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Lead time
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A lead time is the latency between the initiation and completion of a process. For example, the lead time between the placement of an order and delivery of new cars by a given manufacturer might be between 2 weeks and 6 months, depending on various particularities. One business dictionary defines "manufacturing lead time" as the total time required to manufacture an item, including order preparation time, queue time, setup time, run time, move time, inspection time, and put-away time. For make-to-order products, it is the time between release[vague] of an order and the production and shipment that fulfill that order. For make-to-stock products, it is the time taken from the release of an order to production and receipt into finished goods inventory.[1]
Supply chain management
[edit]A conventional definition of lead time in a supply chain management context is the time from the moment the customer places an order (the moment the supplier learns of the requirement) to the moment it is ready for delivery. In the absence of finished goods or intermediate (work in progress) inventory, it is the time it takes to actually manufacture the order without any inventory other than raw materials. The Chartered Institute of Procurement & Supply identifies "total lead time" as a combination of "internal lead time" (the time required for the buying organisation's internal processes to progress from identification of a need to the issue of a purchase order) and "external lead time" (the time required for the supplying organisation's processes, including any development required, manufacture, dispatch and delivery).[2] The lead time applicable to material flows within a supply chain may be paralleled by the concept of "information lead time". Mason-Jones and Towill report that reductions in both material flow lead time and information lead time are necessary to secure supply chain performance improvements.[3] Several writers have referred to the importance of "information enriched supply chains" in this context.[3][4]
Manufacturing
[edit]In the manufacturing environment, lead time has the same definition as that used in supply chain management, but it includes the time required to ship the parts from the supplier. Shipping time is included because the manufacturing company needs to know when the parts will be available for material requirements planning purposes. It is also possible to include within lead time the time it takes for a company to process and have the part ready for manufacturing once it has been received. The time it takes a company to unload a product from a truck, inspect it, and move it into storage ("put-away time") is not trivial.[5] With tight manufacturing constraints or when a company is using Just In Time manufacturing, it is important for supply chain to know how long their own internal processes take.
Lead time consists of:[6]
- Preprocessing Lead Time (also known as "planning time" or "paperwork"): the time required to release a purchase order (if you buy an item) or create a job (if you manufacture an item), from the time you learn of the requirement.
- Processing Lead Time: the time required to procure or manufacture an item.
- Postprocessing Lead Time: the time to make a purchased item available in inventory from the time you receive it (including quarantine, inspection, etc.)
Example
Company A needs a part that can be manufactured in two days once Company B has received an order. It takes three days for company A to receive the part once shipped, and one additional day before the part is ready to go into manufacturing.
- If Company A's Supply Chain calls Company B they will be quoted a lead time of 2 days for the part.
- If Company A's Manufacturing division asks the Supply Chain division what the lead time is, they will be quoted 5 days since shipping will be included.
- If a line worker asks the Manufacturing Division boss what the lead time is before the part is ready to be used, it will be 6 days because setup time will be included.
Possible ways of shortening the lead time:
To best meet the customer needs, a company should work towards the shortest possible lead time in manufacturing, production, and delivery. It can be helped by:
- Improving each processing step's efficiency through minimizing waste, quickly resolving any bottlenecks.
- Applying production leveling (Heijunka) to both supply chain management and production process steps.
- Automating all possible actions along the process.
- Reducing the length of the idle (waiting) process stages, as these are often the most wasteful and can be the easiest ones to tackle for a start.
Order lead time
[edit]When talking about Order Lead Time (OLT) it is important to differentiate between the definitions that may exist around this concept. Although they look similar, there are differences between them that help the industry to model the order behavior of their customers. The four definitions are :
- The Actual Order Lead Time (OLTActual)[7] The order lead-time, refers to the time which elapses between the receipt of the customer's order (Order Entry Date) and the delivery of the goods."[8]
- The Requested Order Lead Time (OLTRequested) represents the time between the Order Entry Date and the customer requested delivery date; this measurement could help the company to understand the order behavior of the customers and help to design profitable models to fulfill customer needs.[9][10]
- The Quote Order Lead Time (OLTQuote) is the agreed time between the Order Entry Date and the supplier's committed deliver date of goods as stipulated in a supply chain contract.[10]
- The Confirmed Order Lead Time (OLTConfirmed) represents the time between the Order Entry Date and the by the supplier confirmed delivery date of goods.[10]
OLT formulas
[edit]- OLTRequested = Wish Date – Order Entry Date
The OLTRequested will be determined by the difference between the date the customer wants the material in his facilities (wish date) and the date when they provided its order to the supplier.
- OLTQuote = Quote Date – Order Entry Date
The OLTQuote will be determined by the difference between the date the customer agree to receive the material in their facilities (Quote date) and the date when the order is provided to the supplier.
- OLTActual = Delivery Date – Order Entry Date
The OLTActual will be determined by the difference between the day the provider deliver the material (Delivery date) and the date when they enter the order in the system.
- OLTConfirmed = Confirmed Date – Order Entry Date
The OLTConfirmed will be determined by the difference between the date the confirmed date by the provider to deliver the material in the customer facilities (Confirmed date) and the date when they provide the order to the supplier.
Average OLT based on volume
[edit]The Average OLT based on Volume (OLTV) is the addition of all the multiplications between the volume of product we deliver (quantity) and the OLT divided by the total quantity delivered in the period of time we are studying for that specific facility.
By doing this the company will be able to find a relation of volume weighted between the quantities of material required for an order and the time requested to accomplish it. The volume metric could be applied to the 4 types of OLT.
The figure obtained from this calculation will be the average time (e.g. in days) between order placing and the requested delivery date of a specific customer under consideration of the average quantities ordered during that particular time.
Potential application areas for order lead time measurement
[edit]The correct analysis of OLT will give the company:
- Better understanding of the market behavior making it able to develop more profitable schemas that fit better with customer needs (Revenue Management).
- Increases company ability to detect and correct any behavior that is not within terms agreed in the contract (by penalization or different contract schema).
- The OLT measurement creates an opportunity area to improve the customer relations by increasing the level of communication with them.
Project management
[edit]In project management, lead time is the time it takes to complete a task or a set of interdependent tasks.[citation needed] The lead of the entire project would be the overall duration of the critical path for the project.[citation needed]
According to the PMBOK (7th edition) by the Project Management Institute (PMI), lead time is the "time between a customer request and the actual delivery."[11] The lead time is a deliverable metric and a customary measure.[12] The lead time shows the amount of elapsed time from a chunk of work or story entering the backlog, to the end of the iteration or release.[12] A smaller lead time means that the process is more effective and the project team is more productive.[12]
Lead time is also the saved time by starting an activity before its predecessor is completed.[citation needed]
According to the PMBOK (7th edition) by PMI, lead is "The amount of time whereby a successor activity can be advanced with respect to a predecessor activity".[11] An example would be scheduling the start of a 2-week activity dependent with the finish of the successor activity with a lead of 2 weeks so they will finish at the same time.
Other uses
[edit]Journalism
[edit]Lead time in publishing describes the amount of time that a journalist has between receiving a writing assignment and submitting the completed piece. This is the production period of a particular publication before releasing it to the public as the issue date. Depending on the publication, lead times can be anything from a couple of hours to many months/years.
Medicine
[edit]Lead time (when referring to a disease) is the length of time between detection of a disease through screening and the moment in time where it would have normally presented with symptoms and led to a diagnosis. An example of this is seen with breast cancer population screening, where women who are asymptomatic have a positive test result with mammography, whereas the underlying disease would have taken many more years to manifest.
Video games
[edit]Lead time in video games can refer to the amount of time certain special, important actions in high-twitch action games, such as using health-recovering items, may need to take in order to be completed successfully. Lead time can be used to prevent players from abusing helpful abilities or items by making them a little more difficult to use safely, requiring some strategy, risk or caution.
See also
[edit]Citations
[edit]- ^ BusinessDictionary, Manufacturing Lead time Archived 2020-09-25 at the Wayback Machine, accessed 16 August 2019
- ^ CIPS in partnership with Profex Publishing, Procurement and Supply Operations, 2012, revised 2016, pp. 64-65
- ^ a b Mason-Jones, R. and Towill, D., Total cycle time compression and the agile supply chain, International Journal of Production Economics, 62 (1999) 61-73, accessed on 7 September 2024
- ^ Christopher, M., 1998, full citation missing, referenced by Bell, S., in Established Buying Theory, archived on 18 December 2007, accessed on 7 September 2024
- ^ Sunol, H., Warehouse Operations: Optimizing the Put-Away Process, Cyzerg Warehouse Technology, published 16 November 2018, accessed 16 August 2019
- ^ Lead Times Archived 2022-12-23 at the Wayback Machine. "Lead times in supply chain" Supply Chain Consultant Website.
- ^ Kumar, Anurag (June 1989). "Component Inventory Costs in an Assembly Problem with Uncertain Supplier Lead-Times". IIE Transactions. 21 (2): 112–121. doi:10.1080/07408178908966214.
- ^ Gunasekaran, A.; Patel, C.; Tirtiroglu, E. (1 January 2001). "Performance measures and metrics in a supply chain environment". International Journal of Operations & Production Management. 21 (1/2): 71–87. doi:10.1108/01443570110358468.
- ^ Cousens, Alan; Szwejczewski, Marek; Sweeney, Mike (20 March 2009). "A process for managing manufacturing flexibility". International Journal of Operations & Production Management. 29 (4): 357–385. doi:10.1108/01443570910945828.
- ^ a b c Silva, L., 2013, "Supply Chain Contract Compliance Measurements" Master thesis (work in progress), Aalto University, Finland.
- ^ a b Project Management Institute 2021, Glossary §3 Definitions.
- ^ a b c Project Management Institute 2021, §2.7.2.1 Deliverable metric.
References
[edit]- Project Management Institute (2021). A guide to the project management body of knowledge (PMBOK guide). Project Management Institute (7th ed.). Newtown Square, PA. ISBN 978-1-62825-664-2.
{{cite book}}: CS1 maint: location missing publisher (link)
Lead time
View on GrokipediaDefinition and Components
Basic Definition
Lead time is the total duration from the initiation of a process—such as the placement of an order or the start of a task—to its completion, such as the delivery of goods or the availability of output. According to the Association for Supply Chain Management (ASCM, formerly APICS), it represents the span of time required to perform a process or series of operations, encompassing activities like order preparation, processing, transportation, and inspection in a logistics context.[9] The term "lead time" originated as an Americanism in the 1940s, initially within manufacturing contexts to describe delays in production scheduling and material procurement. By the mid-20th century, it had generalized across industries, becoming a standard metric in operations and logistics as supply chains grew more complex.[10] Lead time profoundly influences efficiency, customer satisfaction, and overall costs in any process-oriented system. Extended lead times elevate inventory holding costs by necessitating larger safety stocks and amplify the risk of stockouts, potentially disrupting operations and eroding profitability.[1] Conversely, shorter lead times enhance responsiveness and resource utilization, fostering competitive advantages.[11] Examples illustrate its broad applicability: in retail, lead time measures the interval from a customer order to product shipment, while in general workflows, it tracks the end-to-end duration from initiating a task to achieving the desired outcome. These periods often include sub-components like procurement and production, though the focus remains on the aggregate timeline.[1][2]Types and Components
Lead time encompasses various types that reflect its scope within operational processes. Cumulative lead time denotes the total process time required to assemble a product from its lowest-level components to the finished item, assuming no inventory is available at the start. It represents the longest duration required across all bill-of-material paths to assemble a product from its lowest-level components to the finished item, assuming no inventory is available at the start. It is calculated by summing lead times along each path in the bill of materials and selecting the maximum.[12][13] This type aggregates all individual stages, providing a holistic view of end-to-end duration. Individual lead times, in contrast, isolate specific phases such as procurement, production, and delivery, allowing targeted analysis of bottlenecks.[9] Lead times are further classified as internal or external: internal lead time covers the controllable duration for in-house activities like processing and assembly, while external lead time involves uncontrollable elements from suppliers, such as sourcing delays. The components of lead time break down its anatomy into sequential elements that collectively determine overall latency. Information lead time refers to the period for order transmission, processing, and communication across the supply chain, often reduced through digital integration.[14] Material lead time encompasses sourcing and procurement, from requisition to receipt of raw materials or parts. Production lead time includes queue, setup, and processing durations during manufacturing. Delivery lead time involves transportation, handling, and final shipment to the customer. These components sum to form the total lead time, with each influenced by operational interdependencies.[9] Several factors shape the variability and length of these components. Supplier reliability directly impacts material lead time by affecting procurement timeliness and consistency in deliveries. Process variability, such as fluctuations in manufacturing throughput or equipment downtime, extends production lead time through unpredictable queues and setups. Transportation modes—ranging from air freight for speed to sea shipping for cost—influence delivery lead time based on distance, infrastructure, and logistics efficiency. Strategies like just-in-time (JIT) systems target minimization of these components by aligning material flows with demand, thereby compressing information and production phases while reducing excess inventory buffers.[15][16] Lead time structures are commonly represented through visual aids to clarify component sequencing and interrelations. Diagrams such as value stream maps depict the flow from information receipt to delivery, highlighting wait times and value-adding steps in a linear timeline. Gantt-like charts adapt this for supply chains by illustrating overlapping components, such as parallel procurement and production planning, to identify compression opportunities without disrupting sequence. These visualizations aid in dissecting total lead time for optimization.[17]Applications in Operations Management
Supply Chain Management
In supply chain management, lead time functions as a pivotal metric for coordinating multi-stage global networks, directly influencing inventory planning by dictating the volume of safety stock required to buffer against uncertainties. Longer lead times, such as those exceeding 120 days from international suppliers, compel organizations to hold excess raw materials—often up to a year's supply—thereby elevating holding costs and tying up capital that could otherwise support operational agility.[18] For demand forecasting, extended lead times amplify the need for precise predictions, as inaccuracies can result in stockouts or overstocking; advanced models like the Prais-Winsten approach have demonstrated up to 47% reductions in inventory costs for parts with four-month lead times, achieving 95.9% customer service levels.[18] In risk management, lead time variability heightens exposure to disruptions in global networks, where delays from transportation or geopolitical factors can cascade across tiers; shorter lead times, by contrast, enhance monitoring and reduce recovery times post-disruption.[19][20] Strategies to mitigate lead time include vendor-managed inventory (VMI) and collaborative planning, forecasting, and replenishment (CPFR), both of which foster inter-organizational coordination to streamline replenishment. VMI empowers suppliers to monitor and replenish retailer inventories, thereby reducing the bullwhip effect—where demand fluctuations amplify upstream—and improving product availability while lowering ordering costs for retailers.[21] CPFR extends this by integrating joint forecasting efforts across the chain, outperforming VMI in inventory reduction and service level enhancements through better demand-supply alignment, though it demands greater trust and resources; simulation studies indicate CPFR's superiority diminishes under short lead times or constrained manufacturing capacity.[21] The 2020s supply chain crises, particularly COVID-19, underscored these strategies' value, as lockdowns and restrictions caused average lead time extensions of 20 days for Chinese suppliers since late 2019, alongside broader transportation delays that idled up to 80-85% of commercial vehicles in regions like India.[22] Lead time integrates deeply with key metrics, shaping safety stock calculations and overall service levels; the standard approach scales safety stock proportionally to the square root of lead time, meaning variability in lead times—such as from autocorrelated demand—necessitates higher buffers to sustain target fill rates.[23] This variability exacerbates the bullwhip effect, where positive demand autocorrelation combined with longer, fluctuating lead times amplifies order variance upstream, potentially eroding service levels if endogenous lead time adjustments are overlooked.[23] Negative autocorrelation in demand can partially offset this by lowering safety stock needs relative to independent demands, but global chains remain vulnerable without coordinated variability controls. Post-2020, supply chain resilience has pivoted toward predictive tools, with AI-driven analytics enabling real-time lead time adjustments to counter disruptions like port delays or demand surges. As of 2025, implementations of AI in supply chains have reported up to 30% reductions in lead times through earlier issue detection and faster decision-making.[24][25] By integrating IoT and cloud data, these systems model scenarios for rerouting shipments or optimizing production, improving on-time in-full delivery; EY's 2024 research highlights that while 25% of leaders remain unprepared for geopolitical risks, AI adoption—rising to 42% for cloud-based tools—bolsters visibility and autonomous decision-making.[25] In 2025 logistics, generative AI further advances this by simulating supplier negotiations and dynamic forecasting, reducing vulnerability to health or trade crises affecting 23% of chains.[25]Manufacturing
In manufacturing, lead time encompasses the total duration from the receipt of raw materials to the output of finished goods, incorporating key stages such as setup, processing, and inspection.[26] This metric is essential for assessing production efficiency, as it highlights bottlenecks in the factory-floor operations where materials are transformed into products through sequential processes.[1] To optimize lead time, lean manufacturing principles emphasize techniques like Single-Minute Exchange of Die (SMED), which systematically reduces setup times by converting internal activities (performed while the machine is stopped) to external ones and streamlining necessary steps, often achieving reductions to under 10 minutes.[27] Complementing this, kanban systems employ visual signals to align production rates directly with customer demand, enabling just-in-time replenishment that minimizes excess inventory and shortens overall lead times by synchronizing workflow.[28] Lead time variability in manufacturing often stems from sources like machine downtime due to equipment failures and quality defects arising from operational errors or inadequate maintenance, which can disrupt processing and inspection stages.[29] A historical benchmark is the Toyota Production System (TPS), developed post-World War II in the 1950s, whose principles of waste elimination and continuous flow have enabled dramatic reductions in lead times, such as from weeks to hours in later implementations, setting a standard for global manufacturing efficiency.[30] As of 2025, the adoption of Industry 4.0 technologies, particularly Internet of Things (IoT) devices, enables real-time lead time monitoring by tracking machine performance and production flows, resulting in average reductions of up to 30% through predictive maintenance that curbs downtime.[31][32]Order Lead Time
Calculation Formulas
The basic formula for lead time is the difference between the completion date and the initiation date of a process, typically measured in days or weeks:This approach provides a straightforward measure of duration from order placement to delivery.[26] For order lead time (OLT) in supply chain contexts, the calculation aggregates the durations of sequential phases:
Procurement time covers sourcing materials, production time encompasses manufacturing, inspection time involves quality checks, and shipping time accounts for transit to the customer.[33] In multi-stage processes, such as assembly lines or supply chains with dependencies, the cumulative lead time is derived by summing the lead times of each individual stage:
where represents the lead time for stage . This summation assumes sequential execution without significant overlaps, enabling planners to forecast total throughput time.[34] To incorporate variability due to uncertainties like supplier delays or quality issues, an expected lead time includes a safety buffer based on the standard deviation of lead times:
Here, is the average lead time across historical data, is its standard deviation, and is the z-score corresponding to the desired service level (e.g., 1.65 for 95% confidence under a normal distribution). This adjustment helps build buffers in inventory or scheduling to mitigate risks.[35] For example, consider an order requiring 10 days for procurement, 5 days for production, 2 days for inspection, and 3 days for shipping. The OLT is calculated as days. If historical data shows a mean LT of 20 days with days and a , the expected LT becomes days, prompting a buffer in planning.[26][35] Historical formulations in Material Requirements Planning (MRP) systems, prominent in the 1980s, integrated lead times through offsetting to schedule orders backward from due dates:
This method, part of the MRP explosion process using bills of materials, ensured component availability by time-phasing requirements across stages.[36]
