APICS Detailed Scheduling and Planning

safety lead time

An element of time added to normal lead time to protect against fluctuations in lead time so that an order can be completed before it's real need date. When used, the MRP system, in offsetting for lead time, will plan both order release and order completion for earlier dates than it would otherwise. Syn: protection time, safety time.

action message

An output of a system that identifies the need for, and the type of action to be taken to correct, a current or potential problem. Examples of action messages in an MRP system include released order, reschedule in, reschedule out, and cancel. Syn: exception message, action report

business-to-business commerce B2B

Business conducted over the internet between businesses. The implication is that this connectivity will cause businesses to transform themselves via supply chain management to become virtual organizations-reducing costs, improving quality, reducing delivery lead time, and improving due date performance

joint replenishment

Coordinating the lot sizing and order release decision for related items and treating them as a family of items. The objective is to achieve lower costs because of ordering, setup, shipping, and quantity discount economies. This term applies equally to joint ordering (family contracts) and to composite part (group technolgy) fabrication scheduling. Syn: joint replenishment system.

point-of-use delivery

Direct delivery of material to a specified location on a plant floor near the operation where it is to be used.

lot splitting

Dividing a lot into two or more sublots and simultaneously processing each sublot on identical (or very similar) facilities as separate lots, usually to compress lead time or to expedite a small quantity. Syn: operation splitting.

demand forecasting

Forecasting the demand of a particular good, component, or service.

target inventory level

In a min-max inventory system, the equvalent of the maximum. The target inventory is equal to the order point plus a variable order quantity. It is often called an order-up-to inventory level and is used in a periodic review system. Syn: order-up-to level.

replanning frequency

In an MRP system, the amount of time between successive runs of the MRP model. If the planner does not run MRP frequently enough, the material plan becomes inaccurate as material requirements and inventory status change with the passage of time.

project plan

In project management, a document that has been approved by upper management that is to be used in executing and controlling a project. It documents assumptions, facilitates communication, and documents the approved budget and schedule. It may exist at a summary or a detalied level.

program evaluation and review technique (PERT)

In project management, a network analysis technique in which each activity is assigned a pessimistic, most likely, and optimistic estimate of its duration. The critical path method is then applied using a weighted average of these times for each node. PERT computes a standard deviation of the estimate of project duration. See: critical path mentod, graphical evaluation and review technique, and network analysis.

project phase

In project management, a set of related project activities that usually go together to define a project deliverable.

productive capacity

In the theory of contraints: The maximum of the output capabilities of a resource (or series of resources) or the market demand for that output for a given time period. See: excess capacity, idle capacity, protective capacity.

safety capacity

In the theory of contraints: The planned amount by which the available capacity exceeds current productive capacity. This capacity provides protection from planned activities, such as resource contention, and preventive maintenance and unplanned activities, such as resource breakdown, poor quality, rework, or lateness. Safety capacity plus productive capacity plus excess capacity is equal to 100 percent of capacity. Syn: capacity cushion. See: protective capacity.

transient state

In waiting line models, early behavior of a characteristic of the model, such as line length, is more erratic than eventual performance of the line. Data are usually not collected from the model until less erratic behavior emerges. See: steady state.

obsolete inventory

Inventory items that have met the obsolescence criteria established by the organization. For example, inventory that has been superseded by a new model or otherwise made obsolescent. Obsolete inventory will never be used or sold at full value. Disposing of the inventory may reduce a company's profit.

process manufacturing

Production that adds value by mixing, separating, forming, and/or performing chemical reactions. It may be done in either batch or continuous mode. See: project manufacturing.

semifinished goods

Products that have been stored uncompleted awaiting final operations that adapt them to different uses or customer specifications.

activation

Putting a resource to work.

shrinkage

Reductions of actual quantities of items in stock, in process, or in transit. The loss may be caused by scrap, theft, deterioration, evaporation, and so forth.

unplanned repair

Repair or replacement requirements that are unknown until remanufacturing teardown and inspection.

rework

Reprocessing to salvage a defective item or part.

inactive inventory

Stock designated as in excess of consumption within a defined period or stocks of items that have not been used for a defined period.

load projection

Syn: load profile.

concurrent engineering

Syn: participative design/engineering

calculated capacity

Syn: rated capacity.

buffer stock

Syn: safety stock

requisition

Syn: see parts requisition.

machine loading

The accumulation by workstation, machine, or machine group of the hours generated from the scheduling of operations for released orders by time period. Machine loading differs from capactity requirements planning in that it does not use the planned orders from MRP but operates solely from released orders. It may be of limited value because of its limited visibility of resources.

supplier measurement

The act of measuring the supplier's performance to a contract. Measurements usually cover delivery reliability, lead time, and price. Syn: purchasing performance measurement. See: vendor measurement.

queue time

The amount of time a job waits at a work center before setup or work is performed on the job. Queue time is one element of total manufacturing lead time. Increases in queue time result in direct increases to manufacturing lead time and work-in-process inventories.

shelf life

The amount of time an item may be held in inventory before it becomes unusable.

machine hours

The amount of time, in hours, that a machine is actually running. Machine hours, rather than labor hours, may be used for planning capacity for scheduling, and for allocating costs.

inventory accounting

The branch of accounting dealing with valuing inventory. Inventory may be recorded or valued using either a perpetual or a periodic system. A perpetual inventory record is updated frequently or in real time, while a periodic inventory record is counted or measured at fixed time intervals (e.g. every two weeks or monthly). Inventory valuation methods of LIFO, or FIFO, or average costs are used with either recording system.

effective date

The date on which a component or an operation is to be added or removed from a bill of material or an assembly process. The effective dates are used in the explosion process to create demands for the correct items. Normally, the bills of material and routing systems provide ofr an effectivity start date and stop date, signifying the start or stop of a particular relationship. Effectivity control also may be serial number rather than date. Syn: effectivity, effectivity date.

inventory investment

The dollars that are in all levels of inventory.

theoretical capacity

The maximum output capability, allowing no adjustments for preventive maintenance, unplanned downtime, shutdown, and so forth.

available time

The number of hours a work center can be used, based on management decisions regarding shift structure, extra shifts, regular overtime, observance of weekends and public holidays, shutdowns, and the like. See: capacity available, utilization

availability

The percentage of time that a worker or machine is capable of working. The formula is: (S-B) availability = ------------ X 100% S where S is the scheduled time and B is the downtime.

rescheduling

The process of changing order or operation due dates, usually as a result of their being out of phase with when they are needed.

scheduled load

The standard hours of work required by scheduled receipts (i.e., open production orders).

planned load

The standard hours of work required by the planned production orders.

idle time

The time when operators or resources (e.g. machines) are not producing product because of setup, maintenance, lack of material, lack of tooling, or lack of scheduling.

project management

The use of skills and knowledge in coordinating the organizing, planning, scheduling, directing, controlling, monitoring, and evaluating of prescribed activities to ensure that the stated objectives of a project, manufactured good, or service are achieved. See: project.

budgeted capacity

The volume/mix of throughput on which financial budgets were set and overhead/burden absorption rates established.

landed cost

This cost includes the product cost plus the costs of logistics, such as warehousing, transportation, and handling fees.

flexibility

1) The ability of the manufacturing system to respond quickly, in terms of range and time, to external or internal changes. Six different categories of flexibility can be considered: mix flexibility, design changeover flexibility, modification flexibility, volume flexibility, rerouting flexibility, and material flexibility (see each term for a more detailed discussion). In addition, flexibility involves converns of product flexibility. Flexibility can be useful in coping with various types of uncertainty (regarding mix, volume, and so on). 2) The ability of a supply chain to mitigate, or neutralize, the risks of demand forecast variability, supply continuity variability, cycle time plus lead-time uncertainty, and transit time plus customs-clearance time incertainty during periods of increasing or diminshing volume.

allocation

1) The classification of quantities of items that have been assigned to specific orders but have not yet been released from the stockroom to production. It is an "uncashed" stockroom requisition. 2) A process used to distribute material in short supply. Syn: assignment. See: reservation

phantom bill of material

A bill-of-material coding and structuring technique used primarily for transient (non stocked) subassemblies. For the transient item, lead time is set to zero and the order quantity to lot-for-lot. A phantom bill of material represents an item that is physically built, but rarely stocked, before being used in the next step or level of manufacturing. This permits MRP logic to drive requirements straight through the phantom item to its components, but the MRP system usually retains its ability to net against any occasional inventories of the item. This technique also facilitates the use of common bills of materials for engineering and manufacturing. Syn: blowthrough, transient bill of material. See: pseudo bill of material.

third-party logistics (3PL)

A buyer and supplier team with a third party that provides product delivery services. This third party may provide added supply chain expertise.

load profile

A display of future capacity requirements based on released and/or planned orders over a given span of time. Syn: load projection. See: capacity requirements plan.

process flow scheduling

A generalized method for planning equipment usage and material requirements that uses the process structure to guide scheduling calculations. It is used in flow environments common in process industries.

network planning

A generic term for techniques that are used to plan complex projects. Two of the best known network planning techniques are critical path method (CPM) and the program evaluation and review technique (PERT).

by-product

A material of value produced as a residual of or incidental to the production process. The ratio of by-product to primary product is usually predictable. By-products may be recycled, sold as-is, or used for other purposes. See: co-product.

standard deviation

A measurement of dispersion of data or of a variable. The standard deviation is computed by finding the differences between the average and actual observations, squaring each difference, adding the squared differences, dividing by n-1 (for a sample), and taking the square root of the result. See: estimate of error.

last in, first out (LIFO)

A method of inventory valuation for accounting purposes. The accounting assumption is that the most recently received (last in) is the first to be used or sold (first out) for costing purposes, but there is no necessary relationship with the actual physical movement of specific items. See: average cost systems.

first in, first out (FIFO)

A method of inventory valuation for accounting purposes. The accounting assumption is that the oldest inventory (first in) is the first to be used (first out), but there is no necessary relationship with the actual physical movement of specific items. See: first-come-first-served rule, average cost system.

risk pooling

A method often associated with the management of inventory risk. Manufacturers and retailers that experience high variability in demand for their products can pool together common inventory components associated with a broad family of products to buffer the overall burden of having to deploy inventory for each discrete product.

low-level code

A number that identifies the lowest level in any bill of material at which a particular component appears. Net requirements for a given component are not calculated until all the gross requirements have been calculated down to that level. Low-level codes are normally calcuated and maintained automatically by the computter software. Syn: explosion level.

forward flow scheduling

A procedure for building process train schedules that starts with the first stage and proceeds sequentially through the process structure until the last stage is scheduled.

mixed-flow scheduling

A procedure used in some process industries for building process train schedules that start at an initial stage and work toward the terminal process stages. This procedure is effective for scheduling where several bottleneck stages may exist. Detailed scheduling is done at each bottleneck stage.

aggregate planning

A process to develop tactical plans to support the organization's business plan. Aggregate planning usually includes the development, analysis, and maintenance of plans for total sales, total production, targeted inventory, and targeted customer backlog for families of products. The production plan is the result of the aggregate planning proccess. Two approaches to aggregate planning exist: (1) production planning and (2) sales and operations planning. See: production planning, sales and operations planning, sales plan

co-product

A product that is usually manufactured together or sequentially because of product or process similarities. See: by-product

machine center

A production area consisting of one or more machines (and, if appropriate for capacity planning, the necessary support personnel) that can be considered as one unit for capacity requirements planning and detailed scheduling.

dedicated line

A production line permanently configured to run well-defined parts, one piece at a time, from station to station.

process train

A representation of the flow of materials through a process industry manufacturing system that shows equipment and inventories. Equipment that perfoms a basic manufacturing step, such as mixing or packaging, is called a process unit. Process units are combined into stages, and stages are combined into process trains. Inventories decouple the scheduling of sequential stages within a process train.

alternate routing

A routing that is usually less preferred than the primary routing but results in an identical item. Alternate routings may be maintained in the computer or off-line via manual methods, but the computer software must be able to accept alternate routings for specific jobs.

order policy

A set of procedures for determining the lot size and other parameters related to an order. See: lot sizing.

inventory policy

A statement of a company's goals and approach to the management of inventories.

operations sequencing

A technique for short-term planning of actual jobs to be run in each work center based upon capacity (i.e., existing workforce and machine availability) and priorities. The result is a set of projected completion times for the operations and simulated queue levels for facilities.

material-dominated scheduling (MDS)

A technique that schedules materials before processors (equipment or capacity). This technique facilitates the efficient use of materials. MDS can be used to schedule each stage in a process flow scheduling system. MRP systems use material-dominated scheduling logic. See: processor-dominated scheduling.

probable scheduling

A variant of scheduling that considers slack time to increase or decrease the calculated lead time of an order. Interoperation and adminstrative lead time components are expanded or compressed by a uniform "stretching factor" until no difference exists between the schedule of operations obtained by forward and backward scheduling. See: lead time scheduling.

central point scheduling

A variant of scheduling that employs both forward and backward scheduling, starting from the scheduled start date of a particluar operation.

dedicated capacity

A work center that is designated to produce a single item or limited number or similar items. Equipment that is dedicated may be special equipent or may be grouped general-purpose equipment commited to a composite part.

gateway work center

A work center that performs the first operation of a particular routing sequence.

e-commerce

Abbreviation for electronic commerce.