Jason Thistlethwaite
109 lines
9.3 KiB
Markdown
109 lines
9.3 KiB
Markdown
#intendedProcesses #opinionated
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STOW stands for **S**patially and **T**emporally **O**ptimized **W**arehousing.
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![[Opinionated Transclude]]
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### STOW is "putaway" by another name... until it's not.
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Other warehouses might call this "putaway". A person doing STOW is responsible for optimizing the storage of goods in the warehouse, both spatially and temporally. That means ensuring the inventory can be accessed quickly and the space is being utilized well.
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This model of "putaway" is organized around the way computer RAM works (hence, opinionated). However, the thought process is that RAM addresses were originally modeled after physical storage methods, and then improved on by top-tier engineers.
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## The main objective of STOW
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The main objective of STOW is making it as fast as possible for key people to find and retrieve particular items from inventory. Efficient use of space is secondary, but still very important. Rather than space, safety and loss prevention should be the focus. When handled appropriately safety-focused storage methods will also use space efficiently.
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### STOW needs to enable the following capacity levels for outbound operations
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Based on models and simulations, a picker needs to be able to locate and pick a given item in about 45 seconds or less (less is better). **To facilitate that, it's recommended that each STOW location be sized and positioned so that it takes no more than 30 seconds to scan every barcode in the location.**
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These metrics were arrived at using [[Chaos Shaping]], with a [[Chaos Measure and Model.ods]], and our reference implementation of a [[Montecarlo throughput simulation]].
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This section is transcluded from [[Outbound Methods and Flows]] (and may not render on the web; just click the link above).
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![[Outbound Methods and Flows#Fulfillment Timeframes]]
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### Recommended methods and practices
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- If it isn't possible to scan every single item in a location within 30 seconds, the location is too large. Consider sub-dividing it or creating bins.
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- Avoid stacking as much as possible. It creates risks of things falling over and slows down picking. In general, no more than 2-3 things should be stacked on each other.
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- STOW is not a revenue generating task, but it needs to be done regularly. With that said, efficiency is key.
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- Be creative with subdividing and binning locations.
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## Related Processes
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People performing STOW should be aware of related processes that guide the way STOW should be performed.
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### Relation to 5S
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STOW has a strong relation to [[5S]] and [[red tagging]]. Where practical, staff doing STOW should be trained on [[5S]] and [[red tagging]].
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### Relation to Kaizen
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STOW is related to [[Kaizen]] in the sense that Linear Kaizen may guide the optimal placement of inventory or traffic lanes. In this kind of Linear Kaizen Event, members of the STOW operators should map the movement flows of inventory and people to better understand who is moving what, where, when, and why.
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## Stakeholders
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[[Dock Team]] is a major stakeholder in the STOW process because they rely on it to quickly pick orders they need to ship out.
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[[Inspection Team]] and [[Refurb Team]] mainly benefit from STOW because they need cleared racks in order to do their work.
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[[Customer Experience]] is also a stakeholder in two different ways. In one case, several of the critical failure modes can result in customer complaints the Customer Experience team has to deal with. Second, Customer Experience often has to locate items for [[rework]] or [[adwork]] when customers request it.
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## Critical Failure Modes
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- Items could be misplaced and become difficult to find, leading to [[Outbound Methods and Flows#Fulfillment Timeframes|delays]] in order [[fulfillment]].
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- Unorganized storage bins can lead to safety issues such as items falling off shelves.
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- Overstuffing could lead to poor utilization of space and wasted resources.
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- Underfilling by facing items that don't properly fill the space can create a perceived shortage of storage.
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- Stacking items can lead to safety issues.
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See [[Things you see in a warehouse]] for example of good and bad STOW.
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### Critcal misunderstandings about STOW
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There are some non-obvious things a person doing STOW should be aware of, otherwise there's a strong possibility of [[Iranian Satanism]] (zealously engaging in sabotaging activities without self awareness).
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#### Clearing rolling racks is usually the wrong place to start
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STOW is often triggered because [[Inspection Team]], [[Refurb Team]], or some other person needs an empty rolling cart to continue their work. However, clearing the rack they already have is usually the wrong place to start because it sets the wrong priorities.
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Basically, if STOW is initiated because an empty rolling rack is needed, then STOW has already failed. This was the intended purpose of the [[Kanban Inventory Flags]] for mobile racks.
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Instead, the best place to start is often looking in the STOW area for rolling carts that can be consolidated with like-size items to produce a cleared cart. When the goal is clearing a specific rack there's often a temptation to shove whatever items will fit into the permanent storage areas. That may quickly produce an empty rolling cart, but it increases the liklihood of critical failure modes.
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#### Avoid homogenous inventory except in small spaces
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It is usually a bad idea to put several units of exactly the same product in a location unless it's very fast and easy to scan every single one.
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For example, putting 30 laptops in the same area is probably not a great idea unless it's very fast to scan each of them.
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#### Chaotic storage and barcodes
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We use [[Chaotic Storage]] as our primary storage method for inventory that has unique barcodes ([[Item Number]], [[ALC]], [[Tracking Number]]). This enables us to essentially put such inventory anywhere it fits without needing to pre-designate particular areas. However, this cannot be done with inventory lacking unit-specific barcodes.
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#### Bulk inventory not tracked by individual units
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For bulk inventory (inventory that is not tracked by specific unit), different practices should be used. Primarily, such inventory should be kept in a bin that is labeled with the ALC of the box it arrived in. This is an advanced checkin method beyond the scope of this document. However, when bulk inventory is checked in this way it can be moved and updated using Box Wizard if the whole bin needs to be moved and Bulk Update if a smaller number of units need to be moved.
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Alternatively, bulk inventory can be updated by location as long as a location includes exactly one [[SKU]]. For example, imagine we have 50 new hard drives that are all the same model number, and we are not tracking them by item number. If we placed all 50 in the location "B-04-05-HD", we can use Bulk Update's "load by location" feature to update or move the hard drives. However, if someone places even a single item in B-04-05-HD that isn't the same SKU, that can no longer be done.
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## Basic adherence to location standards
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The article on [[Location Naming]] should be regularly consulted and updated by anyone involved with STOW. This section will just highlight some basics about location naming and inventory placement.
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### Locations starting with A should be used for inventory that needs to be quickly accessed
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Locations that begin with A should be used for inventory that needs to be quickly accessed. If accessing a location requires any special tools like a ladder or pallet jack, or if the location is typically blocked and hard to access it should not have an "A" designation. If any area beginning with "A" is found to be difficult to access or habitually blocked and the STOW crew is not able to resolve that issue, the location code should be updated to reflect it is not an "A" location anymore.
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This also means that stale or aged inventory found in A locations should eventually be moved to slower locations to free up room in A. For example, if an "A" location has had the same items sitting there for six months, they should probably be moved to a B location.
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## Tools useful for STOW
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[[NMI]] provides some tools and reports that are useful for STOW.
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The primary tools used are the [[STOW Tool]] and [[Bulk Update]], both of which can be accessed from the hotbar. The STOW Tool allows for very fast, chaotic movement of inventory between multiple locations. Bulk Update is better for moving or confirming the location of several different items to the same spot.
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[[Bulk Update]] is useful for things like:
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- Scan everything on a rack or bin to verify it's location.
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- Move an entire location. For example, if a bin labeled "A-01-02-B-1" is being moved to a different place, Bulk Update can "rename" the bin.
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### Location Freshness
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The Location Freshness report shows inventory locations where the items have been in storage for a long time, or where recently received items are mixed with inventory that's been in storage for a long time.
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https://app.ldrprep.com/?page=audit/locationFreshness
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### Warehouse Hotzones
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The Hotzones report shows the most actively used locations in the warehouse, as well as some data about the size of the items. It can be used to identify underutilized areas as well as inventory that would benefit from being moved closer to work areas.
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https://app.ldrprep.com/?page=reports/warehouse2/hotzones
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<iframe src="https://rdash.ldrprep.com/public/dashboards/wb4XMwKhaey7Gl9TJpkBvmBTe2qsWr6LJdQ8rR4I?org_slug=default" style="width: 100%; height: 40vh;"></iframe>
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