Material Flow
The means of this article in the series “little production system” we will have a short insight on material flow without buffers - or simply called pull principle.
Definition
The indicator of material flow without buffer is that only as much material is moved, as in the next step is used and can be processed. Anything beyond that is in the way and obstructed.
The targets:
Avoid overproduction
Stocks are reduced flexibility is elevated
Areas are reduced, distances are shortened
Key elements:
Material is only available on planned and visualized buffers
1 piece or 1 set is delivered by low cost automation
Consumption control / Pull - principle
Mixed transport at short intervals
The material flow is continuous
Transport containers and systems are delivered in smaller quantities and more frequent
Delivery intervals are adjusted to the cycle time
Key Performance Indicators (KPI)
Buffer area
Stock value
Logistics costs
Self assessing the levels of fulfillment of your material flow without buffers.
MICRO LEVEL of production flow
Level 1
Workshop production - Technology island
Level 2
Island production without linking the machines. Installation is flow-oriented
Level 3
In other elements (e.g. TPM, FTQ, Flexible Facilities) corresponding services are provided.
For example: Machines and equipment are in TPM level n. Flexible facilities for “A”- and “B”-parts are available.
Level 4
Upstream and downstream operations are close together, partially interlinked. Transport routes/time are used for testing, marking or washing.
Level 5
Upstream and downstream operations are moved close together and connected by chutes, roller conveyors, etc.
Documentation that should be available
Process layout; material flow without buffer, material flow in cycles and flow production
Micro level stock and buffer
Level 1
Stocks are not visualized.
Level 2
Stocks / buffers between the machines are visualized (place and quantity).
Level 3
Buffers are smaller than a daily amount.
Level 4
One-piece/set flow. Accumulating buffers as keying sequence and/or disturbances are still possible.
Level 5
One-piece/set flow. No buffer between the process steps.
Micro level transportation
Level 1
Transport of the work piece carriers or base frames by handcart between the machines. Unplanned transports.
Level 2
Transport with work piece carrier or base frame in equal, fixed Quantities. No forklift as a means of transport in the field.
Level 3
There are no base frames in use. Transport is carried out with work piece carrier.
Level 4
Manual transport at working height. Uniform transfer heights avoid lifting and lowering procedures.
Level 5
Work pieces are moved from machine to machine via rollers, slides, belts. No means of transport!
Micro level material flow control
Level 1
Manual job control is carried out by specialists. Push principle! High planning and control effort. No visualization available.
Level 2
The material flow is clearly identifiable. Order control is still required. Responsibility for the control lies with the shiftleader.
Level 3
No processed work piece is discharged from the process chain. Interventions in the process chain are only necessary in the event of malfunctions.
Level 4
Only available together with level 5.
Level 5
No order control within the process chain necessary.
Macro level stock and buffers
Level 1
Buffer between the islands are larger than 1 lot (partial lots in motion).
Level 2
Lot sizes are smaller than the daily requirement for “A” and “B” parts. “A” and “B” parts no longer go into stock.
Level 3
Lot sizes correspond to the quantities per handling rack. Buffers between the islands correspond to a maximum daily requirement.
Level 4
Reduced stocks through levelled production for “A”-parts (periodically the same quantity per part number).
Level 5
A buffer (smallest quantity is 1 piece or 1 set) is permitted for control. Levelled and smoothed production for “A” and “B”-parts.
Macro level transportation
Level 1
Transport according to order. In the processing shop, workpieces are loaded from transport racks into processing racks and vice versa.
Level 2
Mixed transports at short intervals, partly still with forklift, partly already with train + trailer between the halls.
Level 3
Continuous transport system (e.g. transport train / overhead conveyor) between upstream and downstream processes. In some cases, workpieces are already placed in the downstream needed racks during the upstream process. No transports between process step I and process step II within the process chain.
Level 4
The transport containers used avoid repackaging between upstream and downstream processes. Example: Workpieces are placed directly on the finishing frame after the last pre-processing step. Uniform transfer heights avoid lifting and lowering
Level 5
Workpieces are transported in workpiece carriers or containers with standardized modular dimensions.
Macro level material flow control
Level 1
Demand-controlled batch size production. "Economic batch sizes".
Level 2
First part numbers in consumption control between assembly and last production process. Previous block formation (during material call-off, during transport, during processing, etc.) no longer applies. In the pre-assembly area, no more than two units from the same batch are processed one after the other.
Level 3
Consumption control for all “A” and “B” parts. Any part can be processed on any day. “C”-parts management for purchased parts through logistics service providers.
Level 4
Levelled production. Consistent consumption control for “A” and “B” parts throughout the entire process chain. Sequenced delivery for selected part numbers.
Level 5
Levelled and smoothed production.
