Lead time
Encyclopedia
A lead time is the latency
(delay) between the initiation and execution of a process. For example, the lead time between the placement of an order and delivery of a new car from a manufacturer may be anywhere from 2 weeks to 6 months. In industry, lead time reduction is an important part of lean manufacturing
.
describes the amount of time that a journalist
has between receiving a writing assignment and submitting the completed piece. Depending on the publication, lead times can be anything from a couple of hours to many months.
realm is the time from the moment the customer places an order (the moment you learn of the requirement) to the moment it is received by the customer. 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.
. It is also possible for lead time to include 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 is non-trivial. 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 is made of:
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.
In very complex manufacturing environment, like the manufacture of microprocessors, a usual Lead Time may be between 5–7 weeks. This is due to the sequence of operations, where there are multiple very similar steps repeated, and none can be skipped. If a manufacture of a CPU requires 35 exposure masks, that translates approximately into 35 x ( photoresist coating, exposure, development, main process step (like etching, diffusion, metal filling), photoresist stripping and/or polishing + other possible steps ) plus additional steps before and after all processing. There are wait times not only associated with scheduling a product into production, since the product lines are busy, but also a beginning run of production goes to scrap (plus tool change and alignment takes time), and there are possible wait times of batches being processed during the production. (Not all machinery works at the same speed, or requires maintenance steps, tool change, plus there is the time it takes to physically transport the silicon wafers from one processing machinery to another in small transport batches.)
lead time is the time it takes to complete a task or a set of interdependent tasks. The lead of the entire project
would be the overall duration of the critical path
for the project.
Lead time is also the saved time by starting an activity before its predecessor is completed.
According to the PMI (2008), lead is a dependency between two activities (p. 140) . 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.
Latency
Latency or latent may refer to:*Latency period , the time between exposure to a pathogen, chemical or radiation, and when symptoms first become apparent...
(delay) between the initiation and execution of a process. For example, the lead time between the placement of an order and delivery of a new car from a manufacturer may be anywhere from 2 weeks to 6 months. In industry, lead time reduction is an important part of lean manufacturing
Lean manufacturing
Lean manufacturing, lean enterprise, or lean production, often simply, "Lean," is a production practice that considers the expenditure of resources for any goal other than the creation of value for the end customer to be wasteful, and thus a target for elimination...
.
Journalism
Lead time in publishingPublishing
Publishing is the process of production and dissemination of literature or information—the activity of making information available to the general public...
describes the amount of time that a journalist
Journalist
A journalist collects and distributes news and other information. A journalist's work is referred to as journalism.A reporter is a type of journalist who researchs, writes, and reports on information to be presented in mass media, including print media , electronic media , and digital media A...
has between receiving a writing assignment and submitting the completed piece. Depending on the publication, lead times can be anything from a couple of hours to many months.
Supply chain management
A more conventional definition of lead time in the supply chain managementSupply chain management
Supply chain management is the management of a network of interconnected businesses involved in the ultimate provision of product and service packages required by end customers...
realm is the time from the moment the customer places an order (the moment you learn of the requirement) to the moment it is received by the customer. 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.
Manufacturing
In the manufacturing environment, lead time has the same definition as that of Supply Chain Management, but it includes the time required to ship the parts from the supplier. The shipping time is included because the manufacturing company needs to know when the parts will be available for material requirements planningMaterial requirements planning
Material requirements planning is a production planning and inventory control system used to manage manufacturing processes. Most MRP systems are software-based, while it is possible to conduct MRP by hand as well....
. It is also possible for lead time to include 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 is non-trivial. 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 is made of:
- Preprocessing Lead Time (also known as "planning time" or "paperwork"): It represents 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: It is the time required to procure or manufacture an item.
- Postprocessing Lead Time: It represents 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.
Semiconductor industry
About Lead time as per company rulesIn very complex manufacturing environment, like the manufacture of microprocessors, a usual Lead Time may be between 5–7 weeks. This is due to the sequence of operations, where there are multiple very similar steps repeated, and none can be skipped. If a manufacture of a CPU requires 35 exposure masks, that translates approximately into 35 x ( photoresist coating, exposure, development, main process step (like etching, diffusion, metal filling), photoresist stripping and/or polishing + other possible steps ) plus additional steps before and after all processing. There are wait times not only associated with scheduling a product into production, since the product lines are busy, but also a beginning run of production goes to scrap (plus tool change and alignment takes time), and there are possible wait times of batches being processed during the production. (Not all machinery works at the same speed, or requires maintenance steps, tool change, plus there is the time it takes to physically transport the silicon wafers from one processing machinery to another in small transport batches.)
Project management
In project managementProject management
Project management is the discipline of planning, organizing, securing, and managing resources to achieve specific goals. A project is a temporary endeavor with a defined beginning and end , undertaken to meet unique goals and objectives, typically to bring about beneficial change or added value...
lead time is the time it takes to complete a task or a set of interdependent tasks. The lead of the entire project
Project
A project in business and science is typically defined as a collaborative enterprise, frequently involving research or design, that is carefully planned to achieve a particular aim. Projects can be further defined as temporary rather than permanent social systems that are constituted by teams...
would be the overall duration of the critical path
Critical path method
The critical path method is an algorithm for scheduling a set of project activities. It is an important tool for effective project management.-History:...
for the project.
Lead time is also the saved time by starting an activity before its predecessor is completed.
According to the PMI (2008), lead is a dependency between two activities (p. 140) . 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.