same type (in this case, PMDA-ODA polyimides) and only when tested under identical conditions. Further work will determine whether this prediction holds for Ducoya G021 in comparison with other PMDA-ODA polyimide polymers.

Why would this be important to Battery Electric Vehicles?

As BEVs increase in torque, while package space and cost must decrease, this can lead to higher PV values as the available load area diminishes. This also reduces the weight of single-speed and multi-ratio transmissions. Epicyclic transmission layouts may particularly benefit from this improvement. Furthermore, Ducoya, being wear-resistant, although still relatively soft compared to metal, allows metallic debris, such as burrs and wear particles from gears, to embed in its material and be removed as contaminants from the lubricating oil. While this embedding must be limited, removing metallics before they can interfere with the proper functioning of the electric motor – often sharing the same lubricating oil as the transmission – can only be beneficial.

Conclusion

An interesting new material that adds a new dimension to accessibility and performance in automotive applications. Here, we have focused on mechanical and tribological properties.

Future Work

Future publications will describe why this unusual and newly applied process using supercritical carbon dioxide should lead to such improved mechanical and tribological performance.

Opportunities arising from the resulting electrical performance in conjunction with the latest high-precision
moulding techniques will be highlighted.

In addition, test results will be published in which the relationship between t·ε2 and wear rates in various
situations, as described above, will have been investigated.

1 DuPont Vespel® SP-21 ISO Reference No. VPE-A10863-00-B0614 published 2010 and 2021.