PPS Glossary
To effectively utilize the database, some core definitions for manufacturing terms are provided in the following. Because their use can be ambiguous, a clear understanding of each terms meaning is essential. If not stated otherwise, the explanations follow Hopp and Spearman's 2nd edition Factory Physics book.
Manufacturing System
A manufacturing system is an objective-oriented network of processes through which entities flow.
Workstation
A workstation is a collection of one or more machines or manual stations that perform (essentially) identical functions. In process-oriented layouts they are physically organized according to the operations they perform. In product-oriented layouts they are organized in lines making specific products.
Customer Order
A customer order is a request from a customer for a particular part number in a particular quantity, to be delivered on a particular date.
Production Job
A job refers to a set of physical materials that traverse a routing, along with the associated logical information. Although a job is triggered by either an actual customer order or the anticipation of a customer order, there is frequently not a one-to-one correspondence between jobs and orders.
Production Part
A part is a piece of raw material, a component, a subassembly that is worked on at the workstations in a plant.
Routing
A routing describes the sequence of workstations passedthrough by a part. Routings begin at a raw material, component, or subassembly stock point and end at either an intermediatestock point or finished-goods inventory.
Throughput Time
The time of a given routing is the average time from release ofa job at the beginning of the routing until it reaches an inventory point at the end of the routing (Time the part spends as WIP). Itcan also be measured for individual workstations.
Throughput
The average output of a production process (machine,workstation, line, plant) per unit time (e.g., parts per hour) is defined as the system’s throughput or sometimes throughput rate. For a plant, line, or workstation, we define throughput to be the average quantity of good (nondefective) parts produced per unit time.
Makespan
The total amount of time to process a fixed number of jobs.
Utilization
The utilization of a workstation is the fraction of time it is not idle for lack of parts. This includes the fraction of time the workstation is working on parts or has parts waiting and is unable to work on them due to a machine failure, setup, or other detractor.
Work-in-Process (WIP)
The inventory between the start and end points of a prodcutrouting is called work in process (WIP). Since routings beginand end at stock points, WIP is all the product between, but notincluding, the ending stock points.
Due Date Reliability
Depicts the extent to which the promised dates for the placed orders can be met. (Nyhuis and Wiendahl, 2008)
Lateness
Lateness describes the deviation of the actual order throughput from the planned order throughput. It can be measured in the output of an order, in its input and in comparison to the planned throughput time. A positive value means the order's completion is delayed; a negative value denotes it is too early. The output lateness directly impacts the delivery lateness and therefore the delivery reliability. (Lödding, 2013)
Setup Time
The time a jobs apends waiting for the station to be set up. Notethat this could actually be less than the station setup time if the setup is partially completed while the job is still being moved to the station.
Operation Time
Synonymous to process time. The time jobs are actually being worked on at the workstation.
Transport Time
Synonymous to move time. The time jobs spend being transported from the previous workstation.
Waiting Time
Waiting time or Queuing Time exists pre and post processing. It described the time jobs spend waiting for processing at the workstation or to be transported to the next station.
Inter-Operation Time
The periods for waiting after processing, transportation and waiting before processing are summarized as the inter-operation time (Lödding, 2013)