Part being tested:
Stabilizer bushings found in stabilizer legs on GK and other brands of vibratory equipment.
Reason for Evaluation:
Three of our Major foundry based customer in North America had experienced sudden and severe unacceptable performance problems, such as side motion and lack of material conveyability, followed by subsequent structural failures. GK was called in to help each of these customers to get them back into a reliable state of performance. The situation had degraded so bad in some situations that schedules were planned around the continued repairs needed until we were available to help sort things out.
On these service calls, the GK Technical Service Engineer discovered that the leg bushings installed by these customers appeared to be similar to our bushings, but noted that our normal identification marks were missing. Further investigation discovered that each of these cases involved replacing General Kinematics leg bushings Part number 10-01-464-01 with bushings from a GK competitor who had claimed his bushings were equivalent, but less expensive. Upon replacing them with the correct bushing designed for the application, the operating characteristics of each of the units involved immediately return to a proper operating level of performance. Basically, General Kinematics knew that the use of these sub-standard parts were causing performance problems and wanted to evaluate why.
Observations and Findings:
The competitor supplied bushing appeared similar in appearance to the General Kinematics bushing. All physical measurements were manufactured close to GKC tolerances except inner sleeve i.d. However, the bushing was made from a different process than the GK, such as a molded process. The rubber was not molded to either inner or outer sleeve.
The volume of compound inside the suspect bushing is far less than that of GK bushing. Our testing results verified this with significantly lesser load and tensional capacities we currently have in the 10-01-464-01 GK bushing. The compound properties of the competitors bushing resulted in a stiffer bushing than the GKC bushing. These tensional results equate to a far shorter bushing life than the GK bushing.
An Independent evaluation and comparison also suggests that “the end user would find these bushings(competitor bushings) identical or very similar in appearance as well as initial use, but would also speculate that longevity and loading capabilities are reduced/minimized when compared to orange (General Kinematics) bushing.”
Obviously, these findings are clearly supported by actual field experiences of our customers.
While these customers thought they were getting a great deal by saving a couple dollars buying bushings from another supplier, the downtime costs and maintenance costs experienced far surpassed any savings they would have accumulated over the life of the machine. Once these customers switched back to genuine GK stabilizer bushings, all their performance issues went away.