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Pizza time types: work order time with REFA

About this app

A kitchen and a timeline with lanes for human and oven: T = tr + m · te. One pizza takes 32 minutes, ten in a row 104, because setup occurs once. Working in overlap uses the waiting time, and the simulation gives 49.4 minutes. Oven capacity from 1 to 4 reveals the bottleneck.

With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.

Work order time according to REFA

The work order time T consists of the setup time tr and the execution time ta = m · te. Setup occurs once per order, the time per unit te for every piece. Within the basic time REFA separates activity time tt and waiting time tw. A person can use waiting time when something else can be done meanwhile.

What the app shows

A kitchen and a timeline with one lane for the human and one for the oven. In the example one pizza takes 32 minutes and ten in a row take 104 minutes, because the oven is preheated once. If the cook prepares the next pizza while one bakes, the simulation gives 49.4 minutes with four oven places.

What you can try

Set the quantity, switch between sequential and overlapping work and change the oven capacity. With a single place the oven becomes the bottleneck and the time rises to 90.5 minutes.

Frequently asked questions

How do you calculate work order time with REFA?
T = tr + m · te: setup time plus quantity times time per unit.
What is the difference between activity time and waiting time?
During activity time tt the person works on the task. During waiting time tw the process runs without them, for example while baking or during automatic machining.
Why does twice the quantity not take twice as long?
Setup occurs once per order and spreads over all pieces. Waiting time can also be used for the next piece.
What can I change in the app?
The quantity, sequential or overlapping work and the number of oven places. A tutor can demonstrate the app on request.

Subject: Industrial Engineering

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