TADM-SystemPosted in: Featured Case Studies | August 19, 2015 at 4:36 pm, by

Ethicon Endo-Surgery (EES), Inc., a Johnson & Johnson, is a company that designs and manufactures advance surgical instruments and medical devices for minimally invasive surgery. Located in Cincinnati, Oh, the company provides a range of surgical products and technologies as well as a full range of profressional medical education and services to its customers.



With growing complexities and variety of its products coupled with the need to keep historical data as required by the FDS’s regulations, the engineers at EES faced difficulties and spent to much time to maintain, update and synchronize the design requirements, actual inspection, and tolerance analysis information of their designing products. This information needs to be accessible, traceable, up-to-date, consistent, and transparent across different levels within the company and its suppliers.

Before implementing the TADM-System, the engineers used Excel spreadsheets to store the aforementioned information and to perform all non-complex, linear tolerances, stacks for quick turn-around analysis. For complex, non-linear tolerance stacks and tolerance stacks with moving parts, advanced tolerance analysis applications were used. As a result, the engineers were forced to manage discrete information in different places and/ or under different applications causing difficulties for the engineers to maintain and update their tolerance stacks. The list below contains the critical facts and needs for the engineers to implement an automated updating system to solve their problems.

  • Each engineering team as EES can work on one or more projects and each project which is a typical 1-2 year long project has several hundreds of tolerance stacks created. For each project, the engineers spend 100+ hours to maintain and update these tolerance stacks. EES has more than 10 engineering teams and each team is working on multiple projects conurrently so these hours can be increased dramatically.
  • Whenever changes are made to the design, the engineers can no longer have confidence over their existing tolerance stacks whether they still meet their requirements or not unless all hundreds of these tolerance stacks are updated to keep up with the design changes that happen frequently.
  • There were cases in the past that some dimensions required for the tolerance stacks were missing from the drawing revisions. Since these drawings are modified frequently, such mistakes can happen and when it happened, it took weeks or months for the engineers to discover and it was very costly each time.
  • The engineers always spent great efforts managing non-conforming parts from suppliers. They realized that inspection data could be more utilized to tackle this problem and to help them cut costs relaxing non-critical tolerances. However, to take this advantage, the inspection data needs to be massaged and arranged before it can be applied to the existing tolerance stacks. This is a very time-consuming effort.


In its attempts to solve the problems, EES has initially started to implement the TADM-System for an engineering team as a pilot program with these following key benefits to be expected and measured.

  • No learning Curve.
  • No need to update tolerance stacks created by TADM or other tolerance analysis applications.
  • The system should help engineers gain more confidence on drawing revisions and tolerance stacks with the features that alerts when the drawing issues are detected.
  • Advanced features e.g. inspection data management and what-if analysis should help engineers manage non-conforming requirements and allow the engineers to realize what impacts are on all the existing tolerance stacks if these requirements are modified/



Since the TADM-System was implemented under the pilot program, all tolerance analysis information has been organized, standardized, and made consistent, up-to-date, and easily accessible to the engineers and the suppliers. The results from this pilot program are shown as follows.

  • The system uses Excel as its interface which is very intuitive and very easy to use.
  • For this pilot program, there are 350+ tolerance stacks created by this system and 10 complex tolerance stacks created by Enventive tolerance analysis software.
  • With the implementation, there is no need to perform updates due to drawing revisions. All tolerance stacks get updated automatically; therefore, 100+ engineering hours to maintain and update tolerance stacks for a project are completely eliminated.
  • The system has also identified several drawing issues before release. If these issues were not discovered as happened in the past, the engineers would find themselves arguing with suppliers over whether parts are made correctly and also spending lots of time and money for reworking.
  • Inspection data from suppliers can now be stored and retrieved to plug into any existing tolerance stacks. Design data and inspection data can then be compared side by side so that non-conforming dimensions can be found quickly. If some dimensions need modifications, What-If feature provided by the TADM-System can allow the engineers to immediately understand the impacts of the modifications on all existing tolerance stacks. Therefore these nonconforming dimensions can be managed quickly effectively.
  • There are 8 engineers using the application to manage all product tolerance analysis. Since all data is stored in the central database, the engineers can be obtaining, storing and updating the tolerance analysis data more effectively, concurrently and accurately.

With the success of this pilot program as shown above, EES is extending the TADM-System to the remaining teams in the company with approximately 200 engineers who will be using this system.