Edition #6 - Designing Out Common Product Failures That Lead to Injury

In the last newsletter we looked at reducing injury risk through thoughtful safety mechanism design. In addition to fail-safe principles (newsletter #4) and good safety mechanism design (newsletter #5), there are other smart design choices that can reduce the chances of common failures. To finish off this series on how good design plays a critical role in reducing product risks, here are four common failures that often lead to injury and how you can reduce those risks:

1. Actuator Failures
TIP: Keep Actuators Close to the Action
The more components between the actuator (e.g., a handle or switch) and the action (e.g., folding or locking), the more failure points. Minimise distance and complexity, especially in safety-critical mechanisms.

For example, when the actuator is physically integrated with the action, such as a simple sliding latch found on a door, the mechanism is very reliable. As the distance and number of components between the actuator and the action increase, so does the potential for failure. Each additional link or moving part introduces a new failure mode. The more safety-critical the function, the more important it is to minimise these points of failure. This may involve reducing the distance or simplifying the connection between the actuator and the action to ensure the mechanism remains robust and dependable.

2. Failure Under Load
TIP: The loaded configuration of a product should be the most robust

Pins and latches should not bear significant loads. Ideally, they should hold a product in a particular configuration when it is unloaded. For a folding product, or any product designed to be disassembled, it’s important to consider how it will be used under typical conditions. Ask yourself: if a key component fails during normal use (eg, when loaded), will the geometry of the product help maintain safety, or will it create a hazard?

For example, consider a folding chair. When the chair is in use, ideally the user's weight should act to keep the chair in its deployed, stable configuration. Their sitting on it should not be working to collapse it, and failure of a small latch or pin should not result in them ending up on the floor. If a latch or pin is keeping the product in the unfolded configuration, it may be bearing a significant load, which could compromise both the product’s durability and its safety over time. Ideally, the product should be designed so that the user must first remove the load, by standing up, before the product can be folded. This ensures that the structure remains stable and secure under normal use and that failure is far less likely to result in injury.

The key questions with any product that is designed to be loaded, are:

• under what configuration(s) does loading occur?
• during this loading, what component is taking the load?

Surprisingly, it is very common that the loaded configuration of a product is also its weakest and this results in product failures in market.

3. Injury as a Result of Uncontrolled Movement
TIP: Moving parts, particularly those that can have some momentum behind them, should always be controlled

If you review a wide range of product incident reports, you’ll notice that injuries frequently occur as a result of uncontrolled movement of a component. For example, let’s say that someone picks up a ladder and one half suddenly swings towards them. In such a moment, there may not be enough time to move fingers out of the way, leading to crushing or even amputation injuries.

A typical mitigation strategy involves adding latches or ties to secure parts of the product during handling or transport. However, if these mechanisms are used, they must automatically engage to be effective, only to be manually released once the product is back in a safe configuration for use. Furthermore, these solutions must accommodate real-world variability, such as situations where the product isn’t fully folded or extended. In such cases, the latch should still engage securely over a range of folding or unfolding angles.

An alternative or complementary approach is the use of dampers or similar mechanisms that slow down component movement, particularly near points of contact where injury could occur. Ensuring there are gaps between components can further reduce these types of risks.

This type of design not only protects users from sudden impacts but also contributes to a perception of control and quality in the product experience.

4. Injury through the Unpredictability of Product Handling
TIP: Guide Safe Use of a Product through Ergonomic Design

Ergonomics is not just about product comfort, it’s about influencing how users interact with your product. It’s a critical tool in designing for safety. If your product is likely to be picked up, moved, handled, or repositioned, there are multiple ways a user might choose to interact with it. By intentionally designing your product with a clear, intuitive, and comfortable method for handling, you reduce risk. This design choice allows you to guide user behaviour and ensure that any potential hazards are either minimised or eliminated. Conversely, if there is no obvious or comfortable way to handle or use the product, users will improvise and that improvisation can lead to misuse, product damage, or injury.

For example, comfortable handles on a product, that are in the ideal location to balance the weight of the product when being carried and that keep hands away from any moving parts or pinch points can reduce risks of injury significantly.

Conversely, sometimes unintentionally, a part of a product lends itself to being a natural handle even though it was never intended to be. This has been the result of many injuries as users consistently picked up or held a product in a way that was completely intuitive, but was also hazardous. This highlights the need to:

• design the product to ensure users engage with it in the way you intend
• performing user testing to verify that they don’t naturally do something different

Designing for safety and durability isn’t just about compliance. It’s about trust, in your product, your brand, and your ability to deliver what your customers expect.

By integrating fail-safe principles, well-considered safety mechanisms, and thoughtful design choices, you’re not just preventing injuries. You’re creating a product that feels solid, reliable, and thoughtfully engineered, because it is.