ENVENTIVE® CONCEPT: AUTOMOTIVE
Shaping the future of mobility
In the mobility race, OEMs increasingly ask for proof of simulation at RFQ stage to ensure that 1st tier suppliers have the necessary tools to design products right and at the first attempt. Used at an early stage of the design, Enventive Concept is the leading tool to master product performance and secure robust tolerance analysis.
Mastering tolerance variations in the automotive industry
Reducing the number of controls to a minimum in the manufacturing plant leads to significant savings and ultimately drives new business.
Enventive Concept empowers the engineering teams in this respect. Users now quickly iterate on their design to ensure each functional condition remains within its targetted limits and does so with the largest possible tolerances.
The results are:
- a faster time to market by reducing the number of: prototypes, ECN, internal discussions…
- an optimal cost for each function by reliably predicting the design variations and applying good GD&T
- customer satisfaction by reliably achieving the product robustness objective.
Problem: Errors in the design are identified only in the production phase (high rate of rejected assembled products)
Solution: Use Enventive Concept to identify angle of the handle at which the system triggers.
Benefits: Predicting tolerance variations early in design removes the risk of being hit by costly stack up problems in the production phase
Problem: The critical stack-up has contributors spread among different views
Solution: Use the 2.5D projection approach to calculate tolerance variation throughout kinematics
Benefits: Calculates complex 3D stack-ups using a robust approach
Problems: Control the pressure on the disk. This parameter could be affected by hundreds of possible contributors.
Solution: Build a complete model of the gearbox
Benefits: Run a tolerance analysis that includes the effect of friction, temperature variation and multi-view combined effects
Problems: The force delivered by the user on the lever must fall between a minimum and maximum value. In this way, the system provides stability and at the same time avoids excessive wearing of the components.
Solution: Run a Tolerance In Motion study (TIM) combined with a force equilibrium.
Benefits: Study the evolution of forces and their tolerance intervals along a kinematics.
Problems: Control the position of the pedal pad.
Solution: Run a Combined Tolerance Analysis to see the X and Y position of the pedal in a single report.
Benefits: Study mulitple stack-ups in parallel.
Problems: A set of x pins must fit in a set of x holes.
Solution: Build a parametric model of the connector using the Pin-in-Hole Pattern tool.
Benefits: The user simply modifies a set of input parameters to change the amount of pins in the connector.
Example on how to improve product robustness
Let’s see how Enventive Concept ensures product tolerances remain within their functional limits…
Here is an extract of an FMEA function involving a blinker:
|Switch must work within specific forces (30 ± 20%)||1) Too low means that accidental operation is possible|
2) Too high means
a) user fatigue
b) broken switch
3) Testing cycle over-runs
4) Field failure returns
|1) Manufacturing Tolerance variations|
2) Frictional variations
|Use Enventive Concept to optimize the consequence of variations on the switch operating efforts|
Forces target values = between 24/36N with a Cpk = 1.00
As we are at the conceptual design phase we want to identify the maximum dispersions that occur throughout the kinematics so that we pinpoint spot the worst position.
We take into consideration the dimensional, geometrical and physical aspects contributing to the dispersion analysis.
We plot them displaying: the nominal, worst case (WC) and statistical dispersions (RSS) to identify and visualize the expected maximum product variations. Knowing where the maximum variation occurs allows us to focus on and optimize the product design so that fewer parts will be rejected during the inspection process.
We have efforts above the functional upper limit occurring at an angle position of 11° so we run an analysis at this position:
We observe a discrepancy between the actual mean result and the targeted mean result. We also observe a difference between the actual Cpk and the target Cpk (1.00)
Here are the actions we choose to take:
- MEAN IMPROVEMENT: we optimize the stiffness value to bring down the mean value to 30
- CPK IMPROVEMENT: we bring the actual Cpk to 1 by reducing the stiffness variation and the free length. We can further improve the tolerances by reducing the tolerancing profile
After optimizing the tolerance analysis report we run a new “tolerance in motion” study to check by the way of a force vs movement graph that the force value now remains within the 36/24N (30 ± 20%) objective with a Cpk = 1.00
With the modifications made we now achieve the FMEA functional conditions in a robust way, laying the foundation for optimal GD&T on the drawings after 3D modelling.