MES in vehicle manufacturing - Route Control

Route Control means based on MES commands, conveyor PLC will decide how to move vehicle forward.

This article will introduce some key route control functions.

1. WBS Route

Vehicle manufacturing has 4 key process: Punch, Welding, Painting, Final Assembly. There’s a WBS buffer zone between Welding Shop and Painting Shop, and a PBS buffer zone between Painting Shop and Final Assembly Shop.

WBS is short of Welded Body Store.

PBS is short of Painted Body Store.

With some painting conditions, if we need to change painting color for next vehicle, then we need to stop machine, and clean, and change oil for it, it will take quite a lot of time. So to reduce machine shut down time and the waste of oil, normally we will schedule the vehicles by same color.

So in WBS area, MES will re-sequence the vehicles by color.

Besides of that, WBS also has functions of:

1) Offers a big buffer zone.

2) Offers a return lane, to return vehicles back to repair.

3) Track vehicle location based on RFID identification.

2. PBS Route

PBS locates between Painting Shop and Final Assembly Shop.

The setup of PBS is based on these requirements:

1) Planners want to align Work Order to Sales Orders.

2) Logistics handlers want some parts delivered by batch in sequence.

3) Production department want to build some model for quite a long time, to reduce operation mistakes.

4) Process department want to balance the lines so workers won’t be tired very soon.

Normally PBS route function is consisted of MES/PLC/HMI/RFID devices, and can be achieved by different methods, such as:

1) MES sends route command by rules automatically..

2) PLC routes by rules automatically.

3) Operators handles by HMI manually.

Diagram 2.5-1 shows an example of PBS route, icon of R stands for an RFID read station:

1) Vehicle leaves Painting Shop, MES collects its travel record, and broadcasts to ERP for back flush.

2) Vehicle comes to PBS In, MES informs conveyor PLC with lane number. Route rule: based on vehicle model.

3) PBS area has a fast lane, 1 return lane, and 4 normal lane. Fast lane is controlled by manually, which allows vehicle come to PBS out directly. Return lane is also controlled by manually, which is used to hold specific vehicles.

4) MES offers route rules such as by minimum VIN number and by model, and informs PLC to move vehicle based on rule. Fox example for minimum VIN number rule, MES will check the minimum VIN of all 4 lanes, and inform PLC to move that vehicle of according lane.

5) Vehicle leaves PBS, and moves along conveyor line, and comes to tear-off-door station, so there’s a sequenced vehicles buffer between PBS Out and tear-off-door station.

 

Diagram 2.5-1: PBS Route

3. Safe Door Control

I’ve introduced Quality Gate in previous article, which controls vehicle moving by using block bar and traffic light.

The same method is also used in Final Assembly Shop, diagram 2.5-2 shows a safe door control process after completing assembly.

1) After completed all assembly, and validated quality good, then vehicle will be driven through Door #1 or #2, forward to Logistics Parking Lot, there the vehicle will be handled by 3rd party company to deliver to car dealer.

2) If a vehicle needs road test, then it will be driven through Door #3, and return back to Final Assembly Shop through Door #4 after test.

3) If a vehicle needs process hold(holding for some time for further quality check), then it will be driven to Process Parking Lot through Door #5, and then drive out through Door #6.

4) Any vehicle with issues found will be driven back to Repair Area through Door #7.

 

Diagram 2.5-2: Safe Door control process