CASE STUDY: Bosch Speeds Up Robust Design of Tools for Home and Garden

Bosch’s battery-powered tools for home and garden depend on mechanisms that are geometrically complex, making it challenging to determine tolerancing values that lead to robust performance and are cost-effective. Complexities can include rotations, floating pin in hole constraints, levers, cams, kinematics, and more.

Until 2021, Bosch’s engineers analyzed the impact of tolerances using spreadsheets. Their sheets had sophisticated formulas with angles, sines, cosines, etc., that were time-consuming to create and maintain.

With the adoption of Enventive Concept, Bosch’s engineers model and analyze tolerances for complex mechanisms more precisely and closer to the reality of performance versus spreadsheets.

Using Concept, Bosch’s engineers rapidly:

• Model mechanisms visually with candidate geometrical dimensioning and tolerance (GD&T) values.
• Calculate tolerancing stack up values precisely across all mechanism positions, automatically taking into account geometric complexities.
• Animate movements.
• Predict failure rates of functional requirements using statistical methods such as RSS or Monte Carlo simulation.
• Detect and rank all contributors to failure rates.
• Iterate GD&T values to achieve targeted level of design robustness.

One example is an on-off mechanism for hedge cutters that rotates a lever to toggle a microswitch. For safety, the mechanism must never fail to turn off the microswitch. For customer satisfaction, the mechanism should reliably turn on the switch.

Using Concept, Bosch’s engineers are able to quickly and confidently determine the tolerances needed to meet their on-off performance requirements while at the same time optimizing production costs.

A second example is blade motion on jig saws. With a switch on the side of the saw, users can change to different pendulum modes, which create a swinging motion to speed up cutting. Using Concept, the engineers can rapidly what-if analyze the impact of mechanism tolerances on the performance of each mode. A key for Bosch is Concept’s ability to analyze tolerances while the mechanism is in motion.

“With Concept we are able to put our engineering design focus on the mechanics rather than the mathematics. We do not need to deal with angles, cosines, sines and so on. Tolerance analysis and prototyping that took weeks to complete with spreadsheets now takes a few days.”

Tibor Bohos

Development Engineer at Bosch Power Tools

Once decisions are reached, the engineers transfer the GD&T results from Concept into their 3D CAD system to complete detailed design. They find that using Concept’s 2D analysis as inputs to 3D CAD simplifies and focuses decision making vs. trying to do it all in 3D.

In some cases Bosch wants to validate design changes for an existing 3D CAD model. Their engineers will import the CAD model into Concept to quickly determine if those changes are acceptable or need to be modified further.

“Concept enables us to model accurately our product performance. Beyond obtaining a failure-rate analysis that reliably predicts reality, we are faster in converging to the optimal solution. This process enhancement has led us to improve our field quality by 15%.”

Robert Soltesz

Engineering Excellence at Bosch Power Tools

With Concept, Bosch finds they shorten time-to-market of products and make faster production decisions.

• One model, many analyses — Once a model is built, engineers save time by quickly analyzing multiple requirements. For instance the same model built for analyzing the hedge cutter switch mechanism also can analyze other potential interference issues, such as between the mechanism and a housing. Doing all these multiple analyses in a spreadsheet requires separate tabs and is much more time consuming.
  
• Fewer prototypes — The far greater precision enabled by Concept’s modeling and calculations means fewer prototypes are needed, saving time, effort, and costs. Before Concept, using spreadsheets, prototyping took weeks. With Concept, Bosch completes their prototyping in days.
  
• Fewer warranty claims — Concept’s greater precision leads to an improvement of 15% in field quality.
  
• Faster production decisions — When changes occur during production, Bosch’s engineers can use Concept to rapidly assess if there are any impacts on assembly or field quality that need to be addressed.