Supply Chain Logistics and Warehouse Management -- Understanding the Supply Chain Logistics Segment (part 1)

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Introduction

Warehouse components are arranged to provide cost-effective and efficient vendor SKU and customer-order flows. These components are 1) the warehouse facility; 2) the material handling equipment layout; 3) warehouse internal operations or activities (with management staff and employees); 4) vendor SKU and customer-order flows for small items, master cartons, or pallets; 5) company informational technology (IT), host, WMS, and warehouse computer systems, (for communications between company departments as well as between the company and vendors and customers); and (6) inventory control, basic warehouse management program, or WMS.

The design team's objective is to design, develop, and implement a WMS program in a cost effective and efficient new (or remodeled) warehouse. To achieve this objective, the design team must understand your company's existing warehouse components (see above) and their interaction with a WMS program. The design team will 1) develop cost justification, 2) design a warehouse with a WMS program, 3) ensure that implementation occurs on time and within the established budget, and 4) review and audit the warehouse after the WMS program is implemented.

After a WMS program is implemented, the result will be a sphere with numerous connection lines and activity points. Between each WMS program transaction point and activity point are vendor WMS-identified SKU and customer-order flows (i.e., travel path and communication lines). In the interaction between a WMS program and a warehouse, the warehouse handles WMS-identified SKUs or customer orders between two WMS-identified positions/drop-points and the warehouse computer (or the employee that controls the SKU- or customer-order-handling equipment); and the WMS program tracks WMS-identified SKUs or customer orders through the inventory control or WMS-identified positions and has transactions sent to a WMS computer that handles data or information.

Warehouse Design Parameters and Operational Aspects

To design a new warehouse (or remodel an existing warehouse), the design team collects, evaluates, reviews, projects, and approves your present and proposed vendor-SKU and customer-order physical transaction volumes, SKU numbers and inventory characteristics, and other operational parameters for each warehouse activity (e.g., new or additional warehouse operations, handling manufacturer lot numbers, serial numbers, expiration dates, hazardous materials, and customer delivery companies or freight forwarders). Warehouse operational design parameters establish transactions for the completion of the vendor-SKU storage and physical-customer order and delivery cycle. These design parameters are

1. The average number of SKU and customer orders per day; the most frequent vendor SKU and customer orders per day; and the peak vendor SKU and customer orders per day;

2. The average SKU number per vendor delivery and customer order; the most frequent SKU number per vendor delivery and customer order; and the peak SKU number per vendor delivery and customer order;

3. The best equipment or technologies for a warehouse, based on vendor SKU and customer order volume;

4. The most frequent SKU number per vendor and delivery vehicle; the average SKU number per vendor and delivery vehicle; and the peak SKU number per vendor and delivery vehicle;

5. SKU specific inventory classification;

6. The present and proposed in-house SKU- and customer-order transport conveyor (or vehicle) travel speeds;

7. The present and proposed vendor SKU and customer-order shipping plan;

8. The down-load time for the IT customer-order host computer, and the time it takes to communicate with warehouse operations (or computer);

9. Customer order priority;

10. Customer service;

11. Profile of the warehouse storage and pick areas;

12. Proposed warehouse design, including vehicle aisle, rack layout, and facility for all required activities, simulations, and computer requirements;

13. Proposed warehouse receiving, in-house transport, storage, order fulfillment, manifest and shipping, and other operational concepts, with SKU and customer-order flow paths; plans should include block, plan view, and detailed view drawings showing all required operational activities.

The data collection and analysis ensures that the proposed warehouse is designed to handle vendor-SKU, customer-order, and WMS-program transactions. Moreover, the features ensure a cost-effective and effective warehouse.

Peak, Average, and Most Frequent SKU or Customer-Order Volumes

Monthly SKU or customer-order volumes are used to project warehouse volume. SKU and customer-order volumes are translated into warehouse- and WMS-program-supported transactions.

Note that vendor SKU transactions are less common than customer-order transactions, but customer orders are more time sensitive. In a small-item warehouse, small items are received as loose SKUs (e.g., single pieces or less than master cartons) in master cartons (or master cartons on a pallet) to have the opportunity to have valued added activities and are shipped as loose single items. In a carton warehouse, a master carton (or a pallet of master cartons) is sent to customers as a single master carton or master cartons on a pallet (or as a replenishment of loose SKUs or single pieces on a pallet to a pick position). Finally, in a pallet warehouse, an SKU is received (and sent to customers) as a single pallet or is sent as a replenishment pallet to a master-carton or single-piece pick area.

Peak, average, and most frequent monthly SKU or customer-order volumes are used to project a warehouse's future transactions. Future SKU or customer-order volumes and transactions are based on present SKU or customer-order volumes handled during a specific time period (e.g., day, week, month, year) and anticipated growth. Future SKU or customer-order volumes are key factors when projecting labor and material handling equipment necessary for order processing, and to justify labor quantity, costs, savings, and other operational expenses associated with a WMS program capital expenditure request.

Vendor-Delivered-SKU and Customer-Order Characteristics

After the design team decides upon an annual SKU- or customer-order volume, the team applies SKU or customer-order characteristics to each volume.

The company's receiving department will have the following vendor-delivered-SKU characteristics:

1. Purchase order number, per purchase order lines, SKUs, master carton SKUs, or pallet SKUs;

2. Receiving documents or tally sheet numbers;

3. SKU master carton or pallet, label numbers;

4. Special receiving dock time slots for vendor delivery.

The customer-order process (or control department) will have the following customer-order characteristics:

1. Customer-order numbers;

2. Customer-order type numbers for single line/single pieces, single line/multiple pieces, multiple lines/multiple pieces, SKU combination, express shipments, orders from foreign countries, and cash on delivery (COD) orders;

3. SKU or printed lines per customer order;

4. Pieces per line and customer order;

5. Shipping package type and size.

Projecting Vendor-SKU and Customer-Order Warehouse Transactions

In a warehouse, an employee or a computer-controlled machine completes each transaction. Each activity has standard or hybrid SKU or warehouse physical activity for a WMS-program-identified SKU (or customer order) and to determine each warehouse activity as a WMS-program scan or non-WMS transaction. A WMS-program transaction is sent to a WMS computer that accounts for a WMS-program-identified SKU or customer order. When the project team plans the ware house with WMS-program activity transactions, each activity is included in a warehouse and WMS-program transaction projection.

SKU and Customer-Order Characteristics

Vendor delivered SKU activity is not as time critical as a customer-order completion activity, which is completed within 24 hours of credit approval. After the design team selects a design-year SKU and order volume, the team applies SKU and customer-order characteristics to each volume. The company's receiving department will have the following vendor delivered SKU characteristics:

1. Purchase order number, per purchase order lines, SKUs, small items, master cartons, or pallets;

2. Receiving documents and tally sheets per purchase order;

3. Master cartons/containers or pallet labels per purchase order.

Vendor-Delivered-SKU Inventory Projection Characteristics

Each SKU group has unique characteristics that determine the storage inventory SKU quantity. A vendor master carton or container inventory quantity with few SKUs is handled as an individual item. Each master carton is given an inventory identification and placed in an identified storage position. Each master carton quantity is then entered into the inventory files. If vendor master cartons or containers are placed on pallets, a storage identification is placed on the pallet, the pallet is placed in an identified storage position, and a pallet SKU quantity is entered into the inventory files.

With a small-item operation, a design-year piece/quantity inventory projection is divided by the piece number into vendor master cartons or containers. SKU inventory projection quantity options for vendor master cartons or containers use an average existing SKU quantity for each master carton or container or to obtain an existing SKU quantity range for each master carton and apply each SKU quantity range percent to the inventory projection.

With a master carton or container warehouse inventory number, a design-year SKU quantity projection is divided by the SKUs for each master carton or container and a master carton container number for each pallet.

Warehouse Operation Storage Position Utilization

A warehouse storage position utilization factor is the percentage of occupied pallets. During peak activity periods, the pallet-storage position factor allows for open pallets to handle vendor delivered and received SKUs.

WMS-Program-Identified Storage-Pallet Locations

To create a WMS-program-identified storage position for a full, high pallet and half, high pallet number, the design team counts the full high and half high pallets and determines the percentage for each pallet type. Full high pallet and half high pallet percentages are applied to the projected pallet inventory. The calculations determine the full high pallet and half high pallet-storage position numbers.

Master Cartons

To obtain a master carton quantity for each pallet, the design team completes a master carton count for each pallet in the warehouse and develops a percentage. Using this percentage, the projected inventory piece quantity is created for each pallet.

Pieces

To obtain a piece quantity for each master carton, your design team completes a SKU piece count for each master carton in a warehouse storage area and develops a percent range. Based on a SKU percent range for each inventory control identified master carton, a projected inventory SKU is projected based on actual SKUs for each master carton percentage.

SKU Life Cycle

The SKU life cycle traces sales over a specific time period. The time period encompasses the first day a SKU is available for sale, is promoted to customers, and majority of sales occur. The life cycle show the SKU's characteristics for each day of the time period.

In a warehouse there are limited storage/pick position numbers. One answer is to design the storage area or pick line with an "ABC approach" with two storage/pick zones. One zone is designated for fast moving SKUs, and one zone is designated for medium/slow moving SKUs. New (or promoted) SKUs are allocated to the "A" zone or the fast-moving zone. Old (or nonpromoted) inventory SKUs are allocated to the "B" and "C" zones or medium/slow-moving zone.

The promotion or life cycle described above is usually linked to TV marketing, catalog, or retail warehouse industries. In other industries, such as dental or pharmaceutical, SKUs are promoted and have a SKU life of two to three months.

To achieve high productivity in the storage area or pick line, storage area and pick line SKUs are allocated to the storage/pick positions. The allocation is based on sales volume and storage and pick area employee productivity rates.

The storage and pick zone numbers, SKU life cycle, and total inventory SKU numbers assist SKU storage area and pick line allocation. To achieve proper SKU hit concentration and density, new and promoted SKUs that been allocated to the "A" storage/pick zone and are plotted on a historical life cycle day number. When the life cycle chart shows a decline for a day number, the SKU is reallocated to the "B" or "C" zone.

Inventory-Control-Identified SKU Storage and Pick Positions

After a warehouse receives a vendor-delivered SKU and checks the vendor quantity against a company purchase order quantity, the SKU is transferred to a storage position and the quantity and position is entered into inventory. Each warehouse storage and pick position has a discreet identification, which is used when customer orders are sent to the warehouse by the host computer.

Projecting Inventory-Control-Identified Storage Position

To project a storage position, the design team must know the storage position number, type, and SKU number for each position. To project inventory volume and the associated storage position number housed in an operation, the projection methods are similar for small items, master car tons, or pallets.

Master Carton and Pallet-Storage Volume

To project the SKU inventory, pallet inventory volume is the SKU volume housed in a storage area, static volume stored in a floor stack, conventional forklift truck, or automatic/computer storage and retrieval system (AS/RS) crane rack, flow rack, hand stack, or standard shelf. A master carton or pallet-storage inventory number is divided into master carton or pallet height, pallet size, and special storage conditions. Master carton or pallet inventory volumes provides fiscal year end master carton or pallet volume; the average volume for a specific number of months; and the average master carton or pallet volume for a predetermined period with the emphasis on a predetermined month period. In most companies, the period is the last three months of the fiscal year.

Master Carton and Pallet Pick-Position Projections

A master carton or pallet warehouse position is the master carton's or pallet's SKU in a pick position.

In a dense storage warehouse, the master carton or pallet position adjacent to the main aisle is the pick position. Based on your existing pick position number, your design team applies a SKU growth number or percent to obtain a SKU number in a design year or SKU growth number or percent and completes calculations to determine a design-year SKU number.

SKU Types: Pallet, Master Carton, and Small Items

Vendor-delivered SKU and customer-order pieces determine equipment type and layout. A warehouse can be set up to handle one SKU type or all SKU types.

Master Carton Warehouse

In a master carton warehouse, a vendor carton or vendor master carton has a SKU inventory and storage position identification, and is handled as individual master cartons or master cartons on a pallet. If a master carton does not have side wall strength, or product is not self-supporting or is not square, master cartons are stored in a container, a tier rack, or a stacking frame (to make stackable and uniform unit loads), or as individual master cartons that optimize the cubic (air) storage space. A container or stacking frame has fork openings and the tier rack is placed on a standard pallet.

A master carton warehouse, to have maximum inventory flexibility and accountability, will determine at the receiving dock how master cartons are handled. If a SKU has a low master carton quantity, the cartons are handled as individual SKUs. If a SKU has a high master carton quantity, the cartons are handled on a four-wheel carton, slip sheet, stacking frame, tier rack, or pallet. This will permit an employee-controlled or AS/RS crane to move the largest number of cartons each trip, thus providing the fewest handlings from receiving, through the storage/pick area, to the shipping dock, and onto the delivery truck.

It is important for the design team to know master carton or container dimensions, including length, width, height, and weight, as well as the smallest, the average, and the maximum size master carton. The size range that is developed can be used to determine storage/pick position, number of cartons for each pallet, and the conveyor travel path window.

Small-Item Warehouse

A small-item warehouse handles small items as single pieces in vendor master cartons, containers, or master cartons/containers on a pallet. Master carton or container dimensions determine the number of items stored on each pallet.

Pallet Warehouse

A pallet warehouse receives, stores, and ships SKUs on pallets. The vendor delivery tally sheet will show a suggested ti and hi or master carton quantity for each pallet. If a master carton ti is within a pallet (bottom support device) perimeter, the master carton hangs over the edge of the pallet (length or width). If a master carton ti overhangs a pallet, the master carton dimensions overhang becomes the storage pallet dimensions. The pallet's dimensions determine floor stack pallet position number in a storage area or pallet number wide in a rack bay between two rack upright posts.

Rack dimensions along with clearances determine rack row and rack bay number that will fit between two building columns.

Pallet height determines the pallet number in the floor stack in the rack bay in the vertical stack. A pallet height is the distance between the bottom deck board and the highest master carton top. The vendor delivery tally will show a suggested ti and hi or master cartons for each pallet that will not exceed the pallet-storage position height.

Pallet weight is the entire pallet, securing material, and total master carton weight. The pallet weight determines pallet number for each floor stack, pallet or load beam level number for each rack bay and design, rack posts base plate thickness, foot print, design, and forklift truck wheel size. The forklift truck or AS/RS crane weight determines the floor thickness and rebar characteristics. The vendor delivery tally will show a suggested ti and hi or master cartons for each pallet that will not exceed the storage/pick position weight capacity.

Pallet Bottom Support Device

A pallet supports a wide SKU mix and is easily handled by forklift, AS/RS crane, or pallet trucks.

The pallet's length, width, and fork entry opening (unit load bottom support device) determine what kind of rack may be used. In a facility that uses a forklift, the pallets hang over the load beams or extend into an aisle or flue space by two to three inches. The forklift's stack requirement determines the width of the aisle.

The fork entry opening is between the pallet's top deck board bottom and bottom deck board top. The entry opening determines a forklift truck or AS/RS crane set of fork/platen length.

Pallet-storage operations use a standard pallet, including captive pallets, throw-away pallets, or exchange pallets; a take-it or leave-it pallet; and a specially engineered or designed pallet.

Warehouse Operation Objective

A warehouse's purpose is to house SKU inventory; ensure that the host computer or IT department communicates between WMS-identified SKU scan transaction locations; ensure staff counts for delivered SKU quantity; ensure quantity and quality are correct; ensure the SKU is available in a storage or pick position; and ensure the customer order is delivered in the correct quantity and on time to the correct address at the budgeted cost for each unit.

To satisfy inventory availability and accuracy objective, a company with manual inventory control should consider implementing a WMS program in their warehouse, implement a WMS program in a remodeled warehouse, upgrade their existing WMS program, or design the new warehouse with a WMS program.

If the company does not have a WMS program, or is considering a WMS program for an existing operation, what are the signals that a warehouse requires a WMS program? A warehouse with a WMS program is designed to move and track inventory or service the customer at the lowest possible operational costs. A warehouse options are (1) store and hold or conventional or (2) across the-dock warehouse operation. Each warehouse type has different SKU and customer order and information flows that are the bases for a future warehouse with a WMS program.

Conventional Warehouse: Store and Hold

A store-and-hold inventory or conventional warehouse has a warehouse receive SKUs or SKU quantity. Each SKU has a company SKU identification, is placed into an assigned SKU inventory file, and is physically placed into a warehouse facility identified storage position. For each customer order, a SKU quantity is withdrawn from a warehouse storage position and replenished to a pick position. After completing a customer order, the SKU inventory in the files is decreased by a moved SKU quantity, identified warehouse position status is updated in inventory files, and the picked SKU is sent to a delivery truck or to a customer address. The conventional warehouse is designed to ensure that SKUs meet the company's quality standards, that the correct identified SKU is transferred from the storage position to the correct pick position, in sufficient quantity, at the assigned time. Next, the warehouse operation ensures that the SKU is withdrawn from the pick position in the correct quantity, in correct condition, on schedule, with a packing list in a protected and labeled shipping container, properly manifested and delivered to a delivery location within the delivery cycle time. Finally, the manifest is scanned and entered into a company host computer files as a completed customer order.

Across-the-Dock Operation

In an across-the-dock warehouse SKU (or customer-order flow operation), the warehouse unloads and counts all SKUs from the vendor delivery vehicle. SKUs are customer-order single SKUs mixed in a master carton, GOH, master carton, pallet, or master carton mix on a pallet. SKUs are prelabeled or labeled on a receiving dock, are sorted by quantity and address, and immediately are either placed in an outbound staging area or loaded directly onto a customer delivery vehicle. With some small-item SKUs an across-the-dock operation completes the sorting or places a price ticket onto each SKU or repacks the SKUs prior to the sorting. SKUs are not entered into a warehouse inventory. An across-the-dock operation is designed to ensure that each SKU meets the company standards, is properly packaged and labeled with a discreet (or sort) identification, is unloaded at a proper time, is sorted or separated by identification, and that the total piece count matches the vendor delivery document and company purchase order. The delivery truck ensures that the order arrives at the delivery location at a specific time that satisfies customer demand at the lowest operating cost. After across-the-dock sorting, there may be a residual SKU quantity, which is identified and placed into a storage position. The SKU quantity and storage position have the same operational procedures as a conventional warehouse.

Information Flows

Warehouse information flow exists in three areas: externally, between the SKU vendor and the company, and between the customer and the company; and internally, between company departments.

The information flow from a company to a SKU vendor occurs via the purchase order issued to the vendor. After receipt of the purchase order, the vendor communicates with the receiving department and establishes a delivery time.

The information flow within a company begins when the purchase order information is sent from the merchandise department to a receiving department. The receiving department notifies a quality control (QA) department that a sample is ready for inspection. The receiving department confirms with the merchandising and finance departments that the purchase order is accurate and complete and that the vendor has completed the contract. The QA department sends information to the receiving and merchandising departments regarding SKU status (e.g., "OK," "rejected"). The storage department sends a SKU deposit to the inventory control department to reserve a storage position. The host computer sends customer orders to a warehouse computer; the warehouse computer sends pick instructions to the pick area printer or pick machine. The storage department sends replenishment to a pick position or transfer from a storage position to a pick position to inventory control department. The pick area sends completed pick transactions and inventory update to a WMS computer. The warehouse computer sends the packing slip to the check and pack station to use as an instruction. The ship scanner/reader reads and sends the identification at the manifest station to the warehouse computer and the delivery company. If necessary, the returns department sends approval to host computer to issue customer credit. The returns station sends information returned SKUs to inventory control. Return SKUs are deposited into a position and sent to a WMS computer for inventory update. Information flows between a customer and company occur when a quantity is sent to the host computer; when the company sends a delivery address and identification to a delivery company; and when, following the completion of an order, the delivery company notifies the company of a nondeliverable package or a customer notice of a customer order over, short, or damaged.

Warehouse Activities

A storage/order fulfillment operation has the following activities:

1. Prepick activities, including a) vendor SKU or delivery truckyard control; b) vendor delivery SKU unloading and palletizing; c) receiving and SKU quality and quantity checking; d) assuring a SKU discreet identification and assigned storage location for each SKU; e) to package some small items and flat wear, SKUs as individual SKUs and to label each SKU with a price ticket; f) internal transport activity; g) deposit and withdrawal in an inventory program of identified storage or pick positions and updating inventory files; and h) inventory control, such as a SKU inventory cycle counts;

2. Customer-order pick activities, including a) printing pick documents and labels, or, for paper less picking, the host or warehouse computer downloads the information to a warehouse computer that controls a pick to light RF or automatic pick machine; b) carton make-up, including the identification label and insertion of the packing list into the container/carton; c) releasing a SKU from an automatic pick position (by manual pick or computer); d) SKU replenishment; and e) trash removal;

3. Post-customer-order pick activities, including a) picked SKU sort to customer-order location; b) sorting SKU quality or quantity check; c) placing the packing slip into a shipping carton, filling container/carton voids, and with a WMS identified customer order associated with a permanent identified pick tote, tote zero scan is sent WMS computer to disconnect a customer order WMS identification to a permanent tote identification; d) sealing containers; e) scanning the shipping label and manifest, and updating the WMS and host computer SKU inventory and customer order files; f) loading and shipping; g) handling customer order returns, credits, and notifying the host computer of a returned SKU disposition, placing a returned SKU into a storage/pick location, and updating the WMS program inventory files; h) handling retail store returned out-of-season SKUs and SKU transfers to another retail store; and i) maintenance, sanitation, and loss-prevention activities.

An across-the-dock operation is a more streamlined warehouse. The activities are vendor delivery vehicle yard control; SKU quality control, count, identification labeling and sorting; and packing and loading onto a customer delivery truck.

Within an across-the-dock warehouse, other activities are 1) vendor SKU preparation; 2) downloading and printing labels; 3) unloading, receiving, and labeling SKUs; 4) quality control, counting, sorting, or separating by identification; 5) sorting, packing, and creating manifests; 6) sorting SKUs held in a shipping dock staging area or direct loading onto delivery trucks; 7) handling residual SKUs and customer order returns, retail store returned out-of-season SKUs, and SKU transfers to another retail store; 8) customer delivery; and 9) maintenance, sanitation, and loss prevention.

Inventory Control

A storage/hold warehouse inventory control activity ensures that SKUs are transferred from a receiving area to a storage area and from a storage position to a pick position in the correct quantity. Other inventory control objectives are 1) proper SKU inventory rotation; 2) accurate inventory counts; 3) assuring minimal "stock outs" or "out-of-stocks." ("Stock out" is when the pick position is depleted but an inventory file indicates an on-hand SKU inventory quantity. "Out of stock" is when the pick position is depleted and the inventory file has no on-hand inventory quantity.); 4) tracking SKU flow through the supply chain or each warehouse; and 5) verifying that each storage/pick transaction is completed and inventory files are updated.

SKU Storage and Pick-Position Locator

A warehouse SKU storage and pick locator is designed to facilitate and identify a storage or pick position. During a SKU storage area deposit transaction, a locator may be employee-directed: a forklift truck driver determines the storage or pick position. This approach features minimal cost, random SKU placement to a position, and a paper-based or RF transaction record. It does not optimize storage/pick transaction employee productivity and it is difficult to track SKUs. A second approach uses the warehouse computer to suggest a storage/pick position based on a storage philosophy. A forklift or an AS/RS crane completes the transaction.

SKU Location in a Storage Area

The concept of SKU warehouse storage location focuses on SKUs' physical position in a storage aisle. The location is determined by a storage position philosophy. This has guidelines based on whether the storage activity used a manual forklift truck or an AS/RS crane. An inventory pro gram either permits an employee to determine the product transaction location or controls the storage strategy by suggesting or directing the transaction location.

Storage position philosophy includes:

1. SKUs' physical width, height, length, and weight. In a storage operation, heavy or short SKUs are located at floor level, tall and light SKUs are located in high positions.

2. SKU velocity, sales, or physical movement for a complete fiscal year. In a storage aisle, fast moving SKUs are located at the aisle start, medium-moving SKUs are located in the middle of the aisle, and slow-moving SKUs are located at the end.

3. SKU value. High-value SKUs are placed in positions with limited or controlled access.

4. SKUs that have specific environmental storage conditions. For example, temperature-sensitive SKUs are located at a low position or in a separate storage area.

5. Hazardous classification. SKUs with such a classification are housed in a position that restricts an SKU flight or has a barrier or pit connected to a containment chamber that restricts flammable liquid run-off.

Inventory Locator: Philosophy and Principles

An inventory locator philosophy influences the arrangement of warehouse equipment and storage/ pick activity locations (i.e., receiving, storage, pick and ship areas). The most important area is the SKU storage/pick area. In a storage/hold operation, storage/pick activities have a large floor area and have the greatest number of employees. Storage layout philosophies and principles are

1. SKU popularity or Pareto's Law (i.e., the "80/20 Rule");

2. ABC theory;

3. Unloading and loading ratio;

4. ABC theory with a family group;

5. Power (or fast moving) SKUs in a single pick area;

6. Family group, including SKU value, environmental issues, and hazardous SKUs;

7. SKU rotation;

8. Rack row and aisle direction;

9. Aisle length, width, and adequacy;

11. Building height;

12. Customer-order picked SKU order fulfillment and sort.

SKU and Customer-Order

Flow through a Facility and Value-Added Activities

Vendor-delivered SKU or customer-order flow has an impact on the warehouse's process. A building's shape, size, number of floors, and the value-added activities also affect the pick line or area location, as well as the vendor-delivered SKU or customer-order flow pattern through a facility.

The design team determines the most cost-effective and efficient flow pattern and value-added activities sequence. Vendor-delivered SKU or customer-order flow patterns are 1) for a single floor facility, a horizontal vendor-delivered SKU or customer-order flow pattern that are either (a) a straight (i.e., "one-way") vendor-delivered SKU flow or customer-order pattern or (b) a two-way pattern (i.e., "U" or "W"); (2) a vertical (i.e., up and down) flow pattern, which is used in a multi floor facility.

Single and Multiple Floors

In metropolitan areas, available sites commercial prices are high but allow buildings to have a 30 to 40-foot clear ceiling above ground level. Building options are, first, a low-bay or ground-floor building. A low-bay or single-floor facility has value-added activities and employee support activities on the ground level floor. This design has the highest square footage for each pick position, low space utilization, and the longest travel distance and time locations. The alternative is a high-bay or multi-floor warehouse. This is good for small-item order fulfillment. Vertical transport equipment would be designed to locate slow moving, light weight/small cube SKUs. Value-added activities, pack areas, administrative support offices, storage area and high volume, heavy weight/high cube SKUs would be placed on an elevated floor. Receiving and shipping dock areas, fast moving and heavy weight/large cube SKUs, and pick and pack areas would be placed on the ground floor.

(As an alternative, heavy/high cube SKUs could be located on the ground floor and pack stations placed on an elevated floor with direct flow to the manifest/shipping area.) In a high-bay, multi-floor facility, the storage area, high-volume, and heavy/high cube SKUs are located on the ground floor. The office, administrative and employee support, low volume, light/small cube SKUs, and value-added activities are located on elevated floors. To assure maxi mum flexibility, elevated floors are designed to support dynamic and static forklift truck loads, one to three high-pallet storage racks, and automatic or other pick lines. The pack area options are either the ground floor or an elevated floor.

SKU Storage

SKU storage concept is a major factor in determining the building's area. A master carton, or pal let warehouse, can either use single master carton, or pallet storage, or dense storage. The preferred storage is determined by SKU number, storage units for each SKU, inventory requirements, and SKU rotation.

Single Deep Storage

Single deep storage has shelves or racks that are serviced by an employee, an employee-controlled forklift truck, or an AS/RS crane. If master cartons are a SKU, an employee, an employee-con trolled high-rise order picker (HROS) vehicle, or AS/RS crane completes the transactions. If using an employee for storage transactions, master cartons are stacked one, two, or more high in a storage position. If a building has a 40- to 60-foot clear ceiling, a VNA lift truck is used; with a 60- to 80-foot ceiling, an AS/RS crane is used. Single deep storage provides maximum access to all SKUs, low storage density (i.e., fewer SKUs per square foot), FIFO, or first-in-first-out, SKU rotation, and requires a large facility.

Dense Storage

Dense storage means that there are two or more SKUs deep in each storage position and the storage position requires one or two aisles to complete storage transactions. In a low-bay building, dense storage layouts use floor stacks or stacking frames/containers/stack racks, two-deep racks, drive-in racks, drive-thru racks, mobile shelves or racks, gravity flow racks, or sort links. In an AS/RS storage operation, dense storage options are gravity or air-flow racks, car-in racks, and two-deep racks.

When compared to a single deep storage concept, dense storage layouts have few aisles, greater product per square foot, and wider SKU numbers; most layouts do not provide a FIFO. SKU rotation requires a smaller facility, and a WMS program with enhancements or dynamic features to track an SKU.

Aisle and Position Identification In a warehouse, each master carton or pallet aisle has identified master-carton or pallet-storage positions that use alphabetical characters, numeric digits, or an alphabetical character and numeric digit mix with a bar-code/RF tag. In a warehouse with a WMS program that has floor stack, drive in, drive-thru, pallet flow rack, or car-in rack storage layout, the format sequence is warehouse, warehouse aisle, bay within an aisle, and level within a bay. Dense storage layouts that use pallet storage have the same SKU for each storage lane. With a WA, NA, high-rise order picker (HROS), or VNA, a forklift truck or AS/RS, or a crane operation with a master-carton or pallet rack system, the identification information sequence is:

1. The first component is an alphabetical character that identifies the warehouse.

2. The storage aisle is identified by an alphabetical character or digit. In a dynamic storage operation, there will be sufficient combinations of characters to identify all storage operations with 26 alphabetical characters and double character usage.

3. The rack bay is identified with numeric digits that progress arithmetically from the aisle entrance to the end of the aisle. Numbers are used in bay identification to the match pallet or rack bay numbers in a nominal building length.

4. The load beam or rack level within a rack bay is identified with an alphabetical character. In a WA, NA, HROS, VNA, AS/RS or tall rack operation, the 26 alphabetical characters will be sufficient to identify all pallet levels in a rack structure. Creating an identification of two numbers separated by an alphabetical character will make it less likely that a forklift truck driver will become confused than with three consecutive numeric or digit components.

5. The master-carton or pallet position in a rack bay is a significant component in a forklift truck driver instruction format. At a SKU position in a bay, the forklift truck driver (or AS/ RS crane) completes directed SKU transactions. The driver reads the SKU position that is assigned to a master carton or pallet position. The SKU position is identified with numbers and is easy to read on a digital display or paper document.

In a pallet-storage warehouse, to ensure accurate and on-time transactions, signs identify each aisle and pallet-storage position. Storage aisle identification options are:

-- One-way vision placard that is placed flat against the end of the aisle, either upright or hanging from the ceiling. The aisle identification faces outward and allows a forklift truck driver to identify an aisle. One-way vision placard is also used to identify each AS/RS aisle on the AS/RS front wall.

-- Two-way vision placard options are:

- Two placards. Each upright frame placard extends outward from an upright post into a main traffic aisle. At a proper elevation a placard is easily recognized and will not be damaged.

- Three placards. Two placards extend outward into a main traffic aisle and an additional placard is placed flat between two placards. With a two-way sign, each aisle number is easily recognized from a main traffic aisle. This approach is used in a forklift truck driver operation.

-- A four-way aisle placard is a ceiling-hung placard with four sides. Each side has an aisle identification. Each aisle number is easily recognized from the main traffic aisle. Next>>

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