Application Technology

By Ian Parker, freelancer, Ianparkerwriter@aol.com

Today, the average car has about 30,000 fasteners and many of them are plastic – coming in a huge range of types. However, the car industry is changing at an ever-faster rate, as we move towards ‘individual transport’ and the evolving requirements that it will bring. 

The most apparent change today is the move from internal combustion engines (ICE) to hybrid and electric vehicles (EVs). Why does that affect fastener requirements? ICE servicing usually occurs once a year, but EV motors are rarely touched throughout the whole of their lives. So, the fasteners on ICE may often be released and re-fitted or replaced. On an electric powertrain, many must last for the whole of the vehicle’s life without being touched and this puts a whole new list of requirements on them. 

One of the main changes is the application of different materials. Years ago, it was mainly nuts, bolts, and rivets, but now the automotive fastener business is taking on new materials for improved strength and also lightness and reusability – electric motors and batteries are heavy, so any weight reduction is welcome and this affects fasteners as much as any other components. 

EVs use fairly high voltages and this may lead to electrical requirements for the fasteners, which was never a requirement on ICE vehicles. This means some EV fasteners have to be coated with insulation. Also, there is pressure for more widely applicable fasteners. With tens of thousands in most cars, it’s welcome if quite a few of them are the same. The development of common fasteners is an increasing requirement. There may soon be no specific fasteners for interior panels and exterior trim pieces – they will be for multi-use. 

With fasteners, stronger does not always mean stiffer. In some applications, a degree of flexibility is welcome. Advanced plastics and even carbon fibre composites are under consideration, but the latter can be brittle. Carbon fibre is also expensive. Fastener engineers are focussed on the further development of steel and aluminium alloys for heavy-duty components, as well as engineering new types of plastic. For weight saving, 0.1g per fastener is significant. 

Fastener failure is still a significant issue in the automotive field and a fastener with a bit of ‘give’ is often preferable to a more ‘rigid’ one. There are numerous examples when a fastener, although apparently well designed and built out of the best materials, is prone to failure.  Even though the particular part has been tested in the laboratory, where it performed flawlessly, it’s a source of constant problems once installed in a vehicle. This is a clear case of misjudgment by the engineers – who looked at the fastener as a single item, not part of the whole car.

When installed in a car, fasteners are exposed to forces, vibrations, and stress, often exceeding the engineer’s expectations. So, it is very important to ‘over engineer’ the part – since they will need to endure forces coming from other sources or parts of the car. For example, a simple bolt that holds suspension components needs to hold everything in place and endure constant forces, vibrations and impacts coming from the road.

Sometimes the fastener design engineer doesn’t fully appreciate the severity of the conditions to which the items will be subjected. Road maintenance has been impacted by the costs of Covid-19 and other unexpected government spending, so in many areas roads are a lot rougher than they used to be and pothole damage is much more frequent now. This situation is likely to exist for some time and it impacts the fasteners on a vehicle just as much as other parts. 

Today, there is little difference between OEM and aftermarket fasteners, but the two are likely to diverge. Aftermarket fasteners will probably stay pretty much as they are today, but OEM fasteners will move towards the permanent, more resilient and lighter designs demanded by hybrid and electric cars. Fasteners, such as lockbolts (which are firmly locked when tightened), blind bolts or wire threaded inserts, all offer better safety, durability and withstand higher loads. Their patents are slightly more complex than for standard rivets or nuts/bolts, but they have superior performance.

It’s important that the right fasteners are available at the right time for the manufacture of the whole vehicle, so the fastener supply chain is of critical significance. Production lines will have innovative processes with minimal downtimes, fully automated stock management and advanced communication between workstations. In such a production environment, fastener supply (and quality) is an essential aspect. Suppliers are creating new kits and assemblies that will reduce the servicing and installation times. Concentrating on the delivery aspect of the fastener industry will help shorten the production times – making final products not only cheaper but easier to complete. Vehicle manufacturers will not want to stop production lines for any reason, certainly not a lack of fasteners. 

Designing fasteners

Introducing and eventually producing new fastener designs requires prototyping as a crucial part of the process. In the prototype stage, engineers use different materials, production processes or approaches and thoroughly test the fastener before giving it the ‘green light’ and shipping the large quantities to OEMs. They are investing state of the art prototyping facilities that makes testing more accurate and gather a wealth of information about specific designs.

Using a digital drawing, firms construct the first prototypes quickly. Those fasteners are not yet ready for thorough testing. However, they are useful for showing the ‘real life’ dimensions of the product, potential design flaws and areas that could use improvement. Then the material is chosen, bearing in mind whether the item is designed to withstand high or low temperatures, high stress, or if it needs to be replaced regularly or permanently fixed in the car. 

There is a wide arrange of special materials and automotive coatings that can be used for many applications. Although most might be simple things, precision and accuracy are the keys to transforming the idea into a functional component. Cold forming is a unique way of shaping metal at near room temperatures. This process might be slower and more expensive but offers more advantages in terms of durability and strength of the final product. It is a crucial benefit for customers who develop fasteners made of steel or aluminium.

Clients often need small scale prototype production, so a supplier might provide them with a Minimum Order Quantity (MOQ) of just 25 pieces. Such an approach, along with high precision manufacturing, provides clients with the chance to try several designs or materials in a short time; gather more data in testing; and make better decisions.

To patent and sell designs, extensive legal work needs to be done. A company may offer PPAP Level 3 and International Material Data System (IMDS) if needed for easier patenting and classification of products. This may be helpful for smaller companies that don’t have legal departments and are unaware of the need for extensive documentation.

So what else can go wrong?

The fastener should match the material it is attached to. For example, if high-quality steel screws have plastic washers, it is quite possible that the washer will fail over a long time, leaving a loose screw and potential part separation. So, when installing a fastener or designing a whole assembly, it is crucial to match the materials and have basic knowledge of the forces the fastener needs to withstand. Most of the fasteners used in the engine bay or suspension need to be steel since they are exposed to extreme heat and chemicals. At the same time, fasteners used in the interior or for holding the specific body panels are usually made from plastic.

Quality plays an enormous part in the world of automotive fasteners. Just because two pins or clips look the same doesn’t mean they will perform the same and have the same life expectancy. Top manufacturers invest a lot of time and effort in high-quality materials, thoroughly tested in various conditions. The price difference is not there by chance and inexpensive fasteners are often much more costly in the end. Don’t be surprised if the reason for fastener failure is simply poor quality materials or poor production/testing processes.

Even though most automotive fasteners are simple mechanical devices, with pretty straightforward fitting, installation is still one of the main reasons for failure. The most common problem is over tightening of bolts and screws, which can make them crumble and fail. Sometimes, fasteners are misplaced and installing the wrong one in the wrong application could result in failure and potential mechanical troubles. Even the best designed fasteners made of the highest quality materials are prone to fail. Bolts, nuts and screws are especially prone to heat cycling, and vibration, and even the slightest amount can be a problem over a prolonged period. No matter how tight they might be, if the vibrations are strong enough, the fasteners will fail eventually.

There are numerous cases of plastic fasteners affected by aggressive chemicals used in a car wash or detailing process. Even though the plastic is made to be durable, it is generally not tested for absolutely all chemicals used in car cosmetics. It is a rare occurrence, but it does happen, and it is mainly due to the poor quality of fasteners installed and overly aggressive chemical compounds used.

View from EJOT

Steve Wynn, sales manager for Industrial Fastening Solutions at EJOT UK, explains: “Fastener development, product modifications, and new joining systems allied to differing vehicle construction materials and methods, have all evolved and they are part of the electrification revolution we are already seeing. There is a shift in product deployment across the range. For example, the escalation in the need for printed microcircuit boards – usually set into a light aluminium casting – is the domain of EJOT’s micro screw range. These threadforming screws provide the performance at a miniaturised level that designers would normally expect to achieve with much larger screws, as an alternative to soldering, gluing, clipping or welding.”

EJOT’s ALtracs Plus threadforming screws offer advantages for EV applications as they act as heat sinks – removing heat that is dispersing throughout the system – whilst providing a strong and vibration resistant joining. 

Steve continues: “Electrification has created a shift in the prevalence of products such as micro screws, which are deployed already to a lesser extent in ICE vehicles. In addition, the ‘infotainments’ that are prioritised by a new generation of vehicle buyers are also increasing the requirement for these types of joining solutions.”

Asia-Pacific is leading the growth

According to Mordor Intelligence, the worldwide automotive fasteners market was valued at US$22.8 billion by end of 2022 and is expected to reach US$27 billion (€25.2 billion) by 2027. This represents a solid CAGR of above 2% during the forecast period.

The Covid-19 pandemic hindered the growth of the automotive industry across the world. Asia-Pacific, being the largest exporter of automotive fasteners, was deeply affected during the crisis, highlights Mordor. The disruptions in supply chain activities; the interruption of large-scale manufacturing; as well as restrictions on travel; resulted in a slowdown of market. 

However, it has recovered well. Japan, China and India are booming in the market – due to presence of automotive giants including Toyota, Suzuki, Mahindra & Mahindra, Isuzu, Dongfeng, SAIC Motor and TATA Motors. In addition, production capabilities have also been improved, which show immense growth potential in the market.

Moreover, growing demand for lightweight vehicles is predicted to provide lucrative opportunities for market players during the forecast period. In addition, as manufacturers are also shifting from standard fasteners to customised fasteners, this new development will help drive demand in market.

Asia-Pacific is projected to account for a notable share of the automotive fasteners market – due to an increase in sale of vehicles across the region. An increase in aftermarket sale of vehicles across the region is also predicted to boost demand for the automotive fasteners market.

So there has never been a more interesting, or more demanding, time to be in the automotive fasteners business. These tiny items look quite unimportant, but are vital to the safe and efficient operation of vehicles. 

As electrification takes over, the older designs will disappear and the newer ones will become prevalent. The rate of change may be governed by the tolerance of society to ICE vehicles. Apart from historic vehicles, they may be scrapped a lot sooner than most people think and the automotive fastener business will have to move fast to keep up. The demands on automotive fasteners will also continue to grow as vehicle systems will be expected to last longer and longer without maintenance.