Tolerance Analysis: From Excel to Digital Quality Twin

How quality assurance makes your engineering and production even more efficient

Published 07/03/2019
Tolerance Analysis: From Excel to Digital Quality Twin

In this article, I would like to offer you a brief overview of the business benefits you can gain from software-based tolerance analysis, the virtual prototype concept and, building upon these, the digital quality twin.

Before addressing any technical background, let’s take a look at a manufacturing company that has already updated its quality assurance processes and tools.

Promising Scenarios

In such a company, the development division designs and optimizes components in a virtual environment. When serial manufacturing begins, real measurement data turn this virtual reality environment into a “real virtuality” environment.

When serial manufacturing begins, real measurement data turn this virtual reality environment into a “real virtuality” environment.

Building on this foundation, the company can …:

  • … virtually assure production step sequencing or new manufacturing procedures – instead of having to conduct costly, drawn-out tests using real-world production materials.
  • … reconcile machine settings with the dimensions of components as they arrive at the start of a shift – instead of only dealing with machine settings reactively when problems arise.
  • … rely on software to determine the causes of manufacturing problems – instead of puzzling them out by trial and error.
  • … reuse previously gained knowledge about manufacturing precision levels when creating new product variants and all-new products – instead of having to take the same hurdles over and over again.

Depending on the manufacturing context, this list can be extended in various ways. One fact remains: These scenarios don’t just sound promising – they can already be achieved today. The above-mentioned examples are from real-world production situations, and I have had the opportunity to participate in some of these projects as a CENIT tolerance management expert.

Feasibility is not the issue. The required technologies are readily available, as are tried and proven approaches to implementation.

Everyone must understand the objective

So how do you go about implementing a similar solution in your own enterprise? In my experience, a core challenge is maintaining a positive attitude to how you establish new processes. As with other Industry 4.0 concepts, an end-to-end quality assurance system will change workflows and accountability structures within company divisions. This can only be made to work if everyone involved pulls in the same direction.

When responsibilities change, the management's overall perspective is required.

That’s why I’d like to start the next section the same way as I begin any project with a client: By emphasizing that management must fully support and guide such a plan.

When responsibilities change, the management's overall perspective is required. And before the path to the goal can be mapped, everyone must understand the objective. Those who call for change must also be able to authorize and fund all associated measures.


Digital Engineering from a Quality Perspective

The concrete steps that must be taken to establish an end-to-end quality assurance regime are easier to understand if we examine the product development process (PDP) from a tolerance management angle.

In the conceptualization and design phase, the engineer develops a component group in accordance with certain specifications. To do this, they rely on CAD authoring programs to create the relevant 3D geometry.

Common CAD software includes options for defining tolerances. But when developing cost-effective manufacturing concepts that link quality targets with optimum tolerances, many companies still rely primarily on tests using real-world prototypes.

To be clear: Real-world testing will still be important and necessary in the future. But with the right approach, the need for such testing, and the effort involved in it, can be reduced significantly.

Tolerance Analysis: Simulation Software instead of Excel Formulas

The first step you can take towards implementing a new quality assurance strategy is to deploy simulation software based on the statistical tolerance calculation methodology.

This type of software lets your experts do the testing at their workstations. They develop virtual prototypes and resolve the core questions of tolerance analysis: Which geometry is important in terms of whether or not a certain requirement is fulfilled? How does it actually contribute to the quality of the product? Which geometries involve special tolerance requirements? Which geometries are less important, and where are wider tolerances acceptable?

By gaining an understanding of the effects of manufacturing deviations on the behavior and quality of the product, you ensure that your engineering fulfills the requirements contained in the specifications. Simultaneously, it offers an ideal cost-benefit ratio with respect to tolerances.

Virtual Measurement data for shorter time-to-market Cycles

The design phase is complete when the development division forwards the virtual prototype, including the tolerance concept (reference system and tolerances), to serial development.

Serial development likewise follows different paths than it used to. As workflows progress, the virtual prototype becomes a virtual (pre-)product, and this delivers virtual measurement data. From this data, the engineers can assess what the critical tolerances and processes in serial manufacturing may be. This in turn lets them determine the optimal measurement strategy.

Additionally, the virtual product can be used to develop assembly and fixture concepts and simulate the manufacturing and assembly processes.

From virtual Reality to real Virtuality

Before starting serial manufacturing, let’s look back over our shoulder. Traditionally, the engineers work with a CAD program that, from the point of view of actual production conditions, represents an abstract, ideal world. In such a development environment, the engineers can only rely on their experience when attempting to reconcile product design with reality.

By setting up the virtual product, your experts have brought the design into a virtual reality in which they can simulate important physical behavior dimensions.

Now we’ll take this a step further, because once serial manufacturing begins, and also during the earlier phases of prototyping and pre-series production, you acquire real-world measurement data.

Based on these data, you can now reconcile the virtual prototype with the real world:

  • Overall, what significant differences are there between the real and the virtual measurement data, and what are the causes of these deviations?
  • Are the assumptions made in the simulation model correct, or are there additional/ other factors that must be considered?
  • In reality, is the component being manufactured in the way that was assumed during simulation?

By reconciling the virtual prototype with real conditions and progressively approximating the two, one gains a model which we describe as the digital quality twin. If you decide you don’t need a real-time linkage between reality and the virtual counterpart, you get the precursor of the digital twin: The digital shadow.

Using the Digital Twin Technology concept to leverage cutting-edge Business Strategies

The list below indicates only a few of the potential benefits:

  • Your business accumulates software-based knowledge, which leads to improved analyses and projections.
  • You achieve a higher DRIFT quota (“do it right the first time”) and are able to bring products to market more quickly.
  • You can actually begin to control and regulate manufacturing processes on a quality basis.
  • As an enterprise that relies on innovative manufacturing, you can use the digital quality twin to ensure a positive ROI for your expenditures.
  • A potential future use: For remote maintenance, the data of the component groups of a delivered machine are uploaded from the measuring archive to the digital quality twin of the series in order to search for errors.

This brief overview offers you an idea of the principal strength of the digital twin technology concept: It provides leverage for new business strategies.

The digital quality twin can therefore play an important role in securing the future of your business. This means that it benefits all stakeholders in your company. Nevertheless, you will encounter many people who want to defend the status quo.

The digital quality twin transforms development environments from virtual reality to real virtuality – and that offers plenty of new perspectives for product development and lean manufacturing.

The digital quality twin transforms development environments from virtual reality to real virtuality – and that offers plenty of new perspectives for product development and lean manufacturing.

Typical reactions include the following: Why should Excel tolerance analysis with simplified two-dimensional models and worst-case scenarios no longer be good enough? Why should the development division invest in introducing a virtual product if other divisions reap the benefits? Why should the quality assurance division collaborate with engineering to develop a measurement concept when it used to decide things alone?

A strong pair: 3D Design and Simulation

This brings us back to the decisionmakers’ mandate to guide the change process. Perhaps you remember the time when 2D drawings were replaced by 3D engineering. I believe that today we are facing a similarly fundamental transformation.

Simulation capabilities enrich the 3D engineering world. They enable the creation of highly realistic virtual development environments.

Where in your company are the processes you would like to change? What business strategy do you wish to pursue? I look forward to a discussion with you! For any and all questions, please feel free to contact me at or by phone at +49/151/52745273.


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