MES in vehicle manufacturing - Broadcasting

Vehicle manufacturing is very complicated, it has lot of processes, and lots of them are interactive from each other.

For automation design, it requires lots of data exchange between different stations/areas/devices/lines, normally it’s via point-to-point communication between PLCs.

And MES as a system covering whole plant/most process/most devices, normally it will be acting as backbone of data exchange of most data.

This article will introduce some cases.

 

1.    Lift on at engine sub-assembly lines

The engine assembly consists of 4 assembly lines: interior line, exterior line, cylinder head sub-assembly line, and piston sub-assembly line. Interior line and exterior line are working one after another, and the 2 sub-assembly lines are quite independent.

To work as per Orders, we need to align sequence of sub-assembly lines with main lines.

This is the way to do it:

1)       When MES receives Work Orders from ERP, it will generate sub-orders of sub-assembly lines.

2)       When engine is lift on at interior line head station, MES will broadcast information to head stations of sub-assembly lines: with Work Order, Engine number, part number, engine model.

3)       Sub-assembly lines will lift on based on the data it received.

Please refer to diagram 2.6-1:

Diagram 2.6-1: Engine lift-on broadcast

 

2.    Process parameters preparation

Now most vehicles plants and engine plants require flexible production, that means same line and same devices can support manufacturing of multiple model types.

This requires line-side devices can work flexibly, can work based on process parameters and profiles automatically.

To make sure daily work continuously, MES is required to broadcast related data to line-side devices.

For example in vehicle’s Final Assembly Shop, when vehicle leaves PBS out, MES will broadcast these information:

1)       Sends VIN marking data to interior line PLC, and VIN marking system of engine line.

2)       Sends VIN number and model type to Torque Gun system; later when vehicle comes to torque station, Torque Gun system sends torque program to torque controller.

3)       Sends VIN number, model type, attributes, software BOM to vehicle calibration system; later when vehicle comes to working station, calibration system write software to vehicle ECU.

4)       Sends VIN number, model type, attributes to vehicle test system; later when vehicle comes to working station, test system will run test programs with according parameters, to check wheels and lamps and other functions.

 

3.    Assembly sheet printing

In vehicle’s Final Assembly Shop, when vehicle leaves PBS out, MES will command printers of sub-assembly lines, to print out assembly sheets.

Assembly sheets are normally A3 or A4 papers, include such information:

1)       Vehicle’s basic data such as VIN number, model type, attributes, color.

2)       Part number, part description, and part barcode label of key parts. Barcode labels are used for error proofing: at key part error proofing stations, worker will scan VIN number, then barcode labels of assembly sheet, then scan vendor’s labels, then MES will check if vendor’s labels are matched with part labels of assembly sheet, if not then raise error.

 

4.    Material Pull

In vehicle Final Assembly Shop, daily production follow JIT(Just In Time) rules, to make sure production is as effective as possible.

Line’s capacity is limited by capacity of workers and machines, the other operations(such as material handling, machine readiness) are supporting them.

The requirement for material handle:

1)       Only store necessary materials to avoid wrong usage.

2)       In case of material shortage, requires supply in time.

Diagram 2.6-2 shows relationship between MES and material handling:

1)       When vehicle travels through key material pull station(such as PBS out, and interior line head), MES will generate vehicle’s travel request based on RFID data, and broadcast to LES(Logistics Execution System).

2)       When LES receives broadcast data, it will cut down storage of line-side material, as they are considered to be consumed soon, and check if it’s smaller than safe storage, if so then trigger a material pull request.

3)       Material handlers will get material from buffer zone or warehouse, and then deliver to assembly line.

Diagram 2.6-2: MES and material handling

 

5.    Material back flush

MES will offer an interface, to broadcast back flush data to ERP.

When vehicle comes out of Welding Shop, Painting Shop, Final Assembly Shop, MES will send out broadcast of VIN number, then ERP will back flash materials of that vehicle.