Automated Spring Testing

Specification

Bosch Diesel has been operating at Jihlava in the Czech Republic since 1992 making components for the world famous Bosch automotive diesel injection systems. Precision springs form a critical part of the assembly, and Bosch needed to test more than 50 different types of spring. With the requirement to test some 500 springs per day, an automated system capable of testing both compression and tension springs ranging from 2 N to 800 N to Bosch’s own exacting test standards was specified. The automated system needed to be simple to operate with rapid re-programming for the different types and capacities of spring. High accuracy and the ability to resolve very small differences as well as pre-conditioning the springs before commencing testing were also vital.

Solution

Natis - Mecmesin’s distributor for the Czech Republic supplied Bosch Diesel with two identical MultiTest 1-i computer controlled force testing systems. Each was equipped with interchangeable loadcells covering the measurement range from 5 N to 1000 N. In addition to standard tension and compression fittings, a special fixture was made to accommodate the smallest springs.

Testing small springs with 25 N loadcell

The powerful Emperor™ software controls the movement of the MultiTest 1-i force testing stand, collects the data, performs calculations and can report on the status of each spring before storing all the results. Part of Bosch’s test specification calls for pre-conditioning the springs by ‘scragging’ or exercising each spring a set number of times before the measurement is made. Emperor™ is programmed to measure the specific requirements of each of the 50 types of spring. Switching between different tests is both simple and quick. Because of the precise nature of the application it was important to Bosch that the measurement of very small distances was made with great accuracy. To achieve this, Emperor™ software has a build-in System Deflection Compensation routine that reduces the uncertainty due to tiny movements in the stand, fixturing and loadcell. Emperor™ software stores the compensation data which can be applied to the test program for each of the 50 spring types.


System

  • MultiTest 1-i computer controlled test frame up to 1000 N
  • Intelligent changeable loadcells (ILC) 5 N, 25 N, 250 N and 1000 N
  • Emperor™ Force ver.1.18 software
  • Probes for tension and compression tests
  • Special fixtures for small compression springs
  • Desktop computer with Windows® XP