CASE STUDY: Brano Relies on Enventive Concept for Tolerance Analysis of Automotive Mechanisms

One example of a Brano application is for backrest seat latches used in automobiles. This mechanism disengages the seat safety lock to allow the user to easily and reliably fold the seats.

The user must be able to unlock the mechanism readily by moving a lever or pulling a strap, but accidental unlocking must be prevented. This system must also be reversible, allowing the user to relock the backrest seat at any time.

The challenge with these mechanisms is that they require a great level of accuracy to work properly and durably. Their functions are made possible by torsion springs and a system geometry that ensure the mechanism’s cams work correctly at various friction levels while preventing unexpected release of the safety lock.

Due to the high level of severity for a seat latch failure, Brano’s automotive manufacturing customers expect a mechanical variational analysis at the Request for Quotation (RFQ) stage that shows the effective and robust performance of a proposed design. Later in the project, more detailed tolerance analysis must confirm the RFQ studies with a deeper level of detail.

Using Excel spreadsheets to show that a design is robust at a detailed, comprehensive level is very difficult.

In variational analysis studies of seat latches and similar types of mechanisms, physical aspects such as friction forces, torques, and their respective tolerances must be taken into account and statistically modeled. This level of analysis is very difficult, if not impractical, to do with spreadsheets.

For instance, a specific design may work when analyzed in a spreadsheet using the nominal and tolerance worst case values and then later with a prototype. However, without a statistical variational analysis approach that combines Geometrical Dimensioning and Tolerancing (GD&T) values with physical impacts, mechanical variations introduced during manufacturing are very likely to lead to a much higher level of Parts per Million (PPM) failure rates than expected — potentially, a very costly problem.

Brano’s engineering team originally tried using 3D tolerance analysis software that is integrated with CAD. However, similar to another Concept user, Danfoss, the conclusion was that the 3D analysis software was difficult to use and required a significant time investment that only a tolerancing specialist could afford.

So, when a peer in the automotive industry recommended Enventive Concept, Brano’s team decided to give it a try.

Thanks to Concept’s powerful features combined with a user-friendly experience, Brano found that after a single and short training program, any product engineer or designer could use Enventive’s software.

“Enventive web trainings are very good.
The team is very friendly, helpful and quick at answering any question.”

Tomáš Prda

Chief Engineer at Brano

The goal for Brano’s engineering team was to go beyond the traditional tolerance analysis that’s usually done after detailed CAD models are completed. They needed help in assessing mechanism tolerances well before their detailed design work, right from the RFQ stage. Today, they use Enventive Concept’s unique functional modeling approach to do this by:

• Combining tolerance analysis of dimensional, geometric and physical parameters
• Automatically calculating variational force equilibrium and plotting variational charts
• Spotting critical dispersions throughout a mechanism system’s range of motion

The benefits? An unprecedented level of insight.

Brano’s team already knew the parameters contributing to variations and failure rates, but until now, no team member was able to establish the direct correlation between all of them.

With Enventive Concept, Brano’s mechanical designers know exactly the percentage of contribution of all parameters, regardless of their type, such as those for: forces, dimensions, perpendicularities, and floating pins in hole. This level of insight enables them to quickly and confidently optimize their mechanical designs.

“Enventive Concept allows us to understand the root cause of our variations,
quantify them and optimize them.”

Tomáš Prda

Chief Engineer at Brano

On top of gaining new understanding, the use of Enventive Concept makes Brano’s design process far more robust and reliable. The trust that Brano’s customers place in the team’s ability to anticipate and reduce the risks for unexpected non-quality is crucial; an approach that fosters long-term success of their partnership.

With the added value of Enventive’s Concept software proven, Brano is working to expand Concept’s use to other complex mechanisms such as double hinges, pedal systems, and more.

 “Enventive Concept brings deeper product knowledge. A direct source of innovation for companies who want to go to the next level.”

Tomáš Prda

Chief Engineer at Brano

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