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Drawer Slides Tested Tough

Versatility Tool Works (VTW) goes to extraordinary lengths to achieve quality. This includes a regimen of testing to monitor and assess the performance of VTW’s design, engineering and manufacturing processes. Results are fed back to an aggressive Continuous Improvement Program.

An example of how testing “improves the breed” can be seen in the performance of Versatility® brand industrial-grade tool storage cabinets.
   
Required: Extreme Performance Drawer Slides
Versatility® cabinets include a line specialized for storage
of press brake and turret punch tooling–a demanding application due to the weights involved. Cabinets can be as large as 96 x 30 x 75, contain as many as 10 drawers, and support as much as 400 lbs. per drawer.

Drawers are supported on each side by telescopic, ball bearing slides. These slides carry the full load of the drawers and must resist deflection forces plus shock loads from dropped tooling. The slides must also provide for smooth operation and reasonable open/close efforts. Finally, they must not fail before delivering a specified number of cycles (measured in tens-of-thousands).   

Testing Cost/Benefit
Drawer slides able to meet these requirements are precision components that represent a significant portion of total cabinet manufacturing costs. In early 2009, drawer slides were tested to see if they could be improved to deliver better customer value. According to Ed Freimuth, Principal of Versatility Tool Works, “We were using premium, off-the-shelf slides but they weren’t giving the service life we wanted. We decided to research reasons for this to find out if we could do better from a cost/benefit perspective, either by procuring different slides or by manufacturing our own.” 

VTW & IIT Collaboration

To help with this research, VTW decided to enlist the aid of the Illinois Institute of Technology (IIT), a Chicago university well known for manufacturing engineering.

VTW has a special tie to IIT. Steve Freimuth, Ed’s brother and another VTW Principal, is an alumnus. Steve contacted Will Maurer, IIT Industry Associate Professor, asking if it might be possible to recruit students to help with research centered on testing and analysis of the design and performance of drawer slides. Maurer considered the undertaking an ideal senior team project. The Freimuths, Maurer, and a team of IIT students collaborated on the testing.

A purpose-built test rig was constructed by VTW and installed in an IIT lab. The rig was programmed to automatically and continuously open and close a drawer, unattended, for days at a time. Different makes and designs of slides, slide-support schemes, and a variety of load conditions (weights, placement in drawers, etc.) were tested.

It was discovered that the original off-the-shelf slides had insufficient yield strength (HRB 55). They deformed, allowing drawers to contact and drag along cabinet housings. Slides made of harder steel (HRB 72) showed no signs of failure after 7,000 cycles; these slides, however, were significantly more expensive. A more cost-effective solution was ultimately found. The original slides were shot peened to increase their hardness (to HRB 67); drawers equipped with these slides showed no signs of wear even after 10,000 cycles.  

According to Steve Freimuth, “The research’s solution was counterintuitive in that it called for combining store bought slides with in-house processing (shot peening). This approach costs out well and should provide customers with lower owning and operating costs over the life of a cabinet.”