Other Voices: The ins and outs of designing and implementing conveyor systems

Editor’s Note: The following column by James W. Trufan, PE, senior project consultant for St. Onge Company, is part of Modern’s Other Voices column. The series features ideas, opinions and insights from end-users, analysts, systems integrators and OEMs. Click here to learn about submitting a column for consideration.
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As with successful athletes and teams in all sports, maximizing the performance of a conveyor system starts with good execution of the fundamentals.

Whether investing a few hundred thousand dollars or millions, there are some things you definitely want to know before starting down that path. This article will talk about those key fundamentals that can sometimes be overlooked. We will also talk about other aspects that often do not receive the consideration they are due.

First of all, start with the end in mind. The initial phase involves data analysis of order profiles, volumes, volume fluctuations, product mix (in terms of handling attributes) and trending based on the historical data. An important step is to identify key growth factors and assumptions that impact how much volume the conveyor system is expected to handle.

Once you have a handle on how much volume the conveyor system is expected to handle, pay special attention to peak volume. The seasonal peak must be established, translated into weekly peaks and ultimately the daily peak. This is determined by historical patterns and customer service level requirements. Finally the peak demand and operational hours available generate the cartons per hour requirement.

The final step, which is a science unto itself, is translating the design requirements into cartons per minute through each process flow of the system. Visio schematics are a good tool creating representation of the cartons per minute. The cartons per minute are used to determine conveyor speeds and also dictate the appropriate type of sorter, wherever cartons need to be diverted to one of multiple destinations.

Two examples of types of conveyors and their uses:

Belt conveyor (transport)
Pros

• Less costly than accumulation for transport over long distances
• Controls carton spacing precisely even at high speeds

Cons

• When downstream conveyor stops entire length of belt must stop

Uses

• Typical for all inclines and declines
• Braking product prior to merges
• Gapping product prior to sortation systems
• Maintain and control carton spacing prior to sorting

Cautions

• Creates hand to mouth scenario so avoid where creating a buffer between operations is important
• Need to pay close attention to pitch declines and inclines (12 degrees max. is a good rule of thumb)

Gravity conveyor (staging)
Pros

• A low cost alternative at 10% to 20% the cost of a power conveyor

Cons

• Cartons are either moved manually or rely on incline

Uses

• Ideal for staging up product behind workstations, also used in various larger buffer systems to stage lanes of cartons

Cautions

• Important to understand nuances of and application of skate wheel, versus rollers, roller spacing

There are far too many types of conveyors to cover in a single article, but the two examples above provide a flavor that there are many factors to consider. Cost and performance will be greatly impacted in the details of conveyor application – type, speeds, carton alignment, merge and sort technologies, and of course, ‘right sizing’ each subsystem.

Jim Trufan, senior consultant with St Onge Co., has more than 25 years of leadership experience in supply chain logistics with a strong background in project engineering and execution. Contact Jim at 717-840-8181 or at [email protected].