Batch or one-piece flow: ten pieces, two ways (3D)
About this app
Two identical lines with processes A, B and C run side by side: in a batch of ten it takes 30 minutes to get ten finished goods, in one-piece flow 12. Inventory triangles grow between the stations while a timeline draws along. Lot size, number of pieces and cycle times are adjustable; a defect at station A shows how much faster flow notices it.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
Batch production and one-piece flow
Three processes A, B and C take one minute per piece each. In batch production a piece only moves on once its whole batch is done: with a lot size of 10 that is 10 + 10 + 10 = 30 minutes until ten finished goods. In one-piece flow every piece moves on right away. The first is done after three minutes, then one comes out every minute, 12 minutes in total. In general, for k stations and n pieces, flow takes T = (k + n − 1) · t and a batch of all n pieces T = n · (sum of cycle times).
What the app shows
Two identical production lines run side by side in 3D: at the back in batches, at the front in one-piece flow. Inventory triangles, as known from value stream mapping, grow between the stations and vanish in flow. Below, a timeline draws every operation live and a clock shows the minute. Key figures compare the first piece, all pieces, work in process (WIP) and buffer stock.
What you try out
Set the lot size to 1, 2, 5 or 10 and watch the lead time shrink. Switch on a defect at station A: in the batch, station B only notices it after ten pieces; in flow, with the next piece. Make one station slower and inventory piles up in front of the bottleneck even in flow. That shows why flow needs a balanced workload.
Frequently asked questions
- What is one-piece flow?
- One-piece flow is flow production with a lot size of 1: each piece goes straight to the next station after processing, without waiting for other pieces. This shortens the lead time, lowers inventory and reveals defects immediately.
- How do you calculate the lead time in batch and in flow?
- With k stations of equal cycle time t and n pieces, a batch of all pieces takes k · n · t, in the example 3 · 10 · 1 = 30 minutes. Flow takes (k + n − 1) · t, i.e. (3 + 10 − 1) · 1 = 12 minutes.
- What are the prerequisites for one-piece flow?
- A balanced workload across stations, standardised work, passing on only good parts and responsibility of the team. If one station is slower, inventory piles up in front of it even in flow.
- How does the “Batch or one-piece flow” app work?
- You start the clock and watch two lines work in sync. Lot size, number of pieces, cycle times and a defect at station A are adjustable; the timeline and the key figures update live.
Subject: Industrial Engineering
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