Carpet Tufting is a Tough Environment

Details

Components:

Simplicity Plain bearings

Retrofit or OEM:

Retrofit

Industries:

Machine Tools

Problem:

High speed reciprocating short strokes create high impact loads on the system; resulting in worn ball bushings and shafting. 

Solution:

Simplicity bearings contain no rolling elements, thrive in heavy load applications, and push contaminants such as dirt, carpet fiber particulate and grease to the end of the stroke.

The Losses

This carpet manufacturer was experiencing unplanned downtime due to linear bearing failures and massive profit loss due to thousands of yards in scrapped end-product. Poor quality and damaged carpeting were cited as the main reasons the manufacturer lost up to 54,000 yards of carpet to scrap. The root of the problem was found to be the machine’s ball bushings within the push down foot assembly. Specific issues included:

  • High-speed reciprocating short strokes (.5"-.625") that created high impact loads on the system, resulting in high wear on the ball bushings and shafting. This was the main cause of shutdown scenarios where maintenance and product replacement were necessary.
  • High cycle/minute stroke rate that raised high reverse inertia, prompting almost immediate wear of the ball bushings and steel shafting.
  • Spalling from the ball bushings against the shafting that created fine metal particulates that accumulated within the assembly, wore out the seals, and eventually allowed lubricants to contaminate the pushdown foot assembly and ball bushings. These lubricants then mixed with metal particulates to create “black spots” on the finished carpeting. The black spots could not be washed out, resulting in more scrap carpet.
  • Inaccurate tolerances (.005/.007’’) of the ball bushing system which caused a rocking motion along the needle bar. This phenomenon, known as needle wander/loss motion, resulted in the loss of positioning and missed tufts, leading to poor quality carpeting. This occurred almost immediately after the initial installation and grew more prevalent as the system wore down. Throughout the operation, loss motion and contaminated carpet resulted in 34,000-54,000 yards of scrap material and lost profit.
 

The PBC Linear Solution

PBC Linear implemented their Simplicity® self-lubricating bearing into the specified pushdown foot assembly for the carpet tufting machine. Its close tolerance ID bearing (.6240”-.6245”) and close running clearance (.0015”-.0018”) held the needle bar in tight position, solving the problem of wear and progressive wander/loss motion. The bearing’s proprietary FrelonGold® liner ran smoothly along the steel shafting, eliminating wear by evenly disbursing the load throughout the bearing. This success was in contrast to the previous application, which had only a small point of contact between the ball bushing and shafting products. Since Simplicity bearings contain no rolling elements, thrive in heavy load applications and dirty environments, they were able to push contaminants such as dirt, carpet fiber particulates, and grease to the end of the stroke.

Carpet Tufting Figure 2

The Gains

Simplicity bearings were designed to exceed expectations in applications like this. Before Simplicity bearings were installed in the pushdown foot system and undercarriage, the carpet tufting machines were in a state of constant unplanned downtime due to high maintenance costs and upkeep. Now, these updated carpet tufting systems have became the most productive machines in the plant! The linear footage between maintenance rebuilds of the machine were increased from one million linear feet to over three million. The carpet manufacturer was also pleased to report a significant 95% reduction in scrapped product, eliminating millions of dollars in scrap every year that was previously thought of as “an acceptable loss.” Those losses are now profit gains!