Storage Solutions Questions And Answers

Q: What are the weight requirements for the different storage systems?

A: That is a more difficult question than you would expect.  Even the most basic form of pallet rack, which is selective rack, has many variables that influence the capacity of the storage system.  For example, when specifying selective rack, the weight of the pallets stored in the beams must be known before specifying components.  Additionally, it must also be determined if the pallets are going to be stored one, two or three wide on the beam levels.  Finally, the number of beam levels and minimum spacing between the beam levels must be understood in order to properly determine the frame capacity.  Adding to this complexity might be the different pallet support means, whether through pallet supports, tie beams, wire decking or panel decks and their associated capacities and limitations.  When dealing with more complex storage systems, such as drive in/drive thru, push back or pallet flow, the engineering company tasked to specify the proper equipment must have a thorough understanding of the product being stored, along with the application and environment that it is to be utilized in order to avoid crucial mistakes. 

Q:  In a pallet flow system, how do you control the speed or flow of pallets?

A:  This is one of the most critical considerations when designing a pallet flow system.  Heavier pallets require retarding devices, which are simple geared components or rollers, which slow down the pallets as they travel down the lane.  Obviously this is extremely important especially in multi-pallet deep flow lanes with heavy pallets because the lane becomes somewhat of a roller coaster if you don’t control product speed.  This can be very dangerous to nearby operators or the product itself.  On the other hand, if the pallets are relatively light, then misapplied retarding devices might actually cause the pallet to hang in transit hindering productivity.  The major take-away is to ensure that all product characteristics are known and taken into consideration when designing the pallet flow system so that it works the way it is intended to.

Q: What is “clear height” and what are the restrictions associated with pallet rack and “clear height”?

A:  Clear height is the vertical dimension from the finished floor to the level of the lowest underside point of obstructions attached to building ceiling components, such as joists or rafters.  Examples include the sprinkler heads, HVAC ducting or lighting that are suspended from the joists.  This represents the height within which material handling equipment can be installed while leaving clearance for product movement without touching or damaging the joists or obstructions attached to the joists.   The minimum clearance between product and overhead obstructions like sprinklers and joists depends on local codes, but typically we have found that 18” is the minimum acceptable gap. 

Q:  How do you know which way to orient the storage system in the warehouse?

A:  Typically storage systems are comprised of rows, whether they are rows of selective rack, shelving, pushback, drive in/thru, or flow rack.  These rows are typically installed either parallel or perpendicular to warehouse dock doors in a rectangular shaped warehouse.  Since every warehouse or distribution operation is unique, even within the same company, the answer to the question is “it depends”.  Material handling equipment layout depends largely on the desired material flow of the operation, especially as it relates to receiving doors and shipping doors in the building.  Building dimensions are also a critical variable since every warehouse is designed differently and may have varying column spacing, clear height, and/or overhead obstruction.  So after evaluating the ideal material flow for your operation including building characteristics, it usually becomes pretty obvious how the storage system should generally be oriented.  Then it is a matter of tweaking that general layout to maximize based on your goals. 

Q:  How much should a pallet overhang a beam on selective pallet rack?

A:  Typically the pallet should overhang pallet rack support beams by three inches front and back for a total of six inches.  This is one of the important steps when determining the rack frame depth for selective pallet rack.  Since most pallets are 48” deep, then taking away 6” would equate to a frame depth of 42”.  This happens to be the most common frame depth by most major US manufacturers.  The three inch overhang is important because it ensures that the pallet is supported not only by any decking used, but also by the support beams.

Q:  Why do companies perform rack repairs instead of wholesale component replacement?

A:  We have done a lot of rack repairs using splice kits that take out the damaged upright posts and replace with new reinforced ones.  We can do this without major disruptions to operations, such as requiring the product to be emptied out of surrounding bays.  We have found that this is the major advantage and not simply price, because warehouse operations have to keep running and cannot afford to stop everything while the storage system is being repaired.  In many cases, the cost of replacing damaged components is also advantageous when compared to removing product as required for full components replacement. 

Q:  Why do companies decide to choose an engineering company such as TriFactor to design and install the storage system as compared doing it themselves or simply finding a manufacturer’s rep or dealer?

A:  Even though we are an engineering company, we are also a distributor for many storage equipment manufacturers.  So price for equipment is typically the same as you would get if you went to a dealer or manufacturer’s rep.  The key difference is our engineering capability.  Our industrial and mechanical engineers evaluate all variables, from operational material flow, to building characteristics and even slotting or velocity analysis in order to determine the best design.  We have found on many occasions that customers learn hard lessons when trying to self-integrate or take engineering shortcuts on their storage system.  It is always better to plan ahead with someone who knows not just one product, but applications for many competing products.   This helps avoid putting the proverbial square peg in a round hole.

Q:  Where do you see pushback being used most effectively?   I’m having a hard time figuring out why I would spend the money for pushback over pallet flow or just double deep rack?

A:  Most of the time, we use push back rack as the major replenishment component of a pick module and not as a stand-alone storage medium.  A lot of times, full or split case picking, whether from pallet flow or carton flow rack, is done on the lower level of a pick module.  In order to prevent from having to replenish pallet or carton flow rack, full pallets are stored in push back rack immediately above the flow rack.  That way, replenishment can be accomplished more efficiently during picking since operators pull and charge the pallet flow lanes from the push back away from the picking operation.  Pushback is also effective at utilizing otherwise dead wall space for dense storage although it comes at the price of all product stored in LIFO sequencing.