Global Material Handling System Integrators
 
 

Everything You Ever Wanted to Know About AS/RS, But Were Afraid to Ask...

 
ph_sparsleyAutomated Storage and Retrieval Systems – Why on earth would you consider doing that? This is the first of a series of articles on the subject of Automated Storage and Retrieval Systems, the diversity of the technology, and the rules and tricks used to simplify and insure that the application of these systems is correct and justifiable. Article 1 – Simplifying the work needed to make the “Correct Decision” – Technical Utilization Since the introduction of AS/R systems in the United States, the technology has evolved in a number of directions that has resulted in greater capability, and a large diversity in the rules for its application. Needless to say, in the last 40 years or so, these systems have become both Hero and Villain to the enterprises they have served. Success and horror stories are constantly referenced, and depending on which end of the spectrum your counsel is from, you may be influenced to make a decision focused on the wrong issues or for the wrong reasons. Despite the recent surge in popularity of these systems, most projects involving AS/RS come from an intuitive response from having seen a solution to a parallel problem that was addressed with this type of automation. Having been involved with the equipment and its application from near the beginning of its introduction, however, I often ask my clients: “… why would they want to use this approach to merely store material?” This is not simply a facetious question. It is a question designed to get the ultimate user of the system to discuss the functional uniqueness of this method, versus its alternatives. It is a traditional process of selecting the best tool for the job – i.e. while reasons might surface that would cause it to become an alternative, few of us would choose an elephant gun to go squirrel hunting. Many times, project teams take comfort in an approach that everything will be reduced to a bottom-line number on which a pure business decision can be made. To assign a credible dollar value to the hard items is fairly straight forward, albeit a lot of work. The quantification of soft issues, however, is much more difficult, and often results in the rejection of otherwise good solutions. Because of the effort needed to fully assess the benefit of any solution of this magnitude, and this includes  work on the supplier and the user’s side, I try to steer the early discussion of alternatives to a focus on the issue of “Technical Utilization”. I don’t know who first coined this term, but its use has saved many valuable (and, I might add, billable) hours debating the merits of a particular solution that ultimately will be rejected in favor of another, often less technical approach. The term, as I use it, refers to the proportion of time a solution is doing what it can uniquely do – that adds value to the process – that the other alternatives cannot.  

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The equation is not so much mathematical as it is relational. It shouldn’t be used simply to numerically rate each alternative as much as to compare the intuitive magnitudes of difference.  Since AS/R systems are the subject of this series of articles, we’ll use one as an example.

Assume that we are to build a warehouse. Most warehouses are equipped with racks and a device to move loads from an input position to a storage position where they stay until requested. Then, the device that stores the load into the warehouse will be used to retrieve it from the warehouse on demand.

One obvious alternative is to use a conventional, minimally automated approach with racks and forklift trucks. Another would be to use an AS/RS solution. The building will be a spec building with about 35’ clear height. Many of the early AS/RS’s in this country were built with this simple scenario in mind. That loads could be more easily tracked using automation was the basic justification. Damage, theft and errors could be reduced or eliminated by removing the human from the process along with his fork truck further justifying the expenditure. With today’s on-vehicle communications and real time WMS/WCS/SCADA, errors attributed to people are no longer a significant factor. The primary advantage might only be the height of an AS/RS that could reduce building footprint/cost, and the speed at which the system can store and retrieve material. With this in mind, the issues of first cost, labor, scale-ability, and facility utilization all get reduced to simple financial cases, and invariably, the alternative with the lowest technical utilization score loses. In my opinion, a more costly or more automated alternative must have a 20%-30% technical utilization advantage to “stay in the game.” Unless there are other compelling reasons for considering the approach, you are wasting time developing an approach whose TU is significantly and intuitively “out of whack”. And generally speaking, the only compelling reason that seems to prevail is: “… there’s just no other way to do it…is there?” Making an early Technical Utilization assessment often shortcuts the effort of decision making by avoiding the unnecessary work required to develop and cost out an alternative that would ultimately fail. More significantly, it draws attention to the functional values of a solution that need to be more carefully examined and quantified beyond the obvious cost and space issues, allowing faster decisions that lead to quicker implementations and an earlier competitive edge. -------------------------------- In the coming weeks and months, additional articles will be posted to stimulate thought and discussion about the process of design and planning for a project that will possibly involve the use of an AS/RS. These subjects will initially include the topics below. This list will evolve to include topics suggested by readers and other associates dealing with this issue. We would welcome any questions or comments, or even anecdotes about this subject that you would like to discuss either privately – one on one – or openly in this forum. Send your comments and/or suggestions to me through this forum or to SLParsley@bastiansolutions.com. Article 1 – Simplifying the work needed to make the “Correct Decision” – Technical Utilization Article 2 – The options available with the technology Article 3 – Information and data requirements Article 4 – Storage Utilization, Inventory Access and Cost Article 5 – The Relevance of Speed Article 6 – Critical Success Factors

Author: Chris Bratten

Chris is a Sr. Logistics Consultant with Bastian’s Software team based in Louisville, KY. He has a BSME from Rose-Hulman Institute of Technology and a MSME from Purdue University. Since starting with Bastian in 2005 Chris has developed and maintained strong relationships with his clients; designing solutions and working through implementations. He has also helped develop Bastian’s ExactaBEV WES suite, focused on wine & spirits distribution.

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