By Grady Batten and Doug Vanderford

It is said that conveyor chain surge, like beauty, is in the eye of the beholder.

What is acceptable to one may be unacceptable and problematic to another.

Conveyors may not run as smoothly as Mercedes engines, and end users must be realistic and not set their expectations higher than conveyor technology can reasonably achieve. However, most everyone agrees that if the degree of surging adversely affects product quality or interferes with equipment or operational interface, corrective action is required.

Conveyor chain surge is difficult to define due to the fact that each system has its own unique criteria and characteristics that must be evaluated on a case by case basis. A basic definition is when the chain fails to maintain a reasonably smooth forward movement by exhibiting a halting, nearly stop and go thrusting motion that causes hanging parts to swing or even touch.

Unacceptable chain surge can be the result of many factors.

These factors may include:

- Inadequate support structure

- Improper lubrication

- Conveyor component condition (poor fabrication /installation/wear/etc.)

- Loading patterns

- System length and build-up factors

- Excessive takeup pressure

- Operating speeds

- Friction due to build up of coating materials.

While inadequate support and improper lubrication seem to be the biggest culprits, other causes are often discovered. The use of industry standard roller turns (vs. traction wheels) can inherently contribute to some system surging due to higher friction coupled with the chording effect of the chain on the roller turn rollers. In most systems, slight surging is acceptable and not deemed significant or detrimental. However, in systems with sensitive requirements, it is recommended that traction wheel turns be utilized throughout the system in order to maximize smooth chain operation.

Conveyor drives are a factor in surge. When feasible, drives should be positioned in as close proximity as possible toareas of the system in which surge is undesirable (i.e., paint application areas, load/unload, or other areas with special interface requirements). Drives tend to eliminate surge. In some systems, additional drives that otherwise may not be necessary from a chain pull requirement may need to be added to minimize surge in specific areas of the system.

When an existing conveyor is extended or modified, a surge problem could develop. An expansion of a line could change the dynamics of a system to an unpredictable degree. Added chain pull, new loading patterns, different line length and build up factors, etc., may or may not change the characteristics of a system. Existing support structure that may suffice for current line conditions may be unduly stressed due to such expansion and prove inadequate for the new expanded line.

It may be that added support structure, surge suppressors, or replacement of turns will be necessary should unacceptable chain surge develop after the line has been altered.

Some end users have attempted to increase line density by hanging parts too closely together with too little clearance between. In some cases, this action can impose too great a burden on the conveyor by expecting it to operate its chain smoother than design allows. Parts hung with only fractional clearances could be a case in which humans may be demanding too much of the machine.

Still, reasonably smooth forward motion of a conveyor chain is expected by end users and should be provided by installers.

When good design and installation hold hands with rational thinking end users, a happy marriage is inevitable.

Grady Batten, American Automation Inc., and Doug Vanderford,
North Mississippi Conveyor, are 20 plus year veterans in the
conveyor industry. They may be reached, respectively, at: